Behavioral responses to fishing line entanglement of a juvenile bottlenose dolphin in Shark Bay, Australia

Madison L. Miketa, Ewa Krzyszczyk, Janet Mann

Abstract

Entanglement in marine debris has become a serious matter for marine fauna, yet most data come from deceased animals. Here we studied a non-lethal entanglement event involving a female juvenile bottlenose dolphin (Tursiops aduncus), known as EDE, in Shark Bay, Western Australia who has been monitored and observed since birth as part of a long-term study. We compared her behavior before, during, and after entanglement. During entanglement, EDE markedly decreased time spent foraging, and increased time spent traveling. In contrast to before and after entanglement, EDE was mostly alone during entanglement, which may compound the negative impacts in a social species. During entanglement, erratic behaviors including leaps and fast swims were frequent. After entanglement, her activity budget and associations were similar to the period before entanglement. This study marks a rare opportunity to systematically examine the effects of entanglement on dolphin behavior and has implications for other highly social marine species.