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Application of low frequency genetic marking at GPI‐3 * and MDH‐B1,2 * loci to assess supplementary stocking of Atlantic salmon, Salmo salar L., in a Northern Irish stream
Author(s) -
CROZIER W. W.,
MOFFETT I. J. J.
Publication year - 1995
Publication title -
fisheries management and ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.693
H-Index - 55
eISSN - 1365-2400
pISSN - 0969-997X
DOI - 10.1111/j.1365-2400.1995.tb00095.x
Subject(s) - stocking , salmo , biology , population , fishery , electrofishing , genotype frequency , genetic distance , allele frequency , genotype , fish <actinopterygii> , genetic variation , genetics , gene , demography , sociology
At the River Bush salmon station in Northern Ireland, a genetically marked strain of Atlantic salmon, Salmo salar L., was established, with a low frequency (0.194) of a glucose‐6‐phosphate isomerase genotype (GPI‐3* 100/93). As part of a salmon enhancement programme, 43500 of these fish were stocked as swim‐up fry into a tributary of the nearby Margy River in Spring 1990, following a baseline genetic survey which indicated an absence of the GPI–3*93 allele in the wild population. This survey also indicated a significant frequency difference of a malate dehydrogenase allele (MDH‐B1,2*85) present both in the stocked and wild fish. A post‐stocking electrofishing survey in summer 1990 indicated higher summerling densities in stocked sections compared with unstocked (control) sections, with an estimated survival of stocked fry to summerling ranging from 24% to 29%. Genetic analysis based on GPI‐3*100/93 and MDH‐B1,2*100/85 genotypes provided similar estimates of the overall contribution of stocked fish at 59.8% to 61.9%, respectively, although there was a disparity between markers in estimated contributions to stocked and control sections. A further genetic survey in 1991 estimated that 32.2% (MDH) to 69.1% (GPI) of the 1 + parr population consisted of stocked fish, the MDH‐based estimate having declined greatly between summerling and 1 + parr stages. Possible reasons for the disparity of marker results are outlined, and the implications for use of low‐frequency genetic marking discussed.