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

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.

Inverse Correlation between Ovarian Development of Atlantic Salmon (Salmo salar) Smolts and Sea Age

1987 ◽  
Vol 44 (7) ◽  
pp. 1320-1325 ◽  
Author(s):  
E. Michael P. Chadwick ◽  
Ross R. Claytor ◽  
Claude E. Léger ◽  
Richard L. Saunders
Keyword(s):  
Atlantic Salmon ◽  
Salmo Salar ◽  
Significant Positive Correlation ◽  
Ovarian Development ◽  
Fork Length ◽  
Inverse Correlation ◽  
Positive Correlation ◽  
Atlantic Salmon Salmo Salar ◽  
Smolt Age

In order to understand the factors which determine sea age of Atlantic salmon (Salmo salar), ovarian development of smolts was examined in 14 groups which varied in parental sea age, smolt age, and size. Parental sea age of smolts explained most of the variation in ovarian development. Smolts from one-sea-winter parents had a higher percentage of the more advanced oocyte stages in their ovaries, while smolts from two-sea-winter parents had a low percentage, and those from three-sea-winter parents had none. Annual within-stock variation and covariance with freshwater age were not significant. Hatchery-reared smolts had similar ovarian development to their wild counterparts. There was also a significant, positive correlation between fork length of smolts and ovarian development within groups.

Growth and Genetic Variation of Atlantic Salmon (Salmo salar) from Different Sections of the River Alta, North Norway

1986 ◽  
Vol 43 (10) ◽  
pp. 1828-1835 ◽  
Author(s):  
Tor G. Heggberget ◽  
Roar A. Lund ◽  
Nils Ryman ◽  
Gunnar Ståhl
Keyword(s):  
Atlantic Salmon ◽  
Salmo Salar ◽  
Growth Patterns ◽  
Lower Growth ◽  
Local Populations ◽  
Atlantic Salmon Salmo Salar ◽  
Lower Growth Rate ◽  
Growth Differences ◽  
North Norway ◽  
Smolt Age

Growth of young Atlantic salmon (Salmo salar) from three different sections of the River Alta was correlated with estimated growth differences among adult salmon caught in corresponding sections of the river. Young salmon grew most quickly each of the three years investigated in the upper section of the river; further downriver, presmolts had a significantly lower growth rate. Growth calculations based on scale samples from adults indicated corresponding river growth patterns from the three sections. Salmon caught in the upper section of the river had significantly lower smolt age (mean 3.92 yr) and better presmolt growth than salmon caught further downriver (mean smolt age in the middle and lower sections was 4.35 and 4.19 yr, respectively). Correlations between growth differences in young and adult salmon suggest that presmolts that have lived their first years in the upper section of the river apparently return there after having been at sea. Genetic analyses of presmolts indicate that local populations exist. Allele frequency differences at three electrophoretically detectable protein loci give independent support for the existence of genetically differentiated local populations within the River Alta.

Ocean climate influences on critical Atlantic salmon (Salmo salar) life history events

1998 ◽  
Vol 55 (S1) ◽  
pp. 119-130 ◽  
Author(s):  
Kevin D Friedland
Keyword(s):  
Life History ◽  
Atlantic Salmon ◽  
Salmo Salar ◽  
High Mortality ◽  
Basic Knowledge ◽  
Regional Environment ◽  
Thermal Habitat ◽  
Ocean Climate ◽  
Atlantic Salmon Salmo Salar ◽  
First Maturity

Ocean climate and ocean-linked terrestrial climate affect nearly all phases of Atlantic salmon (Salmo salar) life history. Natural mortality in salmon occurs in two main phases: juvenile stages experience high mortality during freshwater residency and pre-adult salmon experience high mortality in estuarine and ocean environments. Freshwater survivorship is well characterized and tends to be less variable than marine mortality. Sources of marine mortality are poorly known due to a lack of basic knowledge about post-smolt distributions and habits. Coherence patterns among regional and continental stock groups suggest broad scale forcing functions play a more important role in defining recruitment than mortality effects associated with individual rivers. The action of mesoscale regional environment is most prominent during the post-smolt year when survival, maturation, and migration trajectories are being defined. During the early weeks at sea, growth mediated survival defines recruitment patterns. A correlation between sea surface water temperature and survival has been observed for salmon stocks in the northeast Atlantic suggesting temperature either directly affects growth or modifies post-smolt behavior. Age at first maturity is controlled by environmental as well as genetic factors. The abundance of two seawinter spawners in North America is directly scaled to the size of overwintering thermal habitat in the northwest Atlantic, which suggests a link between maturation and environment.

Effects of Oceanic Variations and the West Greenland Fishery on Age at Maturity of Icelandic West Coast Stocks of Atlantic Salmon (Salmo salar)

1989 ◽  
Vol 46 (1) ◽  
pp. 16-27 ◽  
Author(s):  
Dennis L. Scarnecchia ◽  
Árni Ísaksson ◽  
S. E. White
Keyword(s):  
Time Series ◽  
Atlantic Salmon ◽  
Salmo Salar ◽  
West Coast ◽  
Strongly Correlated ◽  
The West ◽  
West Greenland ◽  
Atlantic Salmon Salmo Salar ◽  
The Mean ◽  
Salmon Fishery

Investigations were conducted on the effects of oceanic variations (as measured by sea temperatures) and catches by the West Greenland salmon fishery on the sea age composition of Atlantic salmon (Salmo salar) stocks from 21 Icelandic west coast rivers. Annual ratios of grilse to two-sea-winter (2SW) salmon were strongly correlated among the 21 rivers. All eight rivers with time series extending back before the expansion of the West Greenland fishery showed lower ratios during the earlier period. Only 2 of the 21 rivers, however, had significantly declining ratios over their time series. In addition, for only one river was West Greenland catch significantly related to the ratios (P < 0.05), and for only one river did ratios increase when the expanded West Greenland fishery was active. Overall, the effects of the fishery on stock composition are evidently minimal. The mean April–May temperature when the smolts were to migrate out of rivers was significantly and positively related to subsequent ratios for five of the rivers, which, along with correlations among the ratios, indicated that more rapid growth of smolts in their first summer may have increased the ratios of grilse to 2SW salmon on several rivers.

scholarly journals Interannual changes in recruitment of the Atlantic salmon (Salmo salar) population in the River Oir (Lower Normandy, France): relationships with spawners and in-stream habitat

2005 ◽  
Vol 62 (4) ◽  
pp. 695-707 ◽  
Author(s):  
Jean-Luc Baglinière ◽  
Frédéric Marchand ◽  
Vincent Vauclin
Keyword(s):  
Atlantic Salmon ◽  
Salmo Salar ◽  
Survival Rates ◽  
Stream Habitat ◽  
Juvenile Salmon ◽  
Strongly Correlated ◽  
Data Set ◽  
Atlantic Salmon Salmo Salar ◽  
Salmon Population ◽  
The Mean

Abstract Since 1985, the dynamics of the Atlantic salmon (Salmo salar) population in the River Oir, a spawning tributary of the River Sélune (Lower Normandy, France), have been studied from a data set of parr density and the number and the age structure of migrating fish (smolts and adults). Parr densities (1.5–17.4 per 100 m2) and smolt production (0.25–9.2 per 100 m2) varied considerably from year to year. Migrating juveniles were mainly 1 year old. Abundance of parr and smolts was strongly correlated with 0+ densities. Egg-to-smolt survival rates were highly variable year on year (0.044–1.07%). During the juvenile freshwater phase, mortality was highest between the egg and the 0+ stage (97.5–99.9%). The fluctuations in abundance of juvenile salmon appear to be linked to the number and distribution of spawners within the stream during spawning, and also to the amount of silt deposition on the spawning beds. As a result, mortality was highest during the under-gravel phase, and the mean survival rate from egg to smolt was much lower than in rivers less impacted by human activities. Therefore, during the study period, the low production of smolts during some years might lead to a low renewal rate of the salmon population.

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.

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.

Life history variation and growth rate thresholds for maturity in Atlantic salmon, Salmo salar

1998 ◽  
Vol 55 (S1) ◽  
pp. 22-47 ◽  
Author(s):  
Jeffrey A Hutchings ◽  
Megan EB Jones
Keyword(s):  
Growth Rate ◽  
Life History ◽  
Atlantic Salmon ◽  
Salmo Salar ◽  
Optimal Growth ◽  
Age At Maturity ◽  
Early Maturity ◽  
Atlantic Salmon Salmo Salar ◽  
Optimal Growth Rate ◽  
Smolt Age

Based upon published and unpublished data compiled for 275 populations, we describe large-scale spatial and temporal patterns in Atlantic salmon, Salmo salar, life history and model these data to evaluate how changes to life history influence optimal growth rate thresholds for sea age at maturity. Population means (ranges in parentheses) describe the following for salmon throughout its range: smolt length = 14.8 cm (10.5-21.5 cm); smolt age = 2.91 years (1.04-5.85 years); egg-to-smolt survival = 1.5% (0.2-3.2%); grilse length = 56.8 cm (48.5-70.0 cm); sea age at maturity = 1.60 years (1.00-2.64 years); smolt-to-grilse survival = 7.4% (1.3-17.5%). Growth rate thresholds specify the length increase between the smolt and grilse stages above which reproduction after one winter at sea is favoured over later maturity. Our simulations indicated that increased growth generally favours earlier, but never delayed, maturity. Optimal growth rate thresholds for sea age at maturity are highly sensitive to survival but only moderately sensitive to fecundity, smolt size, and smolt age. Depending on an individual's growth rate at sea, early maturity is favoured by decreased smolt age or by increased smolt length, fecundity, or survival (freshwater or marine). We suggest that future Atlantic salmon life history research focus upon reaction norms and growth rate thresholds for age at maturity, demographic and genetic consequences of male parr maturation, and the origin and maintenance of coexisting anadromous and nonanadromous life history polymorphisms.

Variations in Atlantic salmon, Salmo salar L., smolt age in tributaries of the River Teno, Finland

1999 ◽  
Vol 6 (1) ◽  
pp. 83-86 ◽  
Author(s):  
V. Englund ◽  
E. Niemelø ◽  
M. Lønsman ◽  
M. Heino
Keyword(s):  
Atlantic Salmon ◽  
Salmo Salar ◽  
Atlantic Salmon Salmo Salar ◽  
Smolt Age
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