Survey Methodology

MARINElife undertakes monthly surveys on a variety of commercial routes departing from the UK and a number of opportunistic small vessel surveys.

MARINElife routesOn each survey, effort-based cetacean, seals and seabird surveillance work is carried out by a team of experienced volunteer observers using a standardised survey methodology from a well positioned viewing platform such as the ship's bridge. The methodology used was developed by the Cetacean Group of the Mammal Society for use from platforms of opportunity such as commercial ferries.

Cetacean Recording

Cetacean species are recorded on systematic cetacean watches which are maintained continuously from dawn until dusk.

On each trip a team of experienced observers, scan ahead of the ship 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. On commercial vessels, recording is made from the bridge of the ship.

For each sighting, the number of animals is counted, species identified and where possible the age, sex and behaviour of individuals is recorded. As a sighting is made, position and environmental parameters are recorded on standardised sighting pro formas (Evans 1995), including: time, position of the ship (using a global positioning system), position and orientation of the animal(s) relative to the ship, sea state, swell height, wind speed, wind direction and visibility.

At half hourly intervals, effort recordings of ship position, ship speed and environmental recordings are made on standardised pro formas (Evans, 1995).

Effort data enables the number of sightings to be scaled relative to recording effort, enabling calculation of relative species abundance. To maintain the quality of the data collected on dedicated surveys, only trained observers carry out the surveys. All field data collected is computerised and stored in spreadsheet and relational database formats and analysed on a regular basis by MARINElife and external scientists.

Bird Recording

On every survey, there is a designated bird recorder, who is responsible for ensuring that accurate and complete records of all bird sightings are maintained throughout the survey. They are supported by the other surveyor, who will also be competent in identification.  This is to ensure that accurate data is collected for both main areas, cetaceans and seabirds, as well as other marine wildlife species encountered.

On commercial ships, seabird recorders maintain a fixed position throughout surveys, this being towards the middle-right of the bridge, looking ahead. Seabirds and migrating land-birds are recorded throughout the bridge watches within a 2km arc ahead of the ship, on both port and starboard sides. 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. On smaller vessels, in-flight and resting birds ahead of the ship are recorded.

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

Other species

Sightings of other marine wildlife such as seals, sunfish, turtles and sharks are also recorded if encountered during the survey.