Energy-related juvenile winter mortality in a northern population of Atlantic salmon (Salmo salar)

2004 ◽  
Vol 61 (12) ◽  
pp. 2358-2368 ◽  
Author(s):  
Anders G Finstad ◽  
Ola Ugedal ◽  
Torbjørn Forseth ◽  
Tor F Næsje
Keyword(s):  
Atlantic Salmon ◽  
Salmo Salar ◽  
Negative Energy ◽  
Winter Mortality ◽  
Successive Sampling ◽  
Frequency Distributions ◽  
Storage Lipids ◽  
Atlantic Salmon Salmo Salar ◽  
Energy Dependent ◽  
Body Energy

By comparing the population frequency distributions for specific somatic energy between samplings using quantile–quantile (QQ) plots, we tested for energy-related mortality of juvenile (2- and 3-year-old) Atlantic salmon (Salmo salar) sampled at monthly intervals throughout three consecutive winters in a Norwegian river located at 70°N. Between several of the sampling periods, changes in the distributions of specific energy were observed corresponding to removal of low-energy individuals. By using energetic modelling we demonstrated that metabolic processes or feeding could not be responsible for the shifts in the shape of the energy distributions and that negative-energy-dependent mortality was the most likely explanation for the observations. No changes in mean size of the fish or in the shape of the size distributions were observed between successive sampling periods, indicating that mortality was linked to levels of storage energy rather than to body size per se. Our study indicated a critical body energy level for survival of juvenile salmon at approximately 4400–4800 J·g–1, corresponding to a depletion of storage lipids.

Patterns in apparent survival of Atlantic salmon (Salmo salar) parr in relation to variable ice conditions throughout winter

2010 ◽  
Vol 67 (11) ◽  
pp. 1744-1754 ◽  
Author(s):  
Tommi Linnansaari ◽  
Richard A. Cunjak
Keyword(s):  
Atlantic Salmon ◽  
Salmo Salar ◽  
Anthropogenic Impacts ◽  
River Regulation ◽  
Ice Formation ◽  
Winter Period ◽  
Winter Mortality ◽  
Apparent Survival ◽  
Atlantic Salmon Salmo Salar ◽  
Salmon Parr

Apparent within-site survival of Atlantic salmon ( Salmo salar ) parr, individually tagged with passive integrated transponders, was not constant throughout the winter period in a 3-year study (2003–2006) in Catamaran Brook, New Brunswick, Canada. Highest decline in apparent survival (19.4%–33.3% of the study population) occurred prior to any ice formation and coincided with early winter acclimatization period (dynamic temperature and discharge regime). Stream discharge and parr maturity were identified to be relevant factors explaining emigration prior to ice formation. Apparent survival was improved during the period affected by subsurface ice and considerably better when surface ice was prevailing, with a decline in population size between 0% and 15.4%. Overall, observed within-site winter mortality was low (4.4%), and the majority of the loss of tagged salmon parr occurred because of emigration. On average, the within-site population of tagged salmon parr declined by 31.7% over the whole winter (November–April). Our data suggest that anthropogenic impacts, like climate change or river regulation, are likely to affect the apparent survival rate and distribution of juvenile Atlantic salmon because of their effects on natural ice regime in streams.

Effect of 6-, 12-, and 18-month Photoperiod Cycles on Smolting and Sexual Maturation in Juvenile Atlantic Salmon (Salmo salar)

1992 ◽  
Vol 49 (11) ◽  
pp. 2273-2280 ◽  
Author(s):  
J. Duston ◽  
R. L. Saunders
Keyword(s):  
Atlantic Salmon ◽  
Salmo Salar ◽  
Sexual Maturation ◽  
Condition Factor ◽  
Temperature Cycle ◽  
Frequency Distributions ◽  
Atlantic Salmon Salmo Salar ◽  
Sexually Mature ◽  
Mature Male Parr ◽  
Modal Group

The results support the hypothesis that the commencement of smolting can occur during the decreasing phase of the annual photoperiod cycle, and sexual maturation during the increasing phase of the cycle, provided individuals have attained certain (unknown) growth thresholds. Thereafter the completion of smolting is entrained by the increasing phase of the photoperiod cycle, and sexual maturation by the decreasing phase. Three groups of Atlantic salmon (Salmo salar) were raised in freshwater for over 2 yr from the eyed egg stage under photoperiod cycles of either 6-, 12- (control), or 18-mo periodicity and an ambient 12-mo temperature cycle. Smolting was judged by changes in salinity tolerance and condition factor. All groups developed bimodal length–frequency distributions by December following hatch. Fish continued to be recruited into the upper modal group (UMG) beyond the shortest day of the photoperiod cycle, providing temperature was not limiting growth. The 6-, 12-, and 18-mo photoperiod cycles resulted in approximately 50, 60, and 100% of the populations being recruited into the UMG. Sexually mature male parr (1 + yr old) occurred only in the lower modal group of the 6- and 12-mo groups.

Variation in freshwater growth and development among five New England Atlantic salmon (Salmo salar) populations reared in a common environment

2004 ◽  
Vol 61 (12) ◽  
pp. 2314-2328 ◽  
Author(s):  
Mariska Obedzinski ◽  
Benjamin H Letcher
Keyword(s):  
Atlantic Salmon ◽  
New England ◽  
Salmo Salar ◽  
Growth And Development ◽  
Size Variation ◽  
Phenotypic Trait ◽  
Frequency Distributions ◽  
Atlantic Salmon Salmo Salar ◽  
Intensively Managed ◽  
Smolt Age

We examined phenotypic variation in growth and development from the eyed-egg stage to the age-1+ smolt stage among five New England populations of Atlantic salmon (Salmo salar: East Machias, Narraguagus, Sheepscot, Penobscot, Connecticut) reared in a common laboratory environment. Study populations originated from rivers varying in size, latitude, and level of hatchery supplementation and included one reintroduced population (Connecticut was a recipient of Penobscot origin stock). Phenotypic trait differences were found among populations, and the degree of stock variation depended on ontogeny. Eggs were smaller and hatched sooner in the Penobscot (a northern, intensively managed population), but no stock differences were detected in size or growth efficiency from the onset of exogenous feeding to age 0+ summer. Differences again emerged in age 0+ autumn, with the degree of bimodality in length– frequency distributions differing among stocks; the Connecticut had the highest proportion of upper-mode fish and, ultimately, age-1+ smolts. Although genetic effects could not be entirely separated from maternal effects for egg size variation, it is likely that differences in hatch timing and smolt age had a genetic basis. Early emphasis on age-1+ hatchery-reared smolts in the Connecticut may have led to divergence in smolt age between the Penobscot and Connecticut populations in less than eight generations.

Reduced growth, condition factor and body energy levels in Atlantic salmon Salmo salar L. during their first spring in the sea

2010 ◽  
Vol 42 (2) ◽  
pp. 248-259 ◽  
Author(s):  
Henriette Alne ◽  
Maike Oehme ◽  
Magny Thomassen ◽  
Bendik Terjesen ◽  
Kjell-Arne Rørvik
Keyword(s):  
Atlantic Salmon ◽  
Growth Condition ◽  
Salmo Salar ◽  
Condition Factor ◽  
Energy Levels ◽  
Atlantic Salmon Salmo Salar ◽  
Body Energy

Effects of Constant Day Length on Sexual Maturation and Growth of Atlantic Salmon (Salmo salar) Parr

1988 ◽  
Vol 45 (1) ◽  
pp. 60-64 ◽  
Author(s):  
R. L. Saunders ◽  
E. B. Henderson
Keyword(s):  
Atlantic Salmon ◽  
Salmo Salar ◽  
Seasonal Changes ◽  
The Other ◽  
Day Length ◽  
Length Frequency ◽  
Frequency Distributions ◽  
Atlantic Salmon Salmo Salar ◽  
First Feeding ◽  
Sexually Mature

Atlantic salmon (Salmo salar) were reared for 6 mo from first feeding under four photoperiod regimes: LD 12:12, LD 16:8, LD 24:0, and simulated natural (LDN). Water temperature followed seasonal changes but was adjusted so as not to exceed 16 °C in summer or to fall below 6 °C in winter. Growth rates were highest in the LD 24:0 group during the first 3 mo; subsequently, the LD 16:8 fish grew faster than all others. Length–frequency distributions were skewed towards smaller sized fish in January. Sexually mature males were mainly in the lower halves of the length–frequency distributions; females and immature males were distributed throughout. The incidence of mature males was highest in the LDN group (67% of males) but reached high levels (44–58%) in the other groups.

Influence of Parental Smolt Age and Sea Age on Growth and Smolting of Hatchery-Reared Atlantic Salmon (Salmo salar)

1980 ◽  
Vol 37 (9) ◽  
pp. 1379-1386 ◽  
Author(s):  
J. K. Bailey ◽  
R. L. Saunders ◽  
M. I. Buzeta
Keyword(s):  
Atlantic Salmon ◽  
Salmo Salar ◽  
Female Parent ◽  
Strongly Correlated ◽  
Lower Mode ◽  
Frequency Distributions ◽  
Threshold Size ◽  
Atlantic Salmon Salmo Salar ◽  
First Maturity ◽  
Smolt Age

Hatchery-reared Atlantic salmon, Salmo salar, consistently developed bimodal length–frequency distributions by the first November following hatch. In a study of 32 hatchery populations involving two year-classes, mean length in the lower mode showed little variation among populations and was not correlated with either the smolt age or sea age at first maturity of their parents. Mean length and the proportion of individuals in the upper mode were both variable among populations and correlated with parental age variables. Large mean length in the upper mode was strongly associated with early smolting male parents and late maturing female parents. The proportion of individuals in the upper mode was more strongly correlated with the age variables of the female parent. Late smolting and early maturing female parents tended to produce relatively greater proportions of fish in the upper mode. The optimum growth rate which produced the greatest proportion of individuals in the upper mode occurred when 8–15% of the total population matured precociously as parr. A threshold size hypothesis for precocious maturation is discussed.Key words: Atlantic salmon, genetics, growth, bimodality, precocious sexual maturation, smoltification

Importance of Threshold Length and Photoperiod for the Development of Bimodal Length–Frequency Distribution in Atlantic Salmon (Salmo salar)

1991 ◽  
Vol 48 (11) ◽  
pp. 2163-2172 ◽  
Author(s):  
Ove T. Skilbrei
Keyword(s):  
Atlantic Salmon ◽  
Salmo Salar ◽  
Light Stimulus ◽  
Morphological Characteristics ◽  
Continuous Light ◽  
Length Frequency ◽  
Frequency Distributions ◽  
Atlantic Salmon Salmo Salar ◽  
Natural Photoperiod ◽  
Threshold Length

Juveniles of 0 + Atlantic salmon (Salmo salar) were graded in narrow length intervals to test the hypothesis that a threshold length determines the segregation into bimodal length–frequency distributions. In the experiment, 1350 juveniles of an initial length of 70–80 mm were held under different light and temperature conditions. Distinct decreases in temperature for short or long periods did not influence the degree of bimodal segregation and temperature did not, thus, seem to be a winter stimulus for segregation in fish of this size. Transfer of fish from continuous light to natural photoperiod was followed by a segregation in growth rates into lower and upper mode fish. Upper mode fish developed smolt appearance the following spring. Under continuous light the bimodality was weak or absent and these fish did not develop morphological characteristics typical of smolts. It is concluded that the individual decision to enter the upper mode and undergo silvering the following spring is strongly dependent on the length of the fish at the time of the winter light stimulus. Fish smaller than a threshold length of about 75 mm reduce their growth rate in response to the natural photoperiod, while fish above this size enter the upper length–frequency mode.

Microstructure and texture of fresh and smoked Atlantic salmon, Salmo salar L., fillets from fish reared and slaughtered under different conditions

2001 ◽  
Vol 32 (1) ◽  
pp. 1-10 ◽  
Author(s):  
Sjofn Sigurgisladottir ◽  
Margret S. Sigurdardottir ◽  
Helga Ingvarsdottir ◽  
Ole J. Torrissen ◽  
Hannes Hafsteinsson
Keyword(s):  
Atlantic Salmon ◽  
Salmo Salar ◽  
Atlantic Salmon Salmo Salar
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