Introduction

Abstract

It is a well-known phenomenon that all changes in a population depend on reproduction, growth and mortality. The last two processes are most intensely manifested in the early developmental stages (Hjort, 1914; Allen, 1951; Marr, 1956; Bernatowicz et al., 1975; Mahon et al., 1979; Eldridge et al., 1981a, b; and many others). Planktivorous fish larvae are among the most efficient predators at transferring biomass from one particle size to a larger size (Borgmann and Ralph, 1985). Therefore the early life history of fish was recognized as one of the key issues in fishery science (Azeta, 1981; Kernehan et al., 1981; Sherman and Lasker, 1981; Nielsen et al., 1986; Viljanen, 1988). Reproductive strategies and adaptations for early development define the ecological guilds of fishes proposed by Balon (1975a). Evaluating studies on early life history of fishes, Alderdice (1985) found that they often receive less recognition and support than they merit, and drew attention to the multiple advantages of such studies when they are associated with practical goals. He produced a list of ten activities by which these goals could be achieved; they included study of the bioenergetics of growth and development, and of the physiological ecology of early life stages.