Development of a Method for Behavioral Observation of Deep Water Fishes Using Pingers

This study aimed to develop a detailed behavior observation method for deep water fish using pingers and a quantitative echo sounder. We focused on alfonsino (Beryx splendens) inhabiting deep water. The survey was conducted at two locations: one where fishermen operate (experimental area) and another where they do not (control area). First, we set 10 grid survey lines in each survey area and ran using a quantitative echo sounder. The volume backscattering strength was smaller maximum 10 dB than in the experimental area. Second, following the grid survey, we used vertical longlines for confirmation of the fish species with corded pingers and a depth water temperature logger. We measured catch depth of the target. In this study, we observed the detailed behavior of the fishing gear in real time; integrating this information with the catch results could lead to more accurate measurements of the habitat range of deep water fishes.