Satellite telemetry

The satellite telemetry project will focus on two main activities:

1. Movements of Individual basking sharks

Data collected from 'pop-up' satellite telemetry, and other marking/sighting information (e.g. identification of individual sharks through unique fin patterns), will be used to identify movement patterns of basking sharks. Sharks will be fitted with electronic tags in two locations in UK waters, in the western English Channel off Plymouth and in Scottish waters off the Firth of Clyde. The satellite telemetry devices will gather time-related data on depth, ambient light and sea water temperature, which are relayed to "base" via System ARGOS on polar-orbiting NOAA satellites. These data will provide information on the geolocation of the fish at many points through its annual migration cycle, as well as providing detailed information about fish behaviour.

2. Population Dynamics

Understanding population dynamics requires information on sex ratios, growth rates, size at maturity, numbers at age, fecundity, etc. For most fish species, such data are gathered from commercial catches and/or from regular fishing surveys. Because there is currently little or no targeted commercial fishing for basking sharks, and because their vulnerable status precludes fishing surveys, these sources of data are not available for basking sharks. In order to obtain information on the distribution, abundance and population structure for groups of basking sharks in the western English Channel and Firth of Clyde, stratified line transect surveys will be carried out during the summer field seasons of 2001, 2002 and 2003 using a small research vessel.

In addition, the project will liaise with fishermen, strandings co-ordinators and others who are also studying basking sharks to gain maximum information from sharks which have stranded or been taken as bycatch. A pan-European publicity campaign is being mounted to maximise the accessibility of data sources. The information collected will be used in the conventional way to attempt to describe the population demography (e.g. relative abundance of juveniles and adults by sea area) and to estimate mortality and replacement rates.