The Biology of the Clupeoid Fishes

Abstract

Clupeoid populations have undergone striking increases, followed by precipitous and catastrophic declines, which have caused the collapse of the fishing industry. These fluctuations have been caused by great natural variability in recruitment and by its interaction with fishing policy and economics. A probable combination of overfishing and natural changes also caused declines in other clupeoid stocks during the past few decades. Most clupeoids have a short life span; they recruit at 1-3 years of age and rarely live beyond 5-10 years of age except for some herring stocks, especially the Atlanto-Scandian herring. Early maturation implies that the asymptotic length (L∞) is reached rapidly and growth is not very significant in older fish. As a result most overfishing of clupeoids is classed as “recruitment” rather than “growth” overfishing. Nevertheless some classic cases exist of particular year-classes dominating a fishery for several years. In such cases, the importance of the year-class lies in its numbers rather than in the weight increase as the fish becomes older. The aim of this chapter is to describe the present status of knowledge on the behavior and physiology of clupeoids with particular reference to their ecology. Some of the advances have been made possible by improvements in the ability to rear larval stages and to catch, transport and keep the older stages in captivity, and by greatly improved techniques such as aerial photography, video systems, sampling gear, and apparatus. © 1982, Academic Press Inc. (London) Ltd.