Species Distribution Modeling of Deep Pelagic Eels

The ocean's midwaters (the mesopelagic and bathypelagic zones) make up the largest living space on the planet, but are undersampled and relatively poorly understood. The true distribution of many midwater species, let alone the abiotic factors most important in determining that distribution, is not well known. Because collecting specimens and data from the deep ocean is expensive and logistically difficult, it would be useful to be able to predict where species of interest are likely to occur so that sampling effort can be concentrated in appropriate areas. The distribution of two representative midwater fishes, the gulper eel Eurypharynx pelecanoides and the bobtail eel Cyema atrum (Teleostei: Saccopharyngiformes), were modeled with MaxEnt software to examine the viability of species distribution modeling (SDM) for globally distributed midwater fishes using currently available environmental data from the ocean surface and bottom. These species were chosen because they are relatively abundant, easily recognized, and unlikely to have been misidentified in database records, and are true midwater fishes, not known to undertake significant vertical diurnal migration. Models for both species show a generally worldwide distribution with some exceptions, including the Southern Ocean and Bering Sea. Variable contributions show that surface and bottom environmental variables correlate with species presence. Both species are more likely to be found in areas with low levels of silicate. SDM is a promising method for better understanding the ecology of midwater organisms.