scholarly journals A framework for understanding Atlantic salmon (Salmo salar) life history

1998 ◽  
Vol 55 (S1) ◽  
pp. 48-58 ◽  
Author(s):  
Elizabeth A Marschall ◽  
Thomas P Quinn ◽  
Derek A Roff ◽  
Jeffrey A Hutchings ◽  
Neil B Metcalfe ◽  
...  

We took a hierarchical approach to understanding Atlantic salmon (Salmo salar) life history patterns by first comparing salmonids to other teleosts, next comparing Atlantic salmon to other salmonids, and finally, mapping correlations among individual life history traits within Atlantic salmon. The combination of anadromy, large eggs, nest construction and egg burial by females, and large size at maturity differentiates salmonids from most other teleosts. Within the family Salmonidae, there is considerable variation in all traits but Atlantic salmon are generally in the middle of the range. Within Atlantic salmon, we were able to map correlations among individual life history traits, but we found that we still lacked an understanding comprehensive and quantitative enough to allow us to predict how the entire life history should respond to environmental changes. Thus, we proposed several general courses of action: (i) use models to synthesize complex patterns and relationships, (ii) collect long time series of data in individual systems, and (iii) design experiments to assess phenotypic plasticity and how environmental influences differ from genetic effects and constraints.

1999 ◽  
Vol 56 (12) ◽  
pp. 2397-2403 ◽  
Author(s):  
Sveinn K Valdimarsson ◽  
Neil B Metcalfe

Traditionally, behavioural studies on juvenile Atlantic salmon, Salmo salar, have been conducted during the day in summer. It is known that Atlantic salmon become nocturnal in winter, but very little is known about their behaviour at that time. Therefore, observations in a seminatural stream were carried out during the day and night, from February to June, comparing diel and seasonal differences in behaviour between fish adopting alternative life history strategies. The results showed a general trend for more activity in spring than in winter, and the fish were found to be foraging at surprisingly low light levels. There were differences in relative feeding rate between the life history strategies; the early migrant fish foraged mostly during the day whereas the delayed migrant fish did more foraging at night. There is some evidence that the early migrant fish made fewer feeding attempts over the winter, which is surprising, since they grow faster over that period. This suggests differences in foraging efficiency, which could contribute to the separation into these two life history strategies.


2010 ◽  
Vol 67 (2) ◽  
pp. 225-242 ◽  
Author(s):  
Friso P. Palstra ◽  
Daniel E. Ruzzante

Studying population structure and gene flow patterns on temporal scales facilitates an evaluation of the consequences of demographic, physical, and environmental changes on the stability and persistence of populations. Here, we examine temporal genetic variation within and among Atlantic salmon ( Salmo salar ) rivers in Newfoundland and Labrador, Canada, using samples collected over a period of six decades (1951–2004). Our objective was to evaluate temporal changes in population connectivity associated with the closure of a commercial marine fishery. Despite demographic instability, we find that population structure remained temporally stable over more than 50 years. However, age structure can affect results when not taken into consideration, particularly in populations of large effective size where genetic drift is not strong. Where weak signals of genetic differentiation did not complicate analyses, contemporary migration was often asymmetric, yet low, suggesting patterns of intermittent gene flow. Nevertheless, we find some links between changes in population dynamics and contemporary gene flow. These findings may therefore imply that management decisions impacting the contemporary population dynamics of individual Atlantic salmon rivers can also affect the genetic stability of this species as a whole.


1985 ◽  
Vol 42 (3) ◽  
pp. 615-618 ◽  
Author(s):  
Richard L. Saunders ◽  
Charles B. Schom

Atlantic salmon (Salmo salar) demonstrate great variability in their life history; individuals from a given year-class can spawn during several years and can, therefore, breed with salmon from other year-classes. Atlantic salmon can mature after 1–4 sea-winters and some males mature as parr, during the second through fifth years, before going to sea. Salmon may survive to spawn more than once; some spawn several times. This variability in life history may be a safeguard against loss of small stocks through several successive years of reproductive failure, since nonspawning individuals in the river or at sea could spawn in subsequent years. Spawning populations are frequently quite small. The effective spawning population size may be potentially much larger, however, since members of several year-classes, including sexually mature male parr and anadromous adults of various ages, contribute to spawning. The level of inbreeding may be relatively low, since a number of year-classes, each with different sets of parents, are represented during spawning.


1989 ◽  
Vol 67 (6) ◽  
pp. 1453-1461 ◽  
Author(s):  
E. Verspoor ◽  
L. J. Cole

Atlantic salmon (Salmo salar) from Little Gull Lake on the Gander River system of central Newfoundland were found to be electrophoretically polymorphic at 5 of 20 protein loci screened. Four of the polymorphic loci were structural and one was regulatory. Major heterozygote deficiencies relative to Castle–Hardy–Weinberg expectations were detected at the two most polymorphic loci, Aat-3 and Mdh-3,4, and significant nonrandom associations between genotypes at these loci and the other polymorphic loci, Sdh-1, Me-2, and Pgm1-t, were also found. The heterozygote deficiencies and the nonrandom genotype associations were attributable to the admixture of genetically distinct gene pools of resident and anadromous salmon in the lake. This is the first documented case of coexistence of reproductively separated populations of Atlantic salmon of the two life history types, and shows that the sympatric occurrence of the two forms can represent between-population variation.


1977 ◽  
Vol 34 (1) ◽  
pp. 139-141 ◽  
Author(s):  
V. Zitko ◽  
W. G. Carson

The incipient lethal level (ILL) of zinc to juvenile Atlantic salmon (Salmo salar) in fresh water at a water hardness of 14 mg/ℓ varies from 150 to 1000 μg/ℓ as a function of season and developmental stage of the fish. The ILL increases from 500 to 1000 μg/ℓ during the 1st yr and decreases to 150 μg/ℓ in the following spring. The more sensitive stage in the salmon's life history, evidenced by decrease of ILL coincides with and is probably related to initial stages of the parr–smolt transformation.


1998 ◽  
Vol 55 (S1) ◽  
pp. 119-130 ◽  
Author(s):  
Kevin D Friedland

Ocean climate and ocean-linked terrestrial climate affect nearly all phases of Atlantic salmon (Salmo salar) life history. Natural mortality in salmon occurs in two main phases: juvenile stages experience high mortality during freshwater residency and pre-adult salmon experience high mortality in estuarine and ocean environments. Freshwater survivorship is well characterized and tends to be less variable than marine mortality. Sources of marine mortality are poorly known due to a lack of basic knowledge about post-smolt distributions and habits. Coherence patterns among regional and continental stock groups suggest broad scale forcing functions play a more important role in defining recruitment than mortality effects associated with individual rivers. The action of mesoscale regional environment is most prominent during the post-smolt year when survival, maturation, and migration trajectories are being defined. During the early weeks at sea, growth mediated survival defines recruitment patterns. A correlation between sea surface water temperature and survival has been observed for salmon stocks in the northeast Atlantic suggesting temperature either directly affects growth or modifies post-smolt behavior. Age at first maturity is controlled by environmental as well as genetic factors. The abundance of two seawinter spawners in North America is directly scaled to the size of overwintering thermal habitat in the northwest Atlantic, which suggests a link between maturation and environment.


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