Diet of mid-Atlantic Sowerby's beaked whales Mesoplondon bidens

Abstract

This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution and sharing with colleagues.Other uses, including reproduction and distribution, or selling or licensing copies, or posting to personal, institutional or third party websites are prohibited. a b s t r a c tThe first mid-Atlantic diet of Mesoplodon beaked whales is presented, from ten Sowerby's Mesoplodon bidens stranded in the Azores region between 2002 and 2009. This doubles the worldwide number of stomachs sampled, and reveals new feeding habits for this species. The mean number of prey items per stomach was 857 89 (range: 12-238), with fish accounting for 99.3% and cephalopods contributing less than 1% of total prey. Fish otoliths from 15 families and cephalopod lower mandibles from three families were identified, representing 22 taxa. The diet consisted mainly of small mid-water fish, the most numerous being Diaphus sp., Lampanyctus sp. and Melamphaidae species. Myctophids were present in all stranded individuals, followed by Diretmidae, Melamphaidae and Opisthoproctus soleatus, while the remaining fish species were scarce or single occurrences. Consistency of diet in four different years reveals a divergence from all previous records in continental areas, where mainly neritic and shelf-break benthopelagic fish species have been reported. Mid-Atlantic Sowerby's beaked whales' showed dietary plasticity, feeding on the most abundant mid-water groups occurring between 0 and750 m. Trophic level from prey numerical frequency was estimated at 4.4 70.46.

Food habits of Sowerby's beaked whales (Mesoplodon bidens) taken in the pelagic drift gillnet fishery of the western North Atlantic

“…Our fi ndings are similar to those of Pereira et al (2011), who examined the stomach contents of 10 stranded Sowerby's beaked whales from the Azores and found a predominance of small fi sh prey. It is important to note that all but one of the whales that we examined were killed at sea, and, with the exception of the single stranded animal, they were apparently healthy at the time of their death.…”

“…The presence of intact prey in the esophagus of one specimen and the large numbers of prey items in the stomachs that we examined indicate that these animals had been foraging before death. The average minimum number of prey in the stomachs that we examined was more than 600 (4789 fi shes, plus 73 squids, in all 8 stomachs combined), compared with 85 prey in the stranded specimens examined by Pereira et al (2011). We believe the stomach contents of the whales that we examined are representative of the summer diet of Sowerby's beaked whales along the continental shelf break off the northeastern coast of the United States.…”

“…Given the challenges of studying live whales, all published information on the food habits of the Sowerby's beaked whale has been acquired from stranded specimens (Dix et al, 1986;Ostrom et al, 1993;Pereira et al, 2011;Spitz et al, 2011;Santos et al 1,2 ). Recent analysis of the stomach contents of 10 stranded Sowerby's beaked whales from the Azores in the eastern North Atlantic (Pereira et al, 2011) provided evidence that small meso-and bathypelagic fi shes constitute an important part of the diet of this species in this area.…”

“…Recent analysis of the stomach contents of 10 stranded Sowerby's beaked whales from the Azores in the eastern North Atlantic (Pereira et al, 2011) provided evidence that small meso-and bathypelagic fi shes constitute an important part of the diet of this species in this area.…”

Modeling the Potential Distribution and Richness of Cetaceans in the Azores from Fisheries Observer Program Data

“…However, recent research has shown that beaked whales may show dietary plasticity (MacLeod et al, 2003). In the Azores, the diet of Sowerby's beaked whale (Mesoplodon bidens) is composed essentially of meso-and bathypelagic fish, with little contribution from cephalopods (Pereira et al, 2011). Night-time sea surface temperature was retained in the models of all species in this group and, apart from the sperm whale, was highly influential in the models consistent with a seasonal presence of beaked whales in the region ( Table 3).…”