Environmental Engineering Reference
In-Depth Information
expanded rapidly after the early 1950s and reached a plateau by the late 1980s. No
i shing ground is now too remote, no latitude's weather is too forbidding to prevent
the large-scale exploitation of almost every available i sh species, including the
diadromous salmons, smelt, and eels, and pelagic (those living in the water column,
ranging from sardines and still abundant herring to the most endangered tunas) and
demersal i sh (living on or near the ocean bottom: cod, haddock, halibut).
This exploitation has led to an increasing investment in marine aquaculture.
Raising freshwater i sh in ponds, lakes, and reservoirs has a long history in East
Asia and parts of Europe, and it continues to dominate the worldwide aquaculture,
accounting for more than half of the annual i sh output. Marine aquaculture was
traditionally a much less important activity, concentrated on cultivating seaweeds
and culturing oysters and clams: its foremost practitioners included Japan and
Hawaii. In terms of fresh weight, seaweeds still dominate the global aquacultural
output, but the practice now includes the production of more than 50 species of
i sh and marine invertebrates. Leading products in terms of zoomass and value are,
respectively, mollusks (mainly the Pacii c oyster,
Crassostrea gigas
) and crustaceans
(shrimps and prawns), and diadromous species (salmon) top the marine i sh list.
Even such large carnivores as bluei n tuna are now aquacultured (caught young in
the wild and fed to slaughter weight in cages). In turn, this large-scale production
of carnivores has led to a rising demand for other marine zoomass (above all squid
and sardines) for feeding.
The only notable retreat from a mass killing of marine mammals has been
the worldwide moratorium on commercial whale hunting imposed in 1982 by the
International Whaling Commission with a starting date in 1986 (Kalland and
Moeran 1992). This ban has worked, but not perfectly, as several countries (Japan,
Norway, Iceland) continue to conduct small-scale whale hunts, in Japan's case under
the dubious cover of “research” whaling that kills mostly minke, as well as a few
sei and sperm whales, and has been producing annually between 1,000 and 2,000
t of whale meat (Ishihara and Yoshii 2003; ICR 2010).
