A 1994 Faroe Islands stamp depicting the unfortunate orange roughy
Credit: Wikipedia
When fishermen began reeling in orange roughy 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 (Hoplostethus atlanticus), 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.
Even for those that escaped the dinner table, survival is not guaranteed.
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 United States.
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.
Vast schools of these strange-looking fish gather to breed and feed around underwater mountains at depths of one kilometre. This makes them easy targets for trawlers that can gather tonnes of roughy in a single weighted net. Dragging these nets along the seamounts also does an efficient job of decimating deep-sea coral communities.
Slow off the mark
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.
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 are often not caught until they are about 30 years old. As a result, it can take decades for depleted populations to rebound.
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. At the time, it was difficult for managers to monitor catches and it was unclear how much was being landed.
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.
Although catches had been dropping since 1990, the orange roughy still remained one of the most valuable in southern Australia. AFMA reduced the amount that that fishers could catch, but these permitted catches didn't actually decrease the catch, only tracked the catches as they continued to decline.
Diminishing returns
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.
This shift could be permanently crippling fish stocks so that they can't bounce back. Bigger, older fish are able to give their offspring an enormous head start in life. Larvae from older mothers of Pacific rockfish, for example, grow more than three times faster and survive starvation nearly twice as long as larvae from younger females.
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.
These animals are particularly vulnerable to fishing because they grow so slowly and live in an environment where, usually, very little changes. After more than a decade of dragging trawl nets across these deep-water pinnacles, it is uncertain how many of these extraordinary animals still cling to life; and how many have disappeared before they were even described.
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.
Fishing for orange roughy is now prohibited in target zones, and the total allowable catch for 2007 has been reduced.
While hard lessons have been learned about how to better manage fisheries and the need for extreme caution when the prizes are so high, it may be too late for the wide-eyed orange roughy.
For these stocks to recover, it could take longer than the lifespan of an ugly orange fish flapping on a salt-drenched trawler's deck.
Louise Goggin is a science writer and former marine biologist based in Sydney.
