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Population structure, effective population size and adverse effects of stocking in the endangered Australian eastern freshwater cod Maccullochella ikei

Nock, C.J. and Ovenden, J.R. and Butler, G.L. and Wooden, I. and Moore, A. and Baverstock, P.R. (2011) Population structure, effective population size and adverse effects of stocking in the endangered Australian eastern freshwater cod Maccullochella ikei. Journal of Fish Biology, 78 (1). pp. 303-321.

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Article Link(s): http://dx.doi.org/10.1111/j.1095-8649.2010.02865.x

Publisher URL: http://onlinelibrary.wiley.com

Abstract

Microsatellite markers were used to examine spatio-temporal genetic variation in the endangered eastern freshwater cod Maccullochella ikei in the Clarence River system, eastern Australia. High levels of population structure were detected. A model-based clustering analysis of multilocus genotypes identified four populations that were highly differentiated by F-statistics (FST = 0· 09 − 0· 49; P < 0· 05), suggesting fragmentation and restricted dispersal particularly among upstream sites. Hatchery breeding programmes were used to re-establish locally extirpated populations and to supplement remnant populations. Bayesian and frequency-based analyses of hatchery fingerling samples provided evidence for population admixture in the hatchery, with the majority of parental stock sourced from distinct upstream sites. Comparison between historical and contemporary wild-caught samples showed a significant loss of heterozygosity (21%) and allelic richness (24%) in the Mann and Nymboida Rivers since the commencement of stocking. Fragmentation may have been a causative factor; however, temporal shifts in allele frequencies suggest swamping with hatchery-produced M. ikei has contributed to the genetic decline in the largest wild population. This study demonstrates the importance of using information on genetic variation and population structure in the management of breeding and stocking programmes, particularly for threatened species.

Item Type:Article
Corporate Creators:DEEDI
Additional Information:© The Authors. © Journal of Fish Biology. © The Fisheries Society of the British Isles.
Keywords:Conservation; genetic variation; isolation by distance; microsatellite; stocking impact.
Subjects:Aquaculture and Fisheries
Aquaculture and Fisheries > Fisheries > Fishery for individual species
Aquaculture and Fisheries > Fisheries > Fishery conservation
Deposited On:06 May 2011 00:31
Last Modified:06 May 2011 00:31

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