Multispecies ichthyoplankton associations in epipelagic species: is there any intrinsic adaptive function?

Species composition, distribution patterns and abundance of larvae of epipelagic fishes during June 1995 and June 1996, are described in waters of the northeastern Aegean Sea (eastern Mediterranean). Significant interannual differences were found that appeared to be associated with differences in environmental conditions. In June 1996 waters were colder, less saline and richer in zooplankton, which indicated a delay in the spring-to-summer transition during that year. Concurrently, larvae of the small-sized anchovy (Engraulis encrasicolus) were significantly more abundant in 1996 than in 1995. This contrasted with larvae of the middle-sized pelagics: Sardinella aurita, Trachurus mediterraneus, Scomber japonicus and Auxis rochei, which were most abundant in 1995. These results indicate differences in reproductive strategies among pelagic fishes, which we discuss in terms of `income' versus `capital' breeding, as well as inter-specific differences in the performance abilities of the larvae. The multispecies larval association of middle-sized pelagics may be adaptive and result from similar responses among species to the pelagic environment.