Environmental Engineering Reference
In-Depth Information
Hawaii, and New Zealand, but only in Japan have they become a notable part of
everyday diet (Smil and Kobayashi 2012).
In contrast, coastal hunting and the collection of marine species (i sh, mollusks,
other invertebrates, and fatty marine mammals) provided the energetic basis for
some of the i rst permanent human settlements: species-rich coastal waters, regular
migrations of some anadromous i shes (particularly salmon and eels) and whales,
and the possibility of collecting invertebrates inhabiting the intertidal zone (mussels,
clams) made it possible to secure an exceptionally nutritious diet without changing
abodes. Long-distance (open ocean) i shing was a relatively late development, pio-
neered in Atlantic Europe at the beginning of the early modern era, when improved
ship designs made it possible to venture far offshore in search of i sh or whales.
Harvests of marine heterotrophic zoomass in both coastal and open ocean waters
spanned an enormous size spectrum and a large variety of species, traditionally
ranging from whitebait (young i sh of many species whose length is generally less
than 5 cm) to sperm whales, and eventually (after the introduction of steam-powered
whaling ships and large harpoons during the 1860s) even the largest living mammal,
the blue whale. Krill is now the smallest marine heterotrophic species that is har-
vested commercially on a large scale by netting in the Antarctic waters. Its capture
began in 1961, when the Soviet ships caught just 4 t of it, but by early 1980 the
harvest had approached and one year even surpassed 500,000 t before it fell to
around 100,000 t a year and then recovered a bit (FAO 2011a).
Fish species that are most commonly caught by nets (purse seines, used to encircle
i sh schools and then gather the i sh by closing the netting's bottom, or wall-like
vertically hanging gill nets in which swimming i sh get entangled) range from sar-
dines to cod, salmon, and smaller tuna; different kinds of nets are also used to catch
shrimp and the two most commonly sought marine invertebrates, octopus and squid.
Commercial catches of the largest deepwater carnivorous i sh (bluei n tuna and
swordi sh) rely on lines many kilometers long (the longest ones are up to 80 km)
carrying smaller lines baited at regular intervals with hooks. The capture of ocean
heterotrophs goes under the collective term of i shing, but a signii cant share of this
effort involves harvests of invertebrate species. In global terms, the mass of crusta-
ceans (dominated by shrimp and crabs) and mollusks (mostly mussels, clams, and
oysters) has recently added up to more than 15% of all capture in ocean waters,
and in value terms their share has surpassed 20% of the total (FAO 2011a).
Perhaps the most notable fact regarding the modern i shery is that its gradual
expansion has made it truly global. Long-distance i shery became more common
between the world wars, thanks to the diffusion of inexpensive diesel motors. It
