977 research outputs found
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├Ч2 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 (7тАУ8 days) as compared to 29 ┬░C (8тАУ10 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 temperatureтАУsalinity combination for larval survival and metamorphosis of P. merguiensis is 33 ┬░C and 35 ppt. A salinity range of 30тАУ35 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 тАУ Building Mass Balance Trophic and Simulation Models
Glossary of technical terms- Winter School on Towards Ecosystem Based Management of Marine Fisheries тАУ 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
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