tTPWELLM0 AND THE PRODUCTION OF FISH
299
underestimated as a productive area. The region between Burma and
the Andaman Islands appears to be fairly rich during t'hc north-east
monsoon, whereas that off the Malahar coast of India may be as rich and
nearly as extensive as that off southcrn Arabia. The production off
Ceylon and off north-west Australia appears to take placc in both
seasons, but there is not enough information to extract a seasonal trend
(the same effect would appear in any of the major upwelling areas if
classed by winter and summer). The Vietnam upwelling, like that in tlic
Gulf of Thailand, is a minor one, but both are quite intense. The domes
off Java and Sumbawa are, like the others, of rather low intensity.
Those in Indonesia are of moderate productivity, as might be expected
from the obscurity of the physical description of upwelling there
(Wyrtki, 1961).
In Table I V the radiocarbon observations are classified and averaged
by the upwelling areas. The observations by the areas and period sct
out above are expressed as a single average for the upwelling area.
Treating the sampling as adequate in each region the area in km2 is
given within the duration of the upwelling in days; the production of
carbon in each upwelling area is then given as tons C.lOs/year. The
figures have then been rounded off to the levels of 3, 5, 10, 15, 35, 75
and 100 tons C.106/year. The annual production as tons Clyear is that
which occurred during the upwelling season. The assumption that
nothing is produced in periods outside the upwelling seasons is unjustified, but the annual rate expresses differences between upwcllirig
areas which are really between the lengths of the season.
From Table I V it will be seen that the differences in gC/m2 per day
are less than those in tons C.106/year. This is really only to be expcctcd,
because the differences are due to areas and length of season. The
Indian Ocean upwellings are less important than the four major upwellings because the season is usually limited to one monsoon-but the
steady persistence of the monsoon winds makes the south-west Arabian
area, at least, more important than, for example, the Californian area.
Confidence limits have not been calculated for each area, for two
reasons : (1) there are not enough observations to establish seasonal
trends which are important in some areas ; (2) in some areas, e.g. the
Canary Current, the Bay of Bengal and in some parts of the Indonesian
area, observations are few. However, with the exception of those
observations off Orissa during the south-west monsoon there are enough
observations to establish fairly reliable means.
The importance of the upwelling areas may be estimated by classing
them as: (1) >75.10s t C/year, (2) 30-75.106 t C/year, (3) 6-30.106 t C/
year. In the first group are found the major southern upwcllings in the
299
underestimated as a productive area. The region between Burma and
the Andaman Islands appears to be fairly rich during t'hc north-east
monsoon, whereas that off the Malahar coast of India may be as rich and
nearly as extensive as that off southcrn Arabia. The production off
Ceylon and off north-west Australia appears to take placc in both
seasons, but there is not enough information to extract a seasonal trend
(the same effect would appear in any of the major upwelling areas if
classed by winter and summer). The Vietnam upwelling, like that in tlic
Gulf of Thailand, is a minor one, but both are quite intense. The domes
off Java and Sumbawa are, like the others, of rather low intensity.
Those in Indonesia are of moderate productivity, as might be expected
from the obscurity of the physical description of upwelling there
(Wyrtki, 1961).
In Table I V the radiocarbon observations are classified and averaged
by the upwelling areas. The observations by the areas and period sct
out above are expressed as a single average for the upwelling area.
Treating the sampling as adequate in each region the area in km2 is
given within the duration of the upwelling in days; the production of
carbon in each upwelling area is then given as tons C.lOs/year. The
figures have then been rounded off to the levels of 3, 5, 10, 15, 35, 75
and 100 tons C.106/year. The annual production as tons Clyear is that
which occurred during the upwelling season. The assumption that
nothing is produced in periods outside the upwelling seasons is unjustified, but the annual rate expresses differences between upwcllirig
areas which are really between the lengths of the season.
From Table I V it will be seen that the differences in gC/m2 per day
are less than those in tons C.106/year. This is really only to be expcctcd,
because the differences are due to areas and length of season. The
Indian Ocean upwellings are less important than the four major upwellings because the season is usually limited to one monsoon-but the
steady persistence of the monsoon winds makes the south-west Arabian
area, at least, more important than, for example, the Californian area.
Confidence limits have not been calculated for each area, for two
reasons : (1) there are not enough observations to establish seasonal
trends which are important in some areas ; (2) in some areas, e.g. the
Canary Current, the Bay of Bengal and in some parts of the Indonesian
area, observations are few. However, with the exception of those
observations off Orissa during the south-west monsoon there are enough
observations to establish fairly reliable means.
The importance of the upwelling areas may be estimated by classing
them as: (1) >75.10s t C/year, (2) 30-75.106 t C/year, (3) 6-30.106 t C/
year. In the first group are found the major southern upwcllings in the