Production/biomass ratios, size frequencies, and biomass spectra in deep-sea demersal fishes

Abstract

The sizes attained by component species tell much about the way communities and ecosystems are structured and function, and size can be related to foraging mode and strategy. Data on deep demersal fishes from the Porcupine Seabight and Madeira Abyssal Plain in the E North Atlantic (200-5400 m depth) illustrate and investigate these points. Patterns in the frequency distribution of sizes attained by individual species at various depths can be related to probable feeding modes, and these are supported by information on diets. The biomass spectrum for the continental slope is flat suggesting that there is a relatively uniform supply of food there throughout the year. The spiky pattern in the biomass spectrum for the continental rise and abyss suggests that the dominant food sources for fishes there are pulsed, probably in the form of infrequent, random and rapid falls of material from the surface layers. -from Authors