Optimal salinity and temperature for early developmental stages of Penaeus merguiensis De Man

The combined effects of temperature and salinity on the hatching success, survival and development of the larval stages of Penaeus merguiensis were investigated in a 4×2 factorial designed experiment employing two temperatures (29±1 and 33±0.5 °C) and four salinities (25, 30, 35 and 40 ppt). Best percentage of hatch was obtained at 33 °C and 35 ppt (87%) followed by 29 °C and 35 ppt (82%). Similarly during naupliar stages, high survival rate was obtained at 33 °C and 35 ppt (89%). Metamorphosis cycle during the protozoeal stages (protozoea 1 to postlarva 1) was extended and survival rate decreased at 25 ppt. Development to PL1 was faster at 33 °C (7–8 days) as compared to 29 °C (8–10 days) regardless of the salinity levels. Maximum survival during the protozoeal stages was at 35 ppt followed by 48% at 33 °C and 45% at 29 °C. Results showed that salinity exerted a greater influence than temperature on the survival and development of larvae. Based on the results, the best temperature–salinity combination for larval survival and metamorphosis of P. merguiensis is 33 °C and 35 ppt. A salinity range of 30–35 ppt is ideal for larval development

Banana shrimp: low cost technology for broodstock development

Global aquaculture production more than doubled in weight and value between 1986 and 1996, and it currently accounts for over one quarter of aquatic production consumed by humans

Glossary of technical terms- Winter School on Towards Ecosystem Based Management of Marine Fisheries – Building Mass Balance Trophic and Simulation Models

Glossary of technical terms- Winter School on Towards Ecosystem Based Management of Marine Fisheries – Building Mass Balance Trophic and Simulation Model

Imperative need for regulation of marine fisheries in India

The tendency of an unregulated fishery to expand until it becomes unprofitable is both predictable in theory as well as observable in practice. One of the techniques of effective management of fish stocks to obtain the maximum economic yield is the formulation of explicit regulations based on scientific studie

Investigations on fishery and biology of nine species of rays in Mumbai waters

Annual landings of rays by trawlers operating from New Ferry Wharf, Mumbai during 1990-2004 ranged from 205.7 t to 765.1 t with an average of 502.8 t constituting nearly 1 % of trawl catches. The trawling effort increased from 0.95 million hours (mh) in 1990 to 1.73 mh in 2004, whereas the catch rate declined from 0.65 kg h-1 in 1990 to 0.24 kg h-1 in 2004. There were two peak periods of abundance, September-December and February-April. Fourteen species of rays constituted the fishery, of which Himantura alcockii (50.1 %), Himantura bleekari (13.9 %), Amphotistius imbricatus (8.5 %) and Himantura uarnak (8.1 %) formed the mainstay of the fishery. Information on biology of H. alcockii, H. bleekeri, A. imbricatus, Pastinacus sephen, Dasyatis zugei, Gymnura japonica, G. poecilura and Mobula diabolus is also presented. It appears that the resource of rays off Mumbai may not be able to withstand any further increase in fishing effort. Innate biological characteristics such as limited brood size, late maturation and capture of spawning stock are the causes of continuous decline. Conservation measures are required to protect this resource from further depletion

EBFM - can it manage and conserve tropical Asian fish stocks?

Scientists predict two possible futures for EBFM that are not mutually exclusive. The core elements of EBFM, getting singlespecies fishing mortalities right, reducing bycatch, and protecting sensitive habitats, are widely accepted, being implemented, and are reasonably inexpensive. This will mean lowering fishing mortality on all species below the levels that produce MSY and probably lowering even more the exploitation rates on forage species. Various agencies are now using ecosystem indicators to modify their regulations. Essentially, ecosystem impacts of competition and predation are ignored when singlespecies assessments are used on a standalone basis. This aspect of EBFM could Significantly modify management since the US and many other countries use estimates of unfished biomass when making harvest decision

Catch-effort relationship and projection scenarios for the dual-fleet trawl fishery of Mangalore and Malpe, southwest coast of India

Non-equilibriwn surplus production models were fitted to derive the empirical production maxima for the single-day (SDF) and multi-day fleet (MDF) trawlers operating from Mangalore-Malpe bases. The Pella-Tomlinson model fitted for SDF showed that the fishery is presently stabilized at an effort level close to the empirical production maximum (11429 tonnes). While using the Schaefer model, the yield from MDF was found to be ~ excess of the ideal (32406 tonnes). Projection scenari"" using different effort levels for MDF indicate that a 15% lannum decrease in effort from the present can bring back the population to a healthy level by the year 1999. The biological interaction among the different component species of the two fleets are also provided

High abundance of large sized rock cods (Epinephelus spp.) off Karnataka coast during the postmonsoon month of September

some of the multi-day units ventured into deeper waters (60-80 m) and obtained good catches of reef cods (Fig: 1) along with threadfin breams and cuttle fishes. Encouraged by this, more number of multi-day units were put into operation in September of the following year (1995) and got still better catches of reef cods

Exploitation of juveniles of the spinycheek grouper, Epinephelus diacanthus by multiday trawlers along Dakshina Kannada coast

The juveniles in the size range 9-24 cm are in sizeable quantities during October - May at Mangalore and Malpe landing centres of Dakshina Kannada coast. The present study is undertaken to highlight the magnitude of the exploitation of the juveniles of the Spinycheek grouper. Epinephelus diacanthus by trawlers along the Dakshina Kannada coast and its impact on the stock with a brief description on its biology. This species is known to grow to a large size and supports a fishery of some magnitude in other parts of the Indian coast. The results presented here are based on the data collected on the landing of the species at Mangalore and Malpe during 1988/'89 - 1993-'9

Catfish reappeared in Dakshina Kannada Coast

After a gap of several years catfish reappeared in Malpe during September, 1994. Three purse seiners together landed three tonnes of catfish Tachysurus serratus (90 per cent) and T. dussumieri (10 per cent