Age and size composition, growth rate, reproductive biology, and habitats of the West Australian dhufish (Glaucosoma hebraicum) and their relevance to the management of this species

Samples of the commercially and recreationally important West Australian dhufish (Glaucosoma hebraicum) were obtained from the lower west coast of Australia by a variety of methods. Fish <300 mm TL were caught over flat, hard substrata and low-lying limestone reefs, whereas larger fish were caught over larger limestone and coral reef formations. Maximum total lengths, weights, and ages were 981 mm, 15.3 kg, and 39 years, respectively, for females and 1120 mm, 23.2 kg, and 41 years, respectively, for males. The von Bertalanffy growth curves for females and males were significantly different. The values for L∞, k, and t0 in the von Bertalanffy growth equations were 929 mm, 0.111/year, and –0.141 years, respectively, for females, and 1025 mm, 0.111/year, and –0.052 years, respectively, for males. Preliminary estimates of total mortality indicated that G. hebraicum is now subjected to a level of fishing pressure that must be of concern to fishery managers. Glaucosoma hebraicum, which spawns between November and April and predominantly between December and March, breeds at a wide range of depths and is a multiple spawner. The L50’s for females and males at first maturity, i.e. 301 and 320 mm, respectively, were attained by about the end of the third year of life and are well below the minimum legal length (MLL) of 500 mm. Because females and males did not reach the MLL until the end of their seventh and sixth years of life, respectively, they would have had, on average, the opportunity of spawning during four and three spawning seasons, respectively, before they reached the MLL. However, because G. hebraicum caught in water depths >40 m typically die upon release, a MLL is of limited use for conserving this species. Alternative approaches, such as restricting fishing activity in highly fished areas, reducing daily bag limits for recreational fishermen, introducing quotas or revising specific details of certain commercial hand-line licences (or doing both) are more likely to provide effective conservation measures.

Contribution of zooplankton to the fishery of Dharamtar Creek, adjoining Bombay Harbour

The rich zooplankton standing stock of Dharamtar Creek showed a variation of 8 to 5261 (av. 1032) mg C/100 m super(3)/d which led to a turnover of 29 tonnes C/km super(2)/y. The estimated fishery potential from zooplankton production was 0.079 tonnes C/km super(2) or 29.00 tonnes/km/y. The worked out yield in terms of wet weight of fish was 0.059 tonnes/km2u2/d. Experimental trawling within the creek showed a potential of 0.19 tonnes/km super(2)/d suggesting a transfer coefficient of only 31.4% form secondary to tertiary level. Fish eggs and larvae were very common in the area but contributed collectively only 1% to the total zooplankton population. On an average the outer zone sustained relatively higher population of fish eggs and larvae than the interior zone. The mean population density of larvae (334/100 m super(3)) was 3.5 times higher than fish eggs (93/100 m super(3)) suggesting the good survival rate and a congenial environment for larvae to thrive.

Present status and future scope of fisheries in the Andaman group of islands

The coastal area of approximately 2000 km and the water-bodies in between the Andaman and Nicobar islands are rich in fishery potential which range from 0.012-0.47 million tonnes. The fishery is dominated by catches of sardines, perches, carangids, mackerels, Leiognathus elasmobranchs, seerfish, mullets and tunas. About 2050 fishermen, with 1150 country craft, 113 mechanised boats and 1367 different kinds of nets and lines are engaged in active fishing in the island. Numerous bays, lagoons and creeks are available among the group of islands for mariculture activities. The mangroves of these islands provide feeding and nursery grounds for juveniles of penaeid prawns, crabs and finfishes.

Two genera and species of Isopoda new to the fauna of the northern Arabian Sea

The paper is based on the new records of two genera - Lanocira Hansen and Paranthura Bate and Westwood and species L. gardineri Stebbing and P. latipes Barnard from the rocky intertidal zone of Karachi coast. Synonymes, diagnoses and geographical distribution of the genera are given. A list of known species of the genus Lanocira is provided. Both the species are described and illustrated in detail.

Portunus pulchricristatus (Gordon, 1931): an addition to crab fauna of Pakistan (northern Arabian Sea)

Portunus pulchricristatus (Gordon, 1931) is a rare species, to date we have obtained only three specimens, two males and a berried female which can be easily identified with the help of existing descriptions and illustrations. Brief account of the Pakistan material is given below. One male specimen (measuring 11.0 mm in carapace length) has been deposited in the National Museum of Natural History, Leiden (Reg.No.D.42393) the other two specimens housed in the Marine Reference Collection and Resource Centre (MRCC Cat. No.BRAC.491). The abbreviations used are cl. for carapace length and cb. for carapace breadth.