BRDP

Whale, Dolphin & Seabird Monitoring

Introduction to BDRP Methodology

Survey vessel and study area:

The BDRP undertakes monthly surveillance surveys across the Bay of Biscay by travelling aboard the 37500 ton P & O ferry, the Pride of Bilbao. The ferry follows a (more or less) fixed route between Portsmouth, England and Santurtzi (Bilbao), Spain, and samples a representative range of topographical features and underwater habitats found in the Bay of Biscay.

Map of ferry route (dark red line).
Other coloured lines represent depth contours,
from right to left 200m, 1000m, 2000m, 4000m

Survey Method on Each Trip

Cetaceans

Cetacean species are recorded on systematic cetacean watches, which adopt standard recording methodology developed by the Mammal Society /Sea Watch Foundation for effort-based recording (by volunteers) on platforms of opportunity (Evans, 1981, 1995). Watches are maintained continuously from dawn until dusk. On the Portsmouth to Bilbao ferry, the return journey extends over four days, and enables the whole of the route to be sampled at least once during daylight in the summer, and approximately 75% of the route in the winter. On each trip a team of three experienced observers, scan ahead, 22.5° of the bow on both the port and starboard sides. The methodology is essentially that of an unlimited distance single line transect, with every cetacean and other animal visible and identifiable being recorded once only. Recording is made from the bridge of the ship, at a height of 32m and at a ship speed of 15-22 knots.

For each sighting, the number of animals is counted and where possible the age and behaviour of individuals is recorded. At time of sighting the following recordings are also made: time, position of the ship (using the ship's global positioning system), position and orientation of the animal/s relative to the ship, and environmental conditions such as sea state, swell height, wind speed and direction, and visibility. These details are entered onto BDRP recording forms based on a standardised Sea Watch Foundation sighting pro forma (Evans, 1995).

At half hourly intervals, ship position, ship speed and environmental recordings are repeated and entered onto forms again based on a standardised Sea watch Foundation vessel based effort pro forma (Evans, 1995). Effort data enables the number of sightings to be scaled recording effort, and the calculation of relative abundance. To standardise data collection, trips are made at the same time each month (in the third week) and are carried out by a select number of experienced observers. All field data collected is computerised and stored in spreadsheet and relational database formats.

Birds

Seabird data is collected also. On every survey, there is a designated bird recorder, who is responsible for ensuring that accurate and complete records are maintained throughout the survey. The nominated person will ensure continued surveying of seabirds during cetacean activity; ideally by delegating seabird recording to another competent observer, or by handing over the cetacean sighting and continuing with seabird recording (but only once others are definitely on the cetaceans).

They are supported by the other two surveyors, who will also be competent in identification. Great Shearwater This is to ensure that accurate data is collected for both main areas, cetaceans and seabirds, as well as other taxa if possible.

Bird Recorders maintain a fixed position in the bridge throughout surveys, this being towards the middle-right of the bridge, looking ahead. Seabirds are recorded throughout the bridge watches, simultaneously with searching for land birds on migration, cetaceans and other taxa. All identifiable birds seen within a 2km arc and within 20° forward of the bow, on both port and starboard sides, should be recorded. In order to determine relative abundance there is a 300 x 300 metre box offset front right of the bow. Birds that pass through this box are recorded for the box and not for the wider area. Data is recorded onto a single sheet with two columns designating each recording area. Each bird is recorded only once and recorded within minute bands, with care taken to avoid double counting.

The species, numbers and wherever possible the age of birds are recorded, as well as behaviour, especially if birds are recorded in association to fishing boats, fish shoals or cetaceans. In the latter instance, records will be cross-referenced to cetacean sightings forms.