Download
1 / 21
340 likes | 892 Vues
OVERFISHING. The practice of commercial and non-commercial fishing which depletes a fishery by catching so many adult fish that not enough remain to breed and replenish the population. Overfishing exceeds the carrying capacity of a fishery.
E N D
OVERFISHING . . . . The practice of commercial and non-commercial fishing which depletes a fishery by catching so many adult fish that not enough remain to breed and replenish the population. Overfishing exceeds the carrying capacity of a fishery. Catching too many fish; fishing so much that the fish cannot sustain their population. The fish get fewer and fewer, until finally there are none to catch. Fishing with a sufficiently high intensity to reduce the breeding stock levels to such an extent that they will no longer support a sufficient quantity of fish for sport or commercial harvest.
QUOTA A dedicated portion of a species-specific total allowable catch allocated to a country, fishing-group or an individual fishermen.
BOTTOM TRAWLING (Benthic Trawling) A fishing method that drags trawl nets along the sea floor. Non-selective destructive fishing method with a large amount of bycatch.
IUU-FISHING Illegal, unreported and unregulated fishing respecting neither national boundaries nor international attempts to manage high seas resources.
DISCARDS Marine species thrown back after capture. Most discards do not survive.
PELAGIC TRAWLING A fishing method involving towing a trawl net trough the water column. Can be performed by either a single or a combination of ships.
BYCATCH Unintentionally caught marine life while fishing for another species.
Maximum Sustainable Yield, MSY The largest yield (catch) that can be taken from a stock of a species over an indefinite period.
RECRUIT OVERFISHING (A type of overfishing) Depletion of a population to a level where it no longer has the reproductive capacity to replenish itself. There are not enough adults to produce offspring.
UNDERFISHING The deliberate catching of less than the MSY to increase fish stocks and maintain a sustainable fisheries
Causes of Overfishing . . Overcapacity: Worldwide, fishing fleets are two to three times as large as needed to take present day catches of fish and other marine species and as what our oceans can sustainably support. On a global scale we have enough fishing capacity to cover at least four Earth like planets. Destructive Fishing Methods: many fishing methods are unsustainable in their own way. These methods have a large impact on the basic functioning of our marine ecosystems. These unselective fishing practices and gear cause tremendous destruction on non target species. Bycatch/discards and bottom trawling destruction are two examples of this.
Overfishing –Problem? To explain why overfishing is a problem we first have to get an idea on the scale of the problem. • 52% of fish stocks are fully exploited • 20% are moderately exploited • 17% are overexploited • 7% are depleted • 1% is recovering from depletion Thus a total of almost 80% of the world's fisheries are fully- to over-exploited, depleted, or in a state of collapse. Worldwide about 90% of the stocks of large predatory fish stocks are already gone.
Overfishing ---Serious? Two Problems: • We are losing species as well as entire ecosystems. As a result the overall ecological unity of our oceans are under stress and at risk of collapse. • We are in risk of losing a valuable food source many depend upon for social, economical or dietary reasons.
