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21

Figure 6. The World’s most productive fishing grounds are confined to major hotspots, less than 10% of the World oceans.

The maps shows annual catch (tonnes per km

2

) for the World’s oceans. Notice the strong geographic concurrence of con-

tinental shelves, upwelling and primary productivity (see Figures 4 and 5) and the amount of fish caught by fisheries.

(Johnston and Santillo, 2004; Morato

et al

., 2006b). Once deplet-

ed and devastated, often for decades to centuries, fishermen move

on to the next seamount to start the next cycle. However, with

many known seamounts already (over)exploited, recovery of fish

stocks on seamounts varies with each species. Stocks of orange

rough on the Chatham Rise in New Zealand, for example, show

possible improvements after 5 years, whereas the grenadier stocks

in the Northwest Atlantic show no signs after a number of years

of reduced quotas.

The depletion of seamount populations indicates that the current

focus and levels of fishing on seamounts is not sustainable. More

depletion, extirpations, and even species extinctions may follow if

fishing on seamounts is not reduced (Morato

et al

., 2006). Very

common however, rather than fishing until near extinction, is that

the fishing vessels will move on to the next location as soon as the

first is exhausted. With the large capacity of the fleet, the result is

that more and more locations become impacted and damaged.

When primary production and bathymetric maps (showing the dis-

tribution of continental shelves) are compared to the intensity of

fisheries (catch), a clear pattern erupts, reflecting the productivity

and accessibility of these ocean hotspots.