Spatial association of genetically similar Atlantic salmon juveniles and sex bias in spatial patterns in a river

Abstract

Atlantic salmon (Salmo salar) juveniles were electrofished along a 300-m stretch of a river to test for possible associations between genetic similarity and geographical distance between individuals. Multilocus DNA fingerprinting showed that genetically similar juveniles (1-4 years old) were found closer together in the river than less related individuals. However, the association between genetic similarity and geographical distance, although significant, was not strong. This may indicate that factors other than genetic relatedness influence the positioning in the river. A sex bias in the relationship between genetic similarity and geographical distance was caused by a difference between sexually mature and immature males. The study shows that sampling of salmon juveniles should be spread over a wide stretch of the river in order to avoid sampling relatives. Moreover, by including several year classes, the overall degree of genetic similarity is effectively reduced compared with sampling individuals of similar age.1999 The Fisheries Society of the British Isles

Microsatellite DNA Population Structure and Stock Identification of Steelhead Trout (Oncorhynchus mykiss) in the Nass and Skeena Rivers in Northern British Columbia

“…Samples obtained from juveniles may be nonrepresentative of the population because of family sampling (Hansen et al, 1997;Wenburg et al, 1998;Mjlnerd et al, 1999), inclusion of rainbow trout in the sample (Parkinson, 1984a), or perhaps juveniles rearing in nonnatal streams, as in the case of chinook salmon (O. tshawytscha) (Murray and Rosenau, 1989;Scrivener et al, 1994). We generally limited sampling to adults, but obtaining adult samples on many of the rivers surveyed was quite difficult because of the relatively low population abundance and remoteness of the spawning locations in the drainage.…”

Molecular pedigree analysis in natural populations of fishes: approaches, applications, and practical considerations

“…Little evidence was found for the idea of siblings defending adjacent territories, though many related pairs of fry were detected when sampling was carried out soon after emergence. In a contrasting study of the same species, Mjølnerød et al (1999) found that there was a significant association between genetic similarity and position in the river. In particular, they found that genetically similar juveniles were found closer together than less related individuals.…”

Social Recognition of Conspecifics

“…Paradoxically, there is little evidence for kin-biased association patterns in the wild among territorial fishes (Fontaine & Dodson 1999;Garant et al 2000;Carlsson & Carlsson 2002;Brodeur et al 2008), but see Mjølnerød et al (1999) and Carlsson et al (2004). Fraser et al (2005) point out that part of the reason for this may lie in the unavoidable technical limitations of using molecular techniques such as allozymes or mitochondrial DNA and more recently in the use of too few microsatellite DNA loci to allow accurate determination of relatedness levels among sampled fishes.…”

“…Further, Carlsson (2007) points out that kinbiased behaviours may not be expected in populations with large effective population size where the number of siblings and half-siblings is relatively low and opportunity for close kin to interact is reduced. In addition, most genetic analyses of fish populations have calculated the relatedness of fishes caught together in relatively long stream stretches varying from 50 to 300 m (Hansen et al 1997;Carlsson et al 1999Carlsson et al , 2004Mjølnerød et al 1999;Garant et al 2000). Only two previous studies have investigated how relatedness influences patterns of distribution of territorial fishes at high resolution.…”