UPWELLING AND THE PRODUCTION OF FISH
291
D. The equatorial system
The physical structure of the equatorial system has been briefly
described in an earlier section. Figures 5A and BB, p. 268 show the
distribution of phosphorus at 100 m and of zooplankton (Reid, 1962b),
and Fig. 13, p. 295, the distribution of radiocarbon (Koblentz-Mishke,
1965) in the Pacific. The distribution of radiocarbon shows high
productivity along the region of the undercurrent at the equator from
140"W to the Galapagos Islands. I n contrast the phosphoruslzooplankton distributions do not show the undercurrent but the broad
pattern of the North and South Equatorial Currents. Presumably the
zooplankton distributions represent an integration over a period of
time and the zooplankton which might have been produced above the
undercurrent becomes dispersed during that period in the waters of
the South Equatorial Current.
Another important point about the equatorial system is the divergences in the eastern tropics, in the western tropics and in the North
and South Equatorial Currents. The eastern tropical systems between
the two currents form grcat rich triangular areas between California and
Peru, and between Dakar and the Congo, extending hundreds of miles
to scaward. Mr. C. Bowley has told me (and see Bowley et al., 1969)
that the eastern tropical Pacific area of rich production can be picked
off satellite photographs. Dark spots are seen in the upwelling areas
which become bright as the satellite passes overhead and then become
dark again as the satellite starts t o set. These spots are distributed
above the Cromwell Undercurrent and up to a fair distance off the coast
in the California Current. Their physical structure suggests that they
are patches of calm water and their association with the undercurrent
suggests that the phytoplankton is rich there.
There are areas of divergence in the eastern tropical areas of each
ocean on the edges of the equatorial currents and across the domes.
The area off West Africa is most interesting at this point, for the Guinea
Dome (Mazeika, 1967) is extensive, and there is a special coastal upwelling off Ghana and the Ivory Coast (Berrit, 1962) with an area of
divergence in the South Equatorial Current south of it. Because the
coastline runs westerly not very far from the equator, the northern
dome is displaced north-westwards and the areas of coastal upwelling
and of divergence lie about the equator not too far from the coast.
Figure 5B, p. 269, shows that thcrc are rich patches of zooplankton
off New Guinea and the Philippine Islands, which correspond to areas of
divergence there as noticed by Hidaka and Ogawa (1958) (see Fig. 20,
p. 322). Further, there is an extensive area of divergence also reflected
291
D. The equatorial system
The physical structure of the equatorial system has been briefly
described in an earlier section. Figures 5A and BB, p. 268 show the
distribution of phosphorus at 100 m and of zooplankton (Reid, 1962b),
and Fig. 13, p. 295, the distribution of radiocarbon (Koblentz-Mishke,
1965) in the Pacific. The distribution of radiocarbon shows high
productivity along the region of the undercurrent at the equator from
140"W to the Galapagos Islands. I n contrast the phosphoruslzooplankton distributions do not show the undercurrent but the broad
pattern of the North and South Equatorial Currents. Presumably the
zooplankton distributions represent an integration over a period of
time and the zooplankton which might have been produced above the
undercurrent becomes dispersed during that period in the waters of
the South Equatorial Current.
Another important point about the equatorial system is the divergences in the eastern tropics, in the western tropics and in the North
and South Equatorial Currents. The eastern tropical systems between
the two currents form grcat rich triangular areas between California and
Peru, and between Dakar and the Congo, extending hundreds of miles
to scaward. Mr. C. Bowley has told me (and see Bowley et al., 1969)
that the eastern tropical Pacific area of rich production can be picked
off satellite photographs. Dark spots are seen in the upwelling areas
which become bright as the satellite passes overhead and then become
dark again as the satellite starts t o set. These spots are distributed
above the Cromwell Undercurrent and up to a fair distance off the coast
in the California Current. Their physical structure suggests that they
are patches of calm water and their association with the undercurrent
suggests that the phytoplankton is rich there.
There are areas of divergence in the eastern tropical areas of each
ocean on the edges of the equatorial currents and across the domes.
The area off West Africa is most interesting at this point, for the Guinea
Dome (Mazeika, 1967) is extensive, and there is a special coastal upwelling off Ghana and the Ivory Coast (Berrit, 1962) with an area of
divergence in the South Equatorial Current south of it. Because the
coastline runs westerly not very far from the equator, the northern
dome is displaced north-westwards and the areas of coastal upwelling
and of divergence lie about the equator not too far from the coast.
Figure 5B, p. 269, shows that thcrc are rich patches of zooplankton
off New Guinea and the Philippine Islands, which correspond to areas of
divergence there as noticed by Hidaka and Ogawa (1958) (see Fig. 20,
p. 322). Further, there is an extensive area of divergence also reflected