Sea lamprey (Petromyzon marinus) control with selective toxicants has reduced sea lamprey abundance in the Great Lakes to levels which permit survival of desirable fish species, but development of alternate and supplemental control methods is essential since chemicals cannot be used indefinitely. The Task Force addressed hypotheses which relate to regulation of sea lamprey numbers during different life history stages and why sea lampreys appear to affect fish stocks differently in various bodies of water. Examination of the information about the various factors that control sea lamprey abundance, both natural and man-made, permitted the Task Force to develop several hypotheses and to indicate areas where additional emphasis or research could produce new or supplementary control methods. Efforts to develop an integrated program of sea lamprey control should be accelerated by development of present promising areas as well as expansion in new directions. Sea lampreys when compared with teleosts exhibit many features of a prototype vertebrate and some unique specializations. Physiological, biochemical, or behavioral differences between lampreys and teleosts may be exploitable for developing control techniques specific to sea lampreys.Key words: sea lamprey, Great Lakes, population control, barrier dams, integrated pest management, buffer species, physiology, teleosts
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
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