UPWELLIhW AND THE PRODUCTION OF FISH
289
ocean as well as locally. The upwelling is limited to an area between
Cape Guardafui, the eastern end of Socotra Island, 96"N 54-5"E (in
the latitude of Ras Mabber about 250 miles south of Cape Guardafui),
and a point on the Somali coast which shifts with season as shown in
Table 111. It is possible that the biological effects of the upwelling drift
seawards in the swift current (Ryther et al., 1966).
Further particular distributions are given by Swallow and Bruce
(1966), Warren et al. (1966), Stommel and Wooster (1965), and Foxton
(1965). All the data are summarized for wind, surface temperature and
salinity, nutrients and some biological observations in Wooster et al.
(1967) for the north-west Indian Ocean. The areas given in Table I11
are estimated from the latter publication.
Off south-west Arabia there is another coastal upwelling induced by
the south-west monsoon. The oceanographic data given in Wooster
et al. (1967) show that upwelling ceases at the entrance of the Persian
Gulf, but suggests a slight effect on the coasts of Baluchistan during the
same period. This is supported by the work on primary productivity in
the area during the Indian Ocean Expedition by the "Anton Bruun "
(Ryther et al., 1966) showing intense production spreading across the
Arabian Sea to the coasts off Pakistan. The cruise on H.M.S. " Owen "
in the same area shows upwelling and phytoplankton production in
April and May off Karachi (Lee, 1963). The same survey shows a
biological boundary much farther to seaward than suggested by the
oceanographic data quoted above, as might be expected. The areas in
Table I11 were from Wooster et al. (1967).
The work of Ryther et al. (1966) shows high carbon production in a
wedge north-west of Madagascar and some patches on the African coast
at the southern end of the Mozambique channel. The wedge north-west
of Madagascar is presumably related to the divergence between the
Somali and Agulhas Currents (Ivanenkov and Gubin, 1960) as they
split away from the two equatorial currents.
During the south-west monsoon a southerly current is generated,
with a thermocline tilt along the Malabar coast of India. The upwelling
is a very shallow one originating from perhaps 20 m (Darbyshire, 1967),
but the surface water is 6°C cooler than elsewhere. During July to
October, low salinity water spreads over the surface from the rivers and
it is at this period that the peak algal production occurs (Subrahmanyan
and Sarma, 1965). During September and October, the post-monsoon
period, there is a true wind-induced upwelling between Alleppey and
Guilon, off Cochin, and a countercurrent is developed at 75-100m
(Rama Sastry and Myrland, 1959). The situation off the Malabar coast
is complex and probably the production is relatively high, as indicated by
289
ocean as well as locally. The upwelling is limited to an area between
Cape Guardafui, the eastern end of Socotra Island, 96"N 54-5"E (in
the latitude of Ras Mabber about 250 miles south of Cape Guardafui),
and a point on the Somali coast which shifts with season as shown in
Table 111. It is possible that the biological effects of the upwelling drift
seawards in the swift current (Ryther et al., 1966).
Further particular distributions are given by Swallow and Bruce
(1966), Warren et al. (1966), Stommel and Wooster (1965), and Foxton
(1965). All the data are summarized for wind, surface temperature and
salinity, nutrients and some biological observations in Wooster et al.
(1967) for the north-west Indian Ocean. The areas given in Table I11
are estimated from the latter publication.
Off south-west Arabia there is another coastal upwelling induced by
the south-west monsoon. The oceanographic data given in Wooster
et al. (1967) show that upwelling ceases at the entrance of the Persian
Gulf, but suggests a slight effect on the coasts of Baluchistan during the
same period. This is supported by the work on primary productivity in
the area during the Indian Ocean Expedition by the "Anton Bruun "
(Ryther et al., 1966) showing intense production spreading across the
Arabian Sea to the coasts off Pakistan. The cruise on H.M.S. " Owen "
in the same area shows upwelling and phytoplankton production in
April and May off Karachi (Lee, 1963). The same survey shows a
biological boundary much farther to seaward than suggested by the
oceanographic data quoted above, as might be expected. The areas in
Table I11 were from Wooster et al. (1967).
The work of Ryther et al. (1966) shows high carbon production in a
wedge north-west of Madagascar and some patches on the African coast
at the southern end of the Mozambique channel. The wedge north-west
of Madagascar is presumably related to the divergence between the
Somali and Agulhas Currents (Ivanenkov and Gubin, 1960) as they
split away from the two equatorial currents.
During the south-west monsoon a southerly current is generated,
with a thermocline tilt along the Malabar coast of India. The upwelling
is a very shallow one originating from perhaps 20 m (Darbyshire, 1967),
but the surface water is 6°C cooler than elsewhere. During July to
October, low salinity water spreads over the surface from the rivers and
it is at this period that the peak algal production occurs (Subrahmanyan
and Sarma, 1965). During September and October, the post-monsoon
period, there is a true wind-induced upwelling between Alleppey and
Guilon, off Cochin, and a countercurrent is developed at 75-100m
(Rama Sastry and Myrland, 1959). The situation off the Malabar coast
is complex and probably the production is relatively high, as indicated by