DIFFERENTIAL REPRODUCTIVE SUCCESS AND HERITABILITY OF ALTERNATIVE REPRODUCTIVE TACTICS IN WILD ATLANTIC SALMON (SALMO SALAR L.)

We examined genetic differences in the reproduction of an alternative maturation phenotype in Atlantic salmon (Salmo salar) by comparing the spawning behaviour and success among farmed, first-generation hybrid, and wild mature male parr raised in similar environments. Parr competed for spawning opportunities in the presence of either wild or farmed large males. There were no consistent differences among groups in aggression; however, there were differences in spawning participation with respect to large male origin and among parr types. There was a strong negative temporal effect on mature male parr spawning participation that differed by parr type; wild and farmed parr were most likely to participate in early spawnings, with hybrids being the most likely to participate in late spawnings. Overall, parr were also less likely to participate in spawnings involving large farmed males. Variance in reproductive success was higher among parr than among large males. Our results are consistent with the hypothesis that there are genetically based behavioural differences among mature male parr of farmed and wild origin that may potentially lead to differences in reproductive success.

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Comparison, using minisatellite DNA profiling, of secondary male contribution in the fertilisation of wild and ranched Atlantic salmon (Salmo salar) ova

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f98-076 ◽

1998 ◽

Vol 55 (9) ◽

pp. 2011-2018 ◽

Cited By ~ 13

Author(s):

C E Thompson ◽

W R Poole ◽

M A Matthews ◽

A Ferguson

Keyword(s):

Reproductive Success ◽

Atlantic Salmon ◽

Salmo Salar ◽

Minisatellite Dna ◽

Atlantic Salmon Salmo Salar ◽

The Difference ◽

Western Ireland ◽

Minimum Numbers ◽

Representative Samples ◽

Male Genotype

Secondary males, either subdominant adults or, more usually, parr which mature in freshwater, are known to successfully fertilise Atlantic salmon (Salmo salar) ova. This study has estimated the reproductive success of such secondary males in redds formed by pairs of wild and sea-ranched adults. Eight wild and 11 ranched redds were sampled from the Burrishoole system, western Ireland, in two consecutive years. Representative samples of fertilised ova were screened at three minisatellite loci to reconstruct the genotypes of putative anadromous parents and to estimate the proportion of eggs fertilised by secondary males. Multiple paternal genotypes were detected in 18 of the 19 samples, and of the 1484 progeny examined, 593 could not have been derived from the primary adult male genotype. The level of secondary male contribution detected among wild redds from Burrishoole (mean 28.9%) was similar to that found in previous published studies. The level among ranched redds was significantly higher (mean 48.2%) (P = 0.042). The difference was greater when data from 1995 were considered alone, with the average level of secondary male contribution in ranched redds being almost twice that in wild redds. Minimum numbers of secondary males were not significantly different between wild (mean 2.6) and ranched (mean 2.7) redds.

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