In Dead Water

(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.

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.


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