© WWF-Canon / Hélène PETIT
By-catch of Whale shark (Rhincodon typus).
Since the development some 50 years ago of cheaper fishing gear and bigger, faster boats, thousands of kilometres of nets and lines have been set in the world's oceans each day. Modern fishing gear, often invisible to sight and extremely strong, is very efficient at catching the desired fish species - as well as anything else in its path. A staggering amount of marine life is hauled up with the catch, and then usually discarded overboard dead or dying.
The numbers are truly frightening. For example:- Many of the fish and other animals caught in fishing gear are thrown away as unwanted bycatch - amounting to many millions of metric tonnes of marine life wasted each year.
- Over 300,000 small whales, dolphins, and porpoises die from entanglement in fishing nets each year, making bycatch the single largest cause of mortality for small cetaceans and pushing several species to the verge of extinction.
- According to some scientific estimates, as many as 250,000 endangered loggerhead turtles and critically endangered leatherback turtles are caught annually on longlines set for tuna, swordfish, and other fish, with thousands more killed in shrimp trawls.
- 26 species of seabird, including 17 albatross species, are threatened with extinction because of longlining, which kills more than 300,000 seabirds each year.
- 89% of hammerhead sharks and 80 per cent of thresher and white sharks have disappeared from the Northeast Atlantic Ocean in the last 18 years, largely due to bycatch.
- Shrimp trawlers catch as many as 35 million juvenile red snappers each year in the Gulf of Mexico, enough to have an impact on the population.
- Billions of corals, sponges, starfish, and other invertebrates are caught as bycatch every year
Wherever there is fishing, there is bycatch. And the sheer numbers of animals being needlessly killed makes bycatch one of the greatest and most pervasive threats to life in the oceans. Indeed, bycatch could well be the final nail in the coffin for many endangered marine species.
It's also an expensive problem: fishers lose hundreds of millions of dollars a year because of the loss of juvenile and non-target fish to bycatch. On top of this, with so many fish, including juvenile fish, being wastefully discarded, bycatch is contributing to the global problem of overfishing and declining marine ecosystem health, and endangering food security in poorer countries.