Spatial Distributions and Ecology of Pelagic Fish

Abstract

Homogeneity in nature is rare. Even in the regular structure of crystals it is impurities which provide color. The distribution of fish provides no exception to this rule and variations in their distribution are observed on almost all time and space scales. During the 1970's the annual world catch of fish was about 70 million tons with an estimated maximum potential sustained catch of fish taken by traditional methods of 100 million tons (Gulland, 1974). With this degree of sampling, it is reasonable to assume it is known where most of the fish live. The early arguments on the degree of variation took place before the statistics of small samples were understood and later such variability became inter-esting in itself, partly to establish differences between samples and partly to determine the physical or biological origin of such differences and their functional significance. The scale of patches was examined as an end in itself and the study of large patches played a part in the development of the technology of marine science. The use made by animais of the large patches observed is fairly obvious, but in recent years attempts have been made to find what use is made by animais of the small scale variability available to their senses.