How old is that lobster in the tank?

After seafood lovers have taken a table in their favourite restaurant and selected a fine-looking lobster from the glass tanks teeming with live crustaceans, the question of the creature's age may not have crossed their minds. Up until now that is probably just as well.

Because lobsters shed their shells and size is not always a good indicator, there has never been an accurate method to determine their age.

However, research conducted by the University of Leicester has now made it possible to ensure the number of candles on the cake is correct.

Matt Sheehy, of the university's zoology department, has developed a technique for determining age from the amount of a metabolic by-product, lipofuscin age pigment, found in the nerves of lobsters.

Cells in lobsters' nerves do not split like other cells, so the pigment accumulates and allows metabolic byproducts to build up with age.

Peter Shelton, senior lecturer in zoology and research project leader, said that determining age was vital for accurate lobster population modelling. The university has attracted Pounds 126,000 in funding from the Ministry of Agriculture, Fisheries and Food for research into the European lobster in Britain.

Dr Sheehy has been conducting research into crustaceans for nearly ten years and is regarded as a world expert. He came to Leicester last year after working on a project in Western Australia to apply the age measurement technique to the Australian western rock lobster.

Recently, Dr Sheehy was awarded a grant from the WA Fisheries Department to complete the research by measuring the amount of lipofuscin in western rock lobsters whose age is already known. The findings will have major implications for the management of Australia's most valuable fished species. Trade in Panulirus cygnus grosses more than Pounds 120 million annually.

The researchers have also collaborated with Sweden's Institute of Freshwater Biology on a project to apply the technique to crayfish.

Dr Shelton said introduced species such as Turkish and American crayfish were damaging English freshwater systems and it was important to understand crayfish population structure and dynamics.