Bycatch: The single most serious, direct threat to cetaceans.
An estimated 1,000 whales, dolphins and porpoises die each day due to bycatch and entanglement.
Introduction
Cetacean bycatch is the unintended capture of whales dolphins and porpoises by fisheries. Bycatch can be caused
by entanglement in fishing nets, gill nets and long lines, or direct capture by hooks or in trawl nets. Cetacean
bycatch is increasing in intensity and frequency due to increasing human population growth and demand for marine
food
A Serious and Direct Threat to Cetaceans
An estimated 40% of all sea
life caught by fisheries is simply discarded as bycatch. For animals such as shrimp, the level of bycatch rises to a
shocking 85%. A study into one U.S. fishery found that in a single year, 400,000 sharks were captured in nets and
discarded.
Image courtesy California Ocean Alliance
It is estimated that over 1,000 whales, dolphins and porpoises die each day due to entanglement in fishing gear or
marine debris and explains why bycatch and entanglement is now seen as by far the single most serious, direct
threat to cetaceans.
Daily Science reports that hundreds of thousands of whales and dolphins are killed each year as
bycatch in commercial fishing. Many times that number are injured or crippled in their encounters with fishing
equipment. Death is caused by asphyxiation or after months or years of painfully dragging nets and traps through
the ocean. Some cetaceans survive, but with broken teeth and open wounds and severed limbs. Autopsies of
naturally-deceased cetaceans show these encounters to be common. Off the west coast of Scotland, for example, one
in five minke whales has scars of entanglement.
Endangered Whales, Dolphins and Porpoises
Bycatch threatens the survival of many species. For example, more than 70% of the North Atlantic right whale
population bears scars from past fishing gear entanglements. Due to commercial whaling, the right whale population
is now estimated at just 411.
Gill nets are pushing populations to the brink, with the world’s smallest porpoise, the Vaquita in the Gulf of
California (less than 100 remaining) and world’s smallest dolphin, the Maui’s in New Zealand (less than 50
remaining) both threatened with extinction, with numbers declining rapidly year on year.
Reducing Dolphin and Porpoise By-catch
In the EU and UK, certain vessels must use an acoustic deterrent device, known as a 'pinger', to reduce the level
of dolphin and porpoise (cetacean) by-catch.
Data on Endangered Cetaceans
NOAA Fisheries provides helpful data and facts on the status of threatened and endangered whales, dolphins and porpoises and other species.
Whales Killed by Illegal, Unregulated and Unreported Fishing
In addition to the 1,000 cetaceans killed each day as bycatch, a further 100,000 small whales and dolphins are
illegally and unreportedly killed each year.
