Survival and abundance of short‐finned pilot whales in the archipelago of Madeira, <scp>NE</scp> Atlantic

Abstract

Abstract Estimates of population parameters for the short‐finned pilot whale, Globicephala macrorhynchus , are scarce in literature, contributing to an International Union for Conservation of Nature ( IUCN ) status of Data Deficient. In this study, photo‐identification data collected over 7 yr from Madeira were used to estimate for the first time survivorship, capture probability, and abundance in this species using mark‐recapture methodology. The Cormack‐Jolly‐Seber model estimated that the adult island‐associated ( i.e ., resident and regular visitor) whales had a constant survival rate of 0.960 (95% CI : 0.853–0.990) and an annual capture probability varying between 0.372 ( CI : 0.178–0.619) and 0.843 ( CI : 0.619–0.947). A parameterization of the Jolly‐Seber model estimated that 140 island‐associated whales ( CI : 131–151) used the area throughout the course of the study. Based on a closed population model, the most precise (lower CV ) annual estimate of the total number of pilot whales using the southern and eastern waters of Madeira (~900 km 2 ) in a 3 mo period covering summer/autumn was 334 animals ( CI : 260–437). No trend was observed. Despite including biases, the approach used in this study provided plausible estimates of population parameters, which can contribute to the regional conservation strategies.