Subject: FEATURE - Giant of the deep re

r.mallon1@genie.com
Thu, 17 Oct 96 11:38:00 GMT

FEATURE - Giant of the deep remains mystery to scientists

     By Brian Spoors
     ISLE OF ARRAN, Scotland, Oct 17 (Reuter) - The basking shark
is the second largest fish in the sea, it is found in most
oceans of the world except the tropics -- yet scientists know
almost nothing about it.
     "If we don't know anything about a flagship species like
the basking shark, what chance is there of protecting smaller
fish which might be equally deserving attention?" says Dr Mark
O'Connell, an environmental scientist from Durham University's
Department of Biological Sciences.
     The basking shark, which can grow up to 10 metres (33 feet)
long and weigh about three tonnes, is one of 30 shark species
found off western Europe and seeing one is an experience not
easily forgotten. The shoal rises to just below the surface and
apparently basks in the sun.
     Nobody knows why.
     "Fish are influenced by changes in temperature. It could be
that they come to the surface to warm themselves up before a
deep dive," said O'Connell's partner Dr Tim Thom.
     Together they have been establishing a research project on
the huge fish off the Scottish island of Arran.
     Only its close relative the whale shark, found in tropical
waters, is bigger. The great white shark which terrorised the
beaches in Steven Spielberg's "Jaws" is nowhere near as large.
     But unlike the great white or the even more ferocious bull
shark the basking shark is unresearched, harmless and survives
on plankton, "the grass of the ocean," according to O'Connell.
     What the researchers are coming to understand is that while
the fish might be under no threat, there are fewer of them.
     Officially there is no decline in the population. "You go
to official bodies and say "Their numbers are declining' and
they say "Where is your evidence?' and you have to admit there
isn't any," said O'Connell.
     Most of the evidence is flimsily anecdotal.
     "Many, many people have told us of shoals of 20 or 30 fish
a few years ago. Now they talk of four or five and this has
happened countless times," said Thom.
     The basking shark is fished commercially which could be a
factor in their declining numbers. The European Union (EU)
allows a quota of 200 tonnes of basking shark liver to be taken
annually and the Norwegian fleet is the major hunter in Europe.
     Some time ago heavy fishing of the sharks took place off the
coast of County Mayo in the Irish Republic. No basking sharks
have been seen there for years.
     As nobody knows how long the sharks live, how often they
breed or even how they breed, the impact of fishing cannot be
measured and it might be years before the effect is felt.
     "Estimates of the basking shark's gestation period vary
from six months to three years. Take your pick," said
O'Connell.
     Since records began in 1981, and for centuries before that,
according to local memory, the sharks would appear in the
Kilbrannan Sound between Arran and the Kintyre peninsula in mid
May and remain until late September.
     This year the first sighting was not until July and judging
by the dearth of sightings since early September, they have
slipped back into the Atlantic Ocean early too.
     "According to the records there has never been a gap of 18
days between sightings until this year," said Thom.
     The work which O'Connell, Thom and their helpers have begun
is basic and strangled by lack of funding.
     Current funding barely covers costs and doesn't pay
mortgages. Both scientists have had to put aside other work to
make a start on the shark project.
     Observation is as far as it has gone so far. Or it would be
if the sharks co-operated. Even so the team has developed its
procedures so that further work can go ahead efficiently.
     Technology can add to the information considerably, but a
sighting remains the starting point.
     Thom and O'Connell drift off the coast with their equipment
in a high powered rubber launch sweeping the still waters of the
sound. Onshore a string of observers armed with signal flags
scan the narrow stretch of sea.
     The plan is that when a shark is sighted, the boat will race
to it and the researchers will try to attach an electronic tag
to its dorsal fin.
     The tag is "state of the art" but not what they would have
if they had the money to design one from scratch.
     What it will do is record depth and water temperature, and
when the fish surfaces, location, and transmit the data for
about a year via satellite to a computer in Paris from which the
information can be accessed via the Internet.
     "There are many theories about the basking shark but nobody
really knows. I favour the theory of vast migrations," said
Thom.
     That could mean enormous distances -- huge fish swimming
endlessly across oceans from Europe to Newfoundland and down the
U.S. eastern seaboard.
     The research is costly and may not produce any commercial
benefit for a sponsor. But Thom and O'Connell maintain it is
worthy forscientific interest alone.
     "If they become extinct everyone will say to the scientific
community "why didn't you do something?"' said 'Connell. "We
are trying to do that as a preventive measure."