Sex ratio of the sole Euryglossa orientalis (Bl. & Schn.) (family: Soleidae) from the Karachi coast

This paper present a study on sex ratio and reveals segregation or aggregation of males and females in accordance with environmental conditions, the differential behaviour of sexes, and due to fishing.

Observations on spawning and egg capsule of Melongena bucephala (Lamarck)(Mollusca: Gastropoda) from the Karachi coast

No work has been done on the reproduction of Melongena bucephala from northern Arabian Sea (Karachi coast). This paper presents a description of spawning, egg capsule and macromophology of eggs of M. bucephala collected from the rocky shore of Buleji on May 28, 1986 at a tidal height of 0.5m. The individual was found in the act of spawning. The egg mass and development of M. bucephala from Karachi coast are also compared with the Hemifusus ternatanus from the Pacific Ocean (Amio, 1963).

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.

A guide to the fisheries of Ceylon

This bulletin has been written primarily to serve as a handbook to the Indo-Pacific Fisheries Council at its sessions in Colombo during December 1958. It presents an outline of the fishing industry as found in Ceylon today, in non-technical language so that it may also be understood by laymen. The large gaps in our knowledge are brought out in the section on "resources"; the section on "administration" gives an indication of progress made towards solving the problems of the industry, while sections on "fishing methods" and "utilization of catch" will help us to appreciate the handicaps and difficulties of those concerned with the industry. The Government Administration of the fisheries of Ceylon is being assisted to a considerable extent by the generous gifts of machinery and equipment as well as the loan of skilled technical personnel made by other countries through the FAO and the Colombo Plan. The progress made so far has helped to place the industry in a favorable position for further improvements.

Comparative fishing ability and economic efficiency of mechanised trawlers operating along the Kerala coast

This study was undertaken with a view to finding out the comparative fishing ability and economic performance of different fishing vessel sizes 9.15m (30'), 9.76m (32') and 10.97m (36') designed by the Central Institute of Fisheries Technology and operating along the Kerala coast. Data were collected from selected vessels of these sizes for four consecutive fishing seasons from 1964-65 to 1967-68. The catch/unit effort and total effort per year for the 10.97m (36') vessels were much better than those for the 9.76m (32') vessels. The yearly landings and the crew remuneration for the former were about twice those of the 9.76m (32') vessels. The economic efficiency of the 10.97m (36') vessels was also much better. The decline in landings per year in both size groups was more due to the reduction in the effort per year than the decline in catch/unit effort.

A study on length-weight relationship, food and feeding habits of Indian scad, Decapterus russelli (Ruppel, 1830) along the northwest coast of India

Length and weight relationship of Decapterus russelli (Ruppell, 1830) is worked out to be W = 0.00312 L³ which indicates the isometric growth of the fish. Study on food and feeding habits revealed that the species is carnivorous, pelagic, feeding primarily on small crustaceans and small fish species, viz. Acetes indicus, ostracods, Apogon sp., Leiognathus sp., sciaenids, Netnipterus japonicas, Myctophid sp., Trichiurus sp., Therapon sp., D.russelli and occasionally on prawns. It is a selective feeder on Aeetes indicus.

Sinum haliotoideum (Linnaeus, 1758), a gastropod mollusc new to the marine waters of Pakistan (northern Arabian Sea)

Sinum haliotoideum (Linnaeus, 1758) was collected on only two occasions. However, it was given attention when the recently collected specimen netted on 24 August, 1993 was brought live to the laboratory where its movement towards the source of light was noticed, leading to a careful examination and illustration. The specimen survived for 4 days. Illustrations and shell from the earlier collected specimen (August, 1991) were sent to Dr. Alan R. Kabat, division of Mollusck, National Museum of Natural History, Smithsonian Institution, USA, who confirmed that the specimen was Sinum haliotoideum (Linnaeus, 1758). He further informed that this is a moderately common Indo-Pacific species. The material has been deposited in the collections of the Marine Reference Collection and Resource Centre. (MRC) The species being new to the region is briefly described.

Note on Nematopalaemon tenuipes (Henderson, 1893) (Crustacea:Palaemonidae) from the Pakistan coast of Arabian Sea

On a few occasions palaemonid shrimps turned up in the collections from the Karachi fish harbour. The specimens resembled Nematopalaemon tenuipes (Henderson, 1893) but for the walking legs which were invariably missing or incomplete, in the latter case the dactyli were broken at or just near the base. The only reference from Pakistan is in context to its distribution (Holthuis and Miguel, 1984). The abbreviation cl. is used in the text for the carapace length measuring from the orbit to the posterior margin of the carapace.

Stock assessment of soldier catfish Osteogeneiosus militaris along the northwest coast of India

Value of length growth parameters L∞, K and t(sub)0 from age-length relation obtained from length-frequency analysis for the soldier catfish stock were estimated to be 47.6 cm, 0.51 per year and 0.03 year respectively. The age at recruitment (t [sub]r) was 0.58 year and the age at first capture (t[sub]c) 0.83 year. The total mortality (Z) was 0.88 including the present natural mortality (M) of 0.84 and fishing mortality (F) of 0.04. The total stock of this fish along the Northwest coast of India was assessed to be 32,413 tons and the MSY 5,426 tons which is much higher than the current catch of 863.8 tons. The potential yield (P[sub]y) of 38.7 g per recruit could be obtained at the optimum of exploitation (t[sub]y) of 2.84 years.

Estimates of growth, mortality, recruitment pattern and MSY of important resources from the Maharashtra coast

Based on the data collected from the year 1987-1991 the growth, mortality and recruitment pattern of eighteen species of fish, two species of cephalopods and four species of penaeid prawns have been presented in the present communication. The total mortality coefficient, (Z) varied from lowest of 1.20 for O. cuvieri to a highest of 10.78 for P. stylifera. The natural mortality coefficient, (M) varied from 0.52 for T. thalassinus to 3.44 for S. crassicornis. The average annual yield of eighteen species of fish, four species of prawns and two species of cephalopods are 65.083, 38.404 and 11.373 tons as against the MSY of 83.023, 72.460 and 10.475 tons respectively. The MSY estimated for the total fish stock is 1.77.753 tons whereas the present yield is 1.14.859 tons. This indicates that higher yield can be obtained by increasing the effort.

Population dynamics and stock assessment of the spider prawn, Nematopalaemon tenuipes Henderson along the Maharashtra coast

Nematopalaemon tenuipes is an important component of non-penaeid prawn resources of the northwest coast of India. During 1979-82 period, it contributed 29.9% to the non-penaeid prawn and 5.6% to the total fish landings of Maharashtra. The von Bertalanffy growth parameter L∞, K and t(sub)0 were 77.38 mm, 1.31 and -0.02 year for the males while for the females these parameters were respectively 87.23 mm, 1.30 and -0.01 year. The natural mortality coefficient (M) was 3.54 and 3.52 and the average total mortality coefficient (Z) during the period was 9.09 and 7.79 for the males and females respectively. With the exploitation rates of 0.61 and 0.55 for the males and females during the period, the total stock of the species was 26,270 tonnes and the standing stock was 3,418 tonnes. The maximum sustainable yield (MSY) of the species under the prevailing fishing conditions was 15,744 tonnes which is close to the average yield of 14,726 tonnes from the nets. Hence further increase in effort is not suggested.

Studies on the seasonal cycle of sea surface temperatures, salinities and phytoplankton in Puttalam Lagoon, Dutch Bay and Portugal Bay along the west coast of Ceylon.

The monthly average temperatures at Puttalam Lagoon, Dutch Bay, Portugal Bay towards Kovilmunai and Portugal Bay towards Pallugaturai showed a distinct annual cycle. The peak was in April and values gradually fell till September. There was a further gradual fall in temperature from October to January. The highest temperatures in all four stations were in April. The highest salinities in all the stations were from May to October i.e., during the south-west monsoon. The salinities at Dutch Bay and Portugal Bay were high in March and April corresponding to the highest temperatures reached during these months. Two maxima have been observed in phytoplankton production. A primary maximum in May-June and a secondary maximum in October. The primary and secondary maxima are due to the influx of nutrient laden waters from the rivers Kal Aru and Pomparippu Aru. The phytoplankton producing blooms were Rhizosolenia alata. Rhizosolenia imbricata, Chaetoceros lascinosus, Chaetoceros pervianus, Ch,aetoceros diversus, Coscinodiscus gigas, Thallasionema nitzschioides, Thalassiosira subtilis, Thallassiothrix frauenfeldii, Asterionella japonica, Sceletonema costatum, Bacteriastrum varians and Biddulphia sinensis. Sudden outbursts of a single species were common. These diatoms were species of Chaetoceros and Rhizosolenia, and Thallassiothrix frauenfeldii. Wide fluctuations have been observed in the distribution of phytoplankton but no definite conclusions can be drawn as the period of observation was only one year.

Restricted water exchange in the Negombo Lagoon on the west coast of Sri Lanka

Salinity, fresh water and sea level data from the Negombo Lagoon with respect to oceanic sea level and salinity data were considered. The open ocean spring tidal range was 0.57 m, whereas the neap tidal range was 0.10 m. In lagoon, the corresponding spring tidal range was 0.13 m and neap tidal range is 0.05 m. The lagoon tide was strongly choked because of the restricted inlet channel, through which only a limited water exchange could take place over a tidal cycle. Mean water exchange and the residence times for variable fresh water supplies were calculated. These calculations were based on fortnightly measurements of salinity and river discharges in 1993. During this year, salinity varied from 30-5‰ depending on the river inputs which were 20-225 m³ sˉ¹. Corresponding residence times varied from 11-2 days and the tide is dominated the exchange during low discharges of freshwater.

Coastal development and pollution impact on the distribution of macrobenthic communities along the eastern coast of the Gulf of Suez (Egypt)

The configuration for the eastern side of the Gulf of Suez was studied over 241 km from Ras Mohammed to Ras Sudr including 35 station. Litters, tar balls and aged oil patches aggregated in considerable amounts on the beach and shore line of the middle part due to the oil spills from off-shore oil wells. A large reef flat in the shallow intertidal waters exists at stations 1 and 2 (Ras Mohammed, Protected area) and spars coral patches are less frequent at the Stations from 7 to 13. Density and diversity of marine benthos were higher on hard and cobble bottoms compared to muddy sand and sandy substrates. The assemblages of the benthic fauna are dominated by the gastropod Courmya (Thericium) vulgata; the bivalve Brachiodontes variabilis, and the barnacles Chthamalus stellatus, Balanus amphitrite and Tetraclita rubescens. The distribution of the algal cover in the intertidal region shows high abundance of the brown algae, Sargassum latifolium; padina pavonica and Cystoseira trinodis rather than the green and red algae. These species are found in both polluted and unpolluted areas. The changes in benthic structures in the study area depend not only on the state of pollution but also on the type of substrates.

Cephalopod fishery at Kakinada along the east coast of India: Resource characteristics and stock assessment of Loligo duvauceli ·

At Kakinada along the east coast of India, cephalopods were exploited by trawls. Fishery occurred round the year with peak during August-October. Peak abundance and fishery of cuttlefishes coincides with this period, whereas for squids it is during March-May. Cephalopod production continued to increase initially with fishing effort, until 1995, but declined thereafter despite increased fishing effort and expansion of fishing to deeper waters. Fishery, growth, mortality, recruitment pattern and exploitation rates of Loligo duvauceli were studied. Nearly 97% of their catch was by zero year groups. They attain sexual maturity and spawn during the first year itself. Spawning occurred round the year with peak during December-February. Exploitation rate of the species is large, 0.741 compared to Emax (0.44). This indicated that their stock is under heavy fishing pressure and subjected to over-exploitation. Stock also exhibited declining trend over the years during 1995-'99. These necessitate immediate attention to avoid coHapse of the stock and fishery.