Rogue Basin Fisheries Evaluation Program

Transcription

1 963/2 orps of Engineers OREGON / Portland District Research Section November 1985 Oregon Department / I of Fish and Wildlife Fish&Wildlife Rogue Basin Fisheries Evaluation Program Lost Creek Dam Studies Biennial Progress Report Biennial Progress RReport

2 BIENNIAL PROGRESS REPORT ROGUE BASIN FISHERIES EVALUATION PROGRAM LOST CREEK DAM STUDIES Submitted to U.S. Army Corps of Engineers DACW57-77-C-0027 Prepared by Thomas D. Satterthwaite, Barry P. McPherson, Patrick A. Frazier, and Steven P. Cramer Period Covered: 1 January 1983 to 31 January 1984 Date Submitted: November 1985

3 CONTENTS Page SUMMARY... 1 Tasks and Accomplishments in FY 1983 and FY Findings in FY 1983 and FY Management Implications... 2 INTRODUCTION... 3 METHODS... 3 RESULTS MD DISCUSSION... 4 ACKNOWLEDGEMENTS REFERENCES APPENDIXES... 27

4 SUMMARY Tasks and Accomplishments in FY 1983 and FY 1984 Our study plan included thirteen tasks designed to meet four objectives: (1) determine the downstream changes in water flow, temperature, and turbidity which result from the operation of Lost Creek Dam, (2) determine the effects of reservoir operation on the sport fisheries in the river, (3) determine the effects of reservoir operation on the abundance, migration, spawning, and size and age at maturity of adult salmonids, and (4) determine the effects of reservoir operation on the emergence timing, growth rate, abundance, and migration timing of juvenile salmonids. More detailed information on the tasks and activities associated with the objectives of this study can be found in the two project proposals submitted to the United States Army Corps of Engineers (USACE), Portland District, from the Oregon Department of Fish and Wildlife (ODFW), dated 1 October 1982 and 22 August We collected the information necessary to meet all of the tasks and activities outlined within both project proposals, except that scales from the 1984 run of summer steelhead have not yet been analyzed for life history composition, age-specific length, age at smolting, or juvenile growth. We did not develop final estimates of the effects of reservoir operation on downstream river conditions, river fisheries, or juvenile and adult life history parameters. We will develop these estimates of environmental and biological effects after the model being developed by the USACE provides estimates of the dam's weekly effect on downstream temperature since dam completion in We submitted the Phase I Completion Report to the USACE in That report contains analyses of the dam's downstream effects, recommendations for management of its outflow, and recommendations for future research based on data collected through Findings in FY 1983 and FY 1984 In this summary, we present only those findings for activities where we completed the acquisition of data or where additional data clearly revealed new findings not reported previously. We completed two activities during 1983: (1) creel surveys of spring chinook anglers near Grants Pass and summer steelhead anglers near Gold Beach and (2) an evaluation of the depth of water over spring chinook redds in the upper Roque. Task 2.1. We determined that the abundance of spring chinook, but not water temperature, flow, or turbidity, significantly affected angler catch rates and angler effort in the boat fishery for spring chinook in the middle river (km ) during 1982 and We were unable to quantify the influence of high flows on angler catch and angler effort in the bank fishery for summer steelhead in the lower river (km 7-18). High flows in 1983 that decreased the effectiveness of beach seining at Huntley Park (km 13) biased the use of seine catches as an abundance index of summer steelhead. Based on analyses in previous years, we -1-

5 needed to account for effects of fish abundance on angler catch before we could determine the effects of flow on angling. Activity We determined that a 10 inch drop in the water level after the time spring chinook spawn could dewater, to the level of the sill, about five percent of the redds. We also found that a high percentage of the spring chinook redds across from Cole M. Rivers Hatchery (km 253) were partially dewatered during flood control operations. Activity We determined that for each age group of fish the mean lengths of spring chinook that returned in 1984 and fall chinook that returned in 1983 and 1984 were significantly less than the mean lengths of spring and fall chinook that returned during These shorter lengths were caused by slower growth rates of chinook in the ocean in 1983, apparently as a result of the El Nino current. Management Implications We list only those tasks and activities for which we have important new implications not reported previously. Task 2.1. River temperature and flow during the boat fishery for spring chinook in the middle river (km ) had smaller effects than fish abundance on catch rate and angler effort; so enhancement of this fishery could be better achieved through actions to increase run size than actions to manipulate temperature and flow during the fishery. Activity Flood control operations at Lost Creek Dam can kill spring chinook fry because redds near the dam become dewatered, but the extent of mortality will be difficult to predict or measure. Dewatering of spring chinook redds during the filling season (when reservoir outflow can be decreased to an authorized minimum of 700 cfs) may be avoided by maintaining flows below 1,370 cfs near McLeod (km 248) during spawning (15 September-30 October). The potential for dewatering redds spawned at a given flow can be estimated by using a relationship we developed between water levels at the USCG gauge near McLeod (km 248) and the depth of spring chinook redds. Activity Unless an adjustment is made for the effects of ocean events ike El Nino on chinook lengths, the use of 24 inches as a minimum length for mature females will cause smaller-sized adults to be classified as jacks in the harvest. Shorter lengths of chinook caused by events like El Nino will result in age 3 spring chinook and age 4 fall chinook entering the ocean fishery at a later date than in other years. Use of the 24 inch criteria to distinguish adults from jacks would overestimate the number of jacks produced by the 1982 brood and, if used for predictive purposes, would overestimate the number of returning adults to be produced by the 1982 brood. -2-

6 INTRODUCTION The salmonid fishery resource of the Rogue Basin is one of the largest on the western coast of North America. The annual sport and commercial catch of salmon and steelhead averages about 549,000 fish annually and has an estimated value of $31.5 million (unpublished file data from Mick Jennings, ODFW district fishery biologist, Grants Pass, Oregon). The purpose of this study is to determine the effects of Lost Creek Dam on juvenile and adult salmonids in the Rogue River, and to develop criteria for its operation in order to enhance the fishery resource in downstream areas. This report documents our findings for the ninth and tenth years of study. Because data collection is scheduled to extend for at least one more season on most data sets, this report primarily presents comparisons of 1983 and 1984 data with the mean and 95% confidence interval for previous years to provide some perspective of the biological status. Where 1983 or 1984 values are outside the 95% confidence interval of past years, possible reasons for the differences are discussed. Information regarding the study during previous years can be found in: Lichatowich 1974, 1975a, 1975b, 1975c, 1976; McIntyre et al. 1976; Anonymous 1977; Ewing et al. 1977; Lichatowich and Martin 1977; Cramer and Martin 1978a, 1978b, 1979a, 1979b, 1979c; Smith et al. 1978; Cramer 1979a, 1979b; Martin 1979; Noll 1979; Cramer and McPherson 1980, 1981a, 1981b, 1982, 1983; McPherson and Cramer 1980, 1981, 1982, 1983; and Cramer et al METHODS In this section we decribe only new methods used during the report period. Cramer et al. (1985) presented a thorough discussion of all other methods used. A synopsis of all sampling activities in 1983 and 1984 is in Appendix 1. Task 2.1. In 1983, we surveyed the boat fishery for spring chinook between Grants Pass (km 164) and Savage Rapids Dam (km 172). Surveys began on 1 May and continued through 10 June. Five survey days per week were selected randomly. The clerk interviewed anglers between 0800 and 1100 hours. Interviews consisted of requests for: (1) amount of time fished, and (2) types and numbers of salmonids captured. The number of boats containing anglers were counted at 0800 hours. Whenever possible, the clerk examined fish for identifying marks. We placed a thermograph 1 km upstream of the fishery where we also recorded Secchi disc depths daily at We obtained records of daily flows from the United States Geological Survey (USGS) gauge at Grants Pass (km 164). Activity During 1983, we measured the water depth over spring chinook redds between Rogue Elk Park (km 245) and Cole M. Rivers Hatchery (km 253). Unlike 1982 when we tried to sample several representative sites between these two points, we measured the sill depth (to the nearest 0.5 inch) of every redd we were able to locate within the survey area. We measured 128 redds on 11 October and 21 redds at other sites on 25 October. We estimated the potential for redds to be dewatered by comparing redd depths at the USGS gauge near McLeod (km 248). -3-

7 RESULTS AND DISCUSSION Tasks 1.1 through 1.3. Analyses of changes in temperature, flow, and turbidity are delayed until hydrologic modeling by the USACE is completed. Task 2.1. Catch rates on spring chinook and angler effort in the boat fishery between Grants Pass (km 164) and Savage Rapids Dam (km 172) decreased significantly from the previous year. Angler catch (±95% confidence interval) was (±0.026) chinook per hour in 1982, but only (±0.020) chinook per hour in Angler effort, as indexed by boat counts at 0800, averaged 6.5 (±1.8) boats in 1982 and only 2.2 (±1.0) boats in A decrease in the abundance of spring chinook apparently accounted for the decline in angler success and effort. Escapement estimates over Gold Ray Dam (km 202) by 15 June decreased from 13,933 in 1982 to 4,988 in We used chinook counts only through 15 June because anglers cease fishing this area around 10 June. Multiple regression analyses confirmed the important influence of fish abundance on catch rates and angler effort. Our estimate of chinook abundance in the fishery area accounted for 50% of the variation in weekly catch rates and 69% of the variation in weekly angler effort (Table 1). River temperature, flow, and water clarity did not account for significant (P > 0.05) additional variation. We previously identified the importance of run size on angler catch and effort in other spring chinook fisheries in the Rogue (Cramer et al. 1985). Table 1. Regression analyses of angler catch rate and effort for spring chinook between Grants Pass and Savage Rapids Dam, 1982 and 1983.a Dependent Independent Regression Significance variable N R 2 variables coefficient P Weekly catch rate by boat anglers Fish abundanceb 2.575x Constant 1.230x Weekly mean of boat counts at 0800 hours Fish abundanceb 2.556x Constant a Data listed in Appendix 2. b Estimated chinook passage at Gold Ray Dam 1 week later. In the lower river, catch rates of summer steelhead between Clay Banks (km 7) and Lobster Creek (km 18) were high in comparison with predictions based on indexes of steelhead abundance. We previously demonstrated a positive relationship between weekly catch per hour by anglers and weekly catch per seine haul by researchers (Cramer et al. 1985). But, during August 1983, angler catch rates were significantly higher (P < 0.05) than the predictions we developed using seining catch rates (Figure 1 and Appendix 3). -4-

8 04 r -0-95% CI - PREDICTED CATCH RATE -- OBSERVED CATCH RATE z W, Li w~ I w p (I) O t o U U U U b a a I I AUGUST SEPTEMBER Figure 1. Weekly catch rates of summer steelhead by bank anglers between Clay Banks and Lobster Creek and catch rates predicted from weekly seine catches at Huntley Park, The data are listed in Appendix 3.

9 For example, anglers caught 0.39 steelhead per hour one week in the middle of August. In contrast, we predicted from seine catches that the catch rate should have been 0.18 (±0.14) steelhead per hour for anglers. High flows may have been responsible for the significant differences in the predicted versus observed catch rates of summer steelhead in the lower river fishery during August A natural freshet, in conjunction with flow augmentation from Lost Creek Dam, increased flows at Agness (km 48) to record levels in August. These high flows may have improved angling success; but most likely they decreased the capture efficiency of seining. We cannot yet quantify the influence of flow on angler catch rates. However, anglers in the lower river generally experienced good fishing for summer steelhead during 1983, even though flows were the highest on record. In contrast to the lower river, angling for summer steelhead in the Rogue River canyon (km ) was relatively poor during 1983 compared with previous years. Catches during 1984 were similar to catches in Based on records for from Irvine L. Urie (a fishing guide from Medford, Oregon), anglers guided by his staff caught an average of 11.0 and 11.5 steelhead per boat trip in 1983 and 1984, respectively, compared with 22.8 (±13.9) steelhead per boat trip during Angler success in the Rogue Canyon during 1983 and 1984 may have been reduced by low returns of summer steelhead and high flows that accelerated migration or decreased the efficiency of traditional fly-fishing. Task 3.1. Counts of spring chinook passing Gold Ray Dam were less than 13,000 per year in 1983 and 1984 (Table 2), the lowest since the construction of the counting station in 1942 (Appendix 4). Based on scale analyses, abundance of hatchery spring chinook in 1983 and 1984 was average compared with previous years (Table 2). In contrast, abundance of wild spring chinook dropped significantly compared with prior years. Unlike spring chinook, counts of fall chinook passing Gold Ray Dam during 1983 and 1984 were about average (Table 2). This could indicate that returning fall chinook are ascending beyond where they originated, because carcass counts in areas surveyed near Grants Pass indicate that the spawning escapement of fall chinook below Gold Ray Dam in 1983 and 1984 dropped significantly in comparison to previous years. Estimates of run size at river entry (Table 2), and low counts of spawned carcasses in the Applegate River (personal conversation in January 1985 with Chuck Fustish, ODFW research biologist, Grants Pass, Oregon) confirm that fall chinook returns were down in 1983 and 1984, except for those above Gold Ray Dam. Runs of summer steelhead also appeared low during 1983 and Seine catches at Huntley Park during both years were about 60% of average and escapements past Gold Ray Dam were about 80% of average (Table 2). The count of winter steelhead at Gold Ray Dam in 1984 was 8% higher than the average for the previous nine years (Table 2). Indexes of coho abundance indicated that the run was smaller than average in 1983 and larger than average in 1984 (Table 2). Most of these adults were of hatchery origin. Many adult salmon and steelhead returning in 1983 through 1985 experienced unusual ocean conditions during late 1982 and all of

10 Table 2. Indexes of adult salmonid abundance in the Rogue through runs. River, Species, index through Mean t 95% Ci SPRING CHINOOK Passage count at Gold Ray Dam, 1 March-31 July: Wild fish 21,820 ± 6,433 8,579 6,771 Hatchery fisha 4,803 ± 2,975 3,515 5,318 Total fish 26,623 ± 8,401 12,094 12,089 FALL CHINOOK Run size estimate at Huntley Parkb 50, ,900 19,800 19,600 Spawned carcass counts: km C km ± 130C Passage count at Gold Ray Dam, 16 August-30 November 3,845 ± 1,146 3,839 3,148 SUMMER STEELHEAD Fish/seine haul at Huntley Parkb Passage count at Gold Ray Dam, 16 May-31 December 9, ,340 7,581 7,397 WINTER STEELHEAD Passage count at Gold Ray Dam, 1 January-15 May 8, ,584 9,486 10,462 COHO Fish/seine haul at Huntley Parkb 0.30 ± Passage count at Gold Ray Dam, 15 September-15 January 1,820 ± 2,191 1,493 3,236 Entry count at Cole M. Rivers Hatchery, 1 October-31 January 1,890 ± 2,653 1,352 3,699 a Includes unmarked hatchery fish detected by scale analysis. b Preliminary; weighted by annual estimates of sampling efficiency. c Data from 1979 and 1980 excluded to give a more typical estimate of preimpoundment abundance; extensive prespaowning mortality preceded the months of counting in 1983 and

11 because of the El Nino current. As a result, survival rates of chinook and coho in the ocean were lower than in previous years (Johnson 1984). However, some of this effect on salmon returns was off-set because shortened seasons curtailed harvest in the ocean (Anonymous 1985). Activity Spring chinook migrated past Gold Ray Dam later during 1983 and 1984 than in previous years (Table 3). The passage indexes were outside of the 95% confidence intervals for past years in all cases for adults and in five of eight cases for jacks. Migration appears to have been stimulated by high flow. The migration timing at Gold Ray Dam for fall chinook was late in 1983 and early in 1984 (Table 3). Summer steelhead appeared early and winter steelhead appeared to migrate late in both years. The coho run appeared to be early in 1983 and in Table 3. Migration timing through seasons. of adult salmonids passing Gold Ray Dam, Percent passage by index date Fish category and through index date Mean T 95% CI season season Spring chinook jacks: 31 May 15 ± June 40 ± June 64 ± July 88 ± Spring chinook adults: 31 May 36 ± June 67 ± June 88 ± July 96 ± Fall chinook: 15 September 42 ± Coho: 15 November 66 ± Summer steelhead: 31 October 64 ± Winter steelhead: 15 March 64 ± Activity Few fall chinook died prior to spawning in 1983 and Estimates of mortality rates in previous years averaged 26% and ranged from 3% in 1982 to 76% in 1979 (Cramer et al. 1985). We estimate less than 1% of the run died prior to spawning during 1983 and

12 Activity Adult chinook spawned later in 1983 and 1984 than in previous years in the area between Rogue Elk Park (km 245) and Cole M. Rivers Hatchery (km 252). In earlier years, the average date of recovery of female carcasses was 9 October (±3 days). The average date of recovery was 12 October in 1983 and 16 October in The later time of spawning may be the result of the increase in the relative abundance of fall chinook, which spawn later than spring chinook. Fall chinook composed 23% of the chinook count at Gold Ray Dam in 1983 and 20% of the chinook count in From 1974 through 1982, fall chinook composed an average of 13.3% (±4.9%) of the chinook run. Reduced survival of eggs or fry caused by accelerated incubation of eggs below Lost Creek Dam during (Cramer et al. 1985) may be a selection factor favoring fall chinook or the latest spawners among spring chinook. Such selection may have started to show in the 1983 and 1984 returns to the area above Rogue Elk Park. Activity On 16 December 1982, 18 of the 20 chinook redds found near Cole M. Rivers Hatchery were partially dewatered when outflows from Lost Creek Dam dropped to 480 cfs. We found 1 dead adult summer steelhead and 25 dead juvenile steelhead within the dewatered area. We also excavated 4 redds and found 6 live and 1 dead chinook fry. Live fry were found in standing water within the redds, while the dead fry was found in the dewatered portion of a redd. Water temperature was measured in one partially dewatered redd (6.5C) and dissolved oxygen concentrations were measured in two partially dewatered redds (6.5 ppm and 9.8 ppm). Flows remained below 1,000 cfs for 37 hours during flood control operations. High flows from Big Butte Creek (km 250) prevented redds below Bridge Hole from being dewatered. The depth of redds measured during September and October differed significantly among various spawning areas (Table 4). We noted differences of up to 30 inches in the mean depths of redds (Bridge Hole versus Rogue Elk) during These results emphasize the importance of obtaining a representative sample of spawning areas within a reach of river in order to accurately characterize spawning depths utilized within the reach. Table 4. Between-site comparisons of sill depths (inches) of spring chinook redds sampled between Cole M. Rivers Hatchery and Rogue Elk Park, 1982 and Values along a row without a letter in common were significantly different at P < 0.05 using Duncan's multiple range test. Hatchery Bridge North South OJ OJ Robber's Rogue Bar Hole McLeod McLeod Ranch Channel Roost Elk Year (km 253) (km 250) (km 249) (km 249) (km 248)(km 248) (km 247) (km 245) a b b Oc 13.7a 1983 No redds 4 9.8a No redds 2 4 gb 28.Oc 19.2de bd 18.6e -9-

13 We also noted that redds were significantly deeper in 1983 than in 1982 at the three sites where redds were measured in both years (Table 5). Higher flows during 1983 may partially account for the change. At the time we measured redd depth, flows near McLeod (km 248) averaged 1,791 cfs in 1982 and 1,929 cfs in Also, more spring chinook spawned during 1982 (see Task 3.1). At higher densities, some adults may spawn in shallower areas. Table 5. Between-year comparisons of sill depth (inches) of spring chinook redds sampled between Cole M. Rivers Hatchery and Rogue Elk Park, 1982 and Sill depth Difference Site % CI P Bridge Hole (km 250) ± 9.2 < OJ Ranch (km 248) i 2.1 < OJ Channel (km 248) ± 2.9 < All sitesa ± a Includes 5 sites between km 248 and km 253 in 1982 and 6 sites between km 245 and km 250 in Because spring chinook redds were deeper in 1983 than in 1982, fewer would have been dewatered for a specific drop in flow (Figure 2). We estimate that a 10-inch drop in flow near McLeod would have dewatered about 7% of the redds in 1982, but only 3% of the redds in The river can drop 10 inches if spring chinook spawn at flows of about 1,400 cfs and outflows from Lost Creek Dam drop to 700 cfs (and the flow is 100 cfs in Big Butte Creek) during conservation storage season in the succeeding spring. Activity The mean lengths of wild spring chinook that returned in 1983 at ages 31 to 51 were similar to those of fish that returned in , but fish that returned in 1984 were 3.9 to 7.0 cm shorter at a given age than fish in previous years as follows: Age Mean + 95% CI ± ± The shorter lengths of fish were the result of less growth in the ocean during 1983 compared with The growth difference was determined from radius measurements (millimeters at 88X magnification) on scale segments that represented growth in the ocean prior to return for spring chinook that -10-

14 100 loo~~~~~~~~~~~~~~~~~~~~ -._ LIi w60 U) Iin c DROP IN WATER LEVEL (INCHES) Figure 2. The relationship between potential dewatering of spring chinook redds upstream from Rogue Elk Park and drop in river level near McLeod, 1982 and The curves were drawn by eye using data on sill depths of redds from all sites sampled each year (Appendix 5). 0

15 returned during 1984 and as follows: Age and scale segment Mean + 95% CI : ocean entry to annulus : annulus 1 to annulus ± : annulus 2 to annulus : annulus 3 to annulus ± Reduced growth in the ocean was the result of the El Nino current that reduced growth in many chinook and coho stocks from Oregon during 1983 (Johnson 1984). Apparently El Nino did not have a significant effect on growth in 1983 until after spring chinook of ages 31 to 51 left the ocean for the river, primarily in April and May. Spring chinook that returned to the Rogue River at ages 31 to 51 had average growth during the spring prior to entering the river in 1983 compared with previous years. Spring chinook that returned at age 21 in 1983 were an exception. They may have been exposed to different ocean conditions than older fish because they always return to the river later than older age fish (Cramer et al. 1985). Age 21 fish were 3.1 cm shorter in 1983 than the mean length for previous years, yet they were only 1.2 cm shorter in 1984 than previous years. The shorter length of age 21 spring chinook that returned in 1983, and their below-average growth in the spring preceding return, suggests that El Nino began affecting growth of Rogue chinook in late spring. The lack of a major decrease in length of age 21 spring chinook that returned in 1984 suggests that effects of El Nino were diminishing when these fish entered the ocean in late summer or fall of Additionally, age 21 fish returned to the river later than older age fish, possibly benefiting longer from improved ocean conditions in Wild fall chinook sampled at Huntley Park in 1983 and 1984 were significantly shorter than the mean length (centimeters) for previous years as follows: Age Mean t 95% CI ± ± ± Mean radius measurements (millimeters at 88X magnification) on the scale segment from annulus formation to river entry, which represented ocean growth -12-

16 during spring and summer prior to river entry, were significantly less in 1983 than the mean of previous years as follows: Age Mean + 95% CI ± 9.8 ± 5.7 ± 7.5 ± Radius measurements (millimeters at 88X magnification) on scale segments that represented growth in the ocean the year prior to return for fall chinook that returned during 1984 compared with returns in also show that ocean growth in 1983 was poor compared with : Age and scale segment Mean ± 95% CI Ocean entry to annulus 1 31 Annulus 1 to annulus 2 41 Annulus 2 to annulus 3 51 Annulus 3 to annulus ± ± 90.6 ± 73.1 ± The radius measurement that represented growth of age 21 fall chinook in the ocean during the fall (ocean entry to annulus 1) was not significantly less (P > 0.05) for fish that returned in 1984 compared with the mean of past years, possibly because El Nino's effects on growth were diminishing in the fall of Thus, El Nino's effect on length of fall chinook should be minor for the entire 1982 brood, but may show an effect on the 1980 and 1981 broods for each age at which they return. The mean length (centimeters) of returning steelhead that had smolted at ages 1 and 2 and returned in 1983 was similar to lengths in past years for each life history group of wild summer steelhead sampled at Huntley Park: Life history and age at smolting Mean + 95% CI 1983 Half-pounder: 1 2 1st spawning migrant: 1 2 2nd spawning migrant: ± ± ± ± ±

17 No 1st or 2nd spawning migrants that had smolted at age 3 were collected and the six half-pounders that had smolted at age 3 returned at lengths similar to fish in past years. Radius measurements taken on scales of age 2 half-pounders and 1st spawning migrants indicated that ocean growth during 1983 was similar to past years. Apparently, steelhead growth was not limited by El Nino. Similar results were seen in other Oregon stocks of steelhead (personal conversation in January 1985 with Nancy MacHugh, ODFW research biologist, Corvallis, Oregon). The reason that steelhead were not affected has not been determined. Activity The age composition of* wild spring chinook in 1983 and 1984 exhibited some significant differences, from the mean of past years (Table 6). Reasons for the significant (P < 0.05) ) differences from the age composition have not been determined yet. Adults produced from yearling migrants (ages 32 to 62) continued to be a small part of the run (Table 6). Table 6. Age Dam, composition (percent) of wild spring chinook sampled at Gold Ray Age Mean 95% CL Younger spawners have been produced by the first three broods of wild spring chinook reared after dam closure ( broods). The mean age at return of the broods of wild spring chinook ( years) were younger than the mean for the broods (3.84 ±0.21 years). Data from all broods (Appendix 6) indicate that the mean age at return for a brood is negatively correlated to the average spacing of freshwater circuli on adult scales from that brood (r = -0.70, P < 0.05). Mean age at return was not correlated to size or time at ocean entry (P > 0.05). This suggests that wild spring chinook from broods that have faster growth rates in freshwater may return at a younger average age, even if they do not reach a larger size before entering the ocean or if they enter the ocean at an earlier date. However, until we can account for ocean harvest at each age on each brood, we can't be sure. The percentages of age 31 fish among wild fall chinook in 1983 and 1984 were larger than the mean for previous years (Table 7). Reasons for the abundance of age 31 fish have not yet been determined. -14-

18 Table 7. Age composition (percent) Park, of wild fall chinook sampled at Huntley Age Mean 95% CL < The percentage of fish in each life history category of steelhead sampled at Huntley Park in 1983 was similar to the years as shown below: Life history type Mean 95% CL 1983 wild summer mean for previous Half-pounders 1st spawning migrants 2nd spawning migrants 3rd spawning migrants Other life histories The 1983 summer steelhead run contained a significantly higher percentage of half-pounders and a significantly lower percentage of first spawning migrants (P < 0.05); however, these percentages are within the range of annual means for Reasons for the 1983 results have not yet been determined. Activity Chinook fry in the upper Rogue completed times intermediate to previous years as shown here: emergence at Station Mean ± 95% CI Sand Hole High Banks 16 May ± 15 days 17 Apr + 18 days 11 May 4 May 12 Apr Mean length of fry was 5.2 cm on the first day when mean lengths continuously exceeded 4.5 cm at Sand Hole in 1984, so no emergence completion date is given. From 1978 through 1982, chinook fry emerged earlier than before 1978 because of higher water temperatures during the period eggs and sac-fry incubated in the gravel (Cramer et al. 1985). Completion of emergence in 1983 and 1984 may have been accelerated less than in other years after dam -15-

19 closure because (1) water temperatures were lower, (2) more fall chinook (later spawners than spring chinook) may have spawned in the upper Rogue (see Activity 3.31), or (3) the returns may have undergone selection favoring later spawning among spring chinook (see Activity 3.31). Activity Migrant chinook trapped in the middle Rogue during 1983 and 1984 were significantly larger than in previous years. Subyearlings captured at Savage Rapids Dam on 15 July in 1983 and in 1984 averaged 10.5 cm and 11.5 cm, respectively. Migrants trapped on 15 July during averaged 9.7 (±0.6) cm. The large subyearlings captured in 1984 may have included some unmarked hatchery chinook (released in June at a larger size than wild fish) that we were unable to distinguish from wild chinook. Subyearlings were larger by 15 July in 1983 compared with the average for previous years; however, scale analyses suggested growth was below average in Scale measurements indicative of growth rate in spring (band width 1 on spring, summer, and total collections and average circuli spacing on the spring collection) were less than the means for these measurements in previous years (Table 8). A similar comparison could not be made with 1984 data because trapping of juveniles at Table Rock and analysis of juvenile scales for growth indexes was discontinued after Because the growth rate index for summer (band width 2) was above average in 1983, the growth rate indexes for spring and summer combined (average cirucli spacing on summer and total collection) were not significantly less (P > 0.05) than the means for previous years (Table 8). The slower growth rate during the spring may have resulted from the higher flows and decreased river temperatures during the above-average run-off in 1983, based on correlations in previous years (Cramer et al. 1985). The above-average size of subyearlings by 15 July cannot be explained by between-year differences in emergence timing (see Activity 4.11), and is not yet understood. Table 8. Width of the first two bands of circuli and average intercircular spacing (millimeters at 88X magnification) on scales from subyearling chinook sampled at Table Rock, 1983 compared with a Averge circuli Band width 1 Band width 2 spacing Collection season Mean i 95% CI 1983 Mean + 95% CI 1983 Mean + 95% CI 1983 Springb i i Summerc Total i ± ± a No scales were sampled in 1982 and b Calculated from scales collected prior to 1 June. c Calculated from scales collected after 31 May. Band widths 1 and 2 and average circuli spacing on scales of wild spring chinook of all ages that returned in 1983 and in 1984 were generally larger than the means for these measurements in previous years (Table 9). Twenty of the twenty-four indexes of freshwater growth on scales of fish that returned -16-

20 . Table 9. Width of the first two bands of cirucli and average intercircular spacing (millimeters at 88X magnification) on the freshwater portion of scales from adult spring chinook sampled at Gold Ray Dam, Age Band width Mean + 95% Cr ± ± ± ± Band width Mean I 95% CT ± ± ± ± Average cirucli spacing Mean t 95% CI ± ± ± ± Table 10. Width of the first two bands of circuli and average intercircular spacing (millmeters at 88X magnification) on the freshwater portion of scales from adult fall chinook sampled at Huntley Park, Age x Band width Mean + 95% CI ± ± ± ± Band width Mean + 95%TCT ± ± ± e Average cirucli spacing Mean t 95% CI ± ± ± ±

21 in 1983 and in 1984 (all reared in postimpoundment conditions) were above the 95% confidence limits for the means (representing mostly preimpoundment rearing). Similarly, band widths 1 and 2 and average circuli spacing on scales of fall chinook of all ages that returned in 1983 and in 1984 were generally larger than the means for these measurements in past years (Table 10). Sixteen of the twenty-four indexes of freshwater growth on scales of fish that returned in 1983 and in 1984 were above the 95% confidence limits for means and only three of the twenty-four indexes were below the 95% confidence limits. Growth rate during the entire period of freshwater residence (indexed by average spacing) of all fish that returned in 1983 and in 1984 were larger than the mean of previous years (except age 2 fish that returned in 1984), and six of the eight measurements were above the 95% confidence limits for the means. Increases in fish length between times when each freshwater annulus was formed on scales were larger for each smolt age among half-pounder summer steelhead that returned in 1983 than the mean of those that returned in (Table 11). The larger increases in length may be the result of increased flows and decreased water temperatures in the summers of , because this correlation was established with data from previous years (McPherson and Cramer 1983). Although this earlier relationship was significant (P < 0.05) for age 1 smolts only, we believe that it is true for all smolts. The amounts of increase in length during the spring prior to smolting (plus-growth) were significantly less in 1983 than the means for (Table 11). The below average plus-growth probably resulted from higher flows and lower water temperatures during the spring of 1983, because we earlier established a correlation with data from earlier years (McPherson and Cramer 1983). Although this earlier relationship was significant (P < 0.05) for age 2 smolts only, we believe that it is true for all smolts. -18-

22 Table 11. Increase in fish length (centimeters) between each freshwater annulus and during plus-growth in the spring as determined from scales of wild steelhead half-pounders collected at Huntley Park, Annulus 1 to Annulus 1 annulus 2 Smolt age Mean I 95% CI 1983 Mean t 95% CI ± i ± Annulus 2 to annulus 3 Plus-growth Smolt age Mean ± 95% Cl 1983 Mean I 95% CI ± ± ± ± Activity The abundance of wild spring chinook fry appeared to be low in 1983 and 1984 compared with previous years. Mean catch rates of juveniles one month after emergence completion at Sand Hole and High Banks combined averaged 425 (±300) fry per seine haul from 1976 through In 1983 and 1984, catch rates were only 233 and 164 fry per seine haul, respectively. Our abundance index of wild spring chinook smolts migrating to the ocean dropped significantly in 1983 and This index is the trapping rate of subyearling chinook at Savage Rapids Dam weighted for the change in trap efficiency at differing flows (Cramer et al. 1985). The index of smolt abundance was 3,865 in 1983 and 1,013 in From 1974 through 1982, the abundance index averaged 15,708 (±10,685) annually. In 1984, we needed to exclude unmarked hatchery fingerlings from the index of wild smolt abundance because some hatchery fish were released in June instead of October. We excluded the unmarked hatchery fish from the index by expanding the number of marked fish trapped according to the ratio of marked to unmarked chinook at the time of release from Cole Rivers Hatchery. Unlike juvenile spring chinook, the abundance of juvenile fall chinook appeared to be average in 1983 and above average in Catch rates at Matson and Almeda combined averaged 75 and 108 subyearlings per seine haul in 1983 and 1984, respectively. From 1975 through 1981, catch rates of juvenile chinook at these sites averaged 83 (±45) subyearlings per seine haul (Cramer et al. 1985). -19-

23 The abundance of subyearling steelhead appeared lower than in previous years. We caught an average of 7.8 subyearlings per seine haul at Matson, Almeda, Whiskey, and Winkle combined during Between 1975 and 1981, catch rates averaged 13.3 (±6.4) young of the year per seine haul. The Whiskey and Winkle sites were not sampled in 1982 and The decrease in average catch rate during 1984 was greatly infuenced by the highly significant (P < 0.01) drop in catch rate at Winkle, where we caught only 0.9 subyearlings per seine haul. Catches in previous years averaged 8.4 (±2.6) subyearlings per seine haul. Catch rates did not drop significantly (P > 0.05) at any other site. Activity The downstream migration of subyearling chinook appeared late compared with previous years. Indexes of the weekly abundance of chinook passing Savage Rapids Dam indicated that only 17% and 26% of the migrants passed as of 15 July in 1983 and in 1984, respectively. From 1974 though 1982, we estimated an average of 34% (±15%) of the downstream migrants passed the dam by 15 July (Cramer et al. 1985). The late migration was apparently related to low water temperatures during the spring, based on a correlation established by Cramer et al. (1985) with data from previous years. The mean dates of ocean entry chinook adults sampled at Gold Ray mean dates of those sampled during determined from scales of wild spring Dam in 1983 and in 1984 were earlier than as follows: Age Mean t 95% CI Aug ± 10 days 31 4 Sep ± 11 days 41 4 Sep ± 17 days 51 8 Sep ± 21 days 9 Aug Aug Aug Sep Aug Aug Aug Aug 1980 Six of the eight mean dates determined from fish that returned in 1983 and 1984 were earlier than the 95% confidence limits for the mean dates. This earlier date of ocean entry may have been caused by improved freshwater growth (see Activity 4.12), which would allow fish to reach threshold smolt size earlier. The dates of ocean entry determined from scales of wild fall chinook adults sampled at Huntley Park in 1983 and in 1984 compared with the means of those sampled during are as follows: Age Mean t 95% CI Sep ± 10 days 31 3 Sep ± 14 days 41 5 Sep ± 10 days Sep ± 15 days 1 Sep Aug Aug Sep Sep Aug Aug Jul

24 The mean dates of ocean entry for fall chinook that returned at age 31 in 1983 and at age 41 in 1983 and in 1984 were significantly earlier than the mean dates of age 31 and age 4 1 fish sampled in Age 21 fish entered the ocean on similar dates in all years. Age 51 fish that returned in 1983 and in 1984 had small sample sizes of 5 and 8, respectively, which precluded comparisons with age 51 fish from past years. Summer steelhead that returned in 1983 included a lower pecentage of fish that had smolted at age 3 compared with previous years (Table 12). The percentages of age 3 smolts that returned as half-pounders and as 1st and 2nd spawning migrants in 1983 were at or below the 95% confidence limits for the means. This may be the result of improved freshwater growth (see Activity 4.12) that allowed steelhead to reach threshold smolt size at a younger age. The age at smolting for all life histories indicates that the decrease in percentage of age 3 smolts resulted in a similar increase in the percentage of age 2 smolts. Table 12. Smolt age composition at Huntley Park, (percent) of summer run steelhead collected Life history group and age at smolting Mean 95% CL 1983 Half-pounders: st spawning migrants: nd spawning migrants: All life histories: Activit The mean lengths of juvenle chinook at ocean entry (centimeters determined from scales of wild spring chinook sampled as adults -21-

25 at Gold Ray Dam in 1983 and in 1984 were generally larger than in previous years: Age Mean t 95X CI ± 0.55 ± 0.66 ± 0.69 ± Similarly, mean lengths at ocean entry (centimeters) determined wild fall chinook sampled as adults at Huntley Park in 1983 and generally larger than in previous years: Age Mean + 95% CI 1983 from scales of in 1984 were ± ± ± ± These larger sizes at ocean entry reflect the higher growth rates detected on the juvenile portions of adult scales from the 1983 and 1984 runs of spring and fall chinook (see Activity 4.12). Mean lengths of juvenile steelhead scales of half-pounder summer steelhead similar to mean lengths of fish sampled at ocean entry (cm) determined from sampled at Huntley Park in 1983 were during as follows: Age at smolting IMIean 95% Cl ± ± ± The lengths at ocean entry were similar to those of past years despite improved annual growth because plus-growth in the spring prior to smolting was less in 1983 than in past years (see Activity 4.12). -22-

26 ACKNOWLEDGEMENTS The following people assisted with the collection and summarization of data during FY 1983 and FY Many contributed ideas that improved the quality of the program. Randy Baxter Rob Buckmister Steve Criss Ted Daum Dave Haight Ray Hartlerode Steve Stone Ron Boyce Tom Gentry Dave Lehnhardt Rick Madigan Steve Marx Kathy Marcy Dick Palen Al Van Dyke Mike Wallace We would also like to thank Al Smith, Mick Jennings, George Westfall, Al Mirati, and Rik Riikula of the Southwest Region of ODFW for providing periodic assistance with field work. We owe thanks to Mary Buckman for advice on statistics and scale analysis, Wayne Burck for editorial assistance, Jan Ehmke for word processing, Judy Siddon and Lori Turner for typing, and Kathryn Torvik for graphics. -23-

27 REFERENCES Anonymous Rogue Basin fisheries evaluation program, juvenile salmonid, water quality, and laboratory studies. Oregon Department of Fish and Wildlife, Fish Research Project DACW57-75-C-0109, Annual Progress Report, Portland, Oregon, USA. Anonymous ocean salmon fisheries review. Pacific Fisheries Management Council, Annual Review Report, Portland, Oregon, USA. Cramer, S.P. 1979a. Rogue Basin fisheries evaluation program, adult and juvenile salmonid, water quality and hatchery evaluation studies. Oregon Department of Fish and Wildlife, Fish Research Project DACW57-77-C-0027, Annual Progress Report, Portland, Oregon, USA. Cramer, S.P. 1979b. Rogue Basin fisheries evaluation program, adult and juvenile salmonid, water quality and hatchery evaluation studies. Oregon Department of Fish and Wildlife, Fish Research Project DACW57-77-C-0027, Annual Progress Report, Portland, Oregon, USA. Cramer, S.P., and J.T. Martin, editors. 1978a. Rogue Basin fisheries evaluation program, juvenile salmonid and water quality studies. Oregon Department of Fish and Wildlife, Fish Research Project DACW57-75-C-0109, Annual Progress Report, Portland, Oregon, USA. Cramer, S.P., and J.T. Martin, editors. 1978b. Rogue Basin fisheries evaluation program, juvenile salmonid studies. Oregon Department of Fish and Wildlife, Fish Research Project DACW57-75-C-0109, Annual Progress Report, Portland, Oregon, USA. Cramer, S.P., and J.T. Martin, editors. 1979a. Rogue Basin fisheries evaluation program, adult salmonid and water quality studies. Oregon Department of Fish and Wildlife, Fish Research Project DACW57-77-C-0027, Annual Progress Report, Portland, Oregon, USA. Cramer, S.P., and J.T. Martin, editors. 1979b. Rogue Basin fisheries evaluation program, juvenile salmonid studies. Oregon Department of Fish and Wildife, Fish Research Project DACW57-77-C-0027, Annual Progress Report, Portland, Oregon, USA. Cramer, S.P., and J.T. Martin, editors. 1979c. Rogue Basin fisheries evaluation program, adult salmonid and spawning gravel studies. Oregon Department of Fish and Wildlife, Fish Research Project DACW57-75-C-0109, Annual Progress Report, Portland, Oregon, USA. Cramer, S.P., and B.P. McPherson, editors Rogue Basin fisheries evaluation program, juvenile salmonid studies. Oregon Department of Fish and Wildlife, Fish Research Project DACW57-77-C-0027, Annual Progress Report, Portland, Oregon, USA. Cramer, S.P., and B.P. McPherson, editors. 1981a. Rogue Basin fisheries evaluation program, adult salmonid studies. Oregon Department of Fish and Wildlife, Fish Research Project DACW57-77-C-0027, Annual Progress Report, Portland, Oregon, USA. -24-

28 Cramer, S.P., and B.P. McPherson. 1981b. Rogue Basin fisheries evaluation program, adult and juvenile salmonid and water quality studies. Oregon Department of Fish and Wildlife, Fish Research Project DACW57-77-C-0027, Annual Progress Report, Portland, Oregon, USA. Cramer, S.P., and B.P. McPherson Rogue Basin fisheries evaluation program, adult and juvenile salmonid and water quality studies. Oregon Department of Fish and Wildlife, Fish Research Project DACW57-77-C-0027, Annual Progress Report, Portland, Oregon, USA. Cramer, S.P., and B.P.- McPherson, editors Rogue Basin fisheries evaluation program, adult salmonid studies. Oregon Department of Fish and Wildlife, Fish Research Project DACW57-77-C-0027, Annual Progress Report, Portland, Oregon, USA. Cramer, S.P., T.D. Satterthwaite, R.R. Boyce, and B.P. McPherson Rogue Basin fisheries evaluation program, impacts of Lost Creek Dam on the biology of anadromous salmonids in the Rogue River, Volume I. Oregon Department of Fish and Wildlife, Fish Research Project DACW57-77-C-0027, Phase I Completion Report for Lost Creek Dam Evaluation, Portland, Oregon, USA. Ewing, R.D., S.L. Johnson, H.J. Pribble, and J.A. Lichatowich Rogue Basin fisheries evaluation program, Rogue River spring chinook smolt study. Oregon Department of Fish and Wildlife, Fish Research Project DACW57-75-C-0109, Final Smolt Study Report, Portland, Oregon, USA. Johnson, S.L The effects of the 1983 El Nino on Oregon's coho and chinook salmon. Oregon Department of Fish and Wildlife, Information Reports (Fish) 84-8, Portland, Oregon, USA. Lichatowich, J.A Rogue Basin evaluation program, quarterly report. Oregon Department of Fish and Wildlife, Fish Research Project DACW57-75-C-0109, First Quarterly Report, Portland, Oregon, USA. Lichatowich, J.A. 1975a. Rogue Basin fisheries evaluation program, quarterly report. Oregon Department of Fish and Wildlife, Fish Research Project DACW57-75-C-0109, Second Quarterly Report, Portland, Oregon, USA. Lichatowich, J.A. 1975b. Rogue Basin fisheries evaluation program, quarterly report. Oregon Department of Fish and Wildlife, Fish Research Project DACW57-75-C-0109, Third Quarterly Report, Portland, Oregon, USA. Lichatowich, J.A. 1975c. Rogue Basin fisheries evaluation program, quarterly report. Oregon Department of Fish and Wildlife, Fish Research Project DACW57-75-C-0109, Fourth Quarterly Report, Portland, Oregon, USA. Lichatowich, J.A Rogue Basin fisheries evaluation program, adult and juvenile salmonid field studies, and smolt physiology studies. Oregon Department of Fish and Wildlife, Fish Research Project DACW57-75-C-0109, Annual Progress Report (Part 1), Portland, Oregon, USA. -25-