Assessing and Managing Man's Impact on Fish Genetic Resources

Abstract

Historically, human activities have adversely affected the genetic resources of many fish species. We suggest that a continuum of vulnerability to loss of genetic resources exists for fishes. Primary determinants of vulnerability are extent of stock structure in populations and fundamental life history features, such as length of juvenile period, sex ratio, and fecundity. The genetic basis for this trend is the relationship between the subdivided state of a population (its stock structure) and important processes of genetic change, which include selection, gene flow, and genetic drift. We relate various human activities to their effects on genetic resources through these genetic processes, and we review various lines of evidence for a relationship between stock structure and genetic diversity. In general, we found that those species whose populations are subdivided into nearly isolated stocks (e.g. Pacific and Atlantic salmon) are more vulnerable to directional changes in genetic composition as well as reduction in overall genetic diversity through loss of some stocks. We also found that similar changes will be difficult to detect, if they occur at all, in less stock-structured species like walleye.Key words: stock structure, genetic diversity

Genetic Structure and Systematics of Smallmouth Bass, with Emphasis on Interior Highlands Populations

“…When fisheries are exploited without regard for genetic structure, differential fishing pressure can cause elimination of unique subpopulations (Brown et al 1981). Ironically, subpopulations with the most desirable properties (e.g., rapid growth and high catchability) for the fishery and for future enhancement programs may be at the greatest risk (Thorpe and Koonce 1981). In addition, exploited fisheries are often enhanced through artifical propagation programs.…”

Genetic Adaptability of Sarotherodon Melanotheron to Polycyclic Aromatic Hydrocarbons (PAHs) in Some Senegal Hydrosystems

“…Indeed, the sensitivity of allozymes to environmental stresses would reflect the adaptive nature of individuals (Moraga et al, 2002). Anthropogenic factors (such as pollution) thus seem to favor the selection of individuals with a particular genetic makeup within fish populations through differential survival (Thorpe et al, 1981(Thorpe et al, , smith et al, 1983Nevo et al, 1984, Gillespie & Guttman, 1989and Duan et al, 2001). In addition, according to Kopp et al (1994), genotypes that survive exposure to pollution or salinity may be the most tolerant individuals to environmental stress.…”

Genetic diversity and adaptability ofSarotherodon melanotheron(Cichlidae) in coastal ecosystem

“…Sensitivity of allozymes to environmental stress seemed to reflect the adaptive nature of the individuals (MORAGA et al 2002). Anthropogenic factors such as pollution appeared to favour the selection of individuals with particular genetic composition within the fish populations through differential survival of the species (THORPE et al 1981;SMITH et al 1983;GILLESPIE & GUTTMAN 1989;DUAN et al 2001). Moreover, KOPP et al (1994) reported that genotypes that survived an exposure to pollution or salinity can represent the most tolerant individuals in a stressful environment.…”