The Ecology of Cuvier’s beaked whale, Ziphius cavirostris (Cetacea: Ziphiidae), in the Bay of Biscay

Abstract

This dissertation introduces the habitat use and spatial-temporal distribution of Cuvier’s beaked whale (Ziphius cavirostris, Cuvier, 1823) in the Bay of Biscay, from surveys carried out by the Biscay Dolphin Research Programme between 1995 and 2007. I have analysed the spatio-temporal distribution of Cuvier’s beaked whale, using dedicated and opportunistic sightings and the interactions with fixed physical variables (depth, slope and aspect), non-fixed environmental variables (sea surface temperature) in the Bay of Biscay, northeast Atlantic. This study used a differing combination of environmental variables and modelling: GAM (General Additive Model), and ENFA (Ecological Niche Factor Analysis), and PCA (Principal Component Analysis). Geographical Information Systems (GIS) and Remote Sensing were used to achieve this. The habitat preferences of Cuvier’s beaked whale showed strong correlations with water depths >1000m and <4000m and steep slopes, associated with the Capbreton canyon, in the southeast Bay of Biscay and the continental shelf slopes in northern Biscay. Areas of high suitability for Cuvier’s beaked whale were predicted for the Bay of Biscay and predictions showed high habitat suitability areas over continental shelf slopes and submarine canyons. The variety of modelling techniques used to identify the habitat preferences and to predict areas of high suitability for Cuvier’s beaked whale in the Bay of Biscay all proved advantageous. On a global scale, techniques such as these could be applied to help research worldwide for future implementations of protected areas to conserve and maintain this species. The abundance and distribution of Cuvier’s beaked whales varied between years and seasons, with an increase in sightings over time and a seasonal distribution shifting north during spring and summer. Stranding records were also analyzed and compared with the sightings data, which identified regional patterns in seasonal distribution between France, the UK and Ireland. In addition to Cuvier’s beaked whale, this study investigated other deep-diving cetaceans (Northern bottlenose whale, Hyperoodon ampullatus, Sowerby’s beaked whale, Mesoplodon bidens, Sperm whale, Physalus macrocephalus, Pilot whale, Globicephala melas) and non-deep diving cetaceans (Fin whale, Balaenoptera physalus, and Common dolphin, Delphinus delphis) observed in the Bay of Biscay and the English Channel. The Bay of Biscay is the most northerly range of the Cuvier’s beaked whale in the eastern north Atlantic and with year round observations, it could be suggested the population may be resident. This raises the question, could Cuvier’s beaked whale act as a predictor of increasing water temperatures because of climate change by shifting their distribution further north.

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