Posted on 13 June 2003
Every year, around 300,000 whales, dolphins, and porpoises are accidentally caught in fishing gear and die. WWF is calling on the International Whaling Commission to adopt a formal action plan for bycatch mitigation to help stop these needless deaths, the single biggest threat to the survival of many of the world’s cetacean species.
In June last year, a female sperm whale became entangled in a gill net in the Aegean Sea. Turkish rescuers risked their lives to cut the net away from her lower jaw and tail fluke. Finally, after three hours, she was freed.
She was lucky. Around 300,000 other whales, dolphins, and porpoises accidentally caught in fishing gear in the 12 months since then were not.
Over 800 slow deaths each day
These animals — more than 800 every day of the year — died horrible deaths. Most drowned. Some succumbed to shock and exhaustion, others were attacked by sharks while trapped in nets. A few managed to thrash their way to freedom, only to die later from their wounds: deep cuts through their blubber, sliced and twisted fins and tail flukes, netting caught around their mouths. Of those that were still alive when the fishermen hauled up their nets, many died in the crush of the catch. Some were hacked out of the nets while still alive. And even those that were freed were weak, bruised, and disoriented, easy prey for the still-circling sharks.
The deaths occurred around the world, to all types of cetaceans, from all types of fishing. Sei whales were found dead on the US east coast wrapped in fishing line. Common dolphins died in pair trawler nets set for sea bass and mackerel in the English Channel. Dolphins were killed in purse seine nets set illegally for tuna in the Galapagos. Harbour porpoises died in gillnets set for cod in Canada’s Bay of Fundy. Hector’s dolphins drowned in recreational set nets in New Zealand bays. Freshwater tucuxis drowned in nets set by poachers for turtles in the Amazon. Right whales were entangled in US lobster creel pots. False killer whales died on longlines set in the South Pacific. Indeed, almost wherever there was fishing gear, there were cetacean deaths.
Biggest threat to cetaceans
The problem of cetacean bycatch — the accidental death of whales, dolphins, and porpoises in fishing gear — is so large and widespread that the world's leading cetacean scientists believe it is the single biggest threat to the survival of many of the world’s 86 cetacean species.
The scale of the problem stems largely from the advent of cheap synthetic nets — some large enough to hold 12 jumbo jets — and faster, bigger fishing boats. These together spurred a huge expansion in fishing effort over the last 30–40 years, with thousands of kilometres of nets set in the world's oceans each day. Invisible to sight and sonar and too strong for most animals to break free of, these nets are deadly to cetaceans.
Several species already teeter on the edge of extinction. Gillnets in Mexico's Gulf of California kill up to 15 per cent of vaquitas, the world’s smallest porpoise, each year. With only some 500 remaining, this number of deaths cannot be sustained by the species. The same is true for New Zealand’s Maui’s dolphins: fewer than 100 remain due to a high death rate in set nets and pair trawlers. Irrawaddy dolphins in the Philippines, down to around 70 individuals, will soon disappear if nothing is done to keep them from dying in lift nets. And China's freshwater Baiji dolphins are down from 300 in 1989 to just a few individuals. A large number of these deaths were from entanglement in fishing gear.
Even if the animals don’t die in fishing gear, entanglement can still affect their survival and that of their species. For example, some 62 per cent of North Atlantic right whales have scars that indicate they’ve been entangled in fishing gear. The stress of being entangled together with the wounds sustained in escaping could well be compromising the health of these animals. And with only 300 remaining, this extra pressure is not likely to be helping the survival of the species. Similarly although the vast majority of spotted and spinner dolphins caught along with yellowfin tuna in the Eastern Tropical Pacific Ocean are released alive, the repeated stress of being caught may be affecting their overall health and ability to reproduce.
Better than it was
As bad as it is now, it was once a lot worse. Before the 1992 UN ban on the use of driftnets on the high seas, hundreds of thousands of cetaceans died in these nets each year. Large gill nets, which once reached up to 48km in length, were also banned by the UN, in 1991. Although the ban was slow to take effect, the new legal length of around 2km has drastically reduced the number of cetacean deaths. And improvements to the US Eastern Pacific Ocean tuna fishery together with intense regulatory efforts have reduced dolphin bycatch from over 100,000 per year to fewer than 2,000.
But a long way to go
But the fact remains that around 300,000 cetaceans still die each year as bycatch — not to mention countless seabirds, marine turtles, sharks, and juvenile and non-target fish species.
There are various reason for this. One is that although the problem is global, awareness of this issue is low in most parts of the world. Indeed, most countries fail to even record cetacean bycatch deaths, making a global assessment of the problem difficult.
In addition, despite numerous recommendations from the International Whaling Commission (IWC) to mitigate bycatch, many countries have done little to address the problem. Notable exceptions are the US, Canada, Australia, New Zealand, and the UK which took action when the scale of cetacean bycatch in various fisheries became apparent.
Time to move forward
Various simple and relatively inexpensive measures are available that can reduce cetacean bycatch. These include acoustic pingers that alert cetaceans to the presence of fishing gear and setting nets in deeper water. In cases where whales and dolphins migrate in and out of fishing areas, fisheries can be closed temporarily when the animals arrive and reopened when they leave. Other technological, operational, and managerial changes have proven highly effective in some fisheries.
But it is not enough for governments or fisheries to tackle the problem of bycatch in isolation. The global nature of the problem means that a global cooperative effort — involving governments, commercial fishers, artisanal fishers, scientists, and NGOs — is necessary to ensure that bycatch no longer threatens cetacean species.
This is why WWF believes it is time to move the conservation work of the IWC forward, and to adopt a formal action plan for bycatch mitigation. As the globally recognized forum for cetacean conservation, the IWC is the logical and appropriate venue to coordinate such a multinational effort.
A bycatch resolution has been proposed for this year's Annual Meeting of the IWC. If it were adopted, the commission could take the lead on supporting capacity building and training to mitigate cetacean bycatch, working with fishing countries to find solutions, and encouraging governments to provide funding for cetacean bycatch mitigation.
The stakes are high. So far, humans have not caused the extinction of any cetacean species. The IWC resolution — and the political will to follow it up with rapid action to prevent bycatch — would make a substantial contribution to ensuring that this remains the case.
* Emma Duncan is Managing Editor at WWF International.
Modern fishing gear that threatens cetaceans
Gillnets are designed to entangle fish by their gills, and are used around the world. Around 2km long and about 4.5m deep, they are either anchored on or near the sea bed or set to drift (see driftnets below). Gillnets are extremely efficient, catching anything larger than the net’s mesh size, which ranges from a few centimetres to around 50cm. A study of the 1996 California drift gillnet fishery found that for every 22 swordfish caught, one whale or dolphin was killed as bycatch, while a study of the 1992–1994 Danish bottom-set gillnet fishery for cod and turbot in the North Sea found that it caught some 4,500 porpoises per year. Because of their low cost and widespread use, gillnets are responsible for a very high proportion of global cetacean bycatch. Experts agree that wherever there are gillnets, there is cetacean bycatch. Sea birds, marine turtles, and non-target fish are also caught in gillnets.
Driftnets are hung in the ocean through floats at the top and weights at the bottom. Drifting passively in the water, they catch anything that swims into them. The introduction of light synthetic netting in the 1970s allowed huge nets to be used on the high seas. These were first used in the North Pacific by Japanese, Taiwanese, and South Korean fleets to catch tuna and squid. At their height, these driftnet fleets were the largest fishing fleets on earth, with each boat setting as much as 50km of net per day, totalling some 50,000km of net per day. Labelled 'walls of death', the nets have killed hundreds of thousands of whales, dolphins, seabirds, sea turtles, sharks, and other non-target fish. Although now banned on the high seas, in EU waters, and limited in length to 2.5km, the use of larger nets continues, and even legal driftnets still suffer from bycatch.
Pair trawling (or pelagic trawl fishing):
In this method a net up to 800m wide is dragged between two large trawlers for 6–8 hours at a time. One example of the effect of this fishing method on cetaceans is in the English Channel and Irish Sea, where pair trawling is widely used to catch mackerel, sea bass, and pilchard. Hundreds of harbour porpoise and common dolphin carcasses, many with net injuries, wash up on beaches in south west England, Ireland, and northern and western France every year during the pair trawling season. This is only a small fraction of the fatalities, as many carcasses drift out to sea. European scientists estimate that as many as 50 dolphins can become trapped in a single haul. One estimate for the total number of deaths caused by these pair trawler fisheries is as many as 10,000 dolphins per year.
Purse seine nets:
Purse seine nets are lowered onto a school of fish and then pulled closed from beneath like a drawstring purse. The best-known example of their effect on cetaceans is the yellowfin tuna fishery in the Eastern Tropical Pacific Ocean. For unknown reasons, these tuna congregate beneath dolphin schools, so the purse seiners target the dolphins to catch the tuna. Historically, the dolphins were hauled on board with the tuna, and discarded, dead or dying, back into the water. As many as 7 million dolphins may have died in this way since the late 1950s. Consumer pressure in the US in the late 1980s led to improvements to the tuna fishery and the creation of the "Dolphin Safe" label through the Agreement on the International Dolphin Conservation Programme (AIDCP). Through measures such as allowing dolphins to escape the net before it is hauled aboard and the presence of international monitors on the boats to ensure that dolphins aren't killed, dolphin mortality in the Eastern Pacific Ocean tuna fishery has been cut by 98 per cent, to fewer than 2,000 per year. The AIDCP programme is subscribed to by Bolivia, Colombia, Costa Rica, Ecuador, El Salvador, the EU, Guatemala, Honduras, Mexico, Nicaragua, Pànama, Perù, the US, Vanuatu, and Venezuela.
Ghost nets are nets that are lost or abandoned at sea. They continue to catch fish, dolphins, whales, turtles, and other creatures both as they float through the water and after they become snagged on the seabed. When driftnets were allowed on the high seas, an estimated 1,000km of ghost nets were released into the North Pacific each year. Although the current contribution of ghost nets to bycatch is unknown, they are likely to have a large impact: one survey has estimated that a quarter of the rubbish found on the bottom of the North Sea is fishing nets.
Used particularly in the Pacific Ocean, Southern Ocean, and Atlantic Ocean, longlines are a single strand of fishing line set with up to 2000 baited hooks. Any marine animal large enough to bite the bait and hook is captured. Each year these lines unintentionally kill dolphins as well as huge numbers of sea turtles, sea birds (especially albatross and petrels), sharks, and non-target fish.
Baiji or Chinese river dolphin: Lipotes vexillifer
Common dolphin: Delphinus delphis
and Delphinus capensis
False killer whale: Phocaena crassidens
Harbour porpoise: Phocoena phocoena
Hector's dolphin: Cephalorhynchus hectori
Irrawaddy dolphin: Orcaella brevirostris
Maui's dolphin: Cephalorhynchus maui
Northern right whale: Eubalaena glacialis
Sei whale: Balaenoptera borealis
Sperm whale: Physeter macrocephalus
Spinner dolphin: Stenella longirostris
Spotted dolphin (pantropical): Stenella attenuata
Tucuxi: Sotalia fluviatilis
Vaquita: Phocoena sinus
WWF's work on cetacean bycatch
Reducing cetacean bycatch is a focus of WWF’s Species Programme
. WWF convened a summit of the world’s leading cetacean experts in January 2002 in Annapolis, Maryland, US, which was attended by 25 scientists from six continents. The group reached consensus that the single biggest threat facing cetaceans worldwide is bycatch and released a call to action urging governments, scientists, and fishermen to come together to address the problem. WWF has also contributed to the IWC’s Voluntary Fund for Small Cetaceans to support research grants for alternative fishing gear and methods of reducing cetacean bycatch.
was set up under the International Convention for the Regulation of Whaling which was signed in Washington DC on 2 December 1946. The IWC is the only international organization with the authority to regulate whaling and whale conservation worldwide. It now has about 35 voting members.
The IWC Scientific Committee has compiled an impressive portfolio of work on other cetacean conservation concerns, including bycatch. Based on advice from the Scientific Committee, the member countries of the IWC have passed a number of resolutions recommending actions to mitigate bycatch. Unfortunately, not all member nations have acted on those recommendations, and cetacean populations continue to be threatened.
The bycatch issue will be discussed at the 55th Annual Meeting of the IWC, to be held from 15–19 June in Berlin, Germany. Several governments have co-sponsored a resolution on bycatch which could make a substantial contribution to reducing this threat if adopted. WWF
is urging IWC delegates to support this resolution.