The compassionate guide to catching a crab

The timeless summer pursuit of dangling a hook laced with morsels of bacon over the harbour side in the hope of luring a hungry crab has been a rite of passage for generations of children visiting Norfolk's celebrated seaside villages.

Yet while families may look back nostalgically on golden memories of sunny days spent filling buckets full of snared crustaceans, the pursuit affords an altogether different experience for the poor old crab.

This week, visitors to Wells-next-the-Sea in north Norfolk are to be issued with guidelines to ensure that idyllic summer days do not result in lasting damage to the area's crab population. From Friday, those buying plastic buckets and crabbing lines from local shops will be handed a list of dos and don'ts, which it is hoped will put an end to incidents of unintentional crab abuse.

The guidelines, contained in 10,000 free leaflets, will include advice such as limiting the number of aggressive males kept in each bucket, ensuring they are immersed in supplies of fresh sea water and of not placing them in direct sunlight. The initiative follows a study by zoologists from Cambridge University, which found that Wells's native population of shore crabs, or Carcinus maenas, was suffering from a much higher incidence of damaged or missing pincers on stretches of beach where crabbing took place compared with those parts free of bait-dangling tourists.

Experts say the reason for the injury toll is that too many crabbers are overfilling their buckets, resulting in the seabed scavengers becoming stressed and attacking each other. In the very worst cases inadequate conditions result in asphyxiation.

The Cambridge zoologist Helen Green said that during the research project some children were found to be keeping up to 130 crabs at a time. "We want people to carry on crabbing – it is a really important seaside tradition and a very good way for youngsters to learn about marine ecology," she said. "But there was a lack of knowledge. People want to care for the crabs and were asking for more information. But when they are kept in this really confined space they will get stressed and attack each other and even kill each other."

The education programme has won praise from the RSPCA and is being backed by the Wells Field Studies Centre, which promotes understanding of the region's unique wildlife.

But while East Anglia makes much of its association with Carcinus maenas, elsewhere they are not so popular. Known as the common littoral crab, green or European shore crab, it is listed among the top 20 of the world's most invasive alien species, along with such nasties as the malaria mosquito.