Length frequency and growth studies on Cynoglossus macrolepidotus (Bleeker) off Bombay coast

Specimens randomly collected from Sassoon Docks, Bombay, India, at monthly intervals during 1979 to 1981 were considered for age/growth studies. Cynoglossus macrolepidotus, the fish, attained a length of 202 mm at 1 year, 250 mm at 1 1/2 year and 272 mm at 21 months respectively; the maximum length of the fish could be 353 mm and the life span could be 7 years. The scale ring studies showed presence of only 0 to 3+ rings. Majority of the fishes were of 1 and 1+ year class.

Distribution of phytoplankton off Mithapur (Gujarat)

The area off Mithapur, Gujarat, India, is moderately rich in phytoplankton. The peak in phytoplankton population (av. 7.86 x 10 super(4)/l) was recorded in March. The average count of 0.71 x 10 super(4)/l observed in April was very low and later increased to 3.76 x 10 super(4)/l in December. Fifty-two species were recorded from the area. The most common species were Nitzschia closterium, N. pungens, N. seriata, N. sigma, Chaetoceros simplex, C. difficilis and C. sociale. The importance of Nitzschia spp as indicators of organically polluted environment was discussed.

Studies on maturity, spawning and fecundity of Nemipterus japonicus (Bloch) off Bombay coast

Studies indicated spawning season of Nemipterus japonicus off Bombay coast (Maharashtra, India), to be during July to December with peak breeding during November to December. Females attained first maturity at the length range 110-120 mm; 50% maturity and spawning occurred at 135 mm within one year of its age. Overall male: female ratio for the entire period of study was 1:1.01. Relationships of fecundity with total length of fish, total ovary weight and per g. fish weight were worked out as F=(-72674.33) L super(739.73); F =65.44 W super(807.33); F=3112.57 W super(22383.27) and F=467.85 W super(4.96) with coefficient of correlation values (r) 0.9090, 0.9443, 0.9911 and 0.8843 respectively.

Length-weight relationship of Drepane punctata (Cuv. & Val.) at juvenile stage off Bombay coast

The study of the length weight relationship is highly useful to the fishery biologists in the study of population dynamics of fish and for determining the pattern of growth of stock. The parabolic equation for the length-weight relationship of Drepane punctata juveniles off the Bombay coast, expresses the value of "n" 2.83, indicating that the growth rate is less than the cube length.

Phytoplankton distribution in the coastal waters off Porbandar (Saurashtra)

Phytoplankton population (3.37-56.09 x 10 super(4) cells/1) and pigments (chil. a 1.10-26.8 mg/m super(3)) in the waters off Porbandar indicated wide variations. Higher cell counts and lower diversity of species were encountered in the nearshore waters as compared to the waters of the seaward side. The concentration of dissolved oxygen was correlated with the phytoplankton population and pigments. 71 species belonging to 28 genera of algae were recorded. Species of Nitzschia were dominant almost at all stations. Species of Chaetoceros were very common along the middle and western transects.

Studies on selected biological parameters off Mithapur (Gujarat)

The biological characteristics off Mithapur, India, indicated fairly high productivity in terms of macrobenthos and phytoplankton pigment concentration. The area sustained low standing stock of zooplankton. The overall biological productivity of plankton and macrobenthos indicated 30-90% reduction from the premonsoon to postmonsoon period. This decline in the standing stock of plankton and benthos was coinciding with the peak fishing season of the area.

Concentration of toxic metals in benthic organisms off Bombay coast

Concentration of toxic metals namely Zn, Cu, Fe, Cd and Pb in the marine benthos off Bombay Coast, Maharashtra (India) was estimated. Maximum concentration of Zn, Fe and Pb was from the organisms of Thana Creek. Higher concentration of Cu was encountered in benthic organisms off Versova. Cd was detected in some organisms and was maximum in the organisms collected from Mahim.

Distribution of surface sediments off Indus delta on the continental shelf of Pakistan

Surface sediments from the continental shelf area off Indus delta were analysed for their textural characteristics and carbonate content. The sediments are largely silt, silty clay and clayey silty sand. Sandy fraction is dominant in the outer region with relatively high carbonate content. The study shows that distribution of carbonate in sediments off Indus delta continental shelf is controlled by the dilution of terrigenous material and its distance from source area.

The four seam trawl nets operated off Cochin: an analysis of the design aspects: the integration of the various parts of trawl

A study has been made of 22 different designs of four seam trawls operated at Cochin for shrimp trawling. Formulae for the relations between the different parts of the nets have been derived.

Pawn [i.e. prawn] fishery in Gujarat location of new prawn grounds off Veraval

Details about the three departmental vessels, Gulf shrimp, Indian Salmon and Silver Pomfret and gear in the exploratory fishing off Veraval coast are reported. Potential prawn fishing grounds have been located by their operation in section 20-70, 21-69 and 22-69 in the cruises conducted in October, 1962. Observation regarding suitability of gear and composition of catch are given. The possibility of better prawn grounds occurring in areas deeper than the present grounds is indicated.

Deepwater prawns and lobsters off the Kerala coast

Majority of the prawn catch of the Kerala coast comes from the inshore regions within the 10 fathom line. A bottom deposit formed of fine mud rich in humus is found to be the ideal condition for the penaeid prawns. Similarly the lobster is observed in large numbers at localised areas very near the coast in the crevices of rocks. Though it has been observed that prawns and lobsters exist in deep water as well under different conditions, our knowledge about these forms along the Indian coasts is very scanty, being restricted to the works of Spence Bate, Alcock, De Man and Ramadan. Recently, during the cruises of the University Research Vessel Conch off the Kerala Coast (1958-1963) two species of deep water prawns and one species of lobster were collected from depths 100 - 180 fathoms. Of these, Penaeopsis philippi is found in large numbers occupying an almost continuous bed extending from Anjengo to Mangalore, while P. rectacutus has a restricted appearance between Cochin and Calicut. However, some sort of year to year variation has also been observed regarding the abundance of the species at various stations. Peurulus sewelli has a more restricted distribution, the maximum number being found between Puvar and Cochin. Attempt has been made to correlate the occurrence of the species with the hydrological conditions at the bottom and the nature of the substratum. It is observed that Peurulus sewelli occupies a more or less hard bed formed of sand with shell fragments or stones and small percentage of silt, the bottom temperature at the stations varying from 11°C to l4°C. P. sewelli is a more or less permanent inhabitant of the edge of the continental shell off the Kerala Coast worthy of attention for detailed investigation with a view to explore the possibilities of commercial exploitation.

An experiment conducted with a floating trawl net off Cochin

The paper deals with an experiment with a floating trawl net off Cochin, using a pair of curved otter boards and a transducer mounted on the head rope of the net. 32 hauls were made with different towing speeds and warp length keeping one factor constant for varying parameters of the other factor. The working data for 32 hauls are presented and the effect in the fishing depth of the net due to the variation in one factor is mentioned. The 'fishing depth' is indicated in this paper as the distance between the head rope and the bottom. The usefulness of similar experiments with added information on the angle of leading warp at the stern for the exploitation of column fishes in Indian waters is indicated.