Requiem for a fish

Louise Goggin

Cosmos Online
14 March 2007

They can live for over a century, but overfishing has driven the remarkable orange roughy to the brink….When fishermen began reeling in orange roughy [Hoplostethus atlanticus] in the 1980s, some of the fish they dragged from deep below Australia’s ferocious southern seas were an astounding 150 years old. That means they would have hatched around the same time Charles Darwin embarked on his historic voyage aboard the HMS Beagle.

But those orange roughy dumped unceremoniously onto the trawlers’ heaving and salt-sprayed decks, were not destined to become famous. Instead, they ended up on a dinner plate of someone likely not even half their age…

This ugly species is blessed with two idiosyncratic traits: enormous eyes, which allow it to see in the deep ocean gloom; and one of the longest lifespans of any fish. Unfortunately these animals have a firm, white flesh that is highly prized by diners… In the 1980s their discovery brought the kind of profits to Australian and New Zealander fishermen that had not been seen for decades. But those riches were short-lived as trawlers dragged tens of thousand of tonnes of roughy from the inky depths, sparking off a potentially irreversible decline in their populations.

In the late 1970s, when roughy trawling was born, some catches were so massive they split nets and overwhelmed the boats that took them to shore - so much so that large proportions of those catches were lost or dumped. In 1990, 50,000 tonnes of orange roughy were trawled from waters south of Australia - despite a catch limit of half that. The bumper catches stimulated a rapid increase in fishing effort and fleet capacity.

Part of the reason the fish were caught in such great numbers was that they gathered in massive breeding aggregations. However, it now appears that targeting these aggregations may also be preventing the animals from mating successfully. Orange roughy don’t start to breed until they are about 20 years old [and] as a result, it can take decades for depleted populations to rebound.

By 1994, scientists’ best guess was that only 20 per cent of the original orange roughy stocks remained in some places. Although the Australian Fisheries Management Authority (AFMA) had a policy to close the fishery when stocks dropped below this critical threshold, it was not formally implemented.

As well as a shrinking catch, the fish were also getting smaller. In 1992, most of the orange roughy caught off the east coast of Tasmania were between 50 and 60 years old. By 2001 - not even a decade later - most of the fish that were caught were only half that age [and only just of breeding age]…Populations of orange roughy have been so decimated that in November 2006 they became the first commercially harvested fish to be listed as threatened under Australia’s Environment Protection and Biodiversity
Conservation Act.

As well as collecting the precious orange roughy, trawl nets dragged enormous sponges, never-before-seen crabs and strange deepwater fishes from the fragile deep-sea pinnacles. More than 250 invertebrate and 37 fish species have been found on underwater mountains south of Tasmania. One third of these species were new to science and 40 per cent of those were thought to live nowhere else.

While hard lessons have been learned about how to better manage fisheries …it may be too late for the wide-eyed orange roughy. For stocks to recover, it could take longer than the lifespan of an ugly orange fish flapping on a salt-drenched trawler’s deck…