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

Strand, Jo Espen Tau; Davidsen, Jan Grimsrud; Jørgensen, Even H.; Rikardsen, Audun H.

doi:10.1007/s10641-010-9737-3

Cited by 19 publications

(17 citation statements)

References 29 publications

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“…Generally, salmonids spend several days of preadaptation in fresh water before moving to the marine environment (Strand, Davidsen, Jørgensen, & Rikardsen, 2011). Finally, it is noteworthy that there was a correlation (although weakly non-significant) between the assigned proportion and stocking.…”

Section: F I G U R Ementioning

confidence: 90%

Life history and genetic characterisation of sea troutSalmo truttain the Adriatic Sea

et al. 2019

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The brown trout Salmo trutta is characterised by both anadromous (sea trout)and resident populations, naturally occurring in Atlantic and Ponto-Caspian rivers. Sea trout are currently considered absent from rivers of the Mediterranean area, probably because of the non-optimal chemical-physical characteristics of the Mediterranean Sea. However, the occasional bycatch of smoltified S. trutta in the Adriatic Sea is well known among fishermen and the biological explanation of this phenomenon is still controversial. The aim of this study was to compare the genetic diversity of freshwater and marine brown trout to try to understand the factors underlying the presence of putative anadromous brown trout in the Adriatic Sea.2. In this study, we analysed the genetic diversity of: (1) wild brown trout collected from the Esino River (central Italy); (2) a domestic strain of brown trout used for stocking the study area; and (3) a sample of Adriatic sea trout collected near the outlet of the Esino River. Together with genetic analysis, we carried out scale analysis in order to track the freshwater/marine stages of the life cycle in the sea trout samples. The genetic characterisation was carried out by polymerase chain reaction-restriction fragment length polymorphism analysis of the mtDNA fragment ND-5/6 and the nuclear locus LDH-C1* and by genotyping 15 microsatellite loci. The genetic polymorphism obtained was used to investigate intra-and inter-population genetic diversity, rates of genetic introgression between wild and domestic samples and the origin of sea trout specimens by using assignment tests.3. Our genetic analyses demonstrated that the sea trout analysed in this study are from the domestic strain of Atlantic origin used in central Italy for stocking activities. The level of genetic introgression between native and domestic samples is high in the Esino River. The populations more resilient to introgressive hybridisation appeared to be those living in the portion of the river network dominated by carbonate rocks. Assignment tests (GeneClass) suggest the existence of a link between stocking efforts and the freshwater origin of the sea trout. In addition, data obtained from the analysis of scales, size measurement, and sex determination | 461 SPLENDIANI Et AL.

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Section: F I G U R Ementioning

confidence: 90%

Life history and genetic characterisation of sea troutSalmo truttain the Adriatic Sea

et al. 2019

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“…Smolts undergo a preparatory process involving several physiological and morphological changes directed towards optimising the performance in the marine environment Nielsen et al 2001). The physiological changes correlate with migratory activity (Strand et al 2011) and sea water tolerance (Nielsen et al 2001). The non-passing smolts may have reverted to the parr condition (i.e.…”

Section: Discussionmentioning

confidence: 99%

Linking individual behaviour and migration success inSalmo salarsmolts approaching a water withdrawal site: implications for management

Svendsen

Aarestrup

Malte

et al. 2011

Aquat. Living Resour.

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-Seaward migration of immature salmonids (smolts) may be associated with severe mortality in anthropogenically altered channels. Few studies however, have identified distinct behaviours that lead to exposure to adverse habitats or even unsuccessful migration. This study used high resolution telemetry to map migration routes of Atlantic salmon (Salmo salar) smolts approaching a water withdrawal zone associated with an aquaculture facility in a lowland river. Individual smolts were tagged with an acoustic transmitter and released upstream of the water withdrawal zone. A trap was installed downstream of the water withdrawal zone. The trap captured all smolts that passed the water withdrawal zone. The tracking results confirmed previous studies on Pacific salmon showing that Atlantic salmon smolts may perform milling behaviours (i.e. upstream excursions and circular swimming behaviour) in anthropogenically altered channels. Non-milling and milling smolts were compared. Smolts performing milling behaviours covered a larger area (m 2 ) and experienced an increased probability of entering the water withdrawal zone, considered an adverse habitat. Finally, smolts were identified as either passing (67%) or non-passing (33%) the water withdrawal zone based on the recapture data from the trap. In total, 20% of the non-passing smolts entered the aquaculture facility. Several behavioural traits differed between the remaining (80%) non-passing smolts and the passing smolts. In particular, time spent near the water withdrawal zone correlated negatively with the probability of passage. These links between individual behaviours and exposure to adverse habitats and passage probability may be applied to improve management of salmonid populations.

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“…The physiological changes include modifications of plasma ion concentrations ( e.g. chloride Cl − and sodium Na + ) and increases in gill Na + K + ATPase activity (Hoar, 1988; Boeuf, 1994; Strand et al , 2011), thyroid hormones (Iwata, 1995; Hutchison & Iwata, 1998), growth hormone (GH), cortisol and insulin‐like growth factor‐I (Hoar, 1988; Sakamoto et al , 1995).…”

Section: Migration Behaviour During Smolt and Initial Post‐smolt Migrmentioning

confidence: 99%

A critical life stage of the Atlantic salmon Salmo salar: behaviour and survival during the smolt and initial post‐smolt migration

Thorstad

Whoriskey

Uglem

et al. 2012

Journal of Fish Biology

295

394

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The anadromous life cycle of Atlantic salmon Salmo salar involves long migrations to novel environments and challenging physiological transformations when moving between salt-free and salt-rich waters. In this article, (1) environmental factors affecting the migration behaviour and survival of smolts and post-smolts during the river, estuarine and early marine phases, (2) how behavioural patterns are linked to survival and (3) how anthropogenic factors affect migration and survival are synthesized and reviewed based on published literature. The timing of the smolt migration is important in determining marine survival. The timing varies among rivers, most likely as a consequence of local adaptations, to ensure sea entry during optimal periods. Smolts and post-smolts swim actively and fast during migration, but in areas with strong currents, their own movements may be overridden by current-induced transport. Progression rates during the early marine migration vary between 0.4 and 3.0 body lengths s(-1) relative to the ground. Reported mortality is 0.3-7.0% (median 2.3) km(-1) during downriver migration, 0.6-36% (median 6.0) km(-1) in estuaries and 0.3-3.4% (median 1.4) km(-1) in coastal areas. Estuaries and river mouths are the sites of the highest mortalities, with predation being a common cause. The mortality rates varied more among studies in estuaries than in rivers and marine areas, which probably reflects the huge variation among estuaries in their characteristics. Behaviour and survival during migration may also be affected by pollution, fish farming, sea lice Lepeophtheirus salmonis, hydropower development and other anthropogenic activities that may be directly lethal, delay migration or have indirect effects by inhibiting migration. Total mortality reported during early marine migration (up to 5-230 km from the river mouths) in the studies available to date varies between 8 and 71%. Hence, the early marine migration is a life stage with high mortalities, due to both natural and human influences. Factors affecting mortality during the smolt and post-smolt stages contribute to determine the abundance of spawner returns. With many S. salar populations in decline, increased mortality at these stages may considerably contribute to limit S. salar production, and the consequences of human-induced mortality at this stage may be severe. Development of management actions to increase survival and fitness at the smolt and post-smolt stages is crucial to re-establish or conserve wild populations.

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

Cited by 19 publications

References 29 publications

Life history and genetic characterisation of sea troutSalmo truttain the Adriatic Sea

Life history and genetic characterisation of sea troutSalmo truttain the Adriatic Sea

Linking individual behaviour and migration success inSalmo salarsmolts approaching a water withdrawal site: implications for management

A critical life stage of the Atlantic salmon Salmo salar: behaviour and survival during the smolt and initial post‐smolt migration

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