Deep sea fish harvested to extinction

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Deep sea fish harvested to extinction

From the Times online

DEEP-SEA fish, some hardly known to science, are being wiped out by trawlers. A study shows that some North Atlantic species will be on the brink of extinction within 20 years.

Many trawlers have switched to deep-sea fish from traditionally harvested species such as cod and tuna because of concerns that stocks were being overfished.

The move has proved catastrophic to deep-sea fish, which generally breed less prolifically, grow more slowly and mature later than varieties closer to the surface. Declines of up to 99.6 per cent in 26 years have been identified by researchers; many species are expected to vanish by the middle of the century.

Jennifer Devine, of Mem- orial University of Newfoundland, Canada, who conducted the study, said that urgent action was needed to protect deep-sea fish. Her team of researchers looked at five species in the northwest Atlantic and concluded that all were close to extinction.

The fish live at between 600ft (180m) and 9,000ft but are now so rare, the study has found, that they qualify for the World Conservation Union’s Red List for critically endangered species.

The roundnose grenadier, Coryphaenoides rupestris, and the onion-eye grenadier, Macrourus berglax, are both fished commercially, the roundnose being fried or baked and the onion-eye having its livers canned.

The other three fish assessed in the study, the blue hake, Antimora rostrata, the spiny eel, Notacanthus chem- nitzi, and the spinytail skate, Bathyraja spinicauda, are netted by trawlers looking for greenland halibut and redfish.

For the study, data from surveys in the northwest Atlantic from 1978 to 1994 were analysed. It showed that there was an overall decline of 87 to 98 per cent. A further ten years’ data for the two grenadier species showed that over 26 years the roundnose declined by 99.6 per cent and the onion-eye by 93.3 per cent.

The researchers also found that in 17 years four of the five species studied fell in size by between 25 and 57 per cent. Only the spiny eel remained the same size as before.

Ms Devine said it was likely that other species were at risk, but that scientists knew so little about creatures that lived at great depth that it was impossible to find adequate information on their numbers to be sure. The barndoor skate, Dipturus laevis, one of the biggest species of skate at 5ft long, for example, is already known to have been pushed to the verge of extinction.

Ms Devine said that wide- ranging conservation measures should be taken to protect deep-sea fish before it was too late to save them.
... Quote:
Scientific investigation lags behind the collapse of deep sea fisheries. Conservation measures are necessary and lack of knowledge must not delay appropriate initiatives, including the establishment of deep-sea protected areas.

Deep-sea fish are highly vulnerable to disturbance because of their late maturation, extreme longevity, low fecundity and slow growth.

According to the [World Conservation Union] criteria, these five species of deep-sea fish qualify as critically endangered in the northwest Atlantic. The declines occurred on a timescale equal to, or slightly less than, a single generation of these species.
She said.

The five species chosen for the study can grow to more than 3ft long, live up to 60 years, reaching sexual maturity only in their teens. Their habitat is at the bottom, or close to the bottom, of the ocean.

The study was published yesterday by the journal Nature.


Roundnose grenadier Coryphaenoides rupestris: lives at depths of up to 7,200 feet; grows up to 3ft 6in long; feeds on crustaceans and other fish; can be fried or baked

Onion-eye grenadier (also known as roughhead grenadier) Macrourus berglax: up to 9,000ft; grows up to 3ft 3in; feeds on crustaceans, worms and comb jellies; liver canned or rendered into fish oil

Blue hake Antimora rostrata: prefers depth of 750ft but can cope at 9,600ft; grows to almost 2ft long; feeds on deep water invertebrates; no commercial use

Spiny eel Notacanthus chemnitzi: up to 8,200ft; grows up to 4ft long; feeds on sea anemones; no commercial use

Spinytail skate Bathyraja spinicauda: up to 2,600ft; grows to more than 5ft long; feeds on animals on sea bed; no commercial use
By netchicken: posted on 7-1-2006

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