UPWELLING AND THE PRODUCTION OF FISH
309
If we compare the tertiary production by upwelling areas, we find
that the Peru and Benguela Currents are the richest (12 and 18 million
tons wet weighflyear respectively), followed by the Canary Current
(8 million tons wet weight/year) and the California Current (3 million
tons wet weightlyear). The Indian and Indonesian upwellings are much
smaller, generating 1-2 million tons wet weight/year each. Howcver, if
we add them together and take into account the poor sampling of upwellings in the area, a possible figure of 5-10 million tons wet weight/
year emerges as a total for the Indian Ocean and Indonesian region.
If the tertiary production is taken as being composed of fish and
squid, then the annual production is the annual increment t o populations in recruitment and in growth. It is assumed that the maximum
biomass of a fish stock is reached during adult life, because from one
generation t o the next, the weight of gonads must increase by three to
six times t o create the filial stock. Fish in subtropical areas do not
appear t o live very long ; Peruvian anchoveta live for 2 or 3 years and
Californian and South African sardines live for 3 t o 6 years (Davics,
1958; Marr, 1960). Hake, which feed on euphausids, may live somcwhat longer. A rough effective lifcspan in the fishery of about 3 years
would be a reasonable estimate for all fishes. Hence, the stocks available
in the upwelling areas might range from 150-340 million tons wet
weight ; the yield t o all consumers of the tertiary production, of which
man can probably take only half, may be equivalent to a little more than
one year’s recruitment.
In the Californian Current, it was shown that the sardines and
anchovies, together with the hake, predominated. The figure of 3
million t,ons/ytar is not unexpectcd from our knowledge of the sum of
the sardine or anchovy stock and the hake stock. According to Ahlstrom
(1969), about half the fish population consists of anchovies and about
one-sixth of hake ; thus the annual recruitment to the anchovy population might be as much as 1.5 mJlion tons and that to the hake as
much as 0.5 million tons. If the anchovy lives 3 years in the fishery,
the unexploited stock might amount to just over 3 million tons (allowing
for a natural mortality of 33% (Clark and Marr, 1955)). If hake live
6 years in the adult stock, then it would amount to just less than 2
million tons, allowing for a natural mortality of 20%. The tertiary
production in the Peru Currcnt amounts to 12 million tons and the
anchoveta outnumbers all other species in the egg collections by a
factor of ten. If they live in the fishery for 2 years then the total stock
amounts to 24 million tons, and the prescnt annual catch is of the order
of 8-10 million tons. Gulland (1968) has suggested that the total annual
deaths (equal t o total annual production) amount to 18-20 million tons,
309
If we compare the tertiary production by upwelling areas, we find
that the Peru and Benguela Currents are the richest (12 and 18 million
tons wet weighflyear respectively), followed by the Canary Current
(8 million tons wet weight/year) and the California Current (3 million
tons wet weightlyear). The Indian and Indonesian upwellings are much
smaller, generating 1-2 million tons wet weight/year each. Howcver, if
we add them together and take into account the poor sampling of upwellings in the area, a possible figure of 5-10 million tons wet weight/
year emerges as a total for the Indian Ocean and Indonesian region.
If the tertiary production is taken as being composed of fish and
squid, then the annual production is the annual increment t o populations in recruitment and in growth. It is assumed that the maximum
biomass of a fish stock is reached during adult life, because from one
generation t o the next, the weight of gonads must increase by three to
six times t o create the filial stock. Fish in subtropical areas do not
appear t o live very long ; Peruvian anchoveta live for 2 or 3 years and
Californian and South African sardines live for 3 t o 6 years (Davics,
1958; Marr, 1960). Hake, which feed on euphausids, may live somcwhat longer. A rough effective lifcspan in the fishery of about 3 years
would be a reasonable estimate for all fishes. Hence, the stocks available
in the upwelling areas might range from 150-340 million tons wet
weight ; the yield t o all consumers of the tertiary production, of which
man can probably take only half, may be equivalent to a little more than
one year’s recruitment.
In the Californian Current, it was shown that the sardines and
anchovies, together with the hake, predominated. The figure of 3
million t,ons/ytar is not unexpectcd from our knowledge of the sum of
the sardine or anchovy stock and the hake stock. According to Ahlstrom
(1969), about half the fish population consists of anchovies and about
one-sixth of hake ; thus the annual recruitment to the anchovy population might be as much as 1.5 mJlion tons and that to the hake as
much as 0.5 million tons. If the anchovy lives 3 years in the fishery,
the unexploited stock might amount to just over 3 million tons (allowing
for a natural mortality of 33% (Clark and Marr, 1955)). If hake live
6 years in the adult stock, then it would amount to just less than 2
million tons, allowing for a natural mortality of 20%. The tertiary
production in the Peru Currcnt amounts to 12 million tons and the
anchoveta outnumbers all other species in the egg collections by a
factor of ten. If they live in the fishery for 2 years then the total stock
amounts to 24 million tons, and the prescnt annual catch is of the order
of 8-10 million tons. Gulland (1968) has suggested that the total annual
deaths (equal t o total annual production) amount to 18-20 million tons,