State of World Fisheries and Aquaculture 2004 - Library

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The State of World Fisheries and Aquaculture 2004
with a tendency to stabilize since 1998. Skipjack tuna accounts for about 50 percent of
this total, with a reported catch of 2 million tonnes, and remains one of the top species
in world fisheries production.
A recurring pattern in some areas is a long-term change in catch composition
following the depletion of more traditional stocks and the targeting of other lessvaluable
and previously lightly exploited or non-exploited species (Figure 18). For
instance, in the Northwest Atlantic invertebrate catches (molluscs and crustaceans)
have increased and those of demersal fish have declined. In the Northeast Atlantic,
the continuous decline in cod catches since the late 1960s has been counterbalanced
by increasing catches of formerly low-valued fish species such as blue whiting and
sand eels. In the Southwest Atlantic, the decline of the Argentine hake has been
accompanied by an increasing trend in catches of shortfin squid. The decline in
catches of pilchard (or sardine) and pollock in the Northwest Pacific has been partially
compensated for by increases in catches of Japanese anchovy, largehead hairtail and
squids. These changes in the species composition of fisheries catches can have different
causes, including the adaptation of the industry and markets to resources previously
considered as low-value, the effect of fisheries on the structure of marine communities,
and changes in environmental regimes affecting the stock productivity. These effects
are often difficult to discern, particularly in areas where research and monitoring of
resources and environment processes are poorly developed.
FAO monitors the state of exploitation of the main fish stocks or groups of
resources for which assessment information is available. The current global situation
follows the general trend observed in previous years. It is estimated that in 2003
about one-quarter of the stocks monitored were underexploited or moderately
exploited (3 percent and 21 percent respectively) and could perhaps produce more.
About half of the stocks (52 percent) were fully exploited and therefore producing
catches that were close to their maximum sustainable limits, while approximately
one-quarter were overexploited, depleted or recovering from depletion (16 percent,
7 percent and 1 percent respectively) and needed rebuilding. From 1974 to 2003 there
was a consistent downward trend in the proportions of stocks offering potential
for expansion. At the same time there was an increasing trend in the proportion of
overexploited and depleted stocks, from about 10 percent in the mid-1970s to close to
25 percent in the early 2000s (Figure 19).
Of the top ten species that account in total for about 30 percent of the world
capture fisheries production in terms of quantity (Figure 6, p. 9), seven correspond to
stocks that are considered to be fully exploited or overexploited (anchoveta, Chilean