Temporal and spatial habitats of anadromous brook charr in the Laval River and its estuary

Transcription

1 Environ Biol Fish (6) 76: DOI.7/s ORIGINAL PAPER Temporal and spatial habitats of anadromous brook charr in the Laval River and its estuary R. Allen Curry Æ Jacob van de Sande Æ Frederick G. Whoriskey Jr. Received: 19 April 5 / Accepted: March 6 / Published online: 3 June 6 Ó Springer Science+Business Media B.V. 6 Abstract Anadromy in brook charr occurs across the species range, but few studies have examined contiguous seasonal movements and habitat utilization of freshwater and estuarine environments. We used acoustic telemetry to track movements of anadromous brook charr for 1 year in the Laval River, Quebec. Fish entered the marine environment in May and June, inhabited shallow (< 1.7 m), near-shore areas (< 5 m from shore), and rarely ventured beyond the headlands of the bay. They were found where salinities were 1 34 ppt and temperatures 5 18 C. There was a strong tidal periodicity to observed movements with fish running up into bays as they became inundated at high tide and then returning to deep river channels in the bays at low tide. Between late July and early September, the charr returned to freshwater and spawned in the middle R. Allen Curry (&) Æ J. van de Sande New Brunswick Cooperative Fish and Wildlife Research Unit, Canadian Rivers Institute, Biology Department, University of New Brunswick, NB E3B 6E1 Fredericton, Canada racurry@unb.ca J. van de Sande Downeast Salmon Federation, 187 Main Street, P.O. Box 7, Columbia Falls, ME 4623, USA F. G. Whoriskey Jr. Atlantic Salmon Federation, P O. Box 5, E5B 3S8 St Andrews, NB, Canada and upper sections of the river in October and November. Winter habitats were dispersed over 22 km of the river including two lakes. These detailed observations are an important contribution to our understanding of the evolutionary significance of anadromy in this species. The salinity and temperature co-tolerance provides insights into the species post-glacial dispersal, present-day distribution, and potential habitat maps for conservation, restoration, and enhancement programmes. Keywords Brook charr Æ Estuary Æ Salinity Æ Temperature Æ River Æ Winter Introduction The adaptive reasons for anadromy in salmonids most probably relate to more abundant food resources in marine habitats and the requirement for freshwater incubation environments (e.g., Gross et al. 1988). For brook charr, Salvelinus fontinalis, of northeastern North America, marine life is restricted to the spring-fall, open water season, but the periods they exploit marine habitats vary among populations. Northern populations of Quebec including the northshore of the St. Lawrence River typically move from freshwater to their home river estuaries in late April-May and return to freshwater in

2 362 Environ Biol Fish (6) 76: August-September (e.g., Dutil and Power 198; Naiman et al. 1987; Montgomery et al. 199; Lenormand et al. 4). The seaward movement appears to be a function of spring freshets (discharge and temperature) and can be rapid lasting a few days or protracted over five weeks (Naiman et al. 1987; Montgomery et al. 199). Time in salt water varies from 9 to 15 days and this period clearly enhances growth over freshwater brook charr (Dutil and Power 198; Whoriskey et al. 1981; Naiman et al. 1987). Mature brook charr that return to the river appear to require a period of freshwater residence to achieve in-year gonad development, i.e., final ripening, particularly for males (Power 198; Whoriskey et al. 1981; McCormick and Naiman 1984). The fresh water and winter habitats are unknown for northern populations. Similar patterns are observed in populations farther south, although the timing varies and the periods of marine residence are expanded. In the Gaspé region of the southeastern St. Lawrence River and northern New Brunswick, brook charr enter estuaries in early spring and return to freshwater primarily in June and early July with some later returns in August for Gaspé rivers (St. Jean River Castonguay et al. 1982; Petite Cascapedia, Restigouche, and Miramichi rivers R.A. Curry, unpublished data). Duration at sea appears to be < days. In the St. Jean River, winter habitats were the lowest reaches of the river adjacent to the marine environment (Castonguay et al. 1982). On Prince Edward Island (Gulf of St. Lawrence) where rivers are relatively short (< km), and brook charr smaller (< 4 cm fork length), Smith and Saunders (1958) observed movements between fresh water and the brackish estuary throughout the year with the most pronounced movements seaward from October to December and returning to fresh water from April to early July. Marine residence extended over several months and included winter habitats. Farther south along the Atlantic Ocean coast of Nova Scotia, brook charr in the Moser River moved down and into the estuary from April-early June and spent an average of 65 days in the marine environment before they returned to the river primarily in July (White 1941, 1942). They were observed in several fresh water locations during winter. In the Kennebecasis River, a tributary to the Saint John River, NB, both post-spawn adults and juveniles moved down to the lower, freshwater reaches in November-December where they wintered and returned upstream from April-early July with only rare trips to the brackish estuary where they swam through the freshwater lens, < 5 ppt, to visit another river (Curry et al. 2). Inhabiting a marine environment most probably imparts a significant fitness challenge for brook charr because of their relatively poor osmoregulatory ability (McCormick 1994) and dependence on a minimum period of freshwater residence to complete gonad development (McCormick and Naiman 1984). We can also hypothesize that fitness will be enhanced for anadromous brook charr because growth increases in marine environments (Whoriskey et al. 1981; Gross et al. 1988) and body size is positively correlated with reproductive success (van den Berghe and Gross 1986; Blanchfield and Ridgway 1999). These conflicts related to fitness are exemplified by anadromous and resident forms existing in sympatry (Rogers and Curry 4), populations that do not migrate to sea when it is accessible (Curry et al. 2), and the highly variable marine residence times among populations. At present, we know that brook charr are rarely captured outside their home river s estuary beyond several kilometers, capture sites have reported salinities averaging 16 ppt, and duration of residence can vary from days to 4+ months. This information comes from static sampling based on netting and fishing techniques in estuaries and rivers. We have yet to continuously observe individuals moving between marine and freshwater environments and therefore describe actual habitats. The latter information is necessary if we are to resolve the observed variability within tactics and generate meaningful hypotheses about the evolutionary significance of anadromy in this species. We used passive and active acoustic telemetry to identify spatial and temporal changes between freshwater and marine environments in the anadromous population of brook charr of the Laval River, Quebec. Our objective was to describe their selected habitats to determine where fitness advantages and challenges potentially exist and better understand the evolutionary significance of anadromy for the species.

3 Environ Biol Fish (6) 76: Materials and methods The Laval River ( N, W) flows south and empties into the St. Lawrence River near Forestville, Quebec, Canada (Fig. 1). The main stem of the river is 67 km long with 47 km accessible to migrating fishes. The watershed is predominantly forested with some timber harvesting. The river has a 16 km 2 estuary with two distinct bays separated by rocky headlands (Laval and Plongeur; Fig. 2). The bays are shallow (< 3 m deep at high tide) with large portions exposed as mud flats during low tides. Between the islands there are 2 4 m deep channels at low tide. Outside the bays < 4 km offshore, the St. Lawrence River channel drops to >3 m deep. Surface water temperature in the estuary averages 8 C with salinities of 25 3& from May to September, while offshore water temperatures are 1 C and salinities >3& at a depth of 5 m in the channel (Department of Fisheries and Oceans Canada, ocean/gsl/gslmap.html). The river supports a population of Atlantic salmon, Salmo salar, but is best known for its population of large anadromous brook charr, known as sea trout. Four groups of brook charr were captured and tagged. The first two groups were captured by angling in the lower, freshwater reaches of the river (single, barbless hooks; n = 4 charr) from 14 May to 13 June 1999 and short-term gill netting in the estuary from 14 May to 13 June (< min set of m 2 m cm stretched mesh size, monofilament; n = 17). A fish counting fence 4 km from the river mouth was installed and operated by ZEC Forestville and provincial agencies from 5 June to 31 August 1999 (Fig. 1). An additional 16 charr were captured and implanted with acoustic transmitters at the counting fence (5 19 August). From September 1999, another 11 charr were captured in the middle section of the river by angling. For all charr, Vemco 12a acoustic tags were surgically implanted following the combined protocols of Hart and Summerfelt (1975), Summerfelt and Smith (199), and McKinley and Power (1992). Tags were < 2% total body weight of individual charr and the manufacturer s specified tag life was minimum one year (Table 1). On May, three Vemco VR1 remote receiving units were deployed in the lower river (3 m deep) and eight across the mouths of two bays forming the estuary (Fig. 2). The estuary receivers were deployed in 4 5 m of water and not exposed during low tides. The 9% omni-directional reception range of a receiver is 25 m and Fig. 1 The Laval River on the northshore of the St. Lawrence River, Quebec Canada with locations of acoustic receivers deployed from August 1999 to June

4 364 Environ Biol Fish (6) 76: Fig. 2 Locations where brook charr were observed in relation to tidal cycles in the Laval River estuary from May to August Locations of acoustic receivers are indicated (the closest adjacent estuary was km to the east) Table 1 Characteristics of brook charr tracked in the Laval River and its estuary from 1999 to including days tracked and location of initial tagging site in the river: 21 brook charr were tagged in May (exiting river), 16 in August (entering river), and 11 in September (in river) 1999 Fork length (cm) Wet weight (g) Days tracked Initial tagging (km from river mouth) Average Minimum (estuary) Maximum SD N therefore receivers were deployed every 5 m at the outer edge of the estuary to detect any charr moving across this boundary. From May to early August, there was an array of 11 receivers in the lower river and estuary. The closest bay beyond the Laval River was km east where a 12th receiver was also deployed (Fig. 2). By early August, charr were returning to the river and thus six of nine receivers from the marine habitats were re-deployed to the river (13 19 August). Three units remained in the estuary (east, central, and west) until October. From October to June (), 12 units were deployed in the river including one in the main channel of the estuary at the river mouth. From 1 June to 15 August 1999, active tracking by boat with a Vemco VR6 portable hydroacoustic receiver occurred throughout the estuary daily (weather permitting). Laval Bay, Plongeurs Bay, and adjacent near-shore waters were divided into nine sectors, with tracking effort being distributed evenly between sectors at different tide levels. Each sector was then divided into a 25 m grid and transects were run stopping and monitoring for 1 seconds every 25 m. Time, date, temperature, depth, salinity, and GPS coordinates were recorded upon locating individual charr. Depth was determined with an electronic depthsounder; temperature and salinity were recorded with an YSI 3 meter, and location was recorded with a Garmin GPS 12XL GPS unit. Temperature and salinity measurements were taken.5 m above substrate, at half the depth of the water column, and.5 m below the surface. The shallow depth of the bays resulted in a homogenous water column and the three temperatures and salinities are reported as averages herein. From 15 August to 28 October 1999, active tracking along the river occurred daily or weekly. Spawning activity was monitored by visual

5 Environ Biol Fish (6) 76: observation of redd construction and active spawning. Active tracking through holes cut in the ice was conducted once in winter (February) from Lac à Jacques downstream to the estuary. In June, eight of the twelve receivers were retrieved and downloaded. Four were lost due to over-winter ice and water conditions. Vemco TR thermographs were attached to four VR1 receivers in the river and recorded hourly temperatures from 15 May 1999 to 5 April. Two were deployed in pools >3 m depth in the main stem, one at the outlet of Lac á Jacques (4 m deep), and one near the outlet of Lac aux Pin (8 m deep Fig. 1). Because the recorders ceased functioning in early April, we used Environment Canada s daily air temperature data from Baie Comeau ( km to the east) to predict the river temperatures into May (regression of river temperatures on air temperature for each recorder; r 2 s >.8, p s <.5). One thermograph was placed on a central receiver in estuary, May to 15 August 1999 (5 m deep). Active tracking location data was plotted in ArcView (ESRI Inc.) for analysis and representation. Data from individuals tracked for < 3 days were used to support our analysis of seasonal use of selected habitats, but not used for determination of inter-individual variation in habitat preferences for temperature and salinity. Results On 13 May 1999 the average daily river temperature was 4.5 C, on May 13. C, and on 13 June >. C. The river remained warm throughout the summer (>. C on 51 of 78 days, 13 June to 31 August). During the same period, temperatures in the estuary where brook charr were located were C (1 SD, range = C). The four brook charr tagged in the river in May 1999 (%) were detected in the estuary within nine to 21 days following their release (average = 12.5 days). Based on angling records for the river and estuary (ZEC Forestville, unpublished data) and high river temperatures, we believe that all anadromous brook charr had entered the estuary by 13 June Not all tags were located repeatedly in the estuary for a variety of reasons. Nonetheless, active tracking in the estuary produced 148 data points from 19 of 21 individual charr (7 June to 2 August). Individuals were detected in the estuary an average of days. One charr was tracked from the spring (river implantation) through the summer (estuary) through spawning in the fall (river); three additional charr were tracked for the full duration of the summer (estuary) and detected in the river during fall. During the summer, 16 tagged individuals were lost to a combination of legal angling (n =2 confirmed and 6 suspected), predation by seals (active in estuary at low water levels), and possible tag loss or tag-related or other mortality. Brook charr moved extensively within Laval Bay and eight individuals moved regularly into Plonguers Bay (Fig. 2). The maximum period spent in the estuary was 98 days. Rarely did charr move beyond the headlands to areas outside the bays. Only one individual was recorded > m from the bays; it was found km west of Laval Bay near the mouth of the Cochon River (< 5 m from shore; Fig. 2), and it was detected ascending the Laval River in the fall. There was a strong tidal periodicity to the movements within the bays. At low tide, they congregated in deep channels at the mouth of the bays (most recordings for remote receivers) and then moved into the bays as the tide rose (fewer remote receiver recordings). The depth distribution in the estuary ranged from.7 to 4.3 m (average = m), water temperatures ranged from 6. to 17. C ( C), and salinities ranged from 15 to 34 ppt ( ppt, Fig. 3). There was a strong pattern of selected temperature and salinity (Fig. 4). We used this pattern to hypothesize the limits of tolerance for wild brook charr in situ (lines fitted by eye). The four tracked brook charr returning to the river arrived between 3 and 3 August One passed through the counting fence (four km upstream of the estuary) and the remainder had moved upstream within 16 days of the fence s removal (3 August 1999). By early September, all tagged individuals were km upstream of the mouth of the river (27 active tags with 11 tracked through the winter; Fig. 5). They concentrated in a

6 366 Environ Biol Fish (6) 76: Fig. 3 Water depths, temperatures, and salinities selected by brook charr in the Laval River estuary from May to August Frequency Water depth (m) 3 25 Frequency Temperature o C 5 4 Frequency Salinity (ppt)

7 Environ Biol Fish (6) 76: Salinity ppt Temperature o C Fig. 4 Distribution of temperatures and salinities selected by brook charr in the Laval River, The curves are drawn by hand with lower (2.5 C) and upper ( C) temperature limits taken from Claireaux and Audet (1999) and Hokanson et al. (1973), respectively. The dashed lines are the estimated 1 SD. The shaded area is the hypothesized limits to marine habitats for brook charr. Numbers represent average temperature and salinity values in series of pools below a tributary (km 15) that was C cooler than the river when daytime highs were >. C in the main stem. The first signs of spawning (redd construction) were observed upstream of Lac à Jacques on 5 October 1999 when river temperatures were C. Between 12 and 21 October, three individuals moved from known spawning areas in the lower river at km rapidly through Lac à Jacques into the upper section of selected habitats for brook charr estimated from reported literature. (1) Smith and Saunders (1958) Prince Edward Island. (2) Dutil and Power (198) Hudson Bay. (3) Castongauy et al. (1982) Gaspé Peninsula. (4) Montgomery et al. (199) northshore, St. Lawrence River. (5) Trite (196) and Curry et al. (2) Kennebecasis Bay. (6) Lenormand et al. (4) Saguenay River the river (km 22 and subsequently km ). Transit time through the lake was 4 14 h. No activity was observed after 25 October in the upstream reaches (< 4 C). The majority of spawning (six of brook charr) began on 12 October ( 11 C) and occurred in the lower river between km 15.6 and No activity was apparent after 11 November (< 4 C) and they began moving from spawning to over-wintering areas (11 active tags). Fig. 5 Movement patterns of 11 brook charr and river temperatures at Lac à Jacques in the Laval River from August 1999 to May Distance upstream (km) individual charr temperature Lac aux Pins Lac Lac à a'jacques River temperature o C -5 1-Aug-99 -Sep-99 9-Nov Dec Feb- 7-Apr- 27-May-

8 368 Environ Biol Fish (6) 76: Active tracking (February) and the remote receivers recorded brook charr through the winter (November to May). Six of them resided in Lac à Jacques (Figs. 1 and 5), having moved there from up or downstream spawning areas. Three fish were located in the main stem (two upstream and one downstream of Lac à Jacques). The last individual moved to Lac aux Pin (Fig. 5). Average temperatures from January to April at these locations were.4.1, 4.4.1, and..1 C, respectively. Four of the were detected leaving the river and entering the estuary between 23 April and 9 May (three were detected in the estuary from 3 6 May). The declining number of detected tags by spring was most probably a result of the end of battery life. Discussion The larger (>3 cm FL) anadromous brook charr of the Laval River spend their spring and summer in the estuary and returned to freshwaters by late summer where they remained until the following spring. They quickly exited freshwaters for the estuary when river temperatures rose to 4 C and ice cover was waning in the spring. They spent upwards of 9 days in the estuary before returning to the freshwaters in late summer. Postspawning in the fall, they moved into low velocity reaches including two lakes to spend the winter. This broad temporal scale pattern is consistent with other populations of the area (e.g., Dutil and Power 198; Castonguay et al. 1982; Montgomery et al. 199; Lenormand et al. 4), but the relatively protracted duration of summer residence in the saline estuary of the Laval River poses some interesting questions regarding this tactic and anadromy in the species. In theory, the longer an individual spends in the food rich estuary the greater the potential for rapid growth that may be linked to a fitness advantage (van den Berghe and Gross 1986). However, the fitness challenges of anadromy for brook charr predicted by laboratory studies seem to be confirmed by the telemetry data from the Laval River. Rapid descent of rivers by anadromous brook charr and other salmonids is common (as discussed by Naiman et al. 1987), but it is not clear if the stimulus is environmental (e.g., Dutil and Power 198) or physiological (e.g., Boula et al. 2). Laval River brook charr >3 cm FL quickly exited the river in spring traveling km d )1 and then lingered nearshore at the river mouth for up to 21 d (see also Castonguay et al. 1982, Lenormand et al. 4). Large individuals are best adapted to survive osmotic stress (McCormick and Saunders 1987; Claireaux and Audet 1999) and the largest individuals were first to enter the estuary in spring based on angler catches and also observed by Lenormand et al. (4). The cold saline water from the St. Lawrence River mixing in the estuary at this time most probably presented a physiological challenge because Claireaux and Audet (1999) observed that temperatures < 3 C inhibit the ability of brook charr to acclimate to salt water (even though some individuals can adjust to direct transfer to salt water) and survival in salinities >3 ppt is significantly increased after a saltwater acclimation period (Naiman et al. 1987). It is unclear what stimulated the brook charr to move rapidly from the river to the estuary, but there appears to be a period of acclimation spent close to the fresh water in the upper reaches of the estuary. Once acclimated to the marine environment, Laval River brook charr clearly demonstrated a preference for their home estuary during the summer. Only one individual ventured beyond the estuary a distance of < 5 km and subsequently returned. Typically, they remained in the near shore zone < 5 m deep, < 5 m offshore, and closely linked to tidal periodicity as observed in other populations (reviewed by Power 198; see also Montgomery et al. 199; Castonguay et al. 1982) and the cutthroat trout, Oncorhynchus clarki, and Arctic charr (McCart 198; Trotter 1989; Begout Anras and Gyselman 1999). Movements between the estuary and river in summer were rare, most probably because of the warm river temperatures (> C) and poor osmoregulatory abilities of brook charr (e.g., McCormick and Naiman 1985). We suggest that the restricted distribution of the anadromous brook charr to the estuary and its immediate surrounding coastal area is a function of the physiological constraints on the

9 Environ Biol Fish (6) 76: species and the physical environment s control over spatial and temporal variability in water temperature and salinity in the estuary. Brook charr are not the well adapted to sea life (Rousenfell 1957; McCormick 1994). Experimental introduction into 2.5 C salt water caused extreme stress and high mortality of brook charr in June (Claireaux and Audet 1999). In the Laval River estuary, their habitats averaged C and salinities 27 ppt even though colder, saline waters beyond the headlands in the St. Lawrence River and warmer, fresh waters in the river were accessible. Even during low tides, brook charr concentrated in small areas in the channels at the mouths of the bays in the mixing zone between full sea water and fresh water. Similar marine habitats were also selected in other populations (Dutil and Power 198; Castonguay et al. 1982; Lenormand et al. 4) and by Arctic charr (Craig 1984; Begout Anras and Gyselman 1999). The Laval River relationship predicting temperature and salinity tolerance (Fig. 4) implies that fidelity to the home river for anadromous brook charr is primarily due to the species physiological constraints preventing it from crossing the cold ocean to other rivers. While residence in the estuary could enhance fitness by increasing body size, high salinity also inhibits the onset of maturation, particularly for males (McCormick and Naiman 1984; LeFrancois et al. 1997). The shortening photoperiod of late summer induces maturation and thus a period of freshwater residence is required for brook charr to achieve in-year gonad development. The consequence is the forced movement of mature individuals into suboptimal thermal and feeding habitats in the fresh waters of the river where feeding is reported to be reduced (Naiman et al. 1987). Our telemetry data showed that in summer and the start of autumn, maturing individuals in the river found thermal refugia where temperatures were 2 5 C colder than average river temperatures (one site had visible groundwater springs). However, they still had to pass through unfavourable, warm water to arrive at these habitats with poorer food resources. These are two fitness costs of still unknown significance related to extending the benefits of marine residence. The pre-spawning, thermal refugia were not necessarily in proximity to the sites used for spawning and incubation, and some individuals moved well upstream where resident brook charr would be expected to spawn. It is not clear if the two forms reproduce in isolation (e.g., Jones et al. 1997; Boula et al. 2), but this is an important question being addressed across the region (e.g., Castric and Bernatchez 3; Rogers and Curry 4). Post-spawning, individuals moved downstream to either the lower reaches (see also Castonguay et al. 1982, Curry et al. 2), or the two lakes in the system. Both sites provided areas of still water that would minimize energy costs and conserve reserves needed for survival over winter in northern climates (Cunjak and Power 1986; Chisholm et al. 1987) and protect fish from ice accumulations and breakup events (Komadina-Douthwright et al. 1997). Anadromy for brook charr pushes individuals to their physiological extremes in terms of osmoregulation and thermal tolerances. The tolerance limits suggested in this study could help elucidate the patterns of post-glacial dispersal and colonization by brook charr and therefore improve our understanding of genetic linkages among populations (e.g., Fraser and Bernatchez 5). Potential habitat maps based on summer temperature and salinity could also be generated for conservation, restoration, and enhancement programmes for anadromous brook charr (e.g., Whoriskey et al. 1981, Naiman et al. 1987). Acknowledgements We thank D. Courtemanche, D. Cartwright, M.A. Plourde, V. Castric, M. van de Sande, and E. Debien and ZEC Forestville staff for their assistance in the field. This project was funded in part by an NSERC Strategic Grant, References Begout Anras M, Gyselman EC (1999) Habitat preferences and residence time for freshwater to ocean transition stage in Arctic charr. J Mar Biol Assoc UK 79: Blanchfield PJ, Ridgway MS (1999) The cost of peripheral males in a brook trout mating system. Anim Behav 57: Boula D, Castric V, Bernatchez L, Audet C (2) Physiological, endocrine, and genetic bases of anadromy in the brook charr, Salvelinus fontinalis, of the Laval River (Quebec, Canada). Environ Biol Fish 64:

10 37 Environ Biol Fish (6) 76: Castonguay M, Fitzgerald GJ, Coté Y (1982) Life history and movements of anadromous brook charr (Salvelinus fontinalis) in the St-Jean River, Gaspé, Quebec. Can J Zool 6: Castric V, Bernatchez L (3) The rise and fall of isolation by distance in the anadromous brook charr (Salvelinus fontinalis Mitchill). Genetics 163: Chisholm IM, Hulbert WA, Wesche TA (1987) Winter stream conditions and use of habitat by brook trout in high-elevation Wyoming streams. Trans Am Fish Soc 116: Claireaux G, Audet C (1999) Seasonal changes in the hypo-osmoregulatory ability of brook charr: the role of environmental factors. J Fish Biol 56: Craig PC (1984) Fish use of coastal waters of the Alaskan Beaufort Sea: a review. Trans Am Fish Soc 113: Cunjak RA, Power G (1986) Seasonal changes in the physiology of brook trout, Salvelinus fontinalis (Mitchill), in a sub-arctic river system. J Fish Biol 29: Curry RA, Sparks D, VandeSande J (2) Movement patterns of a riverine population of brook trout. Trans Am Fish Soc 131: Dutil JD, Power G (198) Coastal populations of brook trout (Salvelinus fontinalis) in Lac Guillaume- Delisle (Richmond Gulf) Quebec. Can J Zool 58: Fraser DJ, Bernatchez L (5) Allopatric origins of sympatric brook charr populations: colonization history and admixture. Mol Ecol 14: Gross MR, Coleman RM, McDowall RM (1988) Aquatic productivity and the evolution of diadromous fish migration. Science 239: Hart LG, Summerfelt RC (1975) Surgical procedures for implanting ultrasonic transmitters into flathead catfish (Plyodictis olivaris). Trans Am Fish Soc 1:56 59 Hokanson KEF, McCormick JH, Jones BR, Tucker JH (1973) Thermal requirements for maturation, spawning, and embryo survival of brook trout Salvelinus fontinalis. J Fish Res Bd Can 3: Jones MW, Danzmann RG, Clay D (1997) Genetic relationships among populations of wild resident, and wild and hatchery anadromous brook charr. J Fish Biol 51:29 4 Komadina-Douthwright SM, Caisse D, Cunjak RA (1997) Winter movement of radio-tagged Atlantic salmon (Salmo salar) kelts in relation to frazil ice in pools of the Miramichi River. Can Tech Report Fish Aquat Sci 2161 LeFrancois NR, Blier PU, Adambounou LT, Lacroix M (1997) Alteration of gonadal development of brook charr (Salvelinus fontinalis): impact of salinity tolerance following transfer to estuarine conditions. J Exp Zool 279: Lenormand S, Dodson JJ, Menard A (4) Seasonal and ontogenetic patterns in the migration of anadromous brook charr (Salvelinus fontinalis). Can J Fish Aquat Sci 61:54 67 McCart PJ (198) A review of the systematics and ecology of Artic char, Salvelinus alpinus, in the western Arctic. Can Tech Report Fish Aquat Sci. No p McCormick SD (1994) Ontogeny and evolution of salinity tolerance in anadromous salmonids: Hormones and Heterochrony. Estuaries 17:26 33 McCormick SD, Naiman RJ (1984) Osmoregulation in brook trout, Salvelinus fontinalis - II. Effects of size, age and photoperiod on seawater survival and ionic regulation. Comp Biochem Physiol 79A:17 28 McCormick SD, Naiman RJ (1985) Hypoosmoregulation in an anadromous teleost: Influence of sex and maturation. J Exp Zool 234: McCormick SD, Saunders RL (1987) Preparatory physiological adaptations for marine life of salmonids: osmoregulation, growth, and metabolism. Am Fish Soc Symp 1: McKinley RS, Power G (1992) Transmitter attachment/ Implant Laboratory Manual. University of Waterloo, Environmental Research Department, Waterloo, Ontario Montgomery WL, McCormick SD, Naiman RJ, Whoriskey FG, Black G (199) Anadromous behavior of brook charr (Salvelinus fontinalis) in the Moisie River, Quebec. Polskie Archiwum Hydriobiologii 37:43 61 Naiman RJ, McCormick SD, Montgomery WL, Morin R (1987) Anadromous brook charr, Salvelinus fontinalis: Opportunities and constraints for population enhancement. Mar Fish Rev 49: 1 13 Power G (198) The brook charr, Salvelinus fontinalis. In: Balon EK (ed) Charrs: Salmonid fishes of the genus Salvelinus. Dr. W. Junk Publishers, The Hague, The Netherlands, pp Rogers SM, Curry RA (4) Genetic population structure of brook trout inhabiting a large river watershed. Trans Am Fish Soc 113: Rousenfell G (1957) Anadromy in North American salmonidae. U. S. Department of the Interior, Fish and Wildlife Service. Fish Bull 131: Smith MW, Saunders JW (1958) Movements of brook trout (Salvelinus fontinalis, Mitchill) between and within fresh and salt water. J Fish Res Bd Can 15: Summerfelt RC, Smith LS (199) Anesthesia, surgery, and related techniques. In: Schreck CB, Moyle PB (eds) Methods for fish biology. American Fisheries Society, Bethesda, Maryland, USA, pp Trite RW (196) An oceanographical and biological reconnaissance of Kennebecasis Bay and the Saint John River estuary. J Fish Res Bd Can 17: Trotter PC (1989) Coastal cutthroat trout: A life history compendium. Trans Am Fish Soc 118: van den Berghe EP, Gross MR (1986) Length of breeding life of coho salmon (Oncorhynchus kisutch). Can J Zool 64: White HC (1941) Migrating behavior of sea-running Salvelinus fontinalis. J Fish Res Bd Can 5: White HC (1942) Sea life of the brook trout (Salvelinus fontinalis). J Fish Res Bd Can 5: Whoriskey FG, Naiman RJ, Montgomery WL (1981) Experimental sea ranching of brook trout (Salveninus fontinalis, Mitchill). J Fish Biol 19: