Effect of winter food deprivation on growth and sexual maturity of Atlantic salmon (Salmo salar) in seawater

1999 ◽  
Vol 56 (2) ◽  
pp. 201-207 ◽  
Author(s):  
J Duston ◽  
R L Saunders
Keyword(s):  
Atlantic Salmon ◽  
Salmo Salar ◽  
Food Deprivation ◽  
Condition Factor ◽  
Fork Length ◽  
Somatic Growth ◽  
Late Winter ◽  
Similar Degree ◽  
Atlantic Salmon Salmo Salar ◽  
Immature Fish

By identifying individual Atlantic salmon (Salmo salar) smolts (age 1+, mean weight 95 g), a tank study with four treatments (n = 175 fish per tank) indicated that maturation as grilse is associated with changes in somatic growth over many months, from July of the first summer in seawater onwards. The grilse rate in both sexes was associated with a relatively high condition factor from July onwards, but was independent of fork length. Food deprivation in either early winter (November-December, 8.2-4.1°C), late winter (February-April, 0.7-4.0°C), or both early and late winter (double deprived) reduced the female grilse rate (p < 0.01) to 4, 7, and 2% versus 18% in the control, whereas male grilse rate was reduced by a lesser degree (p > 0.05), 43, 39, and 33% versus 44% in the control. Mean condition factor among both maturing and immature fish decreased by a similar degree due to food deprivation but from spring onwards increased by a faster rate among incipient grilse. In a large experiment in four sea cages (each n = 3885 fish) using similar food deprivation treatments, the reduction in grilse rate was statistically significant in both sexes: among males, 28-36 versus 43% in the control; among females, 3-4 versus 6% in the control.

Seawater Adaptation and Parr–Smolt Transformation of Juvenile Atlantic Salmon, Salmo salar

1978 ◽  
Vol 35 (1) ◽  
pp. 93-100 ◽  
Author(s):  
G. J. Farmer ◽  
J. A. Ritter ◽  
D. Ashfield
Keyword(s):  
Moisture Content ◽  
Atlantic Salmon ◽  
Salmo Salar ◽  
Lipid Content ◽  
Condition Factor ◽  
Fork Length ◽  
Temperature Cycle ◽  
Seawater Adaptation ◽  
Migratory Activity ◽  
Atlantic Salmon Salmo Salar

Seawater adaptation of 1- and 2-yr-old Atlantic salmon, Salmo salar, presmolts and smolts was assessed during exposure to salinity increasing from 0.1 to 31‰ by examining changes in the osmotic concentration of their serum, urine, and intestinal fluid. Both age-classes adapted to seawater equally well; the marine osmoregulatory mechanisms apparently function before completion of parr–smolt transformation. Adaptation was possible during the parr stage for fish exceeding 12–13 cm fork length. The timing of transformation was synchronous for 1- and 2-yr-old juveniles as demonstrated by changes in their lipid and moisture content and condition factor (K). Condition factor of juveniles at the Mactaquac Hatchery, New Brunswick (45°58′N), decreased from February until the second half of May, while lipid content decreased from February until the second half of June. Migratory activity of juveniles at this location was maximal during the second half of May coincident with attainment of minimum K values and decreased during the first half of June as K values increased. While timing of changes in lipid and moisture content and K values were similar for juveniles at the Mersey Hatchery, Nova Scotia (44°10′N), lipid content of fish at the more southerly station decreased at a greater rate and migratory activity was apparent earlier. This was probably attributable to the advanced temperature cycle at that location. Smolt-release dates are discussed in terms of the development of the marine osmoregulatory mechanisms and the timing of parr–smolt transformation. Key words: Atlantic salmon, seawater adaptation, parr–smolt transformation, migration, hatchery management

scholarly journals Atlantic salmon (Salmo salar) smolt and early post-smolt migration and survival inferred from multi-year and multi-stock acoustic telemetry studies in the Gulf of St. Lawrence, northwest Atlantic

2018 ◽  
Vol 76 (4) ◽  
pp. 1107-1121 ◽  
Author(s):  
Gérald Chaput ◽  
Jonathan Carr ◽  
Jason Daniels ◽  
Steve Tinker ◽  
Ian Jonsen ◽  
...  
Keyword(s):  
Atlantic Salmon ◽  
Salmo Salar ◽  
Survival Rates ◽  
Fork Length ◽  
Probability Of Survival ◽  
Size Dependent ◽  
Atlantic Salmon Salmo Salar ◽  
Key Points ◽  
Migration Dynamics

Abstract The migration dynamics and inter-annual variation in early at-sea survival of Atlantic salmon (Salmo salar) smolts over 14 years of study are reported for four river populations located in the Gulf of St. Lawrence (Canada). Acoustically tagged smolts were monitored at three points along their migration from freshwater to the Labrador Sea, a migration extending more than 800 km at sea and a period of 2 months. A hierarchical state-space version of the Cormack–Jolly–Seber model was used to estimate apparent survival rates from incomplete acoustic detections at key points. There was a positive size-dependent probability of survival through the freshwater and estuary areas; the odds of survival of a 16 cm smolt were 1.5–1.7 times higher than for a 13.5 cm smolt, length at tagging. Length adjusted (centred to the mean fork length of smolts during the study of 14.6 cm) survivals through the estuary and nearshore waters were estimated to range between 67 and 90% for the two river populations migrating through Chaleur Bay in contrast to lower survival estimates of 28–82% for the two populations from the neighbouring Miramichi Bay. Across the 14 years of study, survival estimates varied without trend for the populations of Chaleur Bay, but declined for the populations migrating through Miramichi Bay. Survival through the Gulf of St. Lawrence was variable but generally high among years and rivers, ranging from 96% day−1 to 99% day−1. Long term, replicated studies at multiple sites using acoustically tagged smolts can provide empirical data to examine hypotheses of the location and timing of factors contributing to smolt and post-smolt mortality of salmon at sea.

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.

Differences in Atlantic Salmon, Salmo salar, from North America and Europe

1972 ◽  
Vol 29 (2) ◽  
pp. 179-185 ◽  
Author(s):  
O. L. Nyman ◽  
J. H. C. Pippy
Keyword(s):  
North America ◽  
Atlantic Salmon ◽  
Salmo Salar ◽  
North American ◽  
Serum Proteins ◽  
Fork Length ◽  
Anisakis Simplex ◽  
Atlantic Salmon Salmo Salar

Differences in electropherograms produced by serum proteins and liver esterases were used to identify North American and European Atlantic salmon (Salmo salar) caught at sea. Division of salmon according to continent of origin was supported by mean river age, mean fork length, and abundance of the two parasites Anisakis simplex and Eubothrium crassum. Consistent differences in electrophoretic behaviour of serum proteins and liver esterases in salmon from the two continents support the suggestion that salmon from North America and Europe represent different subspecies.

Winter temperature and food quality affect age at maturity: an experimental test with Atlantic salmon (Salmo salar)

2012 ◽  
Vol 69 (11) ◽  
pp. 1817-1826 ◽  
Author(s):  
Bror Jonsson ◽  
Anders G. Finstad ◽  
Nina Jonsson
Keyword(s):  
Growth Rate ◽  
Atlantic Salmon ◽  
Direct Effect ◽  
Salmo Salar ◽  
Food Quality ◽  
Condition Factor ◽  
Sea Water ◽  
Winter Temperature ◽  
Age At Maturity ◽  
Atlantic Salmon Salmo Salar

Field studies have revealed that many ectotherms mature younger and smaller in warmer environments although they grow faster. This has puzzled ecologists because the direct effect of factors that accelerate growth is expected to be larger, not smaller size. We tested this experimentally for Atlantic salmon (Salmo salar) at two winter temperatures and diets. Logistic regression revealed that the probability of maturation during the second year in sea water, relative to the probability of older maturation, increased with temperature and growth rate during the first winter. Also, large size and high condition factor 1 year prior to maturation stimulated maturation. In females, a high lipid diet increased the probability of maturation as one-sea-winter fish, and there were significant interactions between winter temperature and food quality and between body size and condition factor the first autumn in sea water. Thus, if the direct effect of temperature on growth rate is the main effect of warming, salmon are likely to attain maturity younger and smaller. Also, richer food decreased age at maturation in females. This finding has consequences for interpretations of climate change impacts on age at maturity in Atlantic salmon and may also hold for many other ectotherm species.

Behaviour and Microhabitat of Young Atlantic Salmon (Salmo salar) during Winter

1988 ◽  
Vol 45 (12) ◽  
pp. 2156-2160 ◽  
Author(s):  
Richard A. Cunjak
Keyword(s):  
Atlantic Salmon ◽  
Salmo Salar ◽  
Activity Pattern ◽  
Fork Length ◽  
Nocturnal Activity ◽  
Atlantic Salmon Salmo Salar ◽  
Sediment Compaction ◽  
Mean Diameter ◽  
Nova Scotian ◽  
Water Depths

Underwater observations at two sites along a small Nova Scotian river were carried out between December and April (water temperature range = 0.5–7.0 °C) to describe the winter microhabitat of young Atlantic salmon (Salmo salar). Salmon (5–15 cm fork length) were consistently found hiding beneath rocks (mean diameter = 16.8–23.0 cm) in riffle-run habitats where mean water depths were 40.9–48.9 cm and mean water velocities were 38.7–45.7 cm∙s−1. Many of the salmon were found overwintering within redd excavations. "Home stones" were distributed closer to midstream than to river banks and where sediment compaction was minimal. Monthly collections of fish (ages 1 and 2) indicated that feeding continued over winter. The data suggest a nocturnal activity pattern and photonegative response by young salmon during winter.

Activity, Respiration, and Excretion of Ammonia by Atlantic Salmon (Salmo salar) Smolt and Postsmolt

1989 ◽  
Vol 46 (5) ◽  
pp. 790-795 ◽  
Author(s):  
A. J. Wiggs ◽  
E. B. Henderson ◽  
R. L. Saunders ◽  
M. N. Kutty
Keyword(s):  
Oxygen Consumption ◽  
Atlantic Salmon ◽  
Spontaneous Activity ◽  
Salmo Salar ◽  
Condition Factor ◽  
Ammonia Excretion ◽  
Initial Increase ◽  
Atlantic Salmon Salmo Salar ◽  
Substantial Change ◽  
Increased Activity

Spontaneous activity, oxygen consumption, and excretion of ammonia by juvenile Atlantic salmon (Salmo salar) were measured over 17 wk as the appearance of the fish changed from early smolt to smolt and then postsmolt. A substantial change in routine oxygen consumption from 66 to 148 mL∙kg−1∙h−1 was primarily correlated with the increase in activity. An initial increase in ammonia excretion from about 5 to about 14 mL∙kg−1∙h−1 was largely correlated with the decline in condition factor from 0.99 to 0.79 suggesting that increased metabolic needs caused by the increased activity were not being met by the amount of food ingested. This is supported by the secondary increase in condition factor (C.F. = 0.93) and decrease in ammonia excretion (to about 7 mg∙kg−1∙h−1) that occurred after the meal size was increased.

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.

Contrasts in development and smolting of genetically distinct sympatric anadromous and nonanadromous Atlantic salmon, Salmo salar

1991 ◽  
Vol 69 (8) ◽  
pp. 2075-2084 ◽  
Author(s):  
Tim P. Birt ◽  
John M. Green ◽  
William S. Davidson
Keyword(s):  
Atlantic Salmon ◽  
Atpase Activity ◽  
Growth Performance ◽  
Salmo Salar ◽  
Salinity Tolerance ◽  
Condition Factor ◽  
Chloride Cells ◽  
Group Differences ◽  
Atlantic Salmon Salmo Salar ◽  
Breeding Populations

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.

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