Temperature-related loss of smolt characteristics in Atlantic salmon (Salmo salar) in the wild

1999 ◽  
Vol 56 (9) ◽  
pp. 1649-1667 ◽  
Author(s):  
Stephen D McCormick ◽  
Richard A Cunjak ◽  
Brian Dempson ◽  
Michael F O'Dea ◽  
Judith B Carey

Atlantic salmon (Salmo salar) that had previously been released as fry in tributaries of the Connecticut River were captured from 1993 to 1997 during their normal spring smolt migration 198 km from the mouth of the river. Smolts had peak levels of gill Na+,K+-ATPase activity and salinity tolerance early in migration (early May), indicating physiological readiness to enter seawater. Significant decreases in gill Na+,K+-ATPase activity (29-66%) and salinity tolerance were seen in smolts at the end of the migratory period (late May and early June). Reduced gill Na+,K+-ATPase activity occurred earlier in warm years and was directly related to the degree-days during migration (r2 = 0.75). Reduced gill Na+,K+-ATPase activity was found at the end of migration in warmer, southern rivers (Connecticut River and Penobscot River, Maine) but not in northern rivers (Catamaran Brook, New Brunswick, and Conne River, Newfoundland). Both hatchery- and stream-reared fish held in the laboratory exhibited a more rapid loss of physiological smolt characteristics when held at higher temperature. The results indicate that late migrants in southern rivers lose physiological smolt characteristics due to high temperatures during spring migration. Delays in migration, such as those that occur at dams, may have negative impacts on smolt survival in warmer rivers.

1981 ◽  
Vol 38 (10) ◽  
pp. 1189-1198 ◽  
Author(s):  
C. E. Johnston ◽  
R. L. Saunders

Six different rearing conditions were used to study the effect of temperature on seasonal changes in growth, condition factor, body silvering, body moisture and lipid content, salinity tolerance, and gill Na–K-ATPase activities of laboratory and pond-reared yearling Atlantic salmon (Salmo salar). Growth during the winter was greatest at the highest rearing temperature (16 °C) whereas those under simulated natural conditions grew slowest. Increasing temperatures in the spring stimulated growth more than constant temperature. Based on increased salinity tolerance, elevated ATPase activity, and growth in salt water, smolt development proceeded at all temperatures up to 16 °C. More smolts were produced in the high thermal regimes resulting in the best growth and the largest proportion of fish reaching smolt size. Unlike some Pacific salmonids, Atlantic salmon develop smolt status at temperatures as high as 16 °C. Yearling smolts can be produced at elevated temperatures and the use of thermal effluents for this purpose is promising.Key words: smoltification, smolt criteria, salinity tolerance, ATPase activity, rearing temperatures, elevated thermal regimes, thermal effluent, Salmo salar


1987 ◽  
Vol 44 (8) ◽  
pp. 1462-1468 ◽  
Author(s):  
Stephen D. McCormick ◽  
Richard L. Saunders ◽  
Eugene B. Henderson ◽  
Paul R. Harmon

Atlantic salmon (Salmo salar) were subjected to artificial photoperiods to determine the manner and extent of photoperiod control of the parr–smolt transformation. Exposure to continuous light (L24) at first feeding and maintained throughout the rearing period inhibited increases in salinity tolerance and gill Na+,K+-ATPase activity that occurred in spring in fish raised under simulated natural photoperiod (SNP). Fish reared under continuous light and returned to SNP in October (L24OCT) underwent normal increases in salinity tolerance and gill Na+,K+-ATPase activity, whereas those returned in December (L24DEC) underwent delayed and intermediate increases. Plasma thyroxine peaks occurred simultaneously in all groups but were diminished in the L24 and L24DEC groups. Plasma 3,5,3′-triiodo-L-thyronine levels were not affected by any photoperiod treatment. Inhibition of the parr–smolt transformation decreased the potential for growth in seawater. In spite of changes in the timing of the transformation induced by photoperiod treatment, salinity tolerance and gill Na+,K+-ATPase activity were strongly correlated; correlation between changes in salinity tolerance and plasma thyroid hormones were, by comparison, weak. The results demonstrate that continuous light applied early in ontogeny and maintained throughout the rearing period inhibits osmoregulatory changes associated with parr–smolt transformation, whereas increasing day length during winter–spring stimulates transformation.


2009 ◽  
Vol 66 (5) ◽  
pp. 865-870 ◽  
Author(s):  
Rocco C. Cipriano

AbstractCipriano, R. C. 2009. Antibody against infectious salmon anaemia virus among feral Atlantic salmon (Salmo salar). – ICES Journal of Marine Science, 66: 865–870. Archived sera from Atlantic salmon (Salmo salar) that returned to the Penobscot River (Maine), Merrimack River (Massachusetts), and Connecticut River (in Massachusetts) from 1995 to 2002 were analysed for antibodies against infectious salmon anaemia virus (ISAV) using an enzyme-linked immunosorbent assay (ELISA). Up to 60 samples were archived per river system per year. In a given year, the number of fish sampled by ELISA for ISAV antibodies in the Penobscot River ranged from 2.9 to 11.2%, and the range of salmon sampled in the Merrimack River and the Connecticut River was 31.3–100% and 20.0–67.5%, respectively. Archived sera were not available for the 1995 and 2002 year classes from the Connecticut River. In all, 1141 samples were processed; 14 serum samples tested positive for antibodies to ISAV. In the Penobscot River, serum from one fish tested positive in each of the 1995 and 1999 year-class returns, and sera from two fish tested positive in the 1998 returns. In the Merrimack River, sera from four fish tested positive in each of the 1996 and 1997 returns, and sera from two fish were positive in the 2002 return. None of the archived sera from Atlantic salmon that returned to the Connecticut River tested positive.


1995 ◽  
Vol 52 (2) ◽  
pp. 243-251 ◽  
Author(s):  
Åse I. Berge ◽  
Arne Berg ◽  
Trygg Barnung ◽  
Tom Hansen ◽  
Hans Jørgen Fyhn ◽  
...  

Groups of Atlantic salmon (Salmo salar), first fed in mid-February 1989, were reared under continuous light (LL) at 12–15 °C until late June. One group remained on LL, while the FEB, MAR, and MAY groups were subjected to segments of a simulated naturally increasing photoperiod (61°N), with initial daylength corresponding to February 1, March 15, and May 1, respectively. The MAR and FEB groups developed important smolt characters (increase in gill Na+,K+-ATPase activity, hypoosmoregulatory ability, and salinity tolerance) during the experiment whereas LL and MAY groups showed only incomplete changes in smolt status. The combination of continuous light during first feeding and early parr stages with a subsequent reduction to short daylength followed by a segment of simulated natural photoperiod allow important parts of the parr–smolt transformation to be completed. The period of exposure to short photoperiod is critical for the synchronization of smolt characters in underyearling Atlantic salmon.


1991 ◽  
Vol 69 (8) ◽  
pp. 2075-2084 ◽  
Author(s):  
Tim P. Birt ◽  
John M. Green ◽  
William S. Davidson

Parameters associated with the parr–smolt transformation were compared in cultured 1+ anadromous and nonanadromous Atlantic salmon derived from wild broodstock collected in Gambo River, Newfoundland. Progeny of nonanadromous salmon were significantly longer at swim-up than progeny of anadromous salmon, although consistent differences in growth performance were not observed during most of the 1 st year of development. Anadromous salmon grew more rapidly than nonanadromous salmon in the spring months during the smolting period. Distinct differences were noted between groups in seasonal levels of body silvering, gill Na+–K+ ATPase activity, and size and number of gill chloride cells. Most male nonanadromous salmon matured as "post-smolts," whereas maturation was not observed among female nonanadromous nor among either sex in the anadromous group. Differences between anadromous and nonanadromous salmon were not observed in seasonal levels of body moisture, plasma Na+ and Cl−, condition factor, or salinity tolerance. Differences noted between groups are probably genetic in nature and suggest that the two forms of salmon in Gambo River represent separate breeding populations.


1978 ◽  
Vol 35 (12) ◽  
pp. 1542-1546 ◽  
Author(s):  
Richard L. Saunders ◽  
Eugene B. Henderson

Gill Na+K+-activated ATPase activity increased during winter–spring in Atlantic salmon (Salmo salar) held at 10 °C and subjected to simulated natural or reciprocal (light/dark ratio opposite that of natural) photoperiods. ATPase activity increased earlier and was greater under the reciprocal than under the natural photoperiod regime. Body lipid decreased and moisture content increased sooner and more sharply in reciprocal than in natural photoperiod fish. Salinity tolerance (to 40‰) increased between March and April. Exposure to 40‰ salinity for periods up to 14 d gave marked increases in ATPase activity over levels measured in freshwater. Gill ATPase activity is a sensitive indicator of the ability of Atlantic salmon to osmoregulate in seawater. Together with lipid-moisture content, tolerance to high salinity, and migratory behavior, gill ATPase activity provides a valid indication of smolt readiness to migrate to sea. Key words: smolt criteria, photoperiod manipulation, Atlantic salmon, smolt physiology, salinity tolerance, osmoregulation


2001 ◽  
Vol 58 (9) ◽  
pp. 1812-1821 ◽  
Author(s):  
Benjamin H Letcher ◽  
Tim L King

Large-scale use of parentage assignment of stocked Connecticut River, U.S.A., Atlantic salmon (Salmo salar) fry to determine stocking tributary of emigrating smolts and returning adults requires both parentage assignment and grandparentage assignment. Using computer simulations, we explored the levels of genetic diversity necessary to provide adequate parentage and grandparentage assignment. When matings were known, as in a hatchery, 95% correct grandparentage assignment typically required at least twofold more alleles per locus than did 95% correct parentage assignment. Parentage assignment with unknown matings (as in the wild when parental genotypes can be assayed) required an intermediate number of alleles per locus and grandparentage assignment with unknown matings required the greatest genetic diversity. Computer simulations using empirical parental genotypes (14 loci) and known P1 matings indicated that the genetic diversity of Connecticut River Atlantic salmon broodstock is sufficient to assign all F1 and 97% of F2 offspring to the correct set of two parents or four grandparents, respectively. Grandparentage assignment with unknown P1 matings was ineffective (assignment success = 20%). These results indicate that the combination of parentage and grandparentage assignment can be used as a non-lethal, permanent, heritable "mark" to identify stocking tributary or other management directed characteristics of stocked fry.


1991 ◽  
Vol 48 (2) ◽  
pp. 164-169 ◽  
Author(s):  
J. Duston ◽  
R. L. Saunders ◽  
D. E. Knox

Two-year-old (2+) Atlantic salmon (Salmo salar) raised under ambient temperature and simulated natural photoperiod (45°N) completed smolting between February and May, exhibiting significant increases in gill Na+, K+-ATPase activity and salinity tolerance (96 h, 37.5 ppt) but no significant changes in plasma osmolality. On May 2 the smolts were divided into four groups (each n = 80) and subjected to a rapid (2–3 h) increase in temperature from ambient (5 °C) to 10, 13, or 16 °C or remained ambient (control) which rose to 12 °C by the end of the experiment on June 5. In the 10, 13, and 16 °C groups, mean gill Na+, K+-ATPase activity (micromoles inorganic phosphorus per milligram protein per hour) declined significantly from 6.6 units on May 2 to 4.3, 3.6, and 2.3 units, respectively, on May 23. In the control group, Na+, K+-ATPase activity showed no significant changes during the study. Plasma osmolality was maintained in all groups between 290 and 304 mosmol∙kg−1. Salinity tolerance tests revealed a significant decline in survival in the 16 °C group from May 2 and in the 10 °C, 13 °C, and control groups from May 13, but no significant differences were observed among the three groups. The results support the hypothesis that increases in freshwater temperature accelerate the loss of hypoosmoregulatory capacity.


1993 ◽  
Vol 50 (3) ◽  
pp. 656-658 ◽  
Author(s):  
Stephen D. McCormick

A gill biopsy, in which a small portion of gill tissue was removed from anesthetized fish, was shown to have no detrimental effect on subsequent survival, growth, and salinity tolerance of juvenile Atlantic salmon (Salmo salar). A method for measurement of Na+, K+ -ATPase activity in this small amount of gill tissue is presented. These methods are useful for nonlethal monitoring of physiological smolt characteristics in salmonids and may have applications in the study of disease, toxicology, and physiological ecology of many fish species.


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.


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