FISHING CRISIS: Many of the Atlantic's deep-sea fish are threatened with extinction within a single generation as a result of fishing. A new survey of five species shows numbers falling to as low as just 2 per cent of original numbers recorded in the late 1970s, writes Dick Ahlstrom, Science Editor
The new research findings from Canada are important for Irish fishing activity, according to Dr John Joyce of the Marine Institute. Deepwater species are increasingly attractive commercial alternatives to shallow-water stocks currently under severe EU catch restrictions.
A group from Memorial University in St John's, Canada, found that the five species, including a mix of commercially fished species and those snared accidentally, have been virtually wiped out since the advent of large-scale deepwater commercial fishing in the 1970s. Details of their study are published this week in the journal Nature.
They looked at roundnose grenadier, onion-eye grenadier, blue hake, spiny eel and spinytail skate. They report that numbers of these fish in Canadian waters plummeted by between 89 per cent and 98 per cent in the 17 years from 1978 to 1994. Numbers have fallen so low that all five should now be classified as "critically endangered".
The Marine Institute here has already organised early studies of deepwater fish, one called the Deepnet Project, and an analysis of deepwater species of commercial interest to Ireland.
Deepnet examined fisheries conducted at between 200m and 1,200m depth. A fleet of about 50 vessels has been operating at these depths to the north and west of Ireland since the mid-1990s, with trawlers targeting monkfish and deepwater sharks.
"These fisheries are not well documented or understood," the report pointed out, adding that "stocks of deepwater sharks have been falling to about 20 per cent of original levels in less than 10 years".
The very different lifestyle of deepwater fish such as the orange roughy, which sexually matures after 20 years and can live to 170, means these fish are at particular risk of overfishing.
"We are dealing with types of fish stocks whose lifestyles are totally different from shallow-water stocks in terms of their longevity and the age at which they become sexually mature," Dr Joyce said.
"Therefore we need to know as much as possible about their lifestyle."