TROUT MOVEMENTS ON DELAWARE RIVER SYSTEM TAIL-WATERS IN NEW YORK STATE

Transcription

1 TROUT MOVEMENTS ON DELAWARE RIVER SYSTEM TAIL-WATERS IN NEW YORK STATE Scott Douglas Stanton BIOLOGICAL FIELD STATION COOPERSTOWN, NEW YORK Occasional Paper No. 34 September 2000 STATE UNIVERSITY COLLEGE AT ONEONTA

2 ABSTRACT In order to detennine the cause of trout movements throughout the Delaware and Beaverkill river systems, a radiotelemetry study, funded by Trout Unlimited (TU) in cooperation with the New York State Department of Environmental Conservation (DEC), was undertaken. In the 1995 year long pilot study, a group of 55 trout, composed of both rainbow and brown trout, were tagged. The fish tagged were found throughout the Beaverkill River, the East Branch of the Delaware River below the Pepacton Reservoir, the West Branch ofthe Delaware River below the Cannonsville Reservoir, and the main stem of the Delaware River below Hancock, New York. In 1996, 56 trout were similarly tagged throughout the same system. In 1997, only one more fish was tagged. The overall goals of this study were to track migration related to seasonal spawning and to detennine the extent of use of tributaries for this spawning. Seasonal movements were also tracked during the wanner months of the year, when certain waters become too wann and potentially force trout to seek cooler thennal refuges present in the river system. The sections of the East and West Branches of the Delaware River, which lie below the New York City Watershed Reservoirs, are tailwater fisheries. Trout there are dependent on cold water releases from these reservoirs throughout the entire year. The West branch receives strong cold water releases of cubic feet per second (cfs) periodically throughout the year, compared to the East branch of the Delaware which only receives 90 cfs (McBride, 1997). Throughout the summer and fall of 1995, trout movement took place throughout the entire watershed, as the fish seemed to seek cooler refuges in relation to the wann water temperatures. Trout tagged in the West Branch of the Delaware remained there throughout the summer, as the cool water releases from the Cannonsville Reservoir kept the water temperatures suitable for their survival. Both brown trout (Sa/mo trutta) and rainbow trout (Oncorhynchus mykiss) showed movement throughout the entire system in the spring and the fall of 1995, and utilized various tributaries for spawning. In 1996, tagging was changed with respect to the number of tags placed in each river. With the West branch fish known to remain stationary throughout the year, fewer tags were used in this area in the continuation in A greater number of tags were put out in the lower East Branch of the Delaware, the main stem of the Delaware, and the Beaverkill River in an effort to study the movements of the trout as the waters there became wann in the summer months. The summer of 1996 showed very different water temperatures than those found in the previous summer. Water levels remained high throughout the season, and trout remained stationary with only slight movements due to sudden discharge releases. Certain fish did show movements in relation to highly turbid water associated with steady heavy rain, and the overflow ofboth reservoir systems. Fall 1996 temperatures cooled the waters again. Water levels in both systems were very low during the months of September and October due to drawdown releases of both the Pepacton and Cannonsville Reservoirs. Discharges as of mid October were at about 35 cfs out of Cannonsville, and steady 90 cfs out of the Pepacton Reservoir (McBride, 1997).

3 11 Brown trout began to move during the fall spawning run with fish from the East branch, Beaverkill, and Delaware River all utilizing various tributaries throughout the watershed. Brown trout within the West Branch had moved up the river and into areas of gravel, which provides ideal spawning habitats. In 1997, the third year of the study, only one more new fish was tagged. This was a twoyear-old female brown trout. This fish was hatchery raised, and tagged purposely in order to determine the migratory action of a fish raised in a hatchery environment. As expected, this fish remained stationary.

4 CONTENTS ABSTRACT.i INTRODUCTION 1 SAMPLE AREA Description Discharge METHODS Tagging offish RESULTS Migration oftrollt. West Branch of the Delaware River Movement Related to Water Temperature Movement Related to Spawning Main Stem ofthe Delaware River. Movement Related to Water Temperature Movement Related to Spawning East Branch of the Delaware River.. Movement Related to Water Temperature Movement Related to Spawning Beaverkill River Movement Related to Water Temperature Movement Related to Spawning CONCLUSIONS Thermal Refuges Spawning Streams LITERATURE CITED APPENDICES

5 INTRODUCTION Following a feasibility study from mid April to the end of May 1994, conducted by NYSDEC, a pilot study was initiated in 1995 on the Delaware River tailwaters and the Beaverkill River. This study was to determine the causes and timing of trout movements within this system, encompassing these two rivers. Funded by the New York State Department of Environmental Conservation (DEC) and Trout Unlimited (TU), the study was continued in 1996 and The goal was to gain insight into different aspects of the migration of the trout species involved. Migration related to seasonal spawning, and the extent ofthe use oftributaries for spawning was determined, as well as the identification of critical habitats. Rainbow and brown trout, both hatchery raised and wild, were used in the study. The extent to which migration is affected by factors such as water temperature and the urge to spawn was considered. Both funding organizations, the NYSDEC and TU, were interested in supporting the study in hopes that a better understanding could be reached regarding the trout resource in order to manage it more productively and to protect it as a wild fishery. These organizations also strive to keep the waters bountiful for the many anglers who utilize the watershed for sport fishing and enjoyment. The Delaware River tailwaters are located below New York City Watershed Reservoirs, and are managed and regulated as a world class trout fishery. The goal of this particular study was to locate prime spawning areas and determine seasonal movements and locations of trout in the system in relation to water temperature and spawning. By determining the spawning movements related to fish migration, as well as locating prime spawning areas, the rivers can be better managed as trout fisheries. By discovering what does, or can, affect the migration of rainbow and brown trout, we are better able to design regulations to be put into effect in areas to improve propagation. These regulations should be in areas where they can best protect these fish, their spawning locations, nursery areas in tributaries, and also cool water refuge areas during the low summer flows. Locating prime spawning areas within the river system will allow management practices to be tailored to protect these areas. It will also document prime spawning locations and allow yearly recruitment of the young of the tracked rainbow and browns, which can then become the brood stock for the Delaware River system. By locating these areas, regulations can be created to protect the tracked fish so that the survival of young trout is insured, or increased. Secondly, due to the trouts' movement into specific locations, areas of cool water refuge can be determined. These are the usual places to which trout can relocate in order to survive the hot, dry summer months. It is during this time that the river is under low discharge conditions requiring releases from the reservoirs. By locating these refugia, releases can be timed to provide considerable benefits to the trout. The Delaware River watershed consists of both the West and East branches of the Delaware River, the main Delaware River, and the Beaverkill River. This watershed is managed as a trout fishery. Anglers from across the country fish the Delaware River system because of the number offish, as well as the quality of the sport of fishing. The West branch and the main stem of the Delaware River are managed for wild fisheries, without any stocking taking place. The East branch and the Beaverkill River are both stocked fisheries.

6 SAMPLE AREA 2 The sample area included the watershed encompassing parts of the Delaware and Beaverkill rivers. This complex system covers an area of243.1 km (l51 river miles) and displays virtually every characteristic that can be found in such a system. By encompassing the entire watershed, data gathered would be more reliable and cover a broader spectrum of characteristics and factors. See Figure 3. N I l I w le 8 0 S 10 IS L... I,! "'\,Iets Figure 3. Salnple Area Used in Study

7 3 The East Branch of the Delaware can most easily be thought ofas two river parts, the upper and lower East branches with the Beaver Kill confluence acting as the dividing line. The upper East branch flows from the Pepacton Reservoir dam for 27.36km (17 miles) before meeting with the Beaver Kill. The Beaver Kill runs 24.l5km (15 miles) from its point of junction with the Willowemoc Creek. The lower East Branch flows for 24.l5km (15 miles) from the town ofeast Branch, NY, where the Beaver Kill meets it, to the town of Hancock, NY. The West branch ofthe Delaware originates at the Cannonsville Reservoir and runs for 89.76km (17 miles) before merging with the East branch. At that point it is known only as the main stem ofthe Delaware River. The upper l6.42km (10.2 miles) are located in the state of New York while the lower l2.07km (7.5 miles) of river form the boundary between the states ofnew York and Pennsylvania (McBride, 1997). The waters of these rivers vary in nature. The Beaver Kill is a Catskill freestone. This means that the stream is a naturally flowing water body without any artificial impoundments, such as a dam. The lower reaches ofthe Beaverkill are susceptible to thermal stress during hot weather. The temperatures here have been known to reach 27 C(80 F). Stream widths average 30.49m (100 ft) near Roscoe and 42.68m (140 ft) at the mouth near East Branch (Sanford, 1991). Stream gradient is 7.32m/16.09km (24 ftlmi.) between Roscoe and Horton, and is 3.96 m/16.09km (13 ft/mile) from Horton to East Branch (McBride, 1997). Wild and stocked brown trout populate the Beaver Kill as well as a few rainbow and brook trout. The Upper East branch tailwater resembles a large spring creek. It is a low gradient stream of 1.98m/16.09 km (6.5 ft/mile) characterized by large stretches offlat water which make for poor trout habitat (McBride, 1997). It receives a cold bottom release from the Pepacton Reservoir. The river averages 24.39m (80 ft) near Downsville and 41.54m (135 ft) wide above the confluence at East Branch (Sanford, 1993a). It possesses a strong wild brown population, as well as a stocking of yearling browns. Approximately 6,000 brown trout yearlings are stocked into each of the four reaches ofthe river, numbering 24,000 (Mc Bride, 1997). There are also small populations of brook trout and rainbow trout in the Upper East branch. The lower East branch is very similar in nature to the Delaware's' main stem. The average width increases from 61.59m (202 ft) below the confluence at East Branch to 87.8m (288 ft) in Hancock (Sanford, 1993a). It is very susceptible to thermal stress with summer water temperatures rising into the 27 C (80 F) area. There are tributary inputs, as well as some springs, which serve as critical cold water refuges. In particular, strong groundwater infiltration between East Branch and Fish's Eddy creates summer thermal refugia which can sustain the adult brown and rainbow trout populations on a year- round basis (Sanford, 1989). These fish are thought to be nomadic, moving away during the hot summer months, and returning when the water cools in temperature, usually during the fall months. The West branch consists of 27.37km (17 miles) ofriffles and pools. It is a low gradient stream 2.23m/16.09km (7.3 ft/mi.) characterized by long stretches of flat water broken by moderate flow and riffles around the many islands found within. The average width is about 60.98m (200 ft) near Deposit and 73.78m(242 ft) near Hancock (Sanford, 1993b). It runs cool throughout its entirety due to large cold water releases from the Cannonsville Reservoir. This branch has the largest population density ofwild brown trout, with rainbow trout in its lower reaches, and is not stocked.

8 4 The main Delaware River is a huge expanse ofpools and riffles. The Delaware flows for 5l6.7km (321 miles) before entering the Atlantic Ocean. The main stem runs for 43.46km (27 miles) downstream to the town of Callicoon. This is the section referred to in this study. The width of the Delaware is much larger, and averages m (360 ft) (Sanford, 1993b). It experiences thermal stress in the summer months, and depends upon the releases from the reservoirs, mainly Cannonsville, to allow it to support the trout fishery. The Delaware is not stocked, and supports a wild rainbow trout fishery. Discharge: Discharges of water into the watershed affect the temperature and quality ofthe waters throughout the entire Delaware River tailwaters system. Thermal releases from Cannonsville Reservoir on the West Branch provide cool water year round. This also maintains the quality of the water. With cool thermal releases, both dissolved oxygen and water temperatures remain at beneficial levels for optimum trout growth and survival. Water releases throughout the warm summer months provide suitable conditions for trout to be active and healthy. Cold water releases also keep baitfish and insect populations active, thereby providing trout with an ample food supply year round. Release schedules are set for the reservoirs in an effort to keep water temperature at optimum ranges for trout growth and survival (McBride, 1997). The West Branch ofthe Delaware River originally received release flows of 33 cubic feet per second (cfs) during the winter and summer flows of 325cfs. Under new release flow programs implemented by the Delaware River Basin Commission and the City ofnew York, new flow release schedules took effect in 1997 (McBride, 1997). The water flow rate was increased from 33 cfs to 45 cfs flow from mid September to May. The summer release of325 cfs usually ran from June 15th to August 15th. It was changed to 160 cfs, and runs from June Ist through September 15th. The East Branch receives a constant flow from the Pepacton Reservoir of 90 cfs year round. This allows the upper East Branch to stay cold year round, and trout thrive in this area. Once water reaches the lower East Branch, flows are too warm for trout survival in the summer months. The Beaverkill River System is a freestone river without any cold water releases. Flows within the Beaverkill are solely dependent on runoff from the watershed. Flow rates are usually very good throughout the spring and early summer months, but during late summer and fall the Beaverkill suffers from very low, warm conditions, causing trout to leave the system in search of cooler water.

9 5 METHODS Migratory behavior of the fish in this study was detennined by the use of radio telemetry. Radio telemetry is well suited for shallow, low conductivity fresh water and also for very turbulent water. The use of radio telemetry is also excellent for searching large areas to find highly mobile species, like trout and salmon (Winter, 1983). Though radio telemetry is costly, involves invasive surgery, and is restricted to those fish captured and put into use, it does enable an observer to unobtrusively locate fish in most habitats (Winter, 1983). Small, surgically implanted radio tags were placed into the abdominal cavity of cm (15-20 inch) rainbow and brown trout (Ross and Kleiner, 1982). The fish were captured by either angling or electroshocking. Fish were anesthetized using MS-222 anesthetic, and a small incision was made just ahead of the ventral fin (Schreck and Moyle, 1990). The tags were then inserted into the abdominal cavity. The antenna, a 30.5cm (12- inch) long strip of Teflon, was left trailing out of the fish just ahead of the anal opening. The fish were then revived and released. (A more detailed discussion follo~.) See Figure 1. 1'ransnli.tter Fig'Jre l.. A radiotagged trout, sbqwblg placement octrausmitter

10 6 Radio telemetry systems usually operate from megahertz (MHz). In an underwater radio transmitter, an oscillator circuit produces electromagnetic vibrations at a given frequency determined by a crystal. These vibrations are then transformed into signals which are transmitted through a loop or straight wire antenna (Winter, 1983). An oscillating, or scanning, receiver receives the signals (Nielsen and Johnson 1983). In this particular study, each radio tag was a Model 2 transmitter manufactured by Advanced Telemetry Systems Inc. Each measured 5.56cm (2.19 inches) long by 1.27cm (0.5 inch) in diameter, weighed ll.34g (0.4 oz), and had a different frequency between 52.0 and MHz. A 3-V lithium battery powered the tags. The antennas used were straight wire, measuring 2.54cm (12 inches) in length. Each fish was implanted with a tag, which had its own independent operating frequency. The radio tags were activated daily for a ten-hour period and then shut off automatically for the next fourteen-hour period. The radio transmitters used in this study were also temperature sensitive, allowing the tag to document the temperature of the water at each fish's location. Temperature, in degrees Celsius (C), can be determined by timing a set number of pulses received. In this particular study, an interval often pulses was chosen. A stopwatch was used to find the time elapsed between the first pulse heard and the beginning of the eleventh pulse- signaling ten elapsed pulses. This value, when multiplied by 100 finds the period reading in milliseconds. Once this number is found, a chart is used as a reference, which contains pre-calculated water temperatures (see Figure 2). The far-left column of the chart is a listing of temperatures in degree C. The temperature values are shown in tenths, and continue along the top row of the chart. The body of the chart consists of periods in milliseconds. To find the temperature which corresponds to the period, you find the period (or the number closest to the period) in the body of the chart. Next, follow the row to the far left column. This yields a number. Then, follow the column to the top from the period. This yields a second number. Adding the two numbers gives you the exact temperature. A separate chart is used for each transmitter frequency (Advanced Telemetry Systems, 1995). At each fish location a river temperature was then taken to determine if the fish is in warmer or cooler water than the temperature determined by the tag. This is called the actual or ambient river temperature. In order to gather this data, it was necessary to wade out into the main current in the riffle area, at least 3.05m (ten feet) from shore, and measure temperature with a hand held, calibrated thermometer. Temperature sensitive tags such as the ones used in this study provide both environmental and physiological parameters related to each fish location. This further allows for understanding animal adaptations and requirements for survival (Winter, 1983).

11 7 Tagging of Fish Fish were captured by either angling or electro-fishing. Capture location, water temperature, date and time of capture, age, sex, length and weight of the fish, and whether it was wild or hatchery raised were noted (see Figure 4). Each fish was given a specific number suffix, and a lettered prefix corresponding to the river of origin and capture location, therefore identifying each specific fish. Appendices A; B, C, and D list specifications of each fish radiotagged in the study. R iva r...jm--i.i_i\~i"';'v\.l.-_j)""",-.;:o;~;..:i""'_~~..j.i...:::.v_~;;..;y_---:- _ Fish Number hi! /1-2- Tag Frequency 5),IeJ~ Species 1</ Len g t h _...:..Lf...;;.,b_:l Weight /030 Location Tagged.LDYJ Fddt / /(jc- Time Tagged_~ ~0~ Date Tag 9 e d _--lo<jy.)...;./_5" ;.k,"",-- Water Temperature 30 () I Collection Method Tag Implanted By Comments ltc+yo-hshl") Fre-o{ rcclc of dorsctl- Figure 4. Data Form used for each fish tagged in study The fish collecting via electro-fishing was done out ofa specially equipped boat which carried a Smith Root variable pulsator which was used to rectify AC (alternating current) to DC (direct current). It provided 1,061 volts (V) at a pulse rate of60 amperage (amps). Amperage to the water was typically amps (McBride, 1997). A probe connected to the pulsator was then placed into the water, conducting the electricity into the surrounding water. The current effectively stunned the fish in a 70.87cm-94.49cm (15 to 20 ft) radius. The fish were then collected with nets. When angling, only artificial lures were used in an effort to minimize stress and mortality to the captured fish. Had live bait been used, the fish would have swallowed the bait and been damaged by the hook. Once the trout were captured, they were placed into a solution oftricaine methane sulfonate (MS-222) anesthetic. The solution caused the fish to lose their equilibrium. Once this occurred, they were removed and placed on a measuring board. Data was collected from each fish. The fish was then placed on a foam surgical table developed for a similar study (Courtois, 1981). SeefigureS.

12 8 Figure 5. L.A. Courtois surgical table A scalpel was used to make a 2.54cm-3.18cm ( inch) incision into the fish's abdominal cavity, just anterior of the pelvic girdle and slightly to the right of the fish's ventral midline. The radio-transmitter was then inserted through the incision. The transmitter's antennae was then passed out through a.38cm (0.15 inch) incision between the pelvic girdle and the anal opening, using the shielded needle technique designed by Ross and Kleiner (Ross and Kleiner, 1982). The antennae trailed under and behind the fish's exterior. The surgical incision was then closed with a.3cm (0.75 inch) curved needle and a monofilament suture, making four or five stitches (McBride, 1997). Throughout the surgery, the gills of the fish were irrigated with a solution of stream water and anesthetic. After surgery, fish were returned to their capture location in an area oflow stream current. This allowed each fish to regain its equilibrium and eventually swim away into deeper water. Actual surgery and recovery time took approximately 15 minutes per fish. See figure 6.

13 9 Figure 6. Trout in place on slirgical table, showing transluitter placement Tags were implanted into trout from April through October in 1995, and from March through June in The single tag in 1997 was implanted on June 3. Tags were programmed to transmit continuously for 10 hours when activated, and then shut down for 14 hours every day (McBride, 1997). From April to October, tags were activated between 8am and 6pm daily. From November until March, tags transmitted from 7am until 5pm daily. The radio-transmitters also measured water temperature, as discussed. Each was individually calibrated by Advanced Telemetry Systems to operate most accurately at temperatures between 10 C and 26 C (50-80 F). The battery ofeach transmitter was guaranteed to transmit a signal for 300 days, although halfofthe tags were expected to transmit for up to 500 days (McBride, 1997). See figure 7.

14 10 Figure 7 Author using hand held antennae to locate tagged trout Trout locations were monitored using a scanning receiver and a loop style antennae. All of the frequencies were entered into the memory of the receiver, and it was programmed to continuously scan through all of these frequencies. As the receiver scanned through the frequencies a pulse was picked up which corresponded with a particular frequency. A signal was heard through the headphones attached to the receiver. As the antennae got closer to the tag, the signal became louder, indicating that I was very close to the fish's location. I would get out of the vehicle and venture closer to the water to locate the fish and take the water temperature. Once the fish's location was documented, it was deleted from the scanning program in the receiver. Fish locations and the distances they traveled were monitored two days a week during the winter months and three or four days a week during the warm summer months and spawning seasons. The monitoring of the locations of each fish was done by either traveling the roads adjacent to the rivers, or by floating a river section in a McKenzie style drift boat. The location of each fish, the date located, discharge flow in the area, temperature of the water, and the time of day were recorded. The number of fish radio-tagged in 1995 was 50. Twelve brown trout were tagged in the Beaverkill River, eight brown trout in the Upper East Branch, and three each of brown and rainbow trout in the lower East branch. Sixteen brown trout and five rainbow trout were radiotagged in the West Branch of the Delaware River, and one brown trout and seven rainbow trout were tagged in the main Delaware River. Because some of the tags were reused, actual numbers

15 11 included in the data, total 55 radiotags. If a fish was caught or found, anglers returned the tag to the DEC and it was reused in a different trout. Scale samples of each fish tagged in 1995 were taken in order to get an accurate count ofthe numbers of hatchery raised and wild trout within the sample. Based on this scale sampling collected on the 1995 radio-tagged trout, it was found that 50% of the Beaverkill fish, 7% ofthe East branch fish, 15% ofthe West branch fish, and none of the main stem Delaware fish tagged were of hatchery origin (Langan, 1996). Of the 55 tags fielded in 1995, 15 rainbow trout were tagged. Seven of these rainbows were 3 years old, four were 4 years old, and four were 5 years old. All rainbow trout tagged were wild fish. A total of 40 brown trout were tagged. Three were hatchery-raised 3 year olds, eight were wild 3 year olds, 11 were wild 4 year olds, four hatchery-raised 4 year olds, eight wild 5 year oids, and one hatchery-raised 5 year old brown. Five wild brown trout were 6 years old. Of the 56 radio-tagged fish fielded in 1996, 19 were rainbow trout. Six of the rainbows were 3 years old, ten were 4 years old, and three were 5 years old. All of the rainbow trout tagged in 1996 were wild fish. 37 brown trout were radio-tagged in Three ofthe browns were wild 3 year olds, six were hatchery-raised 3 year olds, 12 were wild 4 year olds, two hatchery-raised 4 year olds, 12 wild 5 year olds, and two hatchery-raised 5 year old fish. The 1996 radio-tag distribution for the entire study area included six brown and one rainbow trout in the Beaverkill River. In the Upper East branch, there were six brown and one rainbow tagged. In the Lower East branch, six brown and four rainbows were tagged, and in the West branch of the Delaware River, eight brown trout and two rainbow trout were radiotagged. Three ofthe eight brown trout were tagged directly below the dam to act as a control in cold water release flow from the Cannonsville Reservoir on the West branch. A total of21 fish were radio-tagged in the Main Delaware River in 1996, all below Hancock, New York. Eleven browns and 10 rainbows were tagged, and also marked by removing the adipose fin for identification as a 1996 fish in the sample. See figure 8. Only one new fish was radio-tagged in A brown trout from the Beaverkill Fish Hatchery was tagged and released into the Beaverkill River below Roscoe, New York. This fish was the only one in the entire study that was taken directly from the hatchery. It was tagged in order to determine migration activity of hatchery raised fish, and then stocked into a natural stream environment. The fish was a 2-year-old female brown trout measuring 15 inches in length, tagged on June 3, 1997 and then released into the Beaverkill. Water temperatures were very high throughout the entire Beaverkill River system in Flow levels were low because of the hot, dry summer. Water temperatures, approached 27 C (80 F) on the Beaverkill, and had forced most fish to relocate to thermal cool water refuges. Gender proportions ofboth brown and rainbow trout were also documented at the time of capture. It was necessary to know the sex of the fish in order to compare the movement and migration differences related to sex as well as origin of the fish involved. In 1995, there were 18 male fish and 37 female fish tagged. Fourteen males were wild brown trout, two males were hatchery-raised brown trout, and two males were rainbow trout. Of the female fish, 17 were wild brown trout, seven hatchery-raised brown trout, and 13 were rainbow trout.

16 IIA Figure Tagging Locations o N I ""I LEs 71 UPPER EAST BRANCH LOWER EAST BRANCH BEAVER KILL WEST BRANCH N I <.~/ ",'yeo %"~.:\,~~ MIL ( S DELAWARE RIVER Figure 9. Map oftbermal Refuge Areas

17 12 In 1996, 14 male fish and 42 females were tagged. Ofthe male fish, 12 were wild browns and two hatchery-raised. Fifteen females were wild browns, eight hatchery browns, and 19 wild rainbow female trout were tagged. In 1997, the single fish was tagged. Migration of Trout RESULTS Migration of fish is defined as "movement between two or more distinct and usually separate habitats, which occurs regularly, is fairly predictable, involves a majority ofthe population of the species, and is active and directed by the fish" (Northcote, 1991). This movement is generally cyclical, or a return to habitat occupied by the fish in an earlier life stage. Migration can be used to describe any movement of a fish, including a short distance in search of food. In the case described and discussed in this text, it is being used to discuss a class of movement where fish return to the region from which they have migrated for various reasons (Northcote, 1991). Different factors, or a combination of them, may actually cause the migration of fish. All aspects will be addressed. These factors include hormonal urges within the fish, light stimulation, temperature, and their genetic disposition. Trout have many hormonal urges, which contribute to their migratory behavior. Hormones can both initiate and control migration. "Internal physiological changes are presumed to produce a metabolic stress which forces the fish to move into different waters" (Hoar, 1953). Hormones released from the pituitary and thyroid glands cause internal sexual stimuli, which can initiate migration by causing the maturation of the gonads. They can also cause the stimulation of the movement itself. Craig-Bennett, (1931) and Fontaine & Koch, (1950) found that both pituitary injections and increased thyroid activity stimulated fish to mature and, in tum, move. Hoar et ai, (1953) also found that male hormone increases the rate of metabolism and speed of swimming fish. Both gonadic and thyroid hormones are active during upstream migration, affect the activity of fish, and may be a source of activation of the nervous center. These hormones set off the appetitive behavior of the spawning migration (Hoar, 1953). Hormonal changes are a biological stimuli for trout to gather at the mouth of the river system from where they swam as juveniles (Northcote, 1991). The ripening of the gonads provides the primary impetus for the fall migration of trout into tributaries to spawn. Stuart (1953) explained that this internal stimulus is apparently indispensable because there are no reports of immature or non-ripening fish entering spawning tributaries in the fall of the year. Many adult fish fail to ripen each year, but these fish will then remain in the main river without traveling into tributaries. Light stimulation also affects the migration of trout. Photo-periods are lengths of time that a fish is exposed to light in its habitat. Changes in photo-periods, or even the intensity of the light, can directly or indirectly affect the migration. The intensity of the light a fish is exposed to changes over the course of a day or year. Either will affect the fish. "The dynamics of the light

18 13 intensity throughout the year detennines the course of the maturity cycle in fish to a considerable extent. Fishes of temperate latitudes reproduce only at particular times of the year" (Nikolsky, 1963). Light exerts a definite influence on the course of the fish's metabolism and also on the maturation of its gonads. A fish exposed to intense light for a significant amount of time will mature faster than one that is not. The process of homing by fish is not fully understood, and has many different definitions. As related to this research, homing refers to the choice a fish makes to return to the spawning ground used by its parents rather than any other equally probable place (Gerking, 1959). Usually, this is a considerable distance for the fish. Homing is a very important part of population stabilization. It can be caused by unfavorable conditions or by spawning requirements (Gerking, 1959). A study done in Scotland by Stuart (1975) on both young and adult brown trout proved that homing occurred. The young occupied five tributary systems and all migrated to the Dunalastair Reservoir just before the adult spawning run. The spawning run begins in October, and the younger fish returned to the streams in May. The adult fish returned to the reservoir in October and November. Furthennore, homing was supported by the fact that at the mouth of one of the creeks, at a confluence with a second, a small waterfall blocked one passage. The fish, previously marked upstream of the barrier, chose the more difficult route over the unblocked, easier pathway. The study continued for three years, with similar results. As part of the homing process, it is believed that fish use several senses and remember cues that guide them along their pathways. Northcote (1991) sunnised that trout, specifically, may recognize currents and hydraulic conditions, which indicate they have been somewhere before. Trout also use their senses of sight and smell to identify riverbeds and odors of tributaries to reach their destinations. Migration of trout can also occur because ofthennal stress. Water temperature increases over the distance that the water flows. Trout migration is stimulated when water temperatures became too wann for survival. When found outside of their preferred temperature range, trout become less efficient at perfonning life functions. Trout will "exhibit high metabolic demands leading to growth suppression and early mortality if they remain in water temperatures from 17.2 C to 24 C (63 F to 75 F)" (Neilsen and Lisle, 1994). Temperatures above 20 C (68 F) cause trout to become physiologically stressed, with body functions altered. Because of the wann water temperatures, the levels of oxygen available to the trout are depleted. Less oxygen causes the trout to begin to experience respiratory problems. The trout cannot comfortably perfonn bodily functions, and are forced to respire more often in an attempt to take in the needed levels of oxygen. They compete less effectively for food and space with better adapted species and are generally less vigorous and more susceptible to disease and predation (Hokanson et al. 1977; EPA 1976; and Spotila et al. 1979). Once trout are stressed from the high water temperatures, they move to areas of cooler water, known as cool water thennal refuges. Thennal refugia can be spring holes, mouths of tributaries, or areas where cold water flow releases take place. Most of the trout in this study that were radio-tagged in the East Branch of the Delaware and the Beaverkill River system

19 14 moved downstream to locate the cooler water. This occurred because the fish were stressed and they could not travel long distances against the current. The fish found it easier to locate cooler water by drifting with the current until an area of suitable temperature and oxygen level was reached. Based on my data, I theorized that these fish may have grown up in the river, and allowed the current to take them to the cooler areas because they had migrated from there previously, and they recognized the area. Fish growth and populations, including trout, are affected by warm water flows within the Delaware River tail-waters. Trout populations suffer because of the warm water flows. When water temperatures in the Delaware River watershed reached 22 to 26 C (72 F to 79 F), the trout began to move into thermal refugia. Those temperatures exceeding 22 C (70 F) cause growth rates to slow and juvenile fish to become physically stressed and lose body weight. Studies indicate that brown trout that are fed at maximum satiation experience their best growth rates between 14 and 15 C (54 F to 59 F). Their growth rates actually decline in water temperatures above 18 C (64 F) (Elliot, 1975). Brown trout juveniles lose weight regardless of how much food they eat when in these higher temperature ranges. Juvenile rainbow trout data have shown growth rates that are reduced at temperatures exceeding 19 C (65 F) and that population biomass cannot be maintained when weekly mean water temperatures exceeds 21 C (70 F) (Hokanson et ai., 1977). In general, trout located and tagged in the Beaverkill River remained there until water temperatures became too warm. The fish exited the lower portion of the Beaverkill system in the late summer. Fish radiotagged in the upper sections, around Roscoe, NY remained there as the temperatures in this section remain cool enough for year round trout survival. Trout that were radi-otagged throughout the East branch ofthe Delaware reacted very differently than the previously discussed trout. Fish tagged in the upper section remained there year round, with very little movement tracked. Water temperatures in the area from Harvard, upstream to the Pepacton dam at Downsville, remained at an almost constant 10 C (50 F) throughout the spring, summer, and fall months. In the winter, the temperature fell to freezing, although this is suitable for fish survival. The trout had suitable water flow conditions and temperatures for survival and growth. Once the water reaches Harvard, it begins to warm rapidly for two reasons. First, the distance from the dam is considerable, the cool water discharges not reaching all the way to Harvard. Secondly, the width of the river is a factor because the wider the riverbed, the shallower it tends to be. This allows the water to warm faster from the sun. Temperatures below Harvard, down to the confluence of the main Delaware River at Hancock, often reach stressful temperatures in the summer months. This causes the trout to seek out the cooler refuge areas at stream mouths, or to exit the system entirely and locate in another river - usually the West branch of the Delaware. Radio-tagged trout from the lower East branch showed migratory movement related to the increased water temperatures. Fish tagged between Harvard and Hancock tended to seek refuge at the confluence pool ofthe West branch, or else entered the West branch itself. Some of the fish originating from the East branch swam upstream to relocate in areas closer to the dam due to the releases from the Pepacton reservoir throughout the summer months.

20 15 The main Delaware River, below Hancock, New York, supports a high quality trout population. Trout located in the Delaware are ultimately dependent on water released from both its East and West branch tail-waters to survive. Water releases provide the cool temperatures for trout growth and survival downstream in the main Delaware River. Trout radio-tagged in the main Delaware River utilized numerous thermal refuges that were previously unknown. One known thermal refuge is located where the West Branch enters the main Delaware. The trout congregate there in response to the cold water flows coming out of the West branch. Trout radio-tagged most often remained stable throughout the entire summer, with no reason to move. Trout located in the confluence pool all were released and remained on one side of the river in response to the cold water flows from the West branch. A distinct line could be drawn where the East and West branches come together, because the water from the West branch is so much cooler in temperature. It doesn't mix with the warmer flows from the East branch, and creates a cooler refuge on the Pennsylvania side ofthe river. Trout located in the confluence pool all lie on that side ofthe river where the West branch flows are entering. Other thermal refuges were discovered in the main Delaware River system, often located at areas where very cold tributaries enter the main river. The cold water flows enabled trout to congregate at these tributary mouths. Trout further down river, below Hancock, often traveled to these areas in response to increasing temperatures. The trout also found "spring holes" located in the main river. These are deep holes where there may have been a spring in the river, causing the water temperature to be cooler at these points than in the ambient river. The fish spent the warm summer months in these "spring holes". Throughout the radiotelemetry study, both hatchery and wild fish were observed migrating. Both were radi-otagged and observed for movement related to changes in water temperature. In general, it is believed that hatchery-raised fish move less than their wild counterparts. They are also thought to be less hardy, and more easily stressed than a wild fish. Those born and nurtured in the natural stream environment were thought to be better adaptable and stronger. "Using the scope for activity, which measures the amount ofreserve energy available at a given temperature, Dickson and Kramer in 1971, and Hochachka in 1961 reported that domesticated hatchery trout have less energy reserved at higher temperatures than do wild trout" (Behnke, 1991). Secondly, wild trout will move more often than hatchery- raised trout because of their natural instinct, when they sense a physiological change in their body (Behnke, 1991). Once the fish detects a change in its body in response to the stress of warmer temperatures, it will seek cooler waters. In this study, 46 trout were of wild origin, and 10 trout were hatchery raised. Almost half of the fish tagged in the Beaverkill River were of hatchery origin. From the data collected in 1995, 1996, and 1997, the wild trout in the Beaverkill River demonstrated greater movement than the hatchery raised trout. Most ofthe hatchery-raised trout remained in the pool or run where they were captured and tagged, throughout the entire study period. As predicted, trout from hatchery origins were more sedentary, as compared to the wild trout present in the same conditions. Under stressful warm water flow conditions, wild trout exited the river more often than did the radiotagged hatchery trout present there. All ofthe wild fish on the Beaverkill in the 1995 study moved out of the river system to seek cooler water. Previous radiotelemetry studies such as the data collected in 1995 indicated that most hatchery fish stay in the same general area where they were tagged. One fish tagged in 1995 at the

21 16 Ferdons pool, just below Roscoe, was a hatchery raised male brown trout. It remained in the same spot not even moving when it experienced increased water temperatures close to 27 C (80 F), as well as stressful low flow conditions. This fish was thought to have died from the increase in water temperature. A hatchery raised, female brown trout, also in the Beaverkill in 1995, was radio-tagged in the Cemetery Pool. It did not move at all during the time it was tracked. West Branch of Delaware River: Movement Related to Water Temperature: Data collected from the ten trout radio-tagged throughout the West branch of the Delaware River indicates that conditions within this system are suitable for the growth and survival of the trout. Because of the cold water flow releases within the river system, trout are provided with temperatures rarely exceeding 19 C (65 F), and adequate oxygen. Three trout, tagged just below the release area of the Cannonsville Reservoir, acted as a control group. All remained in the area throughout most of the study period. Three fish dropped downstream to just before the weir dam, after the tagging process. One fish, WB 5 2, remained there until the late summer or early fall when it was believed to be creeled just before the closing of trout season in A second fish, WE 6-2, remained throughout all of 1996 and stayed through early April 1997, when it was caught and creeled by an angler. The third fish, WE 7-2, was creeled in late August These fish remained in the area just below the weir dam because of the cold water release flows from the Cannonsville Reservoir during the summer months. Other trout radio-tagged farther downstream from the reservoir remained there throughout the warmer months as well. Water temperatures throughout the length of the West branch, below the Cannonsville Reservoir, remained suitable for the trout. Trout radio-tagged at the release dam in Deposit, four miles downstream from Stilesville, remained here throughout the study period, moving only to spawn. Temperatures at this location rarely exceed 12 C (55 F), even in the warmest summer months. Two fish tagged in the large pool below Deposit, in the "no kill" area, remained there during WE 3-2 is a hatcheryraised, three-year-old brown trout, and remained stationary in the 1997 study period as well. WE 4-2, a wild, four-year old brown trout was stationary until June of It then moved downstream 14 miles to Balls Eddy. This new location is very popular with anglers, and when the fish could not be located later, it was assumed that it was creeled and not reported. West branch fish 8-2 was a wild, 5-year-old brown trout, which was tagged about 12 miles below the release dam. After tagging, it moved downstream slightly, and then remained just above Balls Eddy throughout the entire two-year study period. One fish was tagged 14 miles below the release dam, at Balls Eddy, on the West branch. This fish did not move at all, except to spawn. It was a 5-year-old wild brown trout, WE 2-2, and remained in this location because the water temperatures here never exceeded 16 C (60 F) throughout the summers of 1996 and Another fish tagged at this location, WE 10-2, was a 4-year-old wild brown trout. It exited the West branch entirely to relocate in the main stem of the Delaware River 9.66km (six miles) from where it was radio-tagged. It then remained at the new location throughout the study period, returning to the West branch only to spawn in one of its tributaries in both 1996 and 1997.

22 17 Lastly, two rainbow trout tagged in the West branch showed different movement patterns. A 4-year-old rainbow, WB 1-2, was tagged at Balls Eddy in the early spring of 1996, and exited the system entirely. This movement, from the West branch to the main stem of the Delaware, was believed to be due to the time of season that the fish was tagged. It was assumed that this fish was originally a main stem resident trout, tagged during its migration to spawn. After the tag was implanted, the fish returned to its residence in the main Delaware River, and remained there throughout the remaining study period. The second fish, WB 9-2, was a 4-yearold wild rainbow trout, which was radiotagged in the West branch. The location of the tagging procedure was 16 km (ten miles) below the release dam in June of The fish remained where it was tagged in 1996 and early The fish moved downstream to a West branch tributary to spawn, then relocated, and remained at the stream mouth after spawning took place. Movement Related to Spawning: Brown and rainbow trout located within the West Branch, either spawn within the West branch, or utilize its tributaries for this purpose. Trout radio-tagged in the West branch migrated both upstream and downstream to select spawning sites. Of the two rainbow trout tagged in the West branch, one spawned in a tributary. WB 9-2, the 4-year-old, wild rainbow, moved 6.4 km (four miles) downstream from its tagging habitat, and spawned in Balls Creek, a major tributary to the West Branch. This fish began its journey downstream in late March of 1997 and then entered the creek. It selected a gravel area and redd almost immediately. This fish remained in the creek for 20 days, before exiting and relocating just off ofthe creek mouth for the remainder of the study period. The second rainbow trout was the 4-year-old, wild fish tagged WB 1-2. It traveled upstream from the Delaware River system, and into the West Branch in the spring of This fish relocated near Balls Eddy on the West Branch for the entire spawning season, but never entered a tributary. The following chart summarizes the spawning activity. Rainbow Trout Spawning Activity in the Spring of 1997 on the West Branch Date Tag Frequency(MHz) Fish 10# Spawning Location Sex Time Spent in Tributary (Days) 3/25/ WB9-2 Balls Creek WBDR F 20 Brown trout radiotagged in the West branch utilized both the main river and its tributaries for spawning. Ofthe eight brown trout tagged in the West branch, four of them utilized some of the tributaries to spawn in the fall of 1996 and of In the fall of 1996, fish WB 10-2 and WB 2-2 used these tributaries. WB 10-2 was a wild, 4-year old brown, which migrated upstream from the main Delaware and spawned in Sands Creek in the lower end of the West branch. The fish traveled up the creek 3.2km (two miles) and spawned on a gravel area in the creek bed. WB 10-2 remained in the creek for 6 days before returning to the area where it was prior to spawning time. Spawning migration ofwb 10-2, lasted about four weeks, with

23 18 migration upstream beginning in late September and the fish entering the creek on October 29th, WB 10-2 exited Sands Creek on November 4th, 1996 and returned to the Delaware River. The second brown trout utilizing a tributary of the West branch for spawning was fish WB 2-2. This was a 5-year old, wild fish. It migrated 402.4m (1/4 mile) upstream from its tagging location, and spawned in Balls Creek on the West branch. The fish traveled another 402.4m (1/4 mile) up the creek and spawned on a gravel area. The fish entered the creek on November 12th, 1996 and exited on November 19th, All other brown trout radiotagged in 1996, showed upstream mi gration to known spawning areas within the West branch ofthe Delaware River itself, for the 1996 spawning season. Fall Brown Trout Activity in the Spring of 1996 on the West Branch Date Tag Frequency Fish 10# Spawning Location Sex Time Spent in Tributary(DAYS) 10/29/ WB 10-2 Sands CreekWBDR M 7 11/12/ WB 2-2 Balls CreekWBDR F 7 Of the eight brown trout radio-tagged in 1996, four remained active tags in the following year of Of these four fish able to be tracked again, three of them utilized tributaries of the West branch for their 1997 spawning. WB 3-2 was a 3-year old hatchery male, which spawned in Oquaga Creek, below Deposit, NY. It was radio-tagged in the West branch 1.6km (one mile) below the creek. It began its upstream migration in mid October 1997, and actually entered the creek on November 3 rd, This fish was observed spawning with a female, and entered the creek two days later. Another brown trout, WB 8-2 migrated upstream 1.6km (one mile) to spawn in Roods Creek, another tributary to the West branch. This fish was a wild 5-year-old male which entered the creek on November 4, 1997, and swam 402.4m (1/4 mile) up the creek where it was observed on a redd with a female brown. After spawning, it exited the creek on November 10,1997. The last brown trout which utilized a tributary to spawn was WB This fish, a 4 year old, wild male, entered the same tributary in 1997 as it did in 1996, and followed almost the exact spawning migration pattern in both years, except for the timing. This was attributed to the tributary flow, which was greater in October 1996 than in WB 10-2 did not enter Sands Creek until November 25, 1997 after a fairly heavy rainfall. The fish swam upstream to the exact spawning location as previously, spawned, and then exited one week later. The fish then relocated to its prior location in the main part of the Delaware River system. Brown Trout Activity on West Branch in the Fall of 1997

24 19 Date Tag Frequency(MHz) Fish ID# Spawning Location Sex Time Spent in Tributary(DAYS) 11/3/ WB 3-2 Oquaga CreekWBDR M 2 11/4/ WB 8-2 Roods CreekWBDR M 6 11/25/ WB 10-2 Sands CreekWBDR M 7 Main Delaware River: Movement Related to Temperature: Data collected from radio-tagged brown and rainbow trout in the main Delaware River indicates that the trout are ultimately dependent upon cold water releases from the West branch for growth and survival. Trout in the system migrate to thermal refuge areas. When water temperatures become too warm, these trout become physiologically stressed. Radio-tagged rainbow and brown trout moved both upstream and downstream to locate thermal refuge areas. Once ambient river temperatures reached 22 C (70 F) or above, fish searched out areas of cooler water. Rainbow trout seemed to react quicker than brown trout to warming water temperatures. The rainbows seemed to have moved further in a shorter time period than the browns, whether up or downstream. DR 1-2, a 3-year-old wild rainbow trout, was tagged about l2.9km (8 miles) below Hancock, NY at the Buckingham access site. It showed movement from there in mid June of 1996, when water temperatures reached 19 C (66 F). DR 1-2 traveled 9.66 km (six miles) and relocated at a thermal refuge off of the mouth of the Bouchouville Brook. This fish remained there throughout the summer of 1996 while water temperatures remained a nearly constant 16 C (60 F). Moving upstream only to spawn, DR 1-2 followed almost the same pattern in 1997, relocating to the refuge area in mid June to spend the entire summer, fall and winter there. DR 2-2, a 3-year-old wild rainbow trout, was also tagged at the Buckingham access. It moved downstream in the summer of 1996 when the water temperatures approached 21 C (70 F) at the tagging location. This fish moved close to 64.4 km (40 miles) downstream in late June of 1996, to relocate near a spring hole present off of the mouth of Ten Mile Creek, below Narrowsburg, NY. DR 2-2 remained there all summer until starting a migration back upstream in late September when the river temperatures cooled in the fall. The fish then wintered at the area where it was tagged, and in the spring migrated upstream to a gravel bar in the main Delaware below Hancock, NY to spawn. Subsequently it moved back downstream. The fish spent the summer of 1997 and the rest of the study period, 1.6 km (one mile) upstream from its tagging location. The water temperatures never exceeded 18 C (65 F) there because of cold water releases.

25 20 DR 3-2 was a 5~year-01d hatchery-raised brown trout, which was also tagged at Buckingham access. This fish moved constantly upstream during the summer of It spent most of the summer off of the mouth of Read Creek on the East branch of the Delaware. Local water temperatures never exceeded 20 C (68 F). DR 3-2 moved back downstream in the fall to its original position. After spending the fall and winter at the Buckingham access, the fish moved in mid June 1997 to a large known thermal refuge pool at the Junction Pool of the East and West branches in Hancock. DR 3-2 located there, on the coldwater side where the cool west branch release waters enter the Delaware River. The fish remained there throughout the rest of the study period. The last fish tagged at Buckingham access was DR 4-2. This fish was a four-year-old, wild rainbow trout. It moved downstream in early summer of 1996, traveling 9.66 km (six miles) to locate off the mouth of Abe Lord Creek below Lordville, NY. Water temperatures never exceeded 19 C (66 F) during the summer. DR 4-2 remained through the fall, winter, and early spring It then moved upstream in late spring of 1997 to spawn in the East branch tributary, then relocated back to the tagging location at Buckingham to spend the summer of Water temperatures there stayed a constant 17 C (64 F). A 5-year-old wild brown trout, DR 5-2, was tagged at Lordville, NY. It moved upstream 3.2 km (two miles) when water temperatures reached 25 C (76 F) in July of This fish relocated the 3.2 km (two miles) to the mouth of Equinunk Creek where flows entering the river are at a constant temperature of 18 C (65 F) throughout the summer months. DR 5-2 then returned to Lordville, NY to its tagging location. The fish remained throughout 1996 and most of the 1997 study period, until the tag was recovered along the bank in August of A wild rainbow trout tagged at Lordville, NY moved upstream in the early summer of 1996 and spent the summer months near the mouth ofequinunk Creek, where water temperatures never exceed 18 C (65 F). This fish was never documented again after August 1996, and it is thought that the fish was creeled because the tag was never located after scanning the entire watershed area. Another 4-year-01d, wild rainbow, tagged.8 km (one- half mile) below Lordville, NY, moved downstream 4.03 km (2.5 miles) in the early summer of 1996 when the water temperatures at Lordville reached a stressful 22 C (72 F). DR 9-2 relocated to a thermal refuge downstream, near the mouth of Bouchouville Brook. This fish spent the entire fall and winter there as well, moving upstream to spawn in a main stem tributary, and then returning to the same location in The fish remained there through the summer, fall, and early winter when the study period ended in December of DR 10-2 was a four-year-01d wild brown trout, tagged.8 km (one-half mile) below Lordville, NY in the early spring of In the first part of June, the water temperatures approached 21 C(70 F), and DR 10-2 started moving upstream and reached Hancock by mid June. On June 25, 1996, the fish entered the West branch where water temperatures were cooler. It then swam up the length of the West branch to the large poo110cated just below Deposit, NY. It spent the summer months there, until late September, when it returned to the tagging location

26 21 in early October. DR 10-2 followed the same pattern in 1997, relocating in the West branch around the Balls Eddy area until late September and then returned to the tagging location. DR 11-2 was a wild, 5-year-01d rainbow tagged at Long Eddy, NY in early March Soon after tagging, DR 11-2 moved 16.1 km (10 miles) upstream to an area near Lordville, where it was documented in late April. The fish remained there until late June, when water temperatures approached 24 C (74 F). It then quickly moved 37 km (23 miles) upstream, in 8 days, to relocate in the large pool below Deposit, NY. This pool is in the West branch and the water temperature was 11 C (54 F). DR 11-2 spent the summer months there, and remained through the fall and winter of In the spring of 1997, the fish moved downstream to spawn, returning to the pool and remaining there through the end of the study period. A 5-year-01d, hatchery-raised brown trout, DR 14-2, was tagged 3.2 km (2 miles) upstream of the Buckingham access in late May of The fish moved upstream in late August of 1996, in response to river temperatures of 22 C (70 F). It relocated to a riffle below Hancock, NY where the water temperature was 12 C (62 F) in response to West branch release flows. This fish spawned in an East branch tributary in October of 1996 and then could not be located after that. An angler in the vicinity of the area where DR 14-2 was originally tagged recovered the radio-tag. DR 15-2, a wild, 4-year-old brown trout, was radio-tagged 3.2 km (2 miles) above the access site at Buckingham. During the summer of 1996, this fish traveled upstream to the junction pool in Hancock. The water temperature was 16 C (60 F) throughout the summer months. The same pattern was followed in 1997 by DR 15-2, with the fish traveling from Buckingham to the refuge located on the side of the river where the West branch enters the river. Another fish tagged at this same area above Buckingham, DR 16-2, was a wild, 4-yearold male brown trout. The temperature in the Delaware River at the tagging location was 21 C (69 F). This fish traveled upstream during the summer of 1996 to Hale Eddy, NY located on the West branch of the Delaware, where water temperatures were a cold 14 C (56 F) throughout the entire system. DR 16-2 spent the summer months in the West branch, moved back to its tagging location in the late fall, and in the following summer months of 1997, migrated back upstream to the large thermal refuge in the junction pool of the Delaware river below Hancock. DR {7-2 was a wild', rain60w tagged.[5 KIn (one-ha((mde) 6e(ow the guckingham access. It never showed any movement at all during the two year study period. Numerous attempts were made at trying to move the fish by wading into the river and locating it. The fish was not found. It could have died from complications resulting from the surgery, and the tag was never recovered. Temperatures in this area often reached stressful temperatures of near 24 C (73 F) during the summers of 1996 and 1997, with no reaction from this fish. A 3-year-old, hatchery- raised female brown trout was tagged below Hancock, NY in June of DR 18-2 never moved out of its tagging location, except to spawn, because temperatures never reached above 18 C (65 F). This fish was radio-tagged close to the known thermal refuge located where the cold water releases from the West branch enter the system. DR

27 , a wild rainbow tagged in this same area responded in the same manner, moving only to spawn. DR 20-2 was a wild, 4-year-01d rainbow trout tagged at Lordville, NY. This fish stayed close to the area of spawning, moving downstream about.8 kin (one-half mile) to the mouth of a small brook, called Abe Lord Brook, in the summer months. Temperatures at its tagging location reached 24 C (74 F), while at Abe Lord Brook, temperatures were a cooler 16 C (61 F). This same migratory pattern was followed in the summer of 1997 as had been in The final fish radio-tagged in the Delaware River, DR 21-2, was a wild, 4- year-old brown trout, which was tagged.8 kin (one-half mile) below Buckingham access site in June of Soon after tagging, the river temperatures reached near 21 C (70 F), forcing DR 21-2 to migrate to cooler water. It traveled nearly 16 kin (ten miles) upstream to the large thermal refuge located at the junction pool below Hancock. It spent the summer there and moved back downstream in the fall. DR 21-2 spent the winter and spring below Lordville. In the summer of 1997, the water temperatures at Lordville were near 21 C (70 F), and DR 21-2 migrated downstream to cooler water offofbouchouville Creek mouth, and spent the remainder ofthe study period there. Movement related to Spawning: Both brown trout and rainbow trout in the Delaware River system spawn in the main river or utilize the tributaries of the West, East, or main Delaware rivers itself in which to spawn. Trout radio-tagged in the Delaware River system often traveled great distances of up to 48.3 km (30 miles) to enter tributaries to spawn. In the spring of 1996, five out of seven rainbows tagged before spawning utilized tributaries for their spawning activities. Tributaries of the East branch, West branch, and main Delaware River were all used by rainbows in spawning in Rainbow Trout Activity in the Spring of 1996 on the Main Delaware Data Tag Frequency(MHz) Fish ID# Spawning Location Sex Time Spent in Tributary(DAYS) 3/31/ DR 9-2 Abe Lord CreekDR F 8 4/2/ DR 1-2 Balls CreekWBDR F 6 4/5/ DR 8-2 Shehaw CreekWBDR F 14 4/29/ DR4-2 Read CreekEBDR F 12 6/28/ DR 2-2 Callicoon CreekDR F 14

28 23 Of the ten rainbows radio-tagged in 1996, six utilized tributaries for spawning in Out of these six fish, three of them; DR 9-2, DR 1-2, and DR 4-2 returned to the same tributaries that they used in During the springtime, other rainbows tagged in the Delaware River did show migratory movement, toward areas of spawning gravel which were located in the main Delaware system. Rainbow Trout Spawning Activity on the Main Delaware in thespring of 1997 Data Tag Frequency(MHz) Fish ID# Spawning Location Sex Time Spent in Tributary(DAYS) 3/31/ DR 9-2 Abe Lord CreekDR F 8 4/1/ DR 11-2 Balls CreekWBDR F 6 4/1/ DR 1-2 Balls CreekWBDR F 6 4/1/ DR 20-2 Abe Lord CreekDR F 7 4/21/ DR 19-2 Read CreekEBDR F 7 5/6/ DR4-2 Read CreekEBDR F 14 Eleven brown trout were radiotagged in the Delaware River in Five ofthese fish utilized the tributaries to spawn in during the fall of Tributaries of the East branch, West branch, and Delaware River were all used for brown trout spawning in Brown Trout Activity on the Main Delaware in the Fall of 1996 Date Tag Frequency(MHz) Fish ID# Spawning Location Sex Time Spent in Tributary(DAYS) 10/22/ DR 14-2 Cadosia CreekEBDR F 14 10/23/ DR 16-2 Sands CreekWBDR M 10 10/28/ DR 10-2 Abe Lord CreekDR M 14 10/29/ DR 18-2 Oquaga CreekWBDR F 6 11/11/ DR 15-2 Shehaw CreekWBDR F 32

29 24 In the fall of 1997, three Main Delaware River fish used tributaries for spawning. DR 10-2, DR 15-2, and DR 16-2 used the same tributaries in 1997 where they had spawned in the fall of Spawning in 1997 was almost a month later due to low water conditions, which lasted until late October. Then, heavy rains brought the stream flows back up, allowing the fish to enter the tributaries. The length of stay in the tributaries varied from days to months. Other brown trout in the Delaware River utilized the main Delaware for spawning activity, and began to show movements towards their spawning locations at the predicted time. Brown Trout Activity on the Main Delaware in the Fall of 1997 Date Tag Frequency(MHz) Fish ID# Spawning Location Sex Time Spent in Tributary(DAYS) 11/24/ DR 10-2 Abe LordCreekDR M 7 11/25/ DR 15-2 Shehaw CreekWBDR F 30 11/25/ DR 16-2 Sands CreekWBDR M 32 Four fish radio-tagged in 1996 in the main Delaware River system were also creeled in Ofthese four tags, two were re-implanted into different fish in the system. The fish creeled in 1996 were all caught within three months of tagging. DR 6-2, DR 8-2, DR 12-2, and DR 14-2 were all creeled in early summer East Branch Delaware River: Movement Related to Temperature: Both brown and rainbow trout radio-tagged in the East Branch of the Delaware River in 1996 showed migratory movements towards areas of cooler water in the warm summer months. These were located in the East branch itself, or they moved all the way out ofthe East branch and into the large refugia located where the West branch empties into the main Delaware river at Hancock, NY. Fish radiotagged close to the dam at Downsville, and just downstream, remained throughout the entire year, moving only to spawn. Water temperatures in this region are a near constant 10 C (50 F), which is related to the 90 cfs release flows from the Pepacton Reservoir. EB 1-2, a wild, four-year-old female brown trout, was tagged 3.2 km (two miles) below the Pepacton release dam. She never moved from the tagging location except to spawn. Water temperatures there remained at near 12 C (52 F) throughout the summers of 1996 and EB 2-2, a five-year-old, wild brown trout was tagged 1.6 km (one mile) below Harvard, NY. Water temperatures here vary, often reaching 21 C (68 F) during the summer months, because the river is quite wide and shallow at this point. River widths average 30.5 m (100 feet), and depths average 25.4 em (10 inches). EB 2-2 swam upstream in early summer 1996, toward

30 25 the release dam, and relocated there for two weeks near Shinhopple which is 8 km (5 miles) above the release dam. EB 2-2 slowly worked its way back downstream by midsummer and relocated once again to below Harvard at a large known thermal refuge. This refuge is located in a large deep pool, fed with multiple cold water springs. Another fish, tagged 1.6 km (one mile) below Harvard, NY, was EB 3-2. This rainbow trout relocated to the known thermal refuge just upstream from its tagging location, and spent the entire summer, fall, and winter of 1996 here. EB 3-2 was then creeled in the early summer on June 9, A fish tagged in the lower East branch, EB 4-2, was a wild, four-year-old brown trout. Its tagging location was 8 km (five miles) above Hancock, NY. This fish migrated upstream in the summer of Water temperatures in the lower East branch often reach near 23 C (70 F) in summer months. By late June 1996, water temperatures had reached 25 C (72 F) at the tagging location ofeb 4-2. This fish migrated upstream nearly 32.2 km (20 miles) to relocate at the cold water refuge area just below Harvard, NY where water temperatures were a cool 15 C(60 F). EB 4-2 spent the summer months in the refuge until late September. At this time, EB 4-2 disappeared. The fish could have been creeled and not reported. The radiotag was never recovered. EB 5-2 was a three-year-old, wild brown trout tagged in the lower East branch around Peas Eddy. This fish exited the entire East branch system in the summer of 1996 in response to the warm water temperatures. EB 5-2 swam 8 km (five miles) downstream to the Junction Pool in Hancock, then entered the cooler West branch water, swimming the entire length of the West branch to relocate in the 12 C (54 F) waters below Deposit, NY. This fish slowly moved back downstream throughout the summer months, but stayed solely in the West branch of the Delaware. EB 5-2 spawned in a West branch tributary in the fall of 1996, and was assumed to have perished there. The tag was never recovered. Another radio-tagged fish in the East branch, EB 6-2 was a three-year-old female hatchery raised brown trout tagged about 1.6 km (1 mile) above Hancock, NY. This fish remained in its tagging location until early July of When the water temperatures rose to 25 C (72 F), it moved about 16 km (ten miles) upstream to just above the bridge at Fish's Eddy. Water temperatures here were 20 C (68 F). EB 6-2 remained there throughout the rest of 1996 and the early spring of In late June, 1997, the temperatures reached 26 C (74 F) and EB 6-2 moved back downstream. Leaving the East branch entirely, the fish located in a thermal refuge area on the West branch side of the Junction pool near Hancock. EB 7-2 was a four-year-old, wild brown trout tagged in the same location, 1.6 km (one mile) above Hancock. It followed a similar migratory pattern to EB 6-2. EB 7-2 moved downstream to Hancock in the summer months of 1996, then relocated back to its tagging location for the fall, winter and early spring of When stressful thermal conditions occurred once again in the summer months, it returned to the thermal refuge at the Junction Pool near Hancock in the Delaware River.

31 26 East branch fish EB 8-2, a four-year-old wild brown trout, was radio-tagged 9.66 Ian (six miles) below the release dam in Downsville. Water temperatures at the tagging location never exceeded 17 C (60 F) throughout the entire two year study period. EB 8-2 responded by never moving from the tagging location, except to spawn 1.6 km (one mile) upstream. EB 9-2 followed the same pattern. This fish was a wild brown trout tagged about 6.4 Ian (four miles) below the Downsville release dam, and moved only to spawn. EB 10-2 was a wild, five-year-old brown trout. This fish was tagged just above Harvard, NY. EB 10-2 spent the summer of 1996 at the tagging location where the water temperatures never exceeded 17 C (64 F). EB 10-2 then moved 40 Ian (25 miles) downstream, to spawn in a tributary of the Main Delaware. This fish also utilized another large thermal refuge at the mouth of Bouchouville Brook in the summer of Temperatures of the water in the pool were a cool 15 C (60 F). EB 10-2 remained here throughout the rest of the study period. EB 11-2 was also radio-tagged in the cooler waters of the upper East branch. This threeyear-old brown trout was a hatchery raised female, tagged about 12.8 Ian (eight miles) from the release dam at Downsville. EB 11-2 moved upstream to reach 12 C (55 F) water throughout the summer of This fish spent the summer, fall, winter, and early spring 1997 there, until it was creeled in early June of EB 12-2 was radio-tagged at the junction of the Beaverkill and the East branch in late May of It swam upstream in the East branch directly to the dam in Downsville, and was creeled there in the middle of June, A four-year-old, wild brown trout was tagged in late May of 1996 and identified as EB This fish was radio-tagged in the large riffle of the lower East branch just below where the Beaverkill enters the river. EB 13-2 remained at the tagging location until mid June of Water temperatures reached 22 C (70 F). EB 13-2 then migrated downstream 1.6 km (one mile) until finding a spring hole in the East branch just below the Shad Pool. EB 13-2 relocated there, where water temperatures remained a near constant 15 C (60 F) throughout most of the summer and fall. In late fall, this fish moved back to its tagging location, which could have been its spawning migration. EB 13-2 spent the fall, winter, and spring in the same location. In 1997, the fish then dropped back downstream to the same location as 1996 until late July. This was the last documentation on the position ofeb 13-2 and it was assumed that the fish was creeled and never reported as the radio-tag was never recovered. Another fish tagged in this same location, just below the confluence of the Beaverkill, was EB This was a wild, three-year-old rainbow trout. After tagging, this fish immediately swam upstream into the Beaverkill4.8 Ian (three miles) to Pork Eddy and stayed there all summer in a large deep pool in 18 C (64 F) water. EB 14-2 moved back downstream to spawn in an East branch tributary the following spring. Soon after spawning, the fish relocated to the same location in the Beaverkill until the water temperatures there reached 23 C (74 F) in early June EB 14-2 next moved 38.4 Ian (24 miles) downstream, exited the East branch system entirely and relocated in the large thermal refuge at the Junction Pool in the Delaware below Hancock. EB 15-2 was tagged in the same location, and was a wild, four-year-old rainbow. This fish remained stable through the summer months until late August of Temperatures then reached 23 C (75 F) on hot, sunny days. EB 15-2 could not be documented after this time, and was thought to have been creeled, or the radio-tag malfunctioned.

32 27 East branch rainbow trout EB 16-2, a wild, three-year-01d female, was tagged in the riffle of the East branch just below the confluence of the Beaverkill River. This fish moved into the cooler waters of the upper East branch in the summer of 1996, and in the summer of 1997 swam 40 km (25 miles) downstream to utilize the large thermal refuge area below Hancock on the West branch side of the river. Another fish tagged at this location, EB 17-2 exited the East branch entirely in the summer of 1996 and entered the cold water flows of the West branch. The fish swam all the way up the West branch to the "no kill" area located just below Deposit, NY and remained there throughout the rest of the study period. The last fish radio-tagged in the East branch, EB 20-2, was four-year-01d, wild rainbow trout tagged 1.6km (one mile) above Fish's Eddy. Soon after tagging, it went downstream to Peas Eddy, which is 8 km (five miles) above Hancock. EB 20-2 remained there all winter, and migrated back upstream to spawn in an East branch tributary near to where it was tagged. After spawning, EB 20-2 returned downstream to Peas Eddy, until the water temperatures there reached 26 C (77 F) in early June of It then exited the East branch and spent the rest of the summer below Hancock in the large thermal refuge in the Delaware River on the West branch side. Movement Related to Spawning: Brown and rainbow trout radio-tagged in the East branch of the Delaware River migrated to spawning locations within the river system, or utilized tributaries of the East branch to spawn in. There were two exceptions; one brown, radio-tagged in 1996, spawned in the fall in Little Equinunk Creek, which is a tributary to the Main Delaware River. Another brown trout, tagged in 1996, spawned in the fall of 1996 in Shehawken Creek, which is a tributary of the West branch of the Delaware River. In the fall of 1996, six of the twelve brown trout tagged spawned in tributaries. Ofthe other five brown trout that were active in the fall of 1996, all showed migratory movement during late October through December to spawning areas in the East branch. In the fall of 1997, only one brown trout, EB 1-2 utilized a tributary. This was the same tributary that it used in 1996, Trout Brook. This fish actually used the same gravel area in the stream for spawning both years. Brown trout, which spawned in tributaries in the fall of 1996, stayed in the tributaries for varying lengths oftime. EB 1-2 spent only six days in Trout Brook, while another brown trout, EB 5-2, never exited Shehawken Creek after spawning there in late October. Generally, in 1996, brown trout remained in the tributaries six to fourteen days before they exited and headed back to the river. Brown Trout Activity on the East Branch in the Fall of 1996 Date Tag Frequency(MHz) Fish ID# Spawning Location Sex Time Spent in Tributary(DAYS)

33 28 10/1/ EB 10-2 Little EquinunkDR M 15 10/21/ EB 11-2 Trout BrookEBDR F 6 10/23/ EB 5-2 Shehaw CreekWBDR M unknown 10/28/ EB 1-2 Trout BrookEBDR F 6 10/28/ EB 2-2 Harvard BrookEBDR M 14 11/11/ EB 7-2 Cadosia CreekEBDR M 7 Brown Trout Activity on the East Branch in the Fall of 1997 Date Tag Frequency(MHz) Fish ID# Spawning Location Sex Time Spent in Tributary(DAYS) 11/25/ EB 1-2 Trout BrookEBDR F 14 Six rainbow trout were radio-tagged in the East branch in None of these fish migrated to tributaries to spawn. This was most likely due to the fact that most of the tags were implanted following the spring spawning season. In the spring of 1997, four of the six rainbows spawned in tributaries. All of the fish used tributaries in the East branch for spawning. EB 3-2 spawned in Morrison Brook below Harvard, and EB 14-2, EB 16-2, and EB 18-2 all spawned in Read Creek between Fish's Eddy and East Branch, NY. Length of stay in the streams varied from six to ten days. Rainbows migrated both upstream and downstream to select spawning sites, and entered tributaries from late March through the end of April. Rainbow Trout Activity on the East Branch in the Spring of 1997 Date Tag Frequency(MHz) Fish ID# Spawning Location Sex Time Spent in Tributary(DAYS) 3/25/ EB 3-2 Morrison BrookEBDR F 10 4/21/ EB 18-2 ReadCreekEBDR F 6 4/21/ EB 16-2 ReadCreekEBDR F 7 4/22/ EB 14-2 ReadCreekEBDR F 6

34 29 Beaverkill River: Movement Related to Temperature: Both rainbow and brown trout were radio-tagged in the Beaverkill River in Only one rainbow trout was radio-tagged in the Beaverkill River tagged just below Pork Eddy on the lower Beaverkill. This sole rainbow, BK 6-2, was released after the surgery, never be documented again. It is assumed that the radio-= tag malfunctioned. Brown trout tagged in the Beaverkill showed migratory movements toward cold water areas in the warm summer months when the water in its lower reaches often reach near 27 C (80 F) in the summer months. The width ofthe stream, and its shallow streambed characteristics help account for this high temperature. Trout tagged here exited the system to seek cold water thermal refuges elsewhere. BK 1-2 was a wild, three-year-old female, brown trout tagged about 4.8 km (three miles) downstream of Roscoe, NY. This fish moved further downstream in early summer of 1996, to a deep pool in Cooks Falls, NY. In late June, this fish could no longer be documented. BK 1-2 was believed to have been creeled and never reported. The area where the fish was located is a very popular with local anglers in the community. Beaverkill radio-tagged brown trout BK 2-2, a five year old wild female was tagged in the world famous Cairns Pool, one of the two "no kill" sections present on the Beaverkill River system. Temperatures there reached 22 C (70 F) by late June 1996, and BK 2-2 migrated upstream to the Junction Pool in Roscoe, NY. The Upper Beaverkill and the Willowemoc Creek come together at this junction pool. This area is a cold water refuge, and BK 2-2 spent the entire summer in the large deep pool. After spawning in the fall, the fish returned to their tagging locations for the winter and spring, and then followed the same migratory patterns in the summer of BK 3-2, a five year old, wild, male brown trout, was tagged in the lower Beaverkill in Cemetery Pool, about 1.6 km (one mile) upstream of Horton, NY. Stressful water temperatures of near 23 C (75 F) in both the summers of 1996 and 1997, forced BK 3-2 to seek cooler water present at the mouth of Horton Brook, downstream of the tagging location. This is a large, well known thermal refuge area, where many trout congregated in warm summer months. Water temperatures coming out of Horton Brook, are often up to 9 C (15 F) cooler than ambient river temperatures, creating a known thermal refuge area in the summer. BK 4-2, a three-year-old, hatchery raised, brown trout, was tagged about 3.2 km (two miles) downstream of Horton, NY in late May of Two weeks after tagging, BK 4-2 disappeared. Ifthis fish were creeled, it was never reported. A four-year-old hatchery brown trout, BK 5-2, was tagged on the lower Beaverkill in Horton, NY. It remained there for a couple of weeks after tagging in late May of After temperatures in late June of 1996 reached 23 C (70 F), BK 5-2 started to migrate upstream toward Roscoe, NY, moving constantly upstream throughout the Beaverkill River during the summer of By late July of 1996, BK 5-2 was 4.8 km (three miles) above Roscoe, NY in the cold 16 C (60 F) waters of the upper Beaverkill River, where it remained until late

35 30 September. It migrated back downstream to Mountain Pool near Cooks Falls, NY. Water temperatures there were cooling rapidly through the fall season. BK 5-2 remained there over a spring hole, for the entire 1997 study period, and never moved. Water temperatures at Mountain Pool, ranged from 14 to 16 C (58 to 60 F). Another brown trout, a four-year-old hatchery fish, BK 7-2 was tagged about 6.4 km (four miles) below Horton, NY on the lower Beaverkil1. This fish moved 1.6 km (one mile) upstream to cooler water near Horton. Water temperatures at the tagging location reached 23 C (72 F) in the summer of 1996, and BK 7-2 moved to an area where temperatures were near 20 C (68 F), and stayed there. The fish spawned in a Beaverkill tributary in the fall of 1996, and could not be documented after that time. Movement Related to Spawning: Brown trout utilized tributaries ofboth the Beaverkill River, and Willowemoc Creek to spawn in the fall of BK 3-2, and BK 7-2 utilized Horton Brook on the lower Beaverkill to spawn in BK 2-2 migrated from Junction Pool in Roscoe, NY upstream into the Willowemoc Creek, and onward into Stewart Brook to spawn. Brown Trout Spawning Activity on the Beaverkill in the Fall of 1996 Date Tag Frequency(MHz) Fish ID# Spawning Location Sex Time Spent in Tributary(DAYS) 9/30/ BK 3-2 Horton BrookBK M 98 10/21/ BK 2-2 Stewart BrookWC F 7 12/24/ BK 7-2 Horton BrookBK F unknown In the fall of 1997, only BK 3-2 utilized a tributary, Horton Brook, to spawn. This was the same behavior as in the fall of Brown Trout Activity on the Beaverkill in the Fall of 1997 Date Tag Frequency(MHz) Fish ID# Spawning Location Sex Time Spent in Tributary(DAYS) 10/13/ BK 3-2 Horton BrookBK M 8 8

36 31 Most fish that spawned in the Beaverkill system migrated upstream to either a tributary or a gravel area located in the main river system there. Most did so in a short time, usually one week, while BK 3-2 in 1996 spent a month in the creek before exiting back to the river to spend the winter. CONCLUSIONS Trout are migratory in the Delaware River and its East and West branches, as well as the Beaverkill River. Migratory movements, due to stress caused by low warm water flows and spawning, force trout to move. Migratory movement prior to spawning was noticed in both species. Some ofthe fish in the Delaware River system moved upstream, while others moved downstream. Most ofthe fish radiotagged in this study showed some type of post spawning movement as well. Once the fish had spawned, they would either stay near the spawning area, or immediately return to the place that they occupied before the spawning migration occurred. Movement also occurred after the tag was implanted. Most fish either moved upstream or downstream soon after the surgery. This can be attributed to many factors, including the lingering effects of the anesthesia on the fish's' balance and equilibrium, and the weight of the tag in the body cavity. Most ofthis movement, which took place after the tagging, ranged from 183 m-457 m ( yards) from the tagging site. Brown trout in the radio-tagging project utilized both ofthe main rivers to spawn, as well as the tributaries. The trout spawned in the tributaries of the East branch, West branch, Beaverkill, and the main Delaware River stem. The changing photoperiods, or the length of daylight, influenced the pre-spawning movements ofthese brown trout. In the fall the shorter days stimulate brown trout to migrate to spawn (Arnold et al. 1987). This movement generally begins in late September, with peak spawning periods from late October through late November. Fish generally moved upstream to spawn in the fall, and then remained in their spawning locations for a period of time. The period ranged from 7 days to 4 months. One brown trout, BK 3-2 remained in the spawning tributary until mid winter, when it then exited the tributary and swam downstream. Meyers et al. (1992) explains that post -spawning brown trout often make long, rapid movements downstream directly following their spawning activity. Brown trout radio-tagged in this study also showed homing movements during spawning activity. Four brown trout tagged in 1996 spawned in tributaries and these same four fish utilized the same locations in It is possible that these fish were natives to these streams, and then naturally returned there as adults to have their young. Arnold et al. (1987) explains that brown trout "home with an astonishing precision" and can distinguish exact stream locations and return to them year after year. Brown trout in this study exhibited homing in the main Delaware River, the Beaverkill, and both the East and West branches ofthe Delaware. All ofthe fish that showed homing instincts in the radiotelemetry study were wild fish, which is consistent with other studies, and what one would expect. Hatchery-raised fish should not have had these tendencies, and those tagged did not. Stuart (1957) and Tilzey (1977) explain that brown trout

37 32 populations in both lentic and lotic environments (Wetzel, 1983) exhibit homing behavior into spawning tributaries from its main stem stream. Lentic environments are those in which the waters stand still, and lotic environments are those in which the water is constant movement (Wetzel, 1983). In a population, like the one in the Delaware River, wild fish born in tributaries of the main river are subsequently raised in the system. They become acclimated to their surroundings, and when they become adults, they return to their natal stream to produce their offspring. Rainbow trout radio-tagged in this study showed migratory movements as well. Those tagged throughout the entire Delaware River system migrated to cool water locations, whether upstream or downstream. Locations of cooler water, thermal refuges, were found at tributary mouths, deep pools in the system, and also spring holes located in the Delaware waters. Refuges were also found where the West branch releases cold water throughout the summer months. Many rainbow trout moved downstream from the East branch of the Delaware River, and the Beaverkill to locate at the large thermal refuge located below Hancock. Many of these fish were hatched as young in tributaries, then were raised in the Delaware River. As young adults, they migrated upstream into both the upper and lower East branch to continue their growth and maturity. It is during this stage, that these fish become accustomed to the cold water summer releases from the Delaware's West branch. When water temperatures in the East branch become too warm, these wild rainbows returned to the main Delaware at the point where the West branch enters it. They generally spend the warm summer months there in the cool waters ofthe refuge. In the fall, these fish will then return to the East branch and the Beaverkill as the waters there return to a cooler temperature. They remained through the winter months, until a stimulus causes them to move again. Many of these rainbow trout that are native to the Delaware River system grow up in the main stem, or a tributary. Once these fish become adults, they move throughout both of the east and west branches of the river system. As young fish, these rainbow trout become accustomed to the entire system. The locations of the thermal refuge areas are imprinted into the fish, which means that they possess the knowledge when they are born. The rainbow trout also learn where the mouths ofthe tributaries are, and that this is where there is adequate cold water to survive. The rainbows from the main stem ofthe Delaware River learn that the cold water inflows from the West branch keep the water cool enough in the summer months for survival. The fish will recognize the area, and instinctively know to go there if they are somewhere where the water becomes too warm for their comfort or survival. This temperature related movement is imprinted with smell into these fish at a juvenile stage of development, as they grow into adulthood (Phelps, 1994). Many of the rainbow trout radio-tagged in this study also showed homing instincts while spawning. Most of the rainbow trout tagged in the spring of 1996 spawned in tributaries. Of the fish tagged, five of the seven spawned in tributaries. Three of these five spawned in the same location in the spring ofthe next year, This homing instinct, particularly noticeable in rainbow trout, is a genetic trait carried out by migratory strains present in the Delaware River system. The rainbow trout in the Delaware River system spawn in the tributaries of the Main Delaware River. As adults, they lay their eggs in these tributaries. The young juveniles mature in these streams for two to three years. In this juvenile stage, they imprint different stream

38 33 characteristics, such as stream smell and flow, in relation to their body functions. These fish learn where the cold water flows are from and become accustomed to these areas (Phelps, 1994). Once these small trout reach three years of age, most exit these tributaries to grow to adulthood in the main Delaware River. Once these fish reach brood adult age, when they are mature enough to bear young, they return to the tributaries to spawn. This homing process is solely driven by imprintation of the tributary smell into the fish at a young age, which remains there, for life in the adult fish (Phelps, 1994). In the Delaware River system, specific homing characteristics of the rainbow trout are most noticeable during the spring spawning migration. Fish tagged in the Delaware River showed homing instincts into the tributaries of the Delaware, as well as those tributaries of the East and West branches. Read Creek, an East branch tributary, is a particularly important spawning creek for rainbow trout. This creek has particularly good gravel areas, as well as cover for fish to spawn in the streambed. A secondary tributary used by many of the rainbow trout repeatedly was Balls Creek located on the West branch. Homing instincts are very important, because the trout return to the same specific area during spawning which also allows us to locate nurseries for the young wild trout. These nurseries are located at the same areas year after year, and are the locations upon which the entire trout populations of the river are dependent. As the adult trout enter these nursery areas, they are carrying and delivering the offspring of the future populations, which must produce a large juvenile trout base if the species is to continue. If the juvenile base is depleted, the resulting brood age adults will suffer, and the species will struggle to survive. The rainbow trout that are present throughout the entire river system are genetic offspring of the wild rainbow trout patterned around the main Delaware. These trout may have relocated while growing to adulthood, but were originally born and raised in one of the small tributaries. These tributaries are important nursery areas for the Delaware River trout population, and should be protected during spawning seasons. The rainbow trout present are especially familiar with the changing conditions that frequent the Delaware River system. They become accustomed to the cold water thermal refuges, know where they are located, and migrate to them at the first signs of thennal stress to insure their greatest chance of survival. The rainbow trout of the Delaware river system, particularly those located in the lower reaches of the Beaverkill River and the lower East branch, were raised in a tributary. They imprint, and recall, these tributary locations by smell, so that under warm water conditions, they often move up or downstream seeking a cold water tributary mouth or a large cold water refuge area. Many rainbow trout that are residents of the East branch swim upwards of24 km (15 miles) downstream to the main Delaware branch to the large thermal refuge located where the cold west branch waters enter the main stem. Thermal Refuges: The fish that were tagged used many known thermal refuges. Through the study, other thermal refuges were discovered throughout the system. Many fish travel large distances to relocate to these areas in search of the cooler temperatures.

39 34 The largest known thermal refuge is where the West branch of the Delaware enters the main stem. The entire 27.2 km (17 miles) of river acts as a large refuge because of the cold water, bottom release flows from the Cannonsville Reservoir throughout the summer months. These releases provide the quality water needed for trout growth and survival. A second known refuge in the Delaware system is located just below Hancock, NY on the Pennsylvania side of the river where the West branch empties into the Delaware. This area is an important summer thermal refuge area for both brown and rainbow trout from all areas. They come from the lower Beaverkill, the lower East branch, and the main Delaware River during the warmer summer months. Another known refuge being utilized in the system was located in the Beaverkill River. Cold water mountain stream flows from Horton Brook, a tributary to the Beaverkill, enter it just above Horton, NY. Large numbers of trout from the Beaverkilliocate there during the summer because the water levels become quite low and warm. Many fish traveled to areas previously unknown as thermal refuges. They included the mouths of tiny streams, which entered the main Beaverkill. Lehmberg (1998) explains that warm water temperatures often force trout to move, and they often relocate at the mouths of colder tributary streams. Many small tributary streams such as Abe Lord Creek, Bouchoville Brook, Hankins Brook, and the mouth ofthe Equinunk Creek, all provided the trout with cold flows throughout the summer. Other refuges were also discovered, shown in figure 7. Other trout migrated to areas within the main Delaware and the East branch to congregate. Deep pools, like the one located just below the town of Harvard on the East branch, provided trout with the necessary cold water due to springs in the riverbed. A second large spring was found near Lordville, on the main Delaware, at the bottom of a large pool. Another deep pool was above Long Eddy on the Delaware River. This pool provided the trout with plenty of cool water because of its depth as well as springs seeping into the pool. Many trout congregate in this pool during the warm summer months. Spawning streams: Documentation of spawning streams was done throughout the radiotelemetry study. In the wild trout population, brown or rainbow, spawning or natural reproduction is crucial to population growth. By knowing where these fish spawn, we are able to find out which areas need protection in order to insure succession of the species. Almost all of the tributaries that enter into the Delaware River system serve as spawning streams and therefore nursery areas for the juveniles. Some streams receive more fish during spawning runs solely because of size or streambed characteristics. Some streams are simply too small, and don't allow large runs of fish to find suitable substrate to spawn. Brown trout radiotagged in this study utilized tributaries in both the fall of 1996 and the fall of 1997 for spawning purposes. Brown trout utilized tributaries of the Beaverkill, East Branch, West branch, and the main Delaware River to spawn during the falls of 1996 and Both male and female fish selected spawning streams in the study period. Some streams received more fish than others. Major spawning tributaries that were documented in the study were Sands Creek, Shehawken Creek, Roods Creek, and Balls Creek on the West branch of the

40 35 Delaware. Horton Brook was a major spawning tributary for brown trout on the Beaverkill River. Abe Lord Creek was a major spawning tributary for the Main Delaware River. Rainbow trout radio-tagged in this study utilized tributaries to spawn in both the springs of 1996 and of In the spring of 1996, radio-tagged rainbows were observed in tributaries of the East, West and Main Delaware River branches. Balls Creek and Shehawken Creek are both tributaries of the West branch that were utilized by rainbow trout for spawning activity. Abe Lord Creek and Callicoon Creek, both tributaries to the Main Delaware River were used in the spring of In 1996, radio-tagged trout utilized Read Creek, an East branch tributary, as a spawning stream. In 1997, most ofthese same streams saw fish return to them to spawn the following spring. One major stream that was previously unknown as a major spawning tributary was Read Creek on the East branch ofthe Delaware River. This creek is a spawning area and nursery stream for most of the rainbow trout in the entire Delaware River system. Five radiotagged fish entered this tributary to spawn in the spring of Numerous others were observed spawning in both 1996 and This is a very important spawning tributary to the whole river system and should be protected. Because so many of the tributaries are used as spawning areas by fish throughout the entire Delaware system, these areas should be closed to fishing to protect future generations ofthe trout populations in the Delaware River system.