Transcript Overfishing Practices ppt

OVERFISHING PRACTICES
GILL NETS
DRIFT NETS
LONGLINES
PURSE SEINE NETS
TRAWLERS
BY-CATCH – ALL THE
ANIMALS CAUGHT IN NETS
OR ON LINES WHICH ARE
UNINTENTIONAL AND ARE
USUALLY DEAD AND
THROWN OVERBOARD.
Drift net fishing on the high seas beyond the exclusive economic
zone of any nation was banned in 1991 by the UN General
Assembly because of its potential to harm all fish stocks and
marine animals. Fines for drift net fishing are significant. This
type of fishing involves the use of a net, up to twenty miles in
extent, that is generally anchored to a boat and left to float with
the tide. The net is set out at night and pulled in at sunrise,
making it difficult for aircraft surveillance to catch them in the
act. On average, a drift net vessel can scoop up half a ton of fish
per day. This often results in an over harvesting and waste of
large populations of non-commercial marine species (by-catch)
by its effect of “sweeping the ocean clean”. The by-catch also
includes marine mammals and seabirds.
Nicknamed "walls of death" these nets are made of a
very strong monofilament (single strand) nylon mesh,
and each net is between 8 - 12 meters deep and may be
as long as 65 km, although usually between 32 - 40 km.
The nets are often put into the sea at night, where they
drift with the current, catching and killing anything that
gets in their way, like huge underwater spiders' webs.
This method of fishing is extremely wasteful. Not only is
an estimated 40% to 50% of each catch lost when the
net is hauled in, but uncounted numbers of fish are
injured in the net and may escape only to die later.
These nets also catch many dolphins, whales, seals,
turtles and seabirds which cannot easily see the almost
invisible netting.
Longline fishing is a technique used to catch fish in open waters,
including those who live near the sea floor. A longline includes a main
fishing line up to 100 kilometers in length, with secondary lines
branching off it, each set with hundreds or thousands of barbed, baited
hooks. This technique is used in international waters, as well as waters
controlled by the United States, South America, Australia, New Zealand,
and southern African countries, and targets fish species such as tuna,
swordfish, and Patagonian toothfish.
The Turtle Excluder Device or TED is a grid of bars with
an opening either at the top or the bottom. The grid is
fitted into the neck of a shrimp trawl. Small animals like
shrimp slip through the bars and are caught in the bag end
of the trawl. Large animals such as turtles and sharks, when
caught at the mouth of the trawl, strike the grid bars and
are ejected through the opening.
Japan has secured the help of eleven nations at the IWC in this
way: six East Caribbean states, (Antigua and Barbuda,
Dominica, Grenada, St Lucia, St Vincent and the Grenadines, St
Kitts and Nevis), the Solomon Islands, Guinea, Morocco and
Panama. All of these countries regularly attend IWC meetings
and speak in favor of a resumption of commercial whaling,
voting with Japan on all occasions