Impacts of episodic acidification on in-stream survival and physiological impairment of Atlantic salmon (Salmo salar) smolts

2009 ◽  
Vol 66 (3) ◽  
pp. 394-403 ◽  
Author(s):  
Stephen D. McCormick ◽  
Amanda Keyes ◽  
Keith H. Nislow ◽  
Michelle Y. Monette

We conducted field studies to determine the levels of acid and aluminum (Al) that affect survival, smolt development, ion homeostasis, and stress in Atlantic salmon ( Salmo salar ) smolts in restoration streams of the Connecticut River in southern Vermont, USA. Fish were held in cages in five streams encompassing a wide range of acid and Al levels for two 6-day intervals during the peak of smolt development in late April and early May. Physiological parameters were unchanged from initial sampling at the hatchery and the high water quality reference site (pH > 7.0, inorganic Al < 12 μg·L–1). Mortality, substantial loss of plasma chloride, and gill Na+/K+-ATPase activity, and elevated gill Al occurred at sites with the lowest pH (5.4–5.6) and highest inorganic Al (50–80 μg·L–1). Moderate loss of plasma chloride, increased plasma cortisol and glucose, and moderately elevated gill Al occurred at less severely impacted sites. Gill Al was a better predictor of integrated physiological impacts than water chemistry alone. The results indicate that Al and low pH under field conditions in some New England streams can cause mortality and impair smolt development in juvenile Atlantic salmon and provide direct evidence that episodic acidification is impacting conservation and recovery of Atlantic salmon in the northeastern USA.

2004 ◽  
Vol 61 (12) ◽  
pp. 2392-2400 ◽  
Author(s):  
Francis Juanes ◽  
Stephen Gephard ◽  
Kenneth F Beland

The Connecticut River historically represented the southernmost extent of the North American range of Atlantic salmon (Salmo salar), but the native population was extirpated 200 years ago by dam construction. An extensive restoration effort has relied upon stock transfers from more northerly rivers, especially the Penobscot River (Maine). Recent work has shown differences in age structure between donor and derivative populations. Here we focus on a related life-history trait, the timing of the adult migration. We examined 23 years of migration timing data collected at two capture locations in the Connecticut River drainage. We found that both dates of first capture and median capture dates have shifted significantly earlier by about 0.5 days·year–1. To conclude whether this is a consequence of local adaptation or a coast-wide effect, we also quantified changes in migration timing of more northerly stocks (in Maine and Canada). We found that the changes in migration timing were not unique to the Connecticut River stock and instead observed coherent patterns in the shift towards earlier peak migration dates across systems. These consistent shifts are correlated with long-term changes in temperature and flow and may represent a response to global climate change.


1998 ◽  
Vol 55 (S1) ◽  
pp. 104-118 ◽  
Author(s):  
L P Hansen ◽  
T P Quinn

Atlantic salmon (Salmo salar) are distributed over large areas in the north Atlantic Ocean. They usually move very quickly from freshwater to oceanic areas, whereas there is considerable variation among Pacific salmon in early marine movements. In some areas, Atlantic salmon of exploitable size are sufficiently abundant that commercial high seas fisheries have developed. Such areas are off west Greenland, where North American and European fish are harvested, and in the Norwegian Sea, north of the Faroe Islands, where mainly European fish are exploited. Atlantic salmon feed on a wide range of large crustaceans, pelagic fish, and squid in the marine environment, supporting the hypothesis that Atlantic salmon are opportunistic feeders. In the ocean the salmon grow relatively quickly and the sea age when they become sexually mature depends on both genetics and on growing conditions. Natural marine mortality of salmon is highest during the first few months at sea and the major mortality factor is probably predation. However, marine mortality of Atlantic salmon has increased in recent years, apparently correlated with a decline in sea surface temperatures. Similar relationships between environmental conditions and the growth and survival of Pacific salmon have been reported. Atlantic salmon life histories most closely mimic stream-type chinook salmon or steelhead trout among the Pacific species. Finally, Atlantic and Pacific salmon return to their home rivers with high precision and possible mechanisms controlling the oceanic homing migration are presented and discussed.


1981 ◽  
Vol 38 (12) ◽  
pp. 1612-1625 ◽  
Author(s):  
Richard L. Saunders

This paper discusses the diversity of Atlantic salmon (Salmo salar) expressed as anatomical, physiological, and behavioral differences among stocks in the Atlantic Provinces of Canada and New England, USA. Evidence is reviewed for environmental and genetic influence on a number of stock-specific traits. Unique qualities of particular stocks are described. The loss of salmon from much of its former range is documented and discussed in relation to stock characteristics important in rehabilitation efforts. The mixed stock fisheries in Greenland and Newfoundland are considered from the point of view of interception. It is concluded that identification and management of specific stocks in the Greenland fishery are impracticable at present but that identification of North American components, using discriminant function analysis of scale growth patterns and smolt tagging, should be continued. In Newfoundland knowledge gained from tagging studies allows a significant degree of management of stocks from mainland Canada together with those from Newfoundland and Labrador. Since it is impracticable now to manage the fisheries off Greenland and Newfoundland and off the major Canadian Maritimes salmon-producing rivers—the Miramichi, Restigouche, and Saint John—in strict recognition of stocks, it is suggested that it may be possible to characterize an assemblage of like stocks from given areas and to identify and manage for these in large mixed-stock fisheries. Possible impacts of hatchery plantings are discussed in relation to prospects of success and effects on native stocks. It is concluded that we have the biological basis for evaluating likelihood of success and degree of danger to native stocks from extensive plantings of hatchery-reared juvenile salmon and that such evaluation should be conducted when embarking on projects involving use of hatchery-reared fish as part of a major salmon enhancement program in Atlantic Canada.Key words: genetics, environmental influence, rehabilitation, enhancement, interception, hatcheries, aquaculture


2009 ◽  
Vol 66 (2) ◽  
pp. 278-288 ◽  
Author(s):  
Ove T. Skilbrei ◽  
Jens Christian Holst ◽  
Lars Asplin ◽  
Marianne Holm

Abstract Skilbrei, O. T., Holst, J. C., Asplin, L., and Holm, M. 2009. Vertical movements of “escaped” farmed Atlantic salmon (Salmo salar L.)—a simulation study in a western Norwegian fjord. – ICES Journal of Marine Science, 66: 278–288. To study the vertical distribution of fish that had been allowed to escape, farmed Atlantic salmon were tagged with acoustic tags equipped with depth sensors, and then released on five different dates in the course of a year from two fish farms in the Hardanger Fjord in western Norway. Release stimulated the fish to dive to deeper than 15 m during the first hours or days post-release, often down to 50–80 m. However, during the following 4 weeks, most of the escapees spent most of their time above the pycnocline at depths of 0–4 m. The fish were more widely distributed in the water column after release during winter, but still spent most of the time in the cold surface layers. There was a wide range in the vertical distribution of individual fish, and the proportion of detections below 14-m depth ranged from 0 to 90%. There was a significant diurnal cycle in all seasons except midsummer, when the fish were less abundant in the upper layer during daylight, especially on brighter days. The results suggest that salmon diving activity following escape may complicate the recapture of escaped fish at the farm site but that the subsequent tendency of most fish to stay near the surface, virtually irrespective of the time of year, may facilitate recapture.


1984 ◽  
Vol 41 (3) ◽  
pp. 469-475 ◽  
Author(s):  
D. M. Rimmer ◽  
U. Paim ◽  
R. L. Saunders

Over three summers we used direct underwater observation to examine the summer to autumn differences in seven microhabitat properties of three age-classes of juvenile Atlantic salmon (Salmo salar) in the Little Sevogle River of northeastern New Brunswick. Salmon of all three age-classes occupied a wide range of water depths during summer, but were concentrated mainly in depths of 24–36 cm. In autumn, they occurred in this range almost exclusively. The streambed stones most closely associated with the individual positions of all ages were always <20 cm in summer and mostly (84–92%) <10 cm in diameter. In autumn, all ages were associated with home stones up to 40 cm in diameter, with 65–83% of the stones exceeding 20 cm; the size of home stones selected increased with fish age in autumn. There was no apparent relationship between the water depth and home stone size distributions occupied by all age-classes and available in the stream during either summer or autumn. Summer focal water velocity (velocity at the fish's snout) was predominantly 10–30 cm∙s−1 for 0+, 10–40 cm∙s−1 for 1+, and 30–50 cm∙s−1 for 2+ salmon, but during autumn it was almost always <10 cm∙s−1 for all ages. The bottom and surface water velocities as well as the maximum water velocity within 1 m of fish stations increased with fish age during summer and autumn. At the summer–autumn transition, 0+ salmon selected higher bottom, surface, and maximum water velocities, 2+ salmon selected lower velocities, but selection by 1+ salmon remained unchanged. We view substrate size followed by water depth as the primary properties influencing stream suitability for juvenile Atlantic salmon in autumn.


2003 ◽  
Vol 60 (9) ◽  
pp. 1149-1160 ◽  
Author(s):  
Eva C Enders ◽  
Daniel Boisclair ◽  
André G Roy

Fish activity costs are often estimated by transforming their swimming speed in energy expenditures with respirometry models developed while forcing fish to swim against a flow of constant velocity. Forced swimming models obtained using a procedure that minimizes flow heterogeneity may not represent the costs of swimming in rivers characterized by turbulence and by a wide range of instantaneous flow velocities. We assessed the swimming cost of juvenile Atlantic salmon (Salmo salar) in turbulent flows using two means (18 and 23 cm·s–1) and two standard deviations of flow velocity (5 and 8 cm·s–1). Twenty respirometry experiments were conducted at 15 °C with fish averaging 10 g. Our results confirmed that swimming costs are affected by the level of turbulence. For a given mean flow velocity, swimming costs increased 1.3- to 1.6-fold as turbulence increased. Forced swimming models under estimated actual swimming costs in turbulent flow by 1.9- to 4.2-fold. Spontaneous swimming models overestimated the real cost of swimming in turbulent flow by 2.8- to 6.6-fold. Our analyses suggest that models in which both the mean and the standard deviation of flow velocity are explicitly represented are needed to adequately estimate the costs of swimming against turbulent flows.


2003 ◽  
Vol 60 (3) ◽  
pp. 279-285 ◽  
Author(s):  
Matthew J Raffenberg ◽  
Donna L Parrish

Competitive interactions among stream salmonids in resource-limited environments have been linked to reduced success for many species. Few studies have focused on interactions at scales larger than individual fish or stream reach. We chose to focus our study on these larger scales to provide information for managing species that have complex life histories transcending multiple scales. Our objective was to explore age-0 Atlantic salmon (Salmo salar) growth and survival in relation to trout abundance (introduced rainbow (Oncorhynchus mykiss) and native brook (Salvelinus fontinalis) trout) and prey resources at 24 stream reaches across two Vermont watersheds that flow into the Connecticut River. Simple linear and multilinear regressions were conducted on response and predictor variables related to fish and invertebrate prey. Age-0 Atlantic salmon survival was greatest at the site with highest trout abundance; however, no linear relationships to trout abundance were detected possibly because Atlantic salmon growth and survival were highly variable across sites. In contrast, a positive significant multivariate relationship was identified among age-0 Atlantic salmon survival, the abundance of age-1+ brook trout (i.e., 100–130 mm), and benthic prey abundance. These results suggest that stocking streams based on trout abundance may not increase Atlantic salmon growth and survival during the first summer of life.


1985 ◽  
Vol 248 (6) ◽  
pp. R651-R659 ◽  
Author(s):  
D. J. Nichols ◽  
M. Weisbart

We examined plasma cortisol concentration (PCC), cortisol metabolism, and cortisol protein binding (CPB) in chronically cannulated Atlantic salmon (Salmo salar) during seawater (SW) adaptation. PCC rose significantly 2 h after freshwater (FW) to SW changeover but tended to be lower for 6 days thereafter. Plasma chloride concentrations began to stabilize 24–48 h after entry to SW. Cortisol metabolic clearance rate (MCR) was significantly higher 24 h after SW transfer than in FW; CPB and plasma protein concentration were significantly lower, but cortisol production rate was unchanged. The change in plasma chloride after 24 h in SW was negatively correlated with the change in plasma protein (r = -0.915, n = 9, P less than 0.001). The changes in CPB and plasma protein were correlated with the change in MCR (r = -0.643, n = 14, P less than 0.02; r = -0.850, n = 9, P less than 0.005). We hypothesize that these changes in protein concentration reflect an ion-induced expansion of extracellular volume and lead to increased MCR.


2015 ◽  
Vol 87 (5) ◽  
pp. 1129-1146 ◽  
Author(s):  
J. T. Kelly ◽  
D. T. Lerner ◽  
M. F. O'Dea ◽  
A. M. Regish ◽  
M. Y. Monette ◽  
...  

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