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PAGE ONE :: WORLD NEWS :: ECO

Shark populations feeling the bite

Powered by CDNN - CYBER DIVER News Network
by SOLANA PYNE

NOVA SCOTIA, Canada (26 Jan 2003) -- Shark species are in big trouble.

A new study--the broadest to date--reveals shocking declines.

Even the least affected populations, those of mako sharks, have shrunk by 40% in the past decade or so, scientists estimate; hammerhead numbers have plummeted nearly 90%.

The study makes the case for more active conservation of shark species by limiting fishing and creating no-fishing areas.

Observers have suspected that intense fishing of open-ocean fish, such as tuna and swordfish, is bad news for shark species. Many are accidentally caught in longline fishing, which involves kilometer-long lines with hundreds of baited hooks, and their slow reproductive cycle makes it difficult for them to rebound.

Fishing of sharks themselves complicates the problem.

Studies have shown local drops in certain shark species, but scientists have had trouble assessing the overall drop because many sharks roam widely, making them tough to tally.

To bring the big picture into better focus, Julia Baum, a graduate student in the Department of Biology at Dalhousie University in Halifax, Nova Scotia, looked at data gathered from U.S. longline fishing boats in the northwest Atlantic from Newfoundland to northern Brazil.

For eight types of shark, Baum and colleagues examined records of catches between 1986 or 1992 and 2000.

After running a battery of statistical tests to rule out confounding factors, they concluded that all species other than makos declined by more than 50%.

The team reports its results in the 17 January issue of Science. Fishing is "definitely, without a doubt," what caused the decline, says fisheries biologist Ransom Myers, Baum's adviser.

Although scientists had suspected a sharp decline in shark populations, this study offers the first large-scale proof, says shark biologist Robert Hueter, director of the Center for Shark Research at Mote Marine Laboratory in Sarasota, Florida.

He cautions that the percentages of decline are likely more accurate for pelagics, such as the white and blue sharks, than for more coastal species, such as the hammerheads.

The only way to stem the decline, say Hueter and Myers, is to have international regulations--such as limits on longlining and no-fishing zones--in areas that are important in the sharks' life cycles.

SOURCE - Science, CDNN

 

ENDANGERED SPECIES - Sharks, Rays, Skates and Sawfish

(Editors note: This is not a complete list)

Name: Angular angel shark (Squatina guggenheim).
Status: endangered.
Where: western South Atlantic coastal waters from Southern Brazil to Northern Argentina.
Reasons: bycatch by gillnet and bottom trawling fisheries.

Name: Barndoor skate (Raja laevis).
Status: endangered.
Where: northwest Atlantic.
Reasons: overfishing.
Other: has been extirpated from large parts of its range in Canadian Atlantic and New England coastal waters

Name: Basking shark (Cetorhinus maximus).
Status: endangered.
Where: Atlantic, Pacific, Australian and New Zealand coastal waters.
Reasons: overfishing, bycatch.
Other: some local populations have declined up to 80 percent.

Name: Borneo shark (Carcharhinus borneensis).
Status: critically endangered or already extinct.
Reasons: overfishing.
Where: Pacific Asian coastal waters.

Name: Common sawfish (Pristis pristis).
Status: critically endangered or already extinct.
Reasons: bycatch.
Where: Atlantic, Mediterranean and Black Seas.
Other: once common in the Mediterranean and eastern Atlantic, but is now extirpated from Europe waters and the Mediterranean along with all other sawfishes.

Name: Dusky shark (Carcharhinus obscurus).
Status: endangered.
Where: coastal waters worldwide.
Reasons: overfishing.

Name: Freshwater sawfish, Great-tooth sawfish (Pristis microdon ).
Status: critically endangered.
Where: Indian Ocean and west Pacific coasts, lagoons and estuaries; freshwater lakes, ponds, rivers and streams.
Reasons: overfishing, habitat loss and degradation.

Name: Ganges shark (Glyphis gangeticus).
Status: critically endangered.
Where: Ganges-Hooghly river system, India and Pakistan.

Name: Great white shark (Carcharodon carcharias).
Status: endangered.
Where: worldwide.

Name: Green sawfish (Pristis zijsron).
Status: endangered.
Where: Indian and west Pacific coastal waters and lower reaches of rivers.
Reasons: overfishing, bycatch.

Name: Grey nurse shark (Carcharodon carcharias).
Status: critically endangered.
Where: Australia.
Reasons: overfishing.

Name: Largetooth sawfish (Pristis perotteti).
Status: critically endangered.
Where: Indian Ocean and west Pacific coasts, lagoons and estuaries; freshwater lakes, ponds, rivers and streams.
Reasons: overfishing, bycatch, habitat loss and degradation.

Name: Night shark (Carcharhinus signatus).
Status: endangered.
Reasons: overfishing.

Name: Pincushion ray (Urogymnus ukpam).
Status: endangered.
Where: coasts, lagoons and estuaries, and freshwater lakes, ponds, rivers and streams of Congo, Gabon, and Nigeria.

Name: Sandbar shark (Carcharhinus plumbeus).
Status: critically endangered.
Where: worldwide.
Reasons: overfishing.
Other: western Atlantic population has been reduced by 85-90% in just ten years by overfishing.

Name: Sand tiger shark (Carcharias taurus).
Status: endangered.
Where: Australia.
Reasons: overfishing.

Name: Silver shark (Balantiocheilos melanopterus).
Status: endangered.
Where: Indonesia, Malaysia, and Thailand.
Reasons: overfishing.
Other: a freshwater shark.

Name: Smalltooth sawfish, Wide sawfish (Pristis pectinata).
Status: critically endangered.
Where: Atlantic Ocean, Mediterranean and Black Sea coasts, lagoons, and estuaries, and freshwater lakes, ponds, rivers and streams.
Reasons: overfishing and loss of habitat.
Other: wholly or nearly extirpated from large areas of its former range in the North Atlantic (Mediterranean, US Atlantic and Gulf of Mexico) and Southwest Atlantic coast.

Name: Smoothback angel shark (Squatina occulta).
Status: endangered.
Where: western south Atlantic shelf waters (Brazil to Uruaguay.
Reasons: bycatch by gillnet and bottom trawling fisheries.

Name: Speartooth shark (Glyphis glyphis).
Status: endangered.
Where: Indo-Pacific coastal waters.
Reasons: development, overfishing and habitat destruction.

Name: Spiny dogfish (Squalus acanthias).
Status: endangered.
Where: temperate oceans worldwide.
Reasons: overfishing.

Name: Whale shark (Rhincodon typus).
Status: endangered.
Reasons: overfishing.

Name: Whitefin topeshark (Hemitriakis leucoperiptera).
Status: endangered.
Where: Philippine coastal waters.
Reasons: overfishing.

 

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