Comparative studies of coastal pelagic fish reproductive habitats: the anchovy (Engraulis anchoita) of the southwestern Atlantic

Abstract

A framework of comparative climatology of reproductive habitats of coastal pelagic fishes is extended to the anchovy inhabiting the shelf-sea ecosystem off Argentina, Uruguay, and southern Brazil. Maritime weather reports are summarized to yield distributions of wind stress, cloud cover, insolation, sea-surface temperature, wind mixing index, and Ekman transport. These distributions are considered together with other known aspects of the oceanography of the region and with seasonal and geographical aspects of reproductive activity. Over its extensive range, Engraulis anchoita spawns successfully within three different configurations of environmental processes affecting transport, water column stability, and trophic enrichment. One of these, incorporating a coastal indentation downstream from a coastal upwelling center, is very similar to the most common configuration characterizing spawning grounds of eastern ocean anchovy populations. The second, featuring interleaving water masses and upwelling at the continental shelf break, exhibits similarities to the reproductive habitat of the South African anchovy. The third, involving tidal mixing fronts, has been previously noted primarily in connection with herring of higher-latitude, shallow shelf-sea systems. The study adds support to the idea that similar fish populations in different regions must solve similar basic environmental problems and that various experiences of environmental effects in different populations, when viewed from a properly posed conceptual framework, can add up to a useful accumulation of insight.