Zooplankton Studies in the Indian Ocean
253
IV. Fish Eggs and Larvae
Taking the distribution of fish eggs as an indication of spawning areas, the IOBC
Atlas (IOBC, 1970 b) reveals that such centres are located adjacent to the Saudi Arabian
coast and the northeastern Bay of Bengal. These areas are consistently rich and show a
high range (l00 per haul) throughout the monsoons and also in the day and night
distribution of eggs and larvae. PETER (1967) has recorded for the first time early stages
of the mackerel at 3 stations, one at the head of the Bay of Bengal, the other off Madras
and a third in the Gulf of Oman. It is clear that the IOSN samples have not shown the
existence of a sufficient number of larvae to distinguish the breeding grounds of
commercially important fisheries, particularly sardines and mackerel. While the oceanic
zone is dominated by the larvae of bathypelagic fishes such as gonostomids, stomiatids,
myctophids, etc., the intermediate zone towards the coastal areas is found to be the
richest for fish larvae of economic importance. The families Thunnidae, Scomberomoridae, Carangidae, etc. are all well represented here.
In conclusion it may be stated that the emergence of the northeastern Bay of Bengal
as an area of fish spawning is an important discovery of the IIOE. The poor catches of
fish in the Bay of Bengal should not mislead us and make us overlook the possibilities
of finding rich fishery resources here as indicated by HOE data on fish eggs larvae and
biomass distribution.
V. Mollusca
The family Cavolinidae (Clio, Creseis, Styliola, Hyalocylix and Cuvierina) seems to
be densely distributed off the Somali coast, in the Red Sea, off the south of Java, the
southwest coast of India and the northern part of the Bay of Bengal; the highest peak is
in the Red Sea, the maximum number being 3160 at "Discovery" station 5002 A. The
same station is noted for its peak abundance of Limacinidae, Peraclidae and Cymbulidae
(the highest number is 6920). This is also true in the case of meroplanktonic gastropods
(the maximum number being 3360). Limacinidae, Peraclidae and Cymbulidae are
abundant in the Red Sea and western Arabian Sea off Mauritius, including the Mozambique Channel to the Persian Gulf. During the NE monsoon rich areas of Limacinidae,
Peraclidae and Cymbulidae extend to the west coast of India and also along the meridians
between 75° E and 85° E for a long distance in the central Indian Ocean.
Bivalve larvae are densely distributed around the Somali coast and the southern coast
of Arabia, the SW coast of India, north of Sumatra and south of Java with dense patches
scattered in these areas. Maximum abundance was in the Gulf of Aden. Bivalve larvae
are sparse along the coastal areas of Australia and South Africa and the east coast of India.
In the case of cephalopod distribution, the areas of highest abundance were observed
in the northern part of the Bay of Bengal and also on the western half of the Bay off the
Madras and Andhra coasts. In addition, they are well distributed off the Somali coast,
Arabian coast, Kutch and south of Ceylon. Here again the Bay of Bengal is outstanding
for the abundance of cephalopod larvae.
VI. Other Groups
Amphipods, c1adocerans, euphausids, chaetognaths, medusae, copelates, salps, and
doliolids, ostracods, and polychaetes are all under study at the rOBe. The distribution
253
IV. Fish Eggs and Larvae
Taking the distribution of fish eggs as an indication of spawning areas, the IOBC
Atlas (IOBC, 1970 b) reveals that such centres are located adjacent to the Saudi Arabian
coast and the northeastern Bay of Bengal. These areas are consistently rich and show a
high range (l00 per haul) throughout the monsoons and also in the day and night
distribution of eggs and larvae. PETER (1967) has recorded for the first time early stages
of the mackerel at 3 stations, one at the head of the Bay of Bengal, the other off Madras
and a third in the Gulf of Oman. It is clear that the IOSN samples have not shown the
existence of a sufficient number of larvae to distinguish the breeding grounds of
commercially important fisheries, particularly sardines and mackerel. While the oceanic
zone is dominated by the larvae of bathypelagic fishes such as gonostomids, stomiatids,
myctophids, etc., the intermediate zone towards the coastal areas is found to be the
richest for fish larvae of economic importance. The families Thunnidae, Scomberomoridae, Carangidae, etc. are all well represented here.
In conclusion it may be stated that the emergence of the northeastern Bay of Bengal
as an area of fish spawning is an important discovery of the IIOE. The poor catches of
fish in the Bay of Bengal should not mislead us and make us overlook the possibilities
of finding rich fishery resources here as indicated by HOE data on fish eggs larvae and
biomass distribution.
V. Mollusca
The family Cavolinidae (Clio, Creseis, Styliola, Hyalocylix and Cuvierina) seems to
be densely distributed off the Somali coast, in the Red Sea, off the south of Java, the
southwest coast of India and the northern part of the Bay of Bengal; the highest peak is
in the Red Sea, the maximum number being 3160 at "Discovery" station 5002 A. The
same station is noted for its peak abundance of Limacinidae, Peraclidae and Cymbulidae
(the highest number is 6920). This is also true in the case of meroplanktonic gastropods
(the maximum number being 3360). Limacinidae, Peraclidae and Cymbulidae are
abundant in the Red Sea and western Arabian Sea off Mauritius, including the Mozambique Channel to the Persian Gulf. During the NE monsoon rich areas of Limacinidae,
Peraclidae and Cymbulidae extend to the west coast of India and also along the meridians
between 75° E and 85° E for a long distance in the central Indian Ocean.
Bivalve larvae are densely distributed around the Somali coast and the southern coast
of Arabia, the SW coast of India, north of Sumatra and south of Java with dense patches
scattered in these areas. Maximum abundance was in the Gulf of Aden. Bivalve larvae
are sparse along the coastal areas of Australia and South Africa and the east coast of India.
In the case of cephalopod distribution, the areas of highest abundance were observed
in the northern part of the Bay of Bengal and also on the western half of the Bay off the
Madras and Andhra coasts. In addition, they are well distributed off the Somali coast,
Arabian coast, Kutch and south of Ceylon. Here again the Bay of Bengal is outstanding
for the abundance of cephalopod larvae.
VI. Other Groups
Amphipods, c1adocerans, euphausids, chaetognaths, medusae, copelates, salps, and
doliolids, ostracods, and polychaetes are all under study at the rOBe. The distribution