|(c) Chris Johnson|
Longlines, called "land mines of the sea," consist of fishing line, up
to 60 miles long, baited with as many as 3,000 hooks, and remain in the
water for up to 16 hours. It is estimated that globally up to 10
billion hooks are set every year. The target catch is both tuna and
swordfish, though they incidentally catch all sorts of other marine
Longlining is so destructive because it is non-selective, which means
that it captures anything that bites the bait or becomes entangled in
the lines. This destructiveness has been magnified by an increase in
longlining after the international ban on high seas drift netting and
increased demand for swordfish, tuna, and shark.
It is estimated that worldwide 40,000 sea turtles get caught in
longlines every year. As longlining expands throughout the world,
greater numbers of sea turtles are at risk.
The deaths of sea turtles are not the only harmful impacts of
longlining on the marine environment. This destructive fishing
technique threatens other species of sea creatures and the larger ocean
ecosystem. Below are the impacts of longlines on other marine species:
Seabirds - Longlining has been identified as a major threat a number of
sea bird populations, including albatrosses, petrels, and shearwaters.
The baited hooks attract seabirds, who when attempting to take the
bait, get caught on the hook and drown or else ingest the hooks. The
annual mortality of petrels and albatrosses has been estimated at
Monk seals - In Hawaii, longlining has had a harmful impact on
endangered monk seals that, along with other factors, eventually led to
the designation of critical habitat areas for the seal with a closure
of fishery activities in these areas. For example, in 1990 and 1991, 13
monk seals were found with longline related injuries.
Sharks - Another victim of the incidental capture in longline fisheries
are sharks. These unintended catch, while still alive, have their fins
cut off as products for the Asian market for shark fin soup which
fetches between $25 and $80 a bowl. Increasing public alarm has been
raised about declines in shark populations and the need for increased
regulations. In 1995, the Hawaii-based longline fishing fleet caught
101,773 sharks and roughly 50,000 pounds of dried shark fins were
landed in Hawaii.
The impacts of longlines are not limited to the species listed above.
Since longlines are nonselective fishing gear, they capture anything
that gets caught on their hooks or tangled in their lines. This has a
tremendous impact on overall marine biodiversity.