3 Distribution and Population Ecology

Publisher Summary This chapter elaborates the distribution and population ecology of deep-sea fishes. There are two main deep-sea habitats—the pelagic and benthic realms—and the deep-sea fish faunas that live in these two habitats are quite different. Many fishes of the epipelagic regions belong to well-known and familiar groups, such as the tunas, swordfish and marlins, flying fish, and jacks. Mesopelagic and bathypelagic fishes are taxonomically quite different from those associated with epipelagic regions. The distribution of individual species groups and of community assemblages, which forms the basis for biogeographic schemes, suggests a few large pelagic faunal regions. These regions are characteristic of different parts of the ocean and generally follow the topography and the overall temperature structure and circulation patterns of the ocean. It is found that although mesopelagic fish practice some feeding selectivity, there is broad overlap in the diets of many species. Midwater fish at times appear to switch to whatever is most available without much regard for remaining at the appropriate level of the classical food chain.