Relationship between dispersal of larvae and nursery areas in the Baltic Sea

Publisher Website
Google Scholar
Abstract
As spawning concentrates eggs in certain places, dispersal is essential for larval survival. Inherent to ail dispersal tactics, however, is a risk of death. Dispersal tactics of various species of fish larvae, both marine and freshwater, are compared, with emphasis on the conditions prevailing in the Baltic Sea. Spawning areas set limits for dispersal, but not for the exact extension, or necessarily the direction, of dispersal. An example is given where the larvae of two coastal species sharing the same nursery area stem from completely different spawning sites. Larval ontogeny, behaviour, and environmental conditions determine dispersal tactics. including when and how far to disperse. Species may choose between two tactics: dispersal immediately after hatching or gradual dispersal, that is, after a passive phase when they hide among bottom materials or attached to plants. Most pelagic larvae disperse immediately after hatching. At times, there also seems to be some variability in habitats of larvae within a species. The dispersal tactics of Larvae offer an explanation for the stock-recruitment dilemma. Not only the ability of larvae to enter a nursery area but also the quality and quantity of the nursery area have an influence on year-class strength and population size. (C) 1999 International Council For the Exploration of the Sea.