UPWELLING AND THE PRODUCTION O F FISH
307
It is likely that the best estimate of tertiary production lies between
that derived from the primary production and that from the secondary
production. So column Q1 represents an average of the estimates in
columns 0 and P, and column Qz represents an average of those in
columns 0 and P,. In columns R, and R,, these estimates of tertiary
carbon are put into wet weight. Vinogradov (1953), in his Table 284,
shows that the average water content of plankton-eating fish is about
70% and he also shows in another part of his paper that 45% of the dry
weight of such fish is composed of carbon. So, a carbonlwet weight ratio
of 13.5% was used and so the figures in columns Q, and Q, were raised
by 7.47 to give the figures in columns R, and 8,. I am grateful to
the late Dr. M. B. Schaefer €or pointing out to me that the ratio of carbon
to wet weight used in Gushing (1969, restricted), although perfectly
applicable to copepods, is not applicable to fish.
The total weights (excluding the eastern tropical Pacific) are
691.2-786.5 tons. lo4 carbon/year or 51.64-58-74 tons. lo6 wet weight/
year. The estimates from the eastern tropical Pacific and from the
Marquesas divergences are excluded because the oceanih production
cycle has a third trophic level of very small fish, for example, the
myctophids of the Deep Scattering Layer. At the present time, it is
assumed that these fish will not be exploited because they are widely
dispersed and costly to catch. So the sum of the tertiary production
available in coastal upwellings (as opposed to equatorial ones) is about
50-60 million tons wet weightlyear. If the true transfer coefficient of
energy is higher, say 15%, then the tertiary production would amount
to 75-90 million tons (if the higher transfer coefficient applied to one
transfer) or 112-135 million tons (if the higher transfer coefficient applied to both transfers). So three estimates are available :
Transfer coefficients
(0.10)2
(0-10.0-15)
(0.15)'
Tertiary production
55
83
124
(M tons wet weight)
It must be recalled that a proportion of the secondary production as
calculated is composed of predators and the postulated trapsfer coefficients may be set as 0.09 or 0.135. Then our figures are :
Transfer coefficients
(0.09),
(0.09.0-135)
(0-135),
Tertiary production
50
75
112
(M tons wet weight)
The planktonic tertiary production has not been added to these figures
because we are interested in the production of fish, whigh, for present
purposes, includes pelagic molluscs such as squid. However, in Fig. 15b
A.M.B.--g
11
307
It is likely that the best estimate of tertiary production lies between
that derived from the primary production and that from the secondary
production. So column Q1 represents an average of the estimates in
columns 0 and P, and column Qz represents an average of those in
columns 0 and P,. In columns R, and R,, these estimates of tertiary
carbon are put into wet weight. Vinogradov (1953), in his Table 284,
shows that the average water content of plankton-eating fish is about
70% and he also shows in another part of his paper that 45% of the dry
weight of such fish is composed of carbon. So, a carbonlwet weight ratio
of 13.5% was used and so the figures in columns Q, and Q, were raised
by 7.47 to give the figures in columns R, and 8,. I am grateful to
the late Dr. M. B. Schaefer €or pointing out to me that the ratio of carbon
to wet weight used in Gushing (1969, restricted), although perfectly
applicable to copepods, is not applicable to fish.
The total weights (excluding the eastern tropical Pacific) are
691.2-786.5 tons. lo4 carbon/year or 51.64-58-74 tons. lo6 wet weight/
year. The estimates from the eastern tropical Pacific and from the
Marquesas divergences are excluded because the oceanih production
cycle has a third trophic level of very small fish, for example, the
myctophids of the Deep Scattering Layer. At the present time, it is
assumed that these fish will not be exploited because they are widely
dispersed and costly to catch. So the sum of the tertiary production
available in coastal upwellings (as opposed to equatorial ones) is about
50-60 million tons wet weightlyear. If the true transfer coefficient of
energy is higher, say 15%, then the tertiary production would amount
to 75-90 million tons (if the higher transfer coefficient applied to one
transfer) or 112-135 million tons (if the higher transfer coefficient applied to both transfers). So three estimates are available :
Transfer coefficients
(0.10)2
(0-10.0-15)
(0.15)'
Tertiary production
55
83
124
(M tons wet weight)
It must be recalled that a proportion of the secondary production as
calculated is composed of predators and the postulated trapsfer coefficients may be set as 0.09 or 0.135. Then our figures are :
Transfer coefficients
(0.09),
(0.09.0-135)
(0-135),
Tertiary production
50
75
112
(M tons wet weight)
The planktonic tertiary production has not been added to these figures
because we are interested in the production of fish, whigh, for present
purposes, includes pelagic molluscs such as squid. However, in Fig. 15b
A.M.B.--g
11