Habitat selection, fine-scale spatial partitioning and sexual segregation in Rajidae, determined using passive acoustic telemetry

Abstract

Habitat selection is the process by which an individual makes an active decision to make use of a particular habitat when others are available. The ability to infer habitat selection therefore requires observations of movement through space and time which can be particularly challenging for marine species that are cryptic and do not regularly visit the sea surface. Rajidae (skates) are benthic mesopredators that inhabit turbid coastal waters and exhibit site fidelity, making them an ideal group for studying habitat selection and resource partitioning using a fixed, passive acoustic receiver array in the western English Channel, UK. Using network analysis, significant differences were found in the way 4 species of Rajidae occupied different parts of the array; for example, Raja microocellata and R. clavata occupied shallower habitat than R. brachyura and R. montagui. R. montagui and R. brachyura were further separated, with each species detected more frequently at different receivers. Males and females of all 4 species were also detected at different receivers and at different times. These results demonstrate habitat selection, resource partitioning among species and sexual segregation in these 4 species of Rajidae. Our findings are important evidence for management of fisheries, such as the designation of marine protected areas, and further highlight the potential of this method for tracking other mobile marine species in temperate, open coastal regions.