Loss of Microsatellite Diversity and Low Effective Population Size in an Overexploited Population of New Zealand Snapper (Pagrus auratus)

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 99; no. 18; pp. 11742 - 11747
• Main Authors: Hauser, Lorenz, Adcock, Greg J., Smith, Peter J., Julio H. Bernal Ramírez, Carvalho, Gary R.
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences 03.09.2002; National Acad Sciences; The National Academy of Sciences
• Subjects: Alleles; Animal populations; Animals; Biodiversity; Biological Evolution; Biological Sciences; Censuses; effective population size; Evolution; Evolutionary genetics; Fish; Fisheries science; Genetic diversity; Genetic loci; Genetics; Marine; Microsatellite Repeats - genetics; Pagrus auratus; Perciformes - genetics; Population Density; Population estimates; Population genetics; Population size; Snapper; Species Specificity; New Zealand; PSE, New Zealand
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.172242899

Although the effects of overfishing on species diversity and abundance are well documented, threats to the genetic diversity of marine fish populations have so far been largely neglected. Indeed, there seems to be little cause for concern, as even "collapsed" stocks usually consist of several million individuals, whereas population genetics theory suggests that only very small populations suffer significant loss of genetic diversity. On the other hand, in many marine species the genetically effective population size (Ne), which determines the genetic properties of a population, may be orders of magnitude smaller than the census population size (N). Here, microsatellite analyses of a time series of archived scales demonstrated a significant decline in genetic diversity in a New Zealand snapper population during its exploitation history. Effective population sizes estimated both from the decline in heterozygosity and from temporal fluctuations in allele frequency were five orders of magnitude smaller than census population sizes from fishery data. If such low Ne/N ratios are commonplace in marine species, many exploited marine fish stocks may be in danger of losing genetic variability, potentially resulting in reduced adaptability, population persistence, and productivity.