Analysis of environmental, social, and anthropogenic factors as potential drivers of breaching behavior in the Mediterranean fin whale

Abstract

Breaching is frequently reported for many large cetacean species, but this behavior is considered very rare in fin whales (Balaenoptera physalus). Fin whales are regularly observed in the Mediterranean Sea, and they perform seasonal concentration/dispersal movements throughout this basin. This study aimed to investigate the influence that environmental parameters, social factors, and anthropogenic disturbance may have on breaching behavior in fin whales to deepen the understanding of these displays. Fin whale sightings were collected between 2012 and 2020 within the Fixed Line Transect Monitoring Network along the ferry route from Italy to Spain, crossing the mid‐latitudes of the western Mediterranean Sea. Breaching events were analyzed with respect to season, chlorophyll concentration, sea state, group size, fin whale frequency, distance between a breaching event and the closest whales, distance from the observation platform, and maritime traffic. During the study, breaching events were recorded 27 times over 721 fin whale sightings (3.74%), with a higher frequency during summer and fall (>4.96%) compared to spring (1.77%); no events were observed during winter. The most significant variables were distance from the observation platform as an inhibitory factor and distance between whales, possibly related to socialization and communication.