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58

At present capture fisheries yield 110–130 million tonnes of sea-

food annually. Of this, 70 million tonnes are directly consumed

by humans, 30 million tonnes are discarded and 30 million

tonnes converted to fishmeal. Aquaculture, freshwater and ma-

rine fisheries supply about 10% of world human calorie intake

– but this is likely to decline or at best stabilize in the future,

and might have already reached the maximum.

The primary and most important fishing grounds are found

along the continental shelves within less than 200 nautical

miles of the shores. The distribution of these fishing grounds

is patchy and very localized. Indeed, more than half of the 2004

marine landings were caught within 100 km of the coast in

depths generally less than 200 m covering an area of less than

7.5% of the world’s oceans, while 92% was caught in less than

half of the total ocean area.

Climate change and increased CO

2

assimilation in the oceans

will result in increasing ocean acidification, die-back of up to

80% of the world’s coral reefs and disruption of thermoha-

line circulation and other processes. It will particularly impact

dense-shelf water cascading, a “flushing” mechanism that

helps to clean polluted coastal waters and carry nutrients to

deeper areas. Coastal development is increasing rapidly and

is projected to impact 91% of all inhabited coasts by 2050 and

contribute to more than 80% of all marine pollution. Increased

development, coastal pollution and climate change impacts on

currents will accelerate the spreading of marine dead zones,

many in or around primary fishing grounds (Diaz and Rosen-

berg, 2008).

Overfishing and bottom trawling are reducing fish stocks and

degrading fish habitats, and threatening the entire productivity

of ocean biodiversity hotspots, making them more vulnerable

to climate change. Up to 80% of the world’s primary fisheries

stocks are exploited close to or beyond their optimum harvest

capacity and large areas of productive seabeds on some fishing

grounds have been partly or extensively damaged. For example,

over 95% of the damage and change to seamounts has been

caused by bottom trawling, which has been estimated to be

as damaging to the seabed as all other fishing gear combined.

Damaged from overfishing , bottom trawling and pollution, the

worlds fishing grounds are increasingly becoming infested by

IMPACTS OF ENVIRONMENTAL DEGRADATION ON FISHERIES

invasive species mainly through ballast water, with the pattern

closely following the major shipping routes.

The result of unsustainable fishing practices are that we might

no longer able to increase the landings from conventional

fisheries, and might, in fact, be facing a substantial decline

in the world’s fisheries in the coming decade. This will also

have severe impacts on aquaculture production, which relies

on fish for feed.

AQUACULTURE

Aquaculture production has increased more than seven-fold in

weight (from 5 to 36 million tonnes) between 1980 and 2000.

The value generated has grown from US$9 billion in 1984 to

US$52 billion in 2000 (Deutsch

et al

., 2007). In 2006, the world

consumed 110.4 million tonnes of fish, of which 51.7 million

tonnes originated from aquaculture. In order to meet the grow-

ing fish demand, aquaculture will have to produce an additional

28.8 million tonnes – 80.5 million tonnes overall – each year, just

to maintain per capita fish consumption at current levels. Aqua-

culture growth rate is declining, however: a yearly growth rate of

11.8% from 1985 to 1995 slowed to 7.1% during the following de-

cade, and to 6.1% for the 2004–2006 period. In October 2008,

FAO cautioned that a series of emerging challenges need to be

addressed if aquaculture is to meet increasing demand for fish.

THE FEED BOTTLENECK

Almost 40% of all aquaculture production is now directly de-

pendent on commercial feed. Most farmed fish that are con-

sumed in the developing world, such as carps and tilapia, are

herbivores or omnivores. But other species like salmon or

shrimp – often raised in developing countries – are fed other

fish in the form of fishmeal or oil. Salmon, shrimp and trout

aquaculture alone accounts for almost 50% of all fishmeal used

in aquaculture, but provides less than 10% of the production

volumes (Deutsch

et al

., 2007). In 2006, aquaculture con-

sumed 3.06 million tonnes (56%) of world fishmeal production

and 780,000 tonnes (87%) of total fish oil production. Over

50% of the sector’s use of fish oil occurs on salmon farms. Fish-

meal and fish oil production has remained stagnant over the

last decade and significant increases in their production are not