Influences of migration phenology on survival are size-dependent in juvenile Atlantic salmon (Salmo salar)

Long-distance migratory species can reduce mortality risks by synchronizing the migration event and create confusion by swamping predators with high densities. To reduce confusion, predators are known to primarily select aberrant prey. We hypothesized that at the start of their sea sojourn, particularly small and large Atlantic salmon (Salmo salar L., 1758) would spread the risk by also migrating at other times of the year. Based on data from the Norwegian river Imsa between 1976 and 2015, we found that juveniles, 14–19 cm in total length, started their sea sojourn during a short period between late April and early June. However, more than 20% of fish 13 cm or shorter migrated downstream between October and March, whereas 55% of fish 20 cm or longer migrated downstream between July and September. The regular-sized, spring-migrating juveniles had 2–3 times higher survival at sea than similar-sized conspecifics migrating to sea at other times of the year. The survival at sea for smaller juveniles was not improved by migration in spring relative to winter, and the survival of the largest juveniles was similar in spring and summer. Thus, the migration phenology appears adapted to survival in a high-risk environment by changing the timing according to their sizes.

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Feeding by Hatchery-Reared and Wild Atlantic Salmon (Salmo salar) Parr in Streams

Journal of the Fisheries Research Board of Canada ◽

10.1139/f79-202 ◽

1979 ◽

Vol 36 (11) ◽

pp. 1408-1412 ◽

Cited By ~ 65

Author(s):

A. J. Sosiak ◽

R. G. Randall ◽

J. A. McKenzie

Keyword(s):

Atlantic Salmon ◽

Key Words ◽

Salmo Salar ◽

Food Selection ◽

Stomach Contents ◽

Stomach Fullness ◽

Size Dependent ◽

Atlantic Salmon Salmo Salar ◽

Feeding Experience ◽

Salmon Parr

Hatchery-reared Atlantic salmon (Salmo salar) parr were captured 1–3 mo after release in streams, along with wild parr from the same streams. Identification of their stomach contents showed total number of organisms and number of taxa per stomach were greater and there was a higher index of stomach fullness in wild than in hatchery parr resident ≤ 2 mo in a stream. Wild parr consumed more Brachycentridae, Hydroptilidae, Diptera, and Plecoptera than did hatchery parr, but sometimes less Odontoceridae and Heptageniidae. These differences may have arisen from size-dependent food selection, the effects of feeding experience, or possible microhabitat differences between wild and hatchery parr. Key words: salmon parr, hatchery-reared, wild, feeding

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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

ICES Journal of Marine Science ◽

10.1093/icesjms/fsy156 ◽

2018 ◽

Vol 76 (4) ◽

pp. 1107-1121 ◽

Cited By ~ 14

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.

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Seasonal variation in size-dependent survival of juvenile Atlantic salmon (Salmo salar): performance of multistate capture–mark–recapture models

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f08-083 ◽

2008 ◽

Vol 65 (8) ◽

pp. 1649-1666 ◽

Cited By ~ 15

Author(s):

Benjamin H. Letcher ◽

Gregg E. Horton

Keyword(s):

Atlantic Salmon ◽

Salmo Salar ◽

Mark Recapture ◽

Size Dependent ◽

Atlantic Salmon Salmo Salar ◽

Average Survival ◽

Average Probability ◽

Sampling Intervals ◽

Time Invariant ◽

Probability Of Capture

We estimated the magnitude and shape of size-dependent survival (SDS) across multiple sampling intervals for two cohorts of stream-dwelling Atlantic salmon ( Salmo salar ) juveniles using multistate capture–mark–recapture (CMR) models. Simulations designed to test the effectiveness of multistate models for detecting SDS in our system indicated that error in SDS estimates was low and that both time-invariant and time-varying SDS could be detected with sample sizes of >250, average survival of >0.6, and average probability of capture of >0.6, except for cases of very strong SDS. In the field (N ∼750, survival 0.6–0.8 among sampling intervals, probability of capture 0.6–0.8 among sampling occasions), about one-third of the sampling intervals showed evidence of SDS, with poorer survival of larger fish during the age-2+ autumn and quadratic survival (opposite direction between cohorts) during age-1+ spring. The varying magnitude and shape of SDS among sampling intervals suggest a potential mechanism for the maintenance of the very wide observed size distributions. Estimating SDS using multistate CMR models appears complementary to established approaches, can provide estimates with low error, and can be used to detect intermittent SDS.

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Size-dependent susceptibility to infectious salmon anemia virus (ISAV) in Atlantic salmon (Salmo salar L.) of farm, hybrid and wild parentage

Aquaculture ◽

10.1016/j.aquaculture.2005.10.041 ◽

2006 ◽

Vol 254 (1-4) ◽

pp. 82-91 ◽

Cited By ~ 16

Author(s):

K.A. Glover ◽

C. Skår ◽

K.E. Christie ◽

J. Glette ◽

H. Rudra ◽

...

Keyword(s):

Atlantic Salmon ◽

Salmo Salar ◽

Infectious Salmon Anemia Virus ◽

Size Dependent ◽

Atlantic Salmon Salmo Salar ◽

Infectious Salmon Anemia ◽

Salmon Anemia Virus ◽

Anemia Virus

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Evidence for bottom–up trophic effects on return rates to a second spawning for Atlantic salmon (Salmo salar) from the Miramichi River, Canada

ICES Journal of Marine Science ◽

10.1093/icesjms/fss055 ◽

2012 ◽

Vol 69 (9) ◽

pp. 1656-1667 ◽

Cited By ~ 16

Author(s):

Gérald Chaput ◽

Hugues P. Benoît

Keyword(s):

Atlantic Salmon ◽

Salmo Salar ◽

Prey Availability ◽

Positive Association ◽

Small Fish ◽

Bottom Up ◽

Return Rates ◽

Atlantic Salmon Salmo Salar ◽

Trophic Effects ◽

Short Period

Abstract Chaput, G., and Benoît, H. P. 2012. Evidence for bottom–up trophic effects on return rates to a second spawning for Atlantic salmon (Salmo salar) from the Miramichi River, Canada. – ICES Journal of Marine Science, 69: 1656–1667. Increased return rates of consecutive repeat-spawning Atlantic salmon (Salmo salar) have been noted in the Miramichi River during the past two decades, and the short period for their reconditioning at sea suggests that they occupy the southern Gulf of St Lawrence ecosystem. A 40-year time-series of observations was used to examine linkages between return rates to a second spawning for Atlantic salmon in the Miramichi River and changes in the small fish community of the southern Gulf of St Lawrence that is potential prey for adult salmon. The positive association between the variations in the return rates of repeat spawners and the variations in the small fish biomass index early in the reconditioning year at sea provides evidence that abundant food supplies after return to sea following first spawning may be beneficial for the survival of Atlantic salmon to a second consecutive spawning. In contrast, no association was found between prey availability and return rates of alternate repeat spawners that presumably recondition outside the Gulf of St Lawrence.

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Natural recolonization of the Seine River by Atlantic salmon (Salmo salar) of multiple origins

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f09-190 ◽

2010 ◽

Vol 67 (1) ◽

pp. 1-4 ◽

Cited By ~ 25

Author(s):

Charles Perrier ◽

Guillaume Evanno ◽

Jérôme Belliard ◽

René Guyomard ◽

Jean-Luc Baglinière

Keyword(s):

Atlantic Salmon ◽

Salmo Salar ◽

Large River ◽

Long Distance ◽

Seine River ◽

Genetic Analyses ◽

Atlantic Salmon Salmo Salar ◽

Multiple Origins ◽

Population Sustainability ◽

Source Populations

The restoration of previously extinct salmon populations is usually achieved with stocking programmes, but natural recolonization can also occur through the straying of individuals from nearby populations. Here we investigated the origin of Atlantic salmon ( Salmo salar ) that recently recolonized the Seine River (France). The degradation of this river had led to the extinction of the population, but since the 1990s, the water quality has greatly improved. Although no stocking was performed, 162 individual salmon were recently observed by video-counting. Seven fish were sampled for morphological and genetic analyses. These individuals were genotyped at 17 microsatellites markers and their probable source populations were identified using baseline samples from regional and distant populations. Four of the sampled individuals were grilse and three were multi-sea-winter fish. Genetic analyses revealed that the fish partly originated from a nearby stock but also from distant populations, suggesting long-distance straying. This natural recolonization of a large river by strayers from several origins is discussed in terms of population sustainability and management.

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Flavour and off-flavour in wild and farmed atlantic salmon from locations around northern ireland

Water Science & Technology ◽

10.2166/wst.1995.0444 ◽

1995 ◽

Vol 31 (11) ◽

pp. 259-264 ◽

Cited By ~ 6

Author(s):

L. J. Farmer ◽

J. M. McConnell ◽

T. D. J. Hagan ◽

D. B. Harper

Keyword(s):

Northern Ireland ◽

Atlantic Salmon ◽

Salmo Salar ◽

Scientific Basis ◽

Wild Salmon ◽

Farmed Salmon ◽

Atlantic Salmon Salmo Salar ◽

Short Period ◽

Profiling Techniques ◽

Farmed Atlantic Salmon

Sensory profiling techniques were used to investigate the odour and flavour of Atlantic salmon (Salmo salar) from six sources in order to determine (i) whether there was any scientific basis for reports of off-flavours in salmon from certain sources and (ii) whether farmed and wild salmon differed in terms of flavour attributes. There were no consistent differences in odour or flavour between sea-caught wild salmon and farmed salmon. However, river-caught wild salmon showed enhanced ‘earthy’ flavour and odour; GC-odour assessment studies have indicated that 2-methylisoborneol and geosmin contribute to these attributes. For a short period, wild river salmon from one source also suffered from a manure-like off-flavour which has been shown to be due to the presence of skatole. The source of this compound remains uncertain.

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Sensitivity of American Eels (Anguilla rostrata) and Atlantic Salmon (Salmo salar) to Weak Electric and Magnetic Fields

Journal of the Fisheries Research Board of Canada ◽

10.1139/f73-114 ◽

1973 ◽

Vol 30 (5) ◽

pp. 657-663 ◽

Cited By ~ 55

Author(s):

S. A. Rommel Jr. ◽

J. D. McCleave

Keyword(s):

Magnetic Fields ◽

Atlantic Salmon ◽

Electric Fields ◽

Salmo Salar ◽

Ocean Current ◽

Anguilla Rostrata ◽

Long Distance ◽

Atlantic Salmon Salmo Salar ◽

Cardiac Responses ◽

Weak Magnetic Fields

Two long distance migrating fishes, the American eel (Anguilla rostrata) and the Atlantic salmon (Salmo salar), consistently showed conditioned cardiac responses to weak electric fields applied perpendicular but not parallel to their bodies. In fields with a power density of 0.11 × 10−3 pW/cm3, 63% of the eels tested were successfully conditioned, as were 56% of the salmon tested at 0.9 × 10−4 pW/cm3. At greater field intensities greater percentages of salmon and eels were successfully conditioned. However, at two lower intensities fewer salmon and no eels responded. These fields are of the magnitude that occur naturally in ocean currents. As geoelectric fields are perpendicular to the water motion that generates them, this sensitivity might allow a migrating fish to align itself upstream or downstream in an ocean current in the absence of fixed references. Results of magnetic conditioning experiments in eels were equivocal. Attempts to condition salmon to weak magnetic fields were unsuccessful.

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