Insights into the diet of beaked whales from the atypical mass stranding in the Canary Islands in September 2002

Abstract

Stomach contents were analysed from three species of beaked whales which mass-stranded shortly after a naval exercise conducted in the Canary Islands in September 2002. Animals from such mass strandings often contain freshly ingested food in their stomachs and can provide a more reliable guide to feeding habits than other strandings. Food remains recovered from seven Cuvier's beaked whales (Ziphius cavirostris) consisted mainly of oceanic cephalopods, the most numerous being Taonius pavo, Histioteuthis sp., Mastigoteuthis schmidti and Octopoteuthis sicula. Many of the cephalopod species found in the diet appear to undertake daily vertical migrations, being found in shallower waters during the night and moving to deeper waters during the day. Single specimens of Blainville's beaked whale (Mesoplodon densirostris) and Gervais' beaked whale (Mesoplodon europaeus) had eaten both fish and cephalopod prey. The most numerous prey remains belonged to gadid fish and viperfish (Chauliodus sp.) respectively. These results are consistent with the limited published data on diet in these species, with Mesoplodon species having a relatively higher proportion of fish in the diet whereas Ziphius specialises on cephalopods.

Uncommon pelagic and deep-sea cephalopods in the Mediterranean: new data and literature review

“…Very little is known about this species, to the point that the currently available informaavailable information is exclusively a result of the stomach content analyses of the cetaceans (e.g. Mintzer et al, 2008;Santos et al, 2007;Yatabe et al, 2010). This paucity of knowledge also applies to the other species reported in the present study, which increases the value of the limited information preincreases the value of the limited information prethe limited information presented here.…”

Diet of Cuvier’s beaked whales Ziphius cavirostris from the North Pacific and a comparison with their diet world-wide

“…In a study from the Mediterranean, Ommastrephidae contributed 39.9% by mass and only 6.4% by number (Blanco & Raga 2000). Similarly, the family Onychoteuthidae contributed significantly to the diet of whales in the Canary Islands by mass (7.0%) but only 1.3% by number (Santos et al 2007). In New Zealand, onychoteuthids contributed 8% to the diet by number, but mass was not available for comparison (Fordyce et al 1979).…”

“…Our study also adds a small contribution by the family Ancistrocheiridae (<1%) to the known diet of whales from the North Pacific. Ancistrocheirids have previously been identified from specimens in the North Atlantic and the Mediterranean (Podesta & Meotti 1991, Carlini et al 1992, Santos et al 2007). The family Cycloteuthidae has also been previously reported from the Atlantic (Santos et al 2001, Spitz et al 2011), but was identified for the first time from the North Pacific in negligible amounts (<1%).…”

“…In the Bay of Biscay and in Scotland, Octopoteuthidae contributed less than 2% to the diet of the whales by number (Santos et al 2001, Spitz et al 2011). In the Canary Islands, Octopoteuthidae contributed 7.6% by number but contributed less than 1% by mass (Santos et al 2007). Octopoteuthidae may be more important to diet in the Mediterranean with prey importance ranging widely among studies, between 0.4 and 47% by number and 1.8 and 39.1% by mass (Podesta & Meotti 1991, Carlini et al 1992, Lefkaditou & Poulo poulos 1998, Blanco & Raga 2000, Kova<ić et al 2010 Ommastrephidae and Onychoteuthidae are sometimes identified as important cephalopod prey to Cuvier's beaked whales from other regions but were present in only small amounts (<1%) by number and by mass in the North Pacific (Table 2).…”

“…When considering the total number of prey items identified among Cuvier's beaked whales examined world-wide, the data available are heavily weighted towards the North Atlantic. Over 8000 prey items were identified from an individual specimen stranded near Scotland (Santos et al 2001), and prey was identified from 10 specimens stranded over a 10 yr period in the Bay of Biscay (Spitz et al 2011) and from 7 specimens stranded in the Canary Islands (Santos et al 2007). In the Southern Hemisphere, Cuvier's beaked whale stomach content remains have been identified from 5 individuals from South Africa (Ross 1984, Sekiguchi 1994) and 1 whale from New Zealand (Fordyce et al 1979).…”