Selection Differentials in Male and Female North Sea Plaice and Changes in Maturation and Fecundity
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- Rijnsdorp A.D. (1993) Selection Differentials in Male and Female North Sea Plaice and Changes in Maturation and Fecundity. In: Stokes K., McGlade J.M., Law R. (eds) The Exploitation of Evolving Resources. Lecture Notes in Biomathematics, vol 99. Springer, Berlin, Heidelberg
This paper presents an analysis of the selective effects of fishing on reproductive parameters of North Sea plaice. This species has been exploited intensively since the late 19th century, and the fishing mortality substantially exceeded the level of natural mortality. Since the start of biological research in the early 1900s, life history parameters such as growth, onset of sexual maturity and fecundity have changed. In order to evaluate possible genetical effects of exploitation, the mortality imposed by fishing is estimated for males and females separately and factors determining the relationship between fishing mortality and age are analysed. Fitness profiles of various reproductive traits are studied under the present regime of exploitation, employing a simple allocation model of surplus production over somatic growth and reproduction. This model describes the cost of reproduction in terms of decelerated somatic growth and reduced future reproduction. Selection differentials are estimated from the fitness profiles and are compared to the selection differentials estimated from the observed changes in reproductive parameters. It is concluded that the direction of the observed changes is in agreement with the expected change due to selective fishing.
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