Geoscience Reference
In-Depth Information
conditions considerably, which may lead to further spreading of dead zones. For instance,
a higher water temperature leads to an increase in the rate of oxidation of organic mat-
ter and thus of oxygen consumption, which may not be compensated for by an increased
rate of oxygen supply. The changes already observed in the ocean related to global climate
change highlight the need to evaluate this potential at global and regional levels, for in-
stance through the LME Programme. The significance for our society is underlined by the
importance of estuarine and coastal sea food to human development.
The inherent interdependences highlight the necessity for an integrated and compre-
hensive evaluation of ongoing developments. It is not sufficient to address just one prob-
lem, or one component of the whole system. A system-wide approach is required. This
observation is certainly not new, but needs to be stressed. It is supported by confirmation
that integrated fisheries management that limits the harvesting rate to appropriate levels
can reverse the trend of declining fisheries. Highly migratory species subject to interna-
tional fishing are threatened: for example, Atlantic bluefin tuna, and other fish such as cod,
flounder, and sole caught in 'mixed fisheries'. It should be possible to address these prob-
lemsthroughaproperimplementation andenforcementofthe1995UNFishStocksAgree-
ment, which is also part of the Law of the Sea (cf.
Chapters 6
and
10
)
. Hilborn (
1996
)
notes
that the environmental cost of producing more food on land through greater use of fertil-
izers and antibiotics, leading to more chemical run-off and increasing dead zones in estu-
aries and coastal seas, is potentially much higher than would result from fewer fish in the
ocean. However, the interdependence within the marine ecosystem must also be noted. An
increasing proportion of global fisheries is made up of small fish like sardines, anchovies,
and menhaden. These species are also very important for many larger species of fish, mar-
ine mammals, and sea-birds, highlighting the need to limit catches of small fish in order to
avoid further destruction of the whole ecosystem.
