Towards responsible and sustainable fisheries

A billion people dependent on fish in the world  |  From years of  “miraculous fishing” to stock collapse  |  An unlikely return to initial state  |  Impacts
of fisheries on the marine ecosystem as a whole
  |  A worrisome reduction
in fish size
  |  Dynamics of exploitation systems  |  Towards
responsible and sustainable fisheries
  |  The Centre de Recherche
Halieutique Méditerranéenne et Tropicale

Impacts of fisheries on the marine ecosystem as a whole

Fisheries have therefore a strong impact on targeted species. However, their direct and indirect effects on other components of the ecosystem are not to be ignored, for it is indeed the marine ecosystem as a whole which is potentially affected by fisheries.
Certain types of fisheries have direct effects on the habitat of marine species, whether or not they are exploited. Trawling, for example, contributes to the destruction of the benthic habitat. Annually, the surface covered by trawling is estimated at fifty per cent of the surface of continental shelves. This surface represents 150 times the surface of yearly terrestrial deforestration and illustrates the scope of the potential impact on numerous sedentary species. 
There are also indirect effects of fisheries on non-targeted species. Fisheries generally target species of commercial interest, using selective gears  and/or  exploiting adapted zones and seasons. However, the selection process is far from perfect. At-sea discards of catches of incidental species (those with little or no commercial interest) are very high and represent 27 million tons out of a total world catch of 85 million tons (or approximately 30% of declared catches). The International Whaling Commission estimates that between 65,000 and 80,000 dolphins, seals and other sea mammals perish each year in this way.

Approximately 40,000 sea turtles in danger of extinction are caught in nets or other non-selective gears. Another striking yet not isolated example is that of shrimp and crab fisheries which harvest roughly three to ten times their volume in commercially undesirable fish species. For one kilogram of caught shrimp, an average of five to ten kilograms of incidental catches are discarded!! These exploitation practices of marine resources are more and more condemnable in the context of precautionary principles. The world of fisheries is striving today to correct harvesting habits and techniques which no longer seem adapted to conservation imperatives.

 
Campagne océanographique à bord du N/O Olaya de l’IMARPE
Tortue marine