Distribution, encounter rates, and habitat characteristics of toothed cetaceans in the Bay of Biscay and adjacent waters from platform-of-opportunity data

Abstract

Kiszka, J., Macleod, K., Van Canneyt, O., Walker, D. and Ridoux, V. 2007. Distribution, encounter rates, and habitat characteristics of toothed cetaceans in the Bay of Biscay and adjacent waters from platform-of-opportunity data. – ICES Journal of Marine Science, 64: 1033–1043. Data on the distribution and habitat utilization of oceanic marine mammals are difficult to collect and yet such information is beneficial for many conservation and management purposes. Data collected during ferry-based cetacean surveys in the English Channel and Bay of Biscay between 1998 and 2002 were analysed to investigate the distribution, encounter rate, and habitat characteristics of toothed cetaceans there. In all, 17 873 nautical miles were surveyed, and 1008 encounters of 13 identified species, including delphinids, ziphiids, harbour porpoise, and sperm whale, were recorded. The common dolphin was the commonest species, followed in decreasing occurrence by striped and bottlenose dolphins, pilot whale, harbour porpoise, Cuvier's beaked whale, and sperm whales. The distribution of harbour porpoises was restricted to the shallow waters of the western English Channel. Common and bottlenose dolphins were distributed mainly over the continental shelf, although there were some encounters along the shelf edge and in the open ocean. Striped dolphins and pilot whales were sighted in oceanic waters in the central and southern Bay of Biscay. Cuvier's beaked whales and sperm whales were recorded in the deep oceanic waters of the southern Bay of Biscay. Bathymetry clearly plays a significant role in the distribution and habitat partitioning of toothed cetaceans in the region.

Harbour porpoise habitat preferences: robust spatio-temporal inferences from opportunistic data

“…Platform-of-opportunity data, collected aboard industrial platforms (oil and gas, renewable energies, seismic exploration), commercial fishing vessels (López et al 2004), passenger ferries (Williams et al 2006, Kiszka et al 2007, MacLeod et al 2008 and by wildlife tour operators (Hauser et al 2006, Ingram et al 2007) are increasingly used in monitoring and for mitigation schemes of marine mammals (Evans & Hammond 2004). To date, such data remain underutilized because their analysis presents several challenges.…”

“…Relating animal sightings to effort can then be used directly to infer relative distributions (e.g. Kiszka et al 2007, Mac Leod et al 2008 ABSTRACT: Statistical habitat modelling is often flagged as a cost-effective decision tool for species management. However, data that can produce predictions with the desired precision are difficult to collect, especially for species with spatially extensive and dynamic distributions.…”

Increased Use Levels, Effort, and Spatial Distribution of Tourists Swimming with Dwarf Minke Whales at the Great Barrier Reef

“…The changes in industry use of reef sites and resulting increases in whale encounters over the six years studied raises the question about whether this represents a rapid growth phase as conceptualized in Duffus and Dearden's (1990) By drawing on industry generated effort data in an attempt to describe spatial and temporal patterns of dwarf minke whale encounters, it is important to recognize that the use of tourism vessels as 'platforms of opportunity' limits the ability of these data to provide insights into the distribution and abundance of whales in the region (Kiszka, MacLeod, van Canneyt, Walker, & Ridoux, 2007). The distribution of whale encounters instead reflect patterns of industry use of the reef and sites that are favoured for various reasons including accessibility and moorings, prevailing wind and weather conditions, reef faunal communities, topography, and the aesthetic appeal of sites to scuba divers and snorkelers.…”

Oceanographic conditions and marine mammals: identifying a potential relationship in the coastal region of the Mexican Central Pacific

“…where n is the number of sightings and e is the effort in kilometers (Kiszka et al 2007). The sighting rate during coastal surveys was calculated for a) each season (winter: from January to February, spring: from April to June, summer: from July to September, and fall: from October to December), and for b) each month during 2011.…”