A group of biologists from the Memorial University of Newfoundland say that the number of some deep-sea fish species in the north Atlantic has declined to the extent that the species meet the World Conservation Union (IUCN) criteria for being critically endangered.
"Our results indicate that urgent action is needed for the sustainable management of deep-sea fisheries," say the researchers in a paper published in the Scientific journal Nature .
The study is focused on five species that live on or near the bottom of the Canadian waters in the northern Atlantic Ocean, namely the roundnose grenadier, onion-eye grenadier, blue hake, spiny eel, and spinytail skate.
"This study is unique because we had such a long time series for these species, knew or could infer their generation time, and were able to apply the IUCN criteria," says Jennifer Devine, one of the researchers.
"We believe our study is a crucial piece in the growing pile of evidence that fishing in the deep-sea has detrimental and far-reaching effects on the entire deep-sea ecosystem."
According to the study, the species have decreased between 87 and 98 percent over only 17 years. Also, the two grenadier species have declined by 93.3 and 99.6 percent over a 26-year period.
"No population fluctuates as much as 90% naturally, especially in such a stable environment as the deep-sea. Any changes made to halt these population declines would not be evident for several generations—approximately 100 years," says Devine.
A decline in the oceanic cod, rays, tuna, and other types of fish due to over-fishing in the 1960s and 1970s caused a shift in commercial fishing to the deep-seas. Devine says prior to the 1970s, deep-ocean trawling on the continental slope was non-existent, but it has become important all over the world as shelf fisheries declined. And this is the reason they believe trawling has had an impact on deep-sea fishes and the deep-sea ecosystem.
Because of slow growth, late maturation, long life, and low fertility rates, deep-sea fish are extremely vulnerable to over-fishing.
As one of the initiatives to stop the rapid decline of these species, the researchers have suggested the establishment of "deep-sea protected areas".
"A recent article in Science has shown how a marine protected area in shallower habitat has been effective. Additionally, we have seen the call for reduced fishing mortality on deep-sea stocks in the Northeast Atlantic and believe that could be an appropriate conservation measure," says Devine.
Devine says that so far, they have seen no sign that their research has caught the attention of the authorities or that there is any action planned to help the situation.
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