Kinds and Abundance of Fish Larvae in the Arabian Sea and the Persian Gulf
421
The ichtyogeographical situation changes rapidly as we approach the Indian side of
the Arabian Sea. Here the stations were influenced more by the broad West Indian shelf
and typical coastal characters are reflected in the composition of the fish larvae fauna.
d) Subarea IV: West Coast of India
51 stations, 29 HLN standard hauls, 24 HLN> 100 - 0 m hauls, 16 RT hauls.
Looking just at the frequency of certain families, subarea IV still seems to be quite
similar to subarea II and III, with Gonostomidae and Myctophidae very abundant and
present at 89% and 91 % respectively of all stations. Only the fact that Bregmacerotidae
are more common here (found at 75% of all stations) distinguishes it from subareas II
(60% Bregmacerotidae), and III (20% Bregmacerotidae). The typical difference from
the subareas described before, however, is mainly in genera and species composition.
Many species of myctophids and gonostomids (e.g. Lampanyctus spec. and Cyclothone
spec.) were not found at all off the west coast of India. A total of not more than 65 species
was found in subarea IV. The number of species ranged from 0-45 per station, with an
average of only 9.3 species per station. The diversity was also low:
d
HLN,lOO-Om
night
0.38 (n= 13)
HLN, 100-0 m
day
0.33 (n= 16)
HLN, >100-0 m RT
day and night
day and night
0.38 (n=24)
0.35 (n= 16)
e) Subarea V: Gulf of Oman
25 stations, 14 HLN standard hauls, 12 HLN > 100 - 0 m hauls.
The number of species declined further in subarea V. Here an intensive mixing of
water from the shallow Persian Gulf and from the Arabian Sea takes place, causing a
turbulence that probably results in high nutrient values for this area. Large numbers of
specimens and small numbers of species were typical of the stations in the Gulf of Oman.
Only about 35 different species were caught altogether and the highest number per haul
was 27, the lowest 3. On average, lOA species were present at each station. Most common
were the families Myctophidae and Sudidae, occurring at 91 % and 83% respectively of
all stations. The family Myctophidae showed one species, Benthosema pterota; this
and the high abundance of Sudidae larvae make the stations in the Gulf of Oman very
similar to the stations off Karachi (Pakistan) included in subarea IV. The samples were
not at all diverse. In subarea V very high values of d were quite common:
d
HLN,lOO-Om
night
0.74 (n=7)
HLN,lOO-Om
day
0.54 (n =6)
HLN, >100-0 m
day and night
0.84 (n=13)
The fish larvae fauna of the Persian Gulf no longer shows oceanic elements. The
entire Gulf is a shelf area and such families as the myctophids and gonostomids are
absent from the samples.
421
The ichtyogeographical situation changes rapidly as we approach the Indian side of
the Arabian Sea. Here the stations were influenced more by the broad West Indian shelf
and typical coastal characters are reflected in the composition of the fish larvae fauna.
d) Subarea IV: West Coast of India
51 stations, 29 HLN standard hauls, 24 HLN> 100 - 0 m hauls, 16 RT hauls.
Looking just at the frequency of certain families, subarea IV still seems to be quite
similar to subarea II and III, with Gonostomidae and Myctophidae very abundant and
present at 89% and 91 % respectively of all stations. Only the fact that Bregmacerotidae
are more common here (found at 75% of all stations) distinguishes it from subareas II
(60% Bregmacerotidae), and III (20% Bregmacerotidae). The typical difference from
the subareas described before, however, is mainly in genera and species composition.
Many species of myctophids and gonostomids (e.g. Lampanyctus spec. and Cyclothone
spec.) were not found at all off the west coast of India. A total of not more than 65 species
was found in subarea IV. The number of species ranged from 0-45 per station, with an
average of only 9.3 species per station. The diversity was also low:
d
HLN,lOO-Om
night
0.38 (n= 13)
HLN, 100-0 m
day
0.33 (n= 16)
HLN, >100-0 m RT
day and night
day and night
0.38 (n=24)
0.35 (n= 16)
e) Subarea V: Gulf of Oman
25 stations, 14 HLN standard hauls, 12 HLN > 100 - 0 m hauls.
The number of species declined further in subarea V. Here an intensive mixing of
water from the shallow Persian Gulf and from the Arabian Sea takes place, causing a
turbulence that probably results in high nutrient values for this area. Large numbers of
specimens and small numbers of species were typical of the stations in the Gulf of Oman.
Only about 35 different species were caught altogether and the highest number per haul
was 27, the lowest 3. On average, lOA species were present at each station. Most common
were the families Myctophidae and Sudidae, occurring at 91 % and 83% respectively of
all stations. The family Myctophidae showed one species, Benthosema pterota; this
and the high abundance of Sudidae larvae make the stations in the Gulf of Oman very
similar to the stations off Karachi (Pakistan) included in subarea IV. The samples were
not at all diverse. In subarea V very high values of d were quite common:
d
HLN,lOO-Om
night
0.74 (n=7)
HLN,lOO-Om
day
0.54 (n =6)
HLN, >100-0 m
day and night
0.84 (n=13)
The fish larvae fauna of the Persian Gulf no longer shows oceanic elements. The
entire Gulf is a shelf area and such families as the myctophids and gonostomids are
absent from the samples.