Predation on Atlantic salmon and sea trout during their first days as postsmolts

Dieperink, C.; Bak, B.; Pedersen, Lars‐Flemming; Pedersen, Michael Ingemann; Pedersen, Stig

doi:10.1111/j.1095-8649.2002.tb00917.x

Cited by 97 publications

(57 citation statements)

References 21 publications

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“…In the inner estuary, high concentrations of smolt predators may account for the extreme size-selected survival. Predators have been reported to favour the area around head-of-tide or at constriction points within estuaries during the smolt run (Hvidsten and Lund 1988;Dieperink et al 2002;Jepsen et al 2006). Salmon are first exposed to salt water in the inner estuary and mortality may occur as a result of osmotic stress or an associated reduction in predator avoidance ability (Järvi 1989;Handeland et al 1996).…”

Section: Influence Of Body Size On Survivalmentioning

confidence: 99%

“…Using acoustic telemetry, researchers have estimated mortality rates during the estuarine migration, which is the transition point from riverine to marine habitats, the place the fish spend their first few weeks in the ocean, and a place and time where previous studies have reported intense mortality (Kocik et al 2009;Davidsen et al 2009;Halfyard et al 2012). Causes of estuarine losses may include predation (e.g., Hvidsten and Møkkelgjerd 1987;Hvidsten and Lund 1988;Dieperink et al 2002), osmotic stress (Staurnes et al 1996;McCormick et al 1998), and (or) their interaction (Järvi 1989;Handeland et al 1996).…”

Section: Introductionmentioning

confidence: 98%

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Correlates of estuarine survival of Atlantic salmon postsmolts from the Southern Upland, Nova Scotia, Canada

Halfyard

Gibson

Stokesbury

et al. 2013

Can. J. Fish. Aquat. Sci.

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Acoustic telemetry is a useful tool to monitor the estuarine survival and behaviour of Atlantic salmon postsmolts. Most frequently, survival is reported as the static fraction of tagged postsmolts detected, and while the timing or location of mortality may be reported, covariates of survival or the relationship between migratory behaviour and survival are less often described. In this study, we used acoustic telemetry to follow Atlantic salmon smolts migrating to sea from four rivers in Nova Scotia, Canada. Further, we tested the relationship between migratory behaviour and survival and used mark-recapture models to examine the role of body length and tag-to-body mass as survival covariates. Survival was most heavily impacted in estuarine habitats closest to head-of-tide. Survival was affected by body length at three of four sites. The shape and spatial variability of the body lengthsurvival relationship provided insight on mortality vectors, highlighting the potential roles of predation and osmotic stress. Survival was not influenced by repeated landward-seaward migratory movements; however, there was a significant correlation between residency and survival.Résumé : La télémétrie acoustique est un outil utile pour la surveillance de la survie et du comportement en estuaire des post-saumoneaux de saumon atlantique. Dans la plupart des cas, le taux de survie signalé est la fraction statique de postsaumoneaux marqués détectés et, si le moment et le lieu de la mortalité peuvent être mentionnés, les covariables du taux de survie ou de la relation entre le comportement migratoire et la survie sont moins souvent rapportées. Dans cette l'étude, nous avons fait appel à la télémétrie acoustique pour suivre des saumoneaux de saumon atlantique en migration de la mer vers quatre rivières de la Nouvelle-Écosse (Canada). Nous avons en outre vérifié le lien entre le comportement migratoire et le taux de survie et utilisé des modèles de marquage-recapture pour examiner la longueur du corps et le rapport entre le poids de la marque et celui du corps comme covariables éventuelles du taux de survie. Les impacts sur ce dernier étaient les plus forts dans les habitats estuariens situés les plus près de la limite de marée. Dans quatre sites, la longueur du corps avait une incidence sur le taux de survie. La forme et la variabilité spatiale de la relation entre la longueur du corps et le taux de survie ont mis en lumière des vecteurs de mortalité, faisant ressortir un rôle possible de la prédation et du stress osmotique. Si les déplacements migratoires répétés vers la terre ou vers la mer n'avaient pas d'incidence sur le taux de survie, une corrélation significative a cependant été notée entre le temps de résidence et le taux de survie. [Traduit par la Rédaction]

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Section: Influence Of Body Size On Survivalmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 98%

Correlates of estuarine survival of Atlantic salmon postsmolts from the Southern Upland, Nova Scotia, Canada

Halfyard

Gibson

Stokesbury

et al. 2013

Can. J. Fish. Aquat. Sci.

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“…There is increasing concern that greater rates of marine mortality documented among Atlantic salmon over the past decade may be largely incurred in the near-shore coastal zone, where smolt may be exposed for the first time to a large field of predators (Blackwell & Juanes 1998, Dieperink et al 2002. It is thus imperative to understand the mechanisms employed by Atlantic salmon during this early stage in the marine migration and the influence of environmental factors on migratory patterns.…”

Section: Introductionmentioning

confidence: 99%

Active migration of wild Atlantic salmon Salmo salar smolt through a coastal embayment

Hedger¹,

Martin²,

Hatin³

et al. 2008

Mar. Ecol. Prog. Ser.

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Migration patterns of wild Atlantic salmon Salmo salar smolt were examined in a coastal embayment in the Gaspé peninsula of Québec, Canada. Twenty-four smolt in 2005 and 30 in 2006 were tagged with coded ultrasonic transmitters, and their migration throughout the bay was monitored using an array of fixed VR2 hydrophone receivers. Migration patterns were complex, with some smolt taking a direct route through the coastal embayment and others repeatedly changing direction over short spatial and temporal scales. Migration was mainly an active process with an overall outward (seaward) migration in the face of an inward residual circulation. Swimming direction was mainly outward during nocturnal inflowing currents but was more dispersed during daytime and nocturnal outflowing currents; swimming speed was greater during daytime than during nighttime. This pattern was consistent with smolt migrating offshore nocturnally and using daytime for prey detection and predator avoidance. Salinity had a strong effect: exposure to more saline waters caused increased swimming speeds. These observations are consistent with the hypothesis that smolt exploit an innate compass to maintain a preferred bearing and that the speed and direction of swimming is controlled by salinity and the diurnal cycle.

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“…Several studies have shown that post-smolts are exposed to high predation immediately after sea entry (Reitan et al 1987;Hvidsten and Lund 1988;Dieperink et al 2002) and that the risk of predation increases if fish suffers from osmotic stress (Järvi 1989;Handeland et al 1996;Kennedy et al 2007). It may therefore be suggested that the extended residency of the first smolt group in the lower part of the river was related to their low gill Na + , K + -ATPase activity and a need to improve seawater tolerance before entering seawater.…”

mentioning

confidence: 99%

Seaward migrating Atlantic salmon smolts with low levels of gill Na+, K+ -ATPase activity; is sea entry delayed?

Strand¹,

Davidsen

Jørgensen

et al. 2010

Environ Biol Fish

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Two groups of migrating wild Atlantic salmon (Salmo salar) smolts caught within a 1 week interval in the River Alta, northern Norway, were tagged with acoustic transmitters and measured for gill Na + , K + -ATPase activity in order to compare their smolt status with timing of sea entry. The first group of smolts had low levels of gill Na + , K + -ATPase activity and resided in the lower part of the river twice as long as the second group that had high levels of gill Na + , K + -ATPase activity. This indicates that early migrating smolts may not be completely physiologically adapted for salt water and delay their sea entry, thereby also synchronizing their seaward migration with the later migrating smolts.

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Predation on Atlantic salmon and sea trout during their first days as postsmolts

Cited by 97 publications

References 21 publications

Correlates of estuarine survival of Atlantic salmon postsmolts from the Southern Upland, Nova Scotia, Canada

Correlates of estuarine survival of Atlantic salmon postsmolts from the Southern Upland, Nova Scotia, Canada

Active migration of wild Atlantic salmon Salmo salar smolt through a coastal embayment

Seaward migrating Atlantic salmon smolts with low levels of gill Na+, K+ -ATPase activity; is sea entry delayed?

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