Longitudinal gradients in threshold sizes for alternative male life history tactics in a population of Atlantic salmon (Salmo salar)

2006 ◽  
Vol 63 (9) ◽  
pp. 2067-2075 ◽  
Author(s):  
Nadia Aubin-Horth ◽  
Jean-Francois Bourque ◽  
Gaetan Daigle ◽  
Richard Hedger ◽  
Julian J Dodson
Keyword(s):  
Atlantic Salmon ◽  
Salmo Salar ◽  
Threshold Value ◽  
Environmental Data ◽  
Habitat Characteristics ◽  
Early Maturity ◽  
Habitat Features ◽  
Early Maturation ◽  
Atlantic Salmon Salmo Salar ◽  
Longitudinal Gradients

Atlantic salmon (Salmo salar) males may mature early in life in freshwater, rather than maturing after a migration to sea, if their size is above a threshold value. We analyzed the spatiotemporal variation in size and incidence of the early maturity tactic among males over an 8-year period in six subpopulations on two branches of a river and collected environmental data on each site and across the river scape. A positive longitudinal trend in the frequency of early maturing males that was stable over the 8-year period occurred from the mouth to the head of the river. Threshold sizes for early maturation varied among subpopulations; size thresholds for male parr to mature were higher in downstream habitats and lowest upstream. This pattern was consistent in both river branches over the 8-year period and was not related to either the density of parr or site-specific abiotic habitat characteristics. However, the cumulative incidence of habitat features that could impede migration of large individuals increased with increasing upstream distance. Migration costs may contribute to the observed variation in threshold sizes.

Life history variation and growth rate thresholds for maturity in Atlantic salmon, Salmo salar

1998 ◽  
Vol 55 (S1) ◽  
pp. 22-47 ◽  
Author(s):  
Jeffrey A Hutchings ◽  
Megan EB Jones
Keyword(s):  
Growth Rate ◽  
Life History ◽  
Atlantic Salmon ◽  
Salmo Salar ◽  
Optimal Growth ◽  
Age At Maturity ◽  
Early Maturity ◽  
Atlantic Salmon Salmo Salar ◽  
Optimal Growth Rate ◽  
Smolt Age

Based upon published and unpublished data compiled for 275 populations, we describe large-scale spatial and temporal patterns in Atlantic salmon, Salmo salar, life history and model these data to evaluate how changes to life history influence optimal growth rate thresholds for sea age at maturity. Population means (ranges in parentheses) describe the following for salmon throughout its range: smolt length = 14.8 cm (10.5-21.5 cm); smolt age = 2.91 years (1.04-5.85 years); egg-to-smolt survival = 1.5% (0.2-3.2%); grilse length = 56.8 cm (48.5-70.0 cm); sea age at maturity = 1.60 years (1.00-2.64 years); smolt-to-grilse survival = 7.4% (1.3-17.5%). Growth rate thresholds specify the length increase between the smolt and grilse stages above which reproduction after one winter at sea is favoured over later maturity. Our simulations indicated that increased growth generally favours earlier, but never delayed, maturity. Optimal growth rate thresholds for sea age at maturity are highly sensitive to survival but only moderately sensitive to fecundity, smolt size, and smolt age. Depending on an individual's growth rate at sea, early maturity is favoured by decreased smolt age or by increased smolt length, fecundity, or survival (freshwater or marine). We suggest that future Atlantic salmon life history research focus upon reaction norms and growth rate thresholds for age at maturity, demographic and genetic consequences of male parr maturation, and the origin and maintenance of coexisting anadromous and nonanadromous life history polymorphisms.

Effects of spawning distribution on juvenile Atlantic salmon (Salmo salar) density and growth

2011 ◽  
Vol 68 (1) ◽  
pp. 43-50 ◽  
Author(s):  
Maxim A.K. Teichert ◽  
Anders Foldvik ◽  
Torbjørn Forseth ◽  
Ola Ugedal ◽  
Sigurd Einum ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Atlantic Salmon ◽  
Salmo Salar ◽  
Local Density ◽  
Habitat Characteristics ◽  
Individual Growth ◽  
Dominant Factor ◽  
Atlantic Salmon Salmo Salar ◽  
Local Densities ◽  
Spawning Sites

We test whether the spatial distribution of spawning sites in a natural population is related to the density and individual growth rate of juvenile stream-dwelling salmonids. For this purpose, fine-scale data on the spatial distribution of Atlantic salmon ( Salmo salar ) nest sites, juvenile densities and body size, and habitat characteristics were combined. The area of nests summed over reaches of 25 m in length was positively correlated with local young-of-the-year (YOY) densities and was the strongest predictor of local densities. In turn, increased YOY densities were related to slower growth, and YOY density was the strongest predictor of YOY size. Measured habitat variables had little effect on YOY density over the spatial scale examined, which suggests that redistribution of YOY salmon according to habitat preferences was limited. The distribution of spawning sites was therefore the best predictor of local densities and subsequently YOY growth. Thus, during the YOY stage when dispersal is limited, patchy spawning distributions combined with local density-dependence may be the dominant factor responsible for spatial variation in growth.

scholarly journals Above parr: Lowland river habitat characteristics associated with higher juvenile Atlantic salmon ( Salmo salar ) and brown trout ( S. trutta ) densities

2019 ◽  
Vol 29 (4) ◽  
pp. 542-556
Author(s):  
Jessica E. Marsh ◽  
Rasmus B. Lauridsen ◽  
Stephen D. Gregory ◽  
William R. C. Beaumont ◽  
Luke J. Scott ◽  
...  
Keyword(s):  
Atlantic Salmon ◽  
Salmo Salar ◽  
Brown Trout ◽  
Habitat Characteristics ◽  
Lowland River ◽  
River Habitat ◽  
Atlantic Salmon Salmo Salar ◽  
Juvenile Atlantic Salmon

scholarly journals Life-history genotype explains variation in migration activity in Atlantic salmon (Salmo salar).

2021 ◽  
Author(s):  
Petri T Niemela ◽  
Ines Klemme ◽  
Anssi Karvonen ◽  
Pekka Hyvarinen ◽  
Paul V Debes ◽  
...  
Keyword(s):  
Life History ◽  
Atlantic Salmon ◽  
Salmo Salar ◽  
Life History Strategy ◽  
Dependent Manner ◽  
Life History Variation ◽  
Migration Activity ◽  
Early Maturation ◽  
Atlantic Salmon Salmo Salar ◽  
Activity Measurements

One of the most important life-history continuums is the fast-slow axis, where fast individuals mature earlier than slow individuals. Fast individuals are predicted to be more active than slow individuals; high activity is required to maintain a fast life-history strategy. Recent meta-analyses revealed mixed evidence for such integration. Here, we test whether known life-history genotypes differ in activity expression by using Atlantic salmon (Salmo salar) as a model. In salmon, variation in Vgll3, a transcription co-factor, explains ~40% of variation in maturation timing. We predicted that the allele related to early maturation (vgll3*E) would be associated with increased activity. We used an automated surveillance system to follow ~1900 juveniles including both migrants and non-migrants (i.e. smolt and parr fish, respectively) in semi-natural conditions over 31 days (~580 000 activity measurements). Against our prediction, vgll3 did not explain variation in activity in pooled migrant and non-migrant data. However, in migrants, vgll3 explained variation in activity according to our prediction in a sex-dependent manner. Specifically, in females the vgll3*E allele was related to increasing activity, whereas in males the vgll3*L allele (later maturation allele) was related to increasing activity. These sex-dependent effects might be a mechanism maintaining within-population genetic life-history variation.

Food consumption and growth in maturing Atlantic salmon (Salmo salar)

1999 ◽  
Vol 56 (11) ◽  
pp. 2019-2028 ◽  
Author(s):  
Selina M Stead ◽  
Dominic F Houlihan ◽  
H Anne McLay ◽  
Ray Johnstone
Keyword(s):  
Atlantic Salmon ◽  
Food Consumption ◽  
Salmo Salar ◽  
Growth Rates ◽  
Specific Growth ◽  
Steroid Hormone ◽  
Hormone Levels ◽  
Early Maturation ◽  
Atlantic Salmon Salmo Salar ◽  
Specific Growth Rates

Circulating levels of the steroid hormones 11-ketotestosterone (11-KT) and 17β-estradiol (E2), voluntary food intake, and growth performance were measured in individual Atlantic salmon (Salmo salar) over the year preceding their maturation as grilse. 11-KT and E2 were measured by radioimmunoassay, and X-radiography was used to measure food consumption rates. Two phases of sexual maturation were identified: the early phase (October 1992 - April 1993) was characterized by slowly rising steroid hormone levels concomitant with relatively high rates of food consumption and growth, and in the late phase (May-October 1993), steroid hormone levels increased more rapidly and growth rates decreased in association with inappetence. Significant linear relationships were observed between food consumption and specific growth rates of fish throughout the study (ANCOVA, p < 0.05). Slopes and intercepts of regressions were similar for fish during early maturation, while a lower intercept and steeper slope (ANCOVA, p < 0.05) was observed during the later stages of maturation. In November, January, February, and April, fish in which steroid hormone levels were elevated were significantly heavier than those in which hormone levels were basal. There were no significant differences in specific growth rates (except in February), food consumption, or weight-specific food conversion ratio (except in August and October) associated with maturation status.

scholarly journals Estimating and forecasting pre-fishery abundance of Atlantic salmon (Salmo salar L.) in the Northeast Atlantic for the management of mixed-stock fisheries

2004 ◽  
Vol 61 (8) ◽  
pp. 1359-1369 ◽  
Author(s):  
E.C.E. Potter ◽  
W.W. Crozier ◽  
P-J. Schön ◽  
M.D. Nicholson ◽  
D.L. Maxwell ◽  
...  
Keyword(s):  
Atlantic Salmon ◽  
Salmo Salar ◽  
Statistical Significance ◽  
Geographical Area ◽  
Environmental Data ◽  
Environmental Indices ◽  
Northeast Atlantic ◽  
Atlantic Salmon Salmo Salar ◽  
Mixed Stock ◽  
Reconstruction Model

Abstract Most exploitation of Atlantic salmon (Salmo salar) is restricted to “homewater fisheries”, which operate close to or within the rivers of origin of the stocks, but two “distant-water fisheries” are permitted to operate off the west coast of Greenland and in the Norwegian Sea, and take salmon from a large number of rivers over a wide geographical area. Providing robust quantitative catch advice for these mixed-stock fisheries depends upon the ability to forecast stock abundance for about 2000 salmon river-stocks around the North Atlantic, more than 1500 of which are in Europe. A “run-reconstruction” model is presented for estimating the historic pre-fishery abundance (PFA) of salmon for countries or regions around the Northeast Atlantic, based upon catch data and estimates of non-reporting rates and exploitation rates. These estimates are then used to develop predictive models of PFA on the basis of estimates of the egg deposition, derived from the run-reconstruction model and various environmental data. Although the selected environmental indices correlated with the PFA of both southern and northern European stock complexes, the main statistical significance in the forecast models was provided by temporal trends in the PFA. Clearly, such a model is only tenable in the short term, and will be poor at predicting a major change in stock status. Alternative approaches, based upon juvenile production indices and including Bayesian techniques, are therefore being considered.

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