Illegally set nets trap harbour porpoise

08 December 2005

Joana Doyle, Marine Conservation Officer for the Cornwall Wildlife Trust (CWT) assessed a dead female harbour porpoise found entangled in illegally set nets in St. Austell Bay on Sunday morning. Officers from the Environment Agency seized over 1.5 km of nets and were dismayed to find the snared mammal. The harbour porpoise is one of the smallest cetacean species resident around Cornwall, and is protected internationally as well as within the UK. Gill-nets have been identified as posing the most significant threat to harbour porpoises in the UK. Joana says: "The inshore gill-net fishery is poorly regulated; therefore nobody knows just how much net is down there at any one time, it could be anywhere between 800–5000 km, that’s over 7 times the length of the Cornish coastline."

St. Austell Bay and Mount’s Bay were highlighted by the Cornwall Wildlife Trust Strandings Network as hot-spots for harbour porpoise bycatch during the 2003/2004 winter bass season. Volunteers were called out to 223 dead harbour porpoise strandings around Cornwall alone. Most of these animals showed evidence of having drowned due to entanglement in monofilament gillnets used in the local inshore bass fishery.

In response, the Cornwall Sea Fisheries Committee (CSFC) implemented voluntary codes of practice in St. Austell Bay and Mount’s Bay. The codes state that fishermen should report any bycatch of cetaceans (porpoises/dolphins) to CSFC or the Cornish Fish Producers Organisation. According to the codes, if cetaceans are seen in an area where nets are set, fishermen should inform each other and haul in their nets. After a one-year trial, CWT withdrew its support of the codes as it became clear that there was too much non-compliance, reporting was inadequate and strandings were still occurring in these areas.

Joana is concerned over the effectiveness of voluntary measures: "Surely if these fishermen are not even willing to abide by the law, they are not going to voluntarily report porpoise bycatch or remove their nets when they see porpoises." She continues: "The fishermen that are breaking the law and are not complying with the voluntary codes will cause problems for other gill-netters, as their actions emphasise the need for tighter regulation of gill-net fisheries."

It is not only the porpoise that is at risk of being caught by these types of net. Two weeks ago a very sick bottlenose dolphin stranded itself alive on the slipway in Penzance, Mount’s Bay and died. Although it is thought to have died of old age and disease, the net marks on its skin containing strands of monofilament net prove that this dolphin had at some stage interacted with a gillnet. The bottlenose dolphin is an incredibly important part of Cornwall’s natural heritage, being the species most often encountered by the public. The death of just one of these could have a massive effect on the pod which, since the 1990s, appears to have decreased in size by about half.

The UK is party to several agreements that create legal obligations to protect populations of small cetaceans from bycatch. Closure of specific areas to gillnets has been used to reduce bycatch of cetaceans in USA, New Zealand and by Europe. The UK has only used such measures to protect fish stocks.