Porpoise study

Marine experts and mathematicians are teaming up to examine the impact of by-catch on the population of the UK’s most common marine mammal.

The Sea Mammal Research Unit (SMRU) at the University of St Andrews has been awarded £60,000 by the Ministry of Agriculture, Fisheries and Food to develop a computer model which will give fishing authorities an indication of the likely effect of fishing on the country’s future porpoise population. In turn, it will help the relevant authorities determine the most acceptable ways of limiting or modifying fishing.

The harbour porpoise is the smallest and most common marine mammal in north European waters, however, in recent years their numbers have declined dramatically. In fact, the porpoise has practically disappeared from the Baltic Sea, the eastern English Channel, and the southern North Sea. Previously the porpoise seems to have been abundant in all these areas. Concerns were raised about its status in the Baltic Sea during the 1970s and in the North Sea during the 1980s, but at that time no-one knew how many there were, or what their main threats might be.

Dr Simon Northridge of the SMRU said: “Although vulnerable to a variety of threats resulting from man’s activities, the most significant threat to porpoises appears to be accidental capture or entanglement in fishing gear while they are foraging for food.

“By gathering all available information on porpoise life history, including growth rates, mortality rates and rates of reproduction, together with the best available information on porpoise distribution and fishing net distribution, we should be able to develop a simulation model that will provide the answers we need. If nothing is done to limit fishing activities, the population will continue to dwindle towards extinction”.

Model development for the one-year project will be carried out by the Research Unit for Wildlife Population Assessment (RUWPA) in the School of Mathematics and Statistics. RUWPA is a contract- funded research group specialising in the development of new statistical methods and innovative applications of existing methods. The team have expertise and experience in most aspects of wildlife assessment and survey design. Since its creation in 1993, the group has steadily expanded, and now attracts research funding in excess of a quarter of a million pounds per year from international commissions and government agencies throughout the world.