Anisakis spp. as indicators of latitudinal movements of short‐finned pilot whales, Globicephala macrorhynchus, in the Northeast Atlantic

Abstract

AbstractIn the Northeast Atlantic, it is unclear whether short‐finned pilot whales, Globicephala macrorhynchus (SFPWs), are transient or resident above 40°N. We used Anisakis spp. to identify the latitudes recently visited by a SFPW pod stranded in NW Spain (43°N) in 2020. Analysis of cox2 gene in 30 nematodes from 6 SFPWs revealed the presence of A. simplex sensu stricto (s.s.) (93.3%) and A. pegreffii (6.7%). Morphological analysis of 972 nematodes corroborated species molecular identification and relative proportions; in males (n = 66), the estimated proportions of A. simplex s.s. and A. pegreffii were 86.4% and 13.6%, respectively. These percentages resembled those reported in fish/cetaceans above 40°N, and L4 larvae or adults of A. typica (a tropical‐temperate species found in SFPWs up to 38°N–39°N) were not detected. Population structure of A. simplex s.s. + A. pegreffii in SFPWs suggested a continuous recruitment of nematodes starting at least 3 weeks before stranding. We interpret that either the SFPW pod was within the range of the species (perhaps as a recent northern shift) or represented a vagrant group that visited waters off Northwest Spain for a protracted period. Future analysis on nematode assemblages could shed light on movements and climate‐driven shifts in cetacean distribution.