Time of divergence of growth groups between potential 1+ and 2+ smolts among sibling Atlantic salmon

Thorpe, J. E.; Morgan, R. I. G.; Ottaway, E. M.; Miles, M.S.

doi:10.1111/j.1095-8649.1980.tb02738.x

Cited by 102 publications

(37 citation statements)

References 5 publications

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“…It is not clear if the parr were those that continued, or ceased, to grow in winter. There is clear evidence that a bimodal size distribution may develop in the first year of the life cycle with the large parr growing through the winter to become smolts after 1 year (S1 parr), while the small parr cease feeding in winter and become smolts after at least 2 years (S2 parr) in fresh water (Thorpe 1977(Thorpe , 1986(Thorpe , 1987(Thorpe , 1989Thorpe et al 1980;Nicieza, Braña & Toledo 1991;Thorpe, Metcalfe & Huntingford 1992). Higgins & Talbot (1985) followed the growth and feeding of the two groups of parr from September to June in the laboratory.…”

Section: Discussionmentioning

confidence: 99%

A functional model for maximum growth of Atlantic Salmon parr, Salmo salar, from two populations in northwest England

1997

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1. The chief objective was to develop a functional model for the growth of parr (0+, 1+) of Atlantic Salmon, Salmo salar, from two populations (Rivers Leven and Lune in northwest England), using a model similar to that developed previously for Brown Trout, Salmo trutta. Parr bred from Leven parents were acclimatized to nine fairly constant temperatures (two 0+, two 1+ parr per temperature) in the range 3·8–21·7 °C (variation ± 0·3 at 3·8 °C to ± 1·0 at 21·7 °C). Each fish was kept in a separate tank and fed to satiation on shrimps. The mass and length of each fish was recorded at the start and finish of a growth period of 30 days. Parr (0+, 1+) bred from Lune parents were separated into slow and fast growers, and acclimatized to six very constant temperatures. There were three slow and three fast growers at each of 5·0, 10·0, 15·0 °C for 0+ parr and each of 5·0, 10·0, 13·0, 15·0, 18·0, 20·0 °C for 1+ parr. Procedures were the same as for Leven parr except that the growth period lasted 30 days for the 18 0+ parr and 42 days for the 36 1+ parr. 2. The growth model was an excellent fit (P < 0·001) with no significant differences between parr from the two rivers, fast‐growing parr of different ages (0+, 1+), or fast‐ and slow‐growing 1+ parr. The optimum temperature for the combined data (81 parr) was 15·9 °C with a range for growth of 6·0–22·5 °C. The model failed to fit the data for slow‐growing 0+ Lune parr in experiments from November to February. Growth was reduced in these fish, even though the temperatures were suitable for growth (10, 15°C). 3. The model described approximately the growth of three year‐classes of Atlantic Salmon parr in the River Eden in northwest England. Some of the discrepancies between actual masses and those predicted from the model were consistent and possible reasons for this are discussed.

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Section: Discussionmentioning

confidence: 99%

A functional model for maximum growth of Atlantic Salmon parr, Salmo salar, from two populations in northwest England

1997

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“…The present paper deals with the first decision, which has been formulated as a simple developmental model (Thorpe 1986). In mid-to late summer the growth trajectories of potential emigrant and potential resident individuals in a population diverge (Thorpe et al 1980, Wright et al 1990, Nicieza et al 1991. By November this results in a clearly defined bimodal length frequency distribution (Fig.…”

Section: Introductionmentioning

confidence: 99%

Behavioural influences on life-history variation in juvenile Atlantic salmon, Salmo salar

1992

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“…b) Analyse de l'histogramme de fréquence de taille des tacons 0 T : la mise en évidence d'une éventuelle bimodalité a été réalisée par la méthode de BATTACHARYA (LAURENT et MOREAU, 1974). Par analogie avec ce qui a été décrit par THORPE et al (1980), les individus du mode haut sont supposés smoltifier au printemps suivant, ceux du mode bas restant au moins encore une année en rivière. c) L'estimation des mortalités hivernales suivant l'âge et la taille.…”

Section: "Population De Juvénilesunclassified

Comparaison de deux méthodes d'estimation de la production naturelle de smolts de saumon atlantique (Salmo salar L.).

Baglinière

Maisse

Nihouarn

et al. 1988

Bull. Fr. Pêche Piscic.

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(2) Délégation régionale n°2 du Conseil Supérieur de la Pêche, 84, rue de rennes -35510 CESSON-SÉVIGNÉ, France. RÉSUMÉDeux méthodes d'estimation de la production en smolts de saumon atlantique (Salmo salarL. sont comparées sur la rivière Oir, affluent de laSélune (Basse-Normandie). La première estime h nombre de smolts par l'analyse des caractéristiques de l'habitat et du phénomène de bimodalité di taille observée dans la population 0+ en automne. La seconde méthode évalue la production ei smolts à partir des captures par piégeage.L'étude montre que les estimations réalisées par les deux méthodes sont proches avei cependant des différences plus ou moins importantes selon l'année et la classe d'âge. Elle montn également que les smolts proviennent essentiellement de la population automnale de 0+ à fort croissance. Enfin, les valeurs de taux de survie hivernale utilisées dans la première méthodi permettent d'obtenir des estimations du nombre de smolts 1 + proches de celles faites par piégeage les résultats sont moins fiables pour les smolts 2+. Les résultats sont discutés et différents aspect sont analysés en vue d'améliorer la concordance entre les deux méthodes.Mots-clé : Saumon atlantique, juvéniles, habitat, production, migration, rivière, France. COMPARISON OF TWO METHODS FOR THE ESTIMATION OF THE NATURAL PRODUCTION OF ATLANTIC SALMON SMOLTS {Salmo salar L.) ABSTRACTTwo estimations methods of smolts number are compared in Oir River, tributary of Selune River (Low-Normandy). The first one estimates the smolts number from the analysis of characteristics of the habitat and of growth bimodality phenomena observed in 0+ autumn population. The second method evaluates the smolts production from the catches by trapping.This study shows that the estimations made by the two methods are closed. Nervertheless there exits some more or less important differences according to year and age class. It shows also that the smolts come mainly from the upper mode of 0+ autumn population. Lastly, the overwinter survival rates values used in the first method give 1+ smolts estimations near of those made by trapping, results are less reliable for 2+ smolts.Results are discussed and different aspects are analysed in order to obtain a better agreement between the two methods.

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Time of divergence of growth groups between potential 1+ and 2+ smolts among sibling Atlantic salmon

Cited by 102 publications

References 5 publications

A functional model for maximum growth of Atlantic Salmon parr, Salmo salar, from two populations in northwest England

A functional model for maximum growth of Atlantic Salmon parr, Salmo salar, from two populations in northwest England

Behavioural influences on life-history variation in juvenile Atlantic salmon, Salmo salar

Comparaison de deux méthodes d'estimation de la production naturelle de smolts de saumon atlantique (Salmo salar L.).

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