Size-dependent survival of juvenile Atlantic salmon Salmo salar and brown trout Salmo trutta from the cold river Beiarelva, northern Norway

The growth of Atlantic salmon Salmo salar L. and brown trout Salmo trutta L. in the very cold river Beiarelva is so low that not all individuals reach the critical lengths during their first summer to form scales. Hence, after their first winter, each year-class of Atlantic salmon and brown trout c...

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Main Authors: Arne Johan Jensen, Bjørn Ove Johnsen
Format: Article
Language:English
Published: Norwegian University of Science and Technology 1984-12-01
Series:Fauna Norvegica
Subjects:
Online Access:https://www.ntnu.no/ojs/index.php/fauna_norvegica/article/view/6125
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author Arne Johan Jensen
Bjørn Ove Johnsen
author_facet Arne Johan Jensen
Bjørn Ove Johnsen
author_sort Arne Johan Jensen
collection DOAJ
description The growth of Atlantic salmon Salmo salar L. and brown trout Salmo trutta L. in the very cold river Beiarelva is so low that not all individuals reach the critical lengths during their first summer to form scales. Hence, after their first winter, each year-class of Atlantic salmon and brown trout can be divided into two length groups, with the smaller fish lacking the first annulus, and the larger fish having this annulus. For this reason length-dependent survival for the rest of their freshwater life could be examined. In brown trout the same survival was found in small and larger parr of all year-classes investigated. In Atlantic salmon the same was found in all year-classes except one. In one year-class the survival was significantly less in the smaller group than in the larger. In 2+ and older fish of both Atlantic salmon and brown trout some of the small individuals had grown as long as most of the individuals having the first annulus, whereas others were still the smallest ones in the year-class. Hence, the smallest yearlings are not always the smallest fish in later years. The very good food conditions for the parr in river Beiarelva may explain the good survival of small individuals.
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series Fauna Norvegica
spelling doaj-art-d5c842e170ba4d83a61ba87d94072b022025-08-20T02:12:14ZengNorwegian University of Science and TechnologyFauna Norvegica1502-48731891-53961984-12-01510.5324/fn.v5i0.6125Size-dependent survival of juvenile Atlantic salmon Salmo salar and brown trout Salmo trutta from the cold river Beiarelva, northern NorwayArne Johan Jensen0Bjørn Ove Johnsen1Directorate for Wildlife and Freshwater Fish, Tungasletta 2, NO-7000 Trondheim, NorwayDirectorate for Wildlife and Freshwater Fish, Tungasletta 2, NO-7000 Trondheim, Norway The growth of Atlantic salmon Salmo salar L. and brown trout Salmo trutta L. in the very cold river Beiarelva is so low that not all individuals reach the critical lengths during their first summer to form scales. Hence, after their first winter, each year-class of Atlantic salmon and brown trout can be divided into two length groups, with the smaller fish lacking the first annulus, and the larger fish having this annulus. For this reason length-dependent survival for the rest of their freshwater life could be examined. In brown trout the same survival was found in small and larger parr of all year-classes investigated. In Atlantic salmon the same was found in all year-classes except one. In one year-class the survival was significantly less in the smaller group than in the larger. In 2+ and older fish of both Atlantic salmon and brown trout some of the small individuals had grown as long as most of the individuals having the first annulus, whereas others were still the smallest ones in the year-class. Hence, the smallest yearlings are not always the smallest fish in later years. The very good food conditions for the parr in river Beiarelva may explain the good survival of small individuals. https://www.ntnu.no/ojs/index.php/fauna_norvegica/article/view/6125ActinopterygiiSalmoniformesecologydemographyNorthern Norway
spellingShingle Arne Johan Jensen
Bjørn Ove Johnsen
Size-dependent survival of juvenile Atlantic salmon Salmo salar and brown trout Salmo trutta from the cold river Beiarelva, northern Norway
Fauna Norvegica
Actinopterygii
Salmoniformes
ecology
demography
Northern Norway
title Size-dependent survival of juvenile Atlantic salmon Salmo salar and brown trout Salmo trutta from the cold river Beiarelva, northern Norway
title_full Size-dependent survival of juvenile Atlantic salmon Salmo salar and brown trout Salmo trutta from the cold river Beiarelva, northern Norway
title_fullStr Size-dependent survival of juvenile Atlantic salmon Salmo salar and brown trout Salmo trutta from the cold river Beiarelva, northern Norway
title_full_unstemmed Size-dependent survival of juvenile Atlantic salmon Salmo salar and brown trout Salmo trutta from the cold river Beiarelva, northern Norway
title_short Size-dependent survival of juvenile Atlantic salmon Salmo salar and brown trout Salmo trutta from the cold river Beiarelva, northern Norway
title_sort size dependent survival of juvenile atlantic salmon salmo salar and brown trout salmo trutta from the cold river beiarelva northern norway
topic Actinopterygii
Salmoniformes
ecology
demography
Northern Norway
url https://www.ntnu.no/ojs/index.php/fauna_norvegica/article/view/6125
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AT bjørnovejohnsen sizedependentsurvivalofjuvenileatlanticsalmonsalmosalarandbrowntroutsalmotruttafromthecoldriverbeiarelvanorthernnorway