Seasonal variation in marine growth of sea trout,<i>Salmo trutta</i>, in coastal Skagerrak

Olsen, Esben Moland; Knutsen, Halvor; Simonsen, Jan Henrik; Jönsson, Bror; Knutsen, Jan Atle

doi:10.1111/j.1600-0633.2006.00176.x

Cited by 38 publications

(32 citation statements)

References 29 publications

(71 reference statements)

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“…Instead, they appeared to stay the winter at sea, in estuaries or in some cases in another river according to recaptures of tagged fish, as also reported from some other studies (King et al, 2016;Knutsen et al, 2004;Olsen et al, 2006). Instead, they appeared to stay the winter at sea, in estuaries or in some cases in another river according to recaptures of tagged fish, as also reported from some other studies (King et al, 2016;Knutsen et al, 2004;Olsen et al, 2006).…”

Section: Discussionsupporting

confidence: 79%

Water level influences migratory patterns of anadromous brown trout in small streams

Jönsson

Jonsson

2018

Ecology of Freshwater Fish

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Habitats modify the population ecology of species. Here, we show how low water level influences abundance and size of adult anadromous brown trout (Salmo trutta) entering a small, South Norwegian stream for spawning. After smolting, the fish appear chiefly to feed within 10 km of the home stream. In the autumn, South Norwegian streams typically flood because of heavy rainfall, when the anadromous brown trout entered from the sea. Mean annual duration of the upstream migration period was 34 days and ended when the flooding ended and the water temperature dropped to below 4°C. During most of the migration period, on average two trout ascended the river per day. The sexes entered the spawning area concurrently, and the male:female ratio of the anadromous trout was 1.27. No fish entered when the water depth just downstream of the spawning area was below 5 cm, and mean number of fish increased with increasing water depth to ca. 30 cm, but not at higher flows when the ascent gradually decreased. Mean and maximum size of the entering spawners increased with water depth between 5 and 16 cm. Among those that had been to sea, most were recaptured in the home stream, 4% in other streams, but only two of the strays were caught close to spawning time. The present results illustrate that population traits of anadromous brown trout from a small stream differ from those in larger rivers, probably because of selection associated with water flow.

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Section: Discussionsupporting

confidence: 79%

Water level influences migratory patterns of anadromous brown trout in small streams

Jönsson

Jonsson

2018

Ecology of Freshwater Fish

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“…This does not mean, however, that there is no environmental effect on sea growth. At more southern latitudes, the summer growth of anadromous S. trutta can be higher than that along the Norwegian coast (L’Abée‐Lund et al , 1989; Olsen et al , 2006; de Leeuw et al , 2007), indicating that the growth capacity of the species is higher in a warmer climate with prolonged growth season and possibly richer feeding opportunities than there are along the Norwegian coast.…”

Section: Discussionmentioning

confidence: 96%

Migratory timing, marine survival and growth of anadromous brown troutSalmo truttain the River Imsa, Norway

Jönsson

2009

Journal of Fish Biology

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The aim of the paper was to study sea migration, growth and survival of brown trout Salmo trutta of the River Imsa, 1976-2005. The migratory S. trutta were individually tagged and fish leaving or entering the river were monitored daily in traps located near the river mouth. The mean annual duration of the sea sojourn was 6-9 months for first-time migrants moving to sea between January and June. It was 8-18 months for those migrating to sea between July and December. Veteran migrants stayed 12 months or less at sea and most returned to the river in August. Early ascending fish stayed the longest in fresh water because most returned to sea in April to May. The day number of 50% cumulative smolt descent correlated negatively with mean water temperature in February to March and the February North Atlantic Oscillation index (NAOI). Mean annual sea growth during the first 2 years after smolting was higher for S. trutta spending the winter at sea than those wintering in the River Imsa. First year's sea growth was lower for S. trutta descending in spring than autumn. For first-time migrants, it correlated negatively with the February NAOI of the smolt year. Sea survival was higher for spring than autumn descending first-time migratory S. trutta with a maximum in May (14.9%). Number of anadromous S. trutta returning to the river increased linearly with the size of the cohort moving to sea, with no evidence of density-dependent sea mortality. Sea survival of S. trutta smolts moving to sea between January and June correlated positively both with the annual number of Atlantic Salmo salar smolts, the specific growth rate at sea, and time of seaward migration in spring. This is the first study indicating how environmental factors at the time of seaward migration influence the sea survival of S. trutta.

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“…Trout from streams with low water level during winter may migrate to a neighbouring watercourse for overwintering (Aldvén & Davidsen, 2017) or stay in marine waters (Eldøy et al, 2017;Olsen et al, 2006). Trout from streams with low water level during winter may migrate to a neighbouring watercourse for overwintering (Aldvén & Davidsen, 2017) or stay in marine waters (Eldøy et al, 2017;Olsen et al, 2006).…”

Section: Migration Can Improve Survivalmentioning

confidence: 99%

Environmental influences on life history strategies in partially anadromous brown trout (Salmo trutta, Salmonidae)

et al. 2019

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This paper reviews the life history of brown trout and factors influencing decisions to migrate. Decisions that maximize fitness appear dependent on size at age. In partly anadromous populations, individuals that attain maturity at the parr stage typically become freshwater resident. For individual fish, the life history is not genetically fixed and can be modified by the previous growth history and energetic state in early life. This phenotypic plasticity may be influenced by epigenetic modifications of the genome. Thus, factors influencing survival and growth determine life‐history decisions. These are intra‐ and interspecific competition, feeding and shelter opportunities in freshwater and salt water, temperature in alternative habitats and flow conditions in running water. Male trout exhibit alternative mating strategies and can spawn as a subordinate sneaker or a dominant competitor. Females do not exhibit alternative mating behaviour. The relationship between growth, size and reproductive success differs between sexes in that females exhibit a higher tendency to migrate than males. Southern populations are sensitive to global warming. In addition, fisheries, aquaculture with increased spreading of salmon lice, introduction of new species, weirs and river regulation, poor water quality and coastal developments all threaten trout populations. The paper summarizes life‐history data from six populations across Europe and ends by presenting new research questions and directions for future research.

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Seasonal variation in marine growth of sea trout,Salmo trutta, in coastal Skagerrak

Cited by 38 publications

References 29 publications

Water level influences migratory patterns of anadromous brown trout in small streams

Water level influences migratory patterns of anadromous brown trout in small streams

Migratory timing, marine survival and growth of anadromous brown troutSalmo truttain the River Imsa, Norway

Environmental influences on life history strategies in partially anadromous brown trout (Salmo trutta, Salmonidae)

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