Age and growth of three species of seerfishes Scomberomorus commerson, S. guttatus and S. lineolatus

Length-frequency an:(lysis indicates that the king seer (Scomberomorus cotnmerson) attains a size of 402 mim, 726 mm, 995 mm and 1186 mm total length at 1, 2, 3, and 4 years of age, respectively, the streaked seer (S. Uneolatus) reaches a size of 350 mm, 713 mm, 835 mm and 965 mm total length et 1, 2, 3 and 4 years, respectively, and the spotted seer (S. guttatus a size of 369 mm, 532 mm: and 640 mm at 1, 2, and 3 years, respectively. Back-calculated lengths of fish at the time of ring formation on otoliths figree closely with the results of lengthfrequency analysis. The maximum lengths of king seer, streaked seer and spotted seer met with in the catches are 1936 mm (33 kg), 980' mm (4.6 kg) and 705 mm (2.1 kg), respectively. The theoretical maximum lengths (Lac) computed by Bagenal or Rafail method for the von Bertsfeaffy growth equation are found to be 2081 mm (46.7 kg) for the king seer, 1683 mm (15.7 kg) for the male streaked seer, 1447 ram (24.3 kg) for the female streaked seer and 1278 mm (9.6 kg) for the spotted seer. All the three species develop two rings a year in their otoliths at a regular interval of six months. For all the three species, the exponent in the length-weight relationship is found to be close to 3

Deepsea fishing in Indian waters

The development of Indian marine fIsheries since the early 60s from a traditional, subsistence oriented one into an industrial fisheries was quite substantial. This change got accelerated mainly in the mechanised era of the marine fishery sector. Although with the declaration of the EEZ, an area of 2 million sq. km. came into existence in 1977, there has never been a commercial deepsea fishing worth mentioning. However deepwater trawling conducted by two Mexican trawlers (24 m OAL) imported from the USA in 1972 has paved the way for a humble beginning in the deepsea fishing operations. Gradually by 1982-83 about 11 0 chartered and joint venture deepsea fishing vessels began fishing operations and almost without exception, they exploited mostly the inshore grounds upto 50 m and rarely upto 100 m. But once the depth limitations beyond the 80 m depth line for offshore fIshing operations was enforced in 1983, almost all these chartered vessels left the country

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Need for a systems approach to the development of the coastal agroecosystems in the Gulf of Mannar area

The Gulf of Mannar is bordered by Ramanathapuram, Thoothukudi, Thirunelveli and Kanyakumari districts. Most ofthis coast is dry, and experiences only limited rainfall during the northeast monsoon. The mainstay of the population is comprised by marine fisherfolks, marginal farmers and landless labourers

Coastal biodiversity - Conservation and sustainable management

A management regime based on social acceptance, with the power of moral persuasion from within the group of participants, is the only way to manage widely dispersed resources which are sliared by a multitude of small scale fishermen and various other users

Fishery biology research: glimpses on practices and application for genetic resource conservation

India is bestowed with rich natural resources in which the freshwater, coastal and marine living resources are of prime importance in view of the total dependence of the humanity on these resources for its well-being. Sustained anthropogenic activities such as fishing, coastal industries, shipping and ports, ship breaking, dredging, agriculture and land based industries have profound impacts on these resources ranging from least serious to most serious in nature prompting appropriate regulatory and conservation measures

The seerfish resources

The seerfishcs are inshore pelagic fishes, distributed mainly in areas within 60 m depth contour. The mean annual seerfish catch of 17,852 t for 1964-81 was accounted for almost equally by the east coast (49.66%) and the west coast (50.34%). While the bulk of the east coast catch came from Tamilnadu (47.91%) tod Andhra Pradesh (40.34%), the States of Kerala (35.48%), Maharashtra (23.44%) and Gujarat (23.14%) contributed the bulk to the west coast. The progressively increasing trend from 1964 to 1981 owes to the increasing number of mechanised gilhietters operating for the larger catch including the seerfishes. (23.44%) and Gujarat (23.14%) contributed the bulk to the west coast. The progressively increasing trend from 1964 to 1981 owes to the increasing number of mechanised gilhietters operating for the larger catch including the seerfishes

Stock assessment implications and management options for the small pelagics in the APFIC region

Problems in stock assessment and management of the exploited fish stocks, especially the pelagic fish stocks, are reviewed. The theoretical and practical constraints in the application of the assessment techniques and production modelling with reference to the small pelalgics are indicated. Appropriate approaches to pelflgic fish stock assessment and management are outlined

Splash wave and crown breakup after disc impact on a liquid surface

In this paper we analyze the impact of a circular disc on a free surface using experiments, potential flow numerical simulations and theory. We focus our attention both on the study of the generation and possible breakup of the splash wave created after the impact and on the calculation of the force on the disc. We have experimentally found that drops are only ejected from the rim located at the top part of the splash --giving rise to what is known as the crown splash-- if the impact Weber number exceeds a threshold value \Weber_{crit}\simeq 140. We explain this threshold by defining a local Bond number $Bo_{tip}$ based on the rim deceleration and its radius of curvature, with which we show using both numerical simulations and experiments that a crown splash only occurs when $Bo_{tip}\gtrsim 1$, revealing that the rim disrupts due to a Rayleigh-Taylor instability. Neglecting the effect of air, we show that the flow in the region close to the disc edge possesses a Weber-number-dependent self-similar structure for every Weber number. From this we demonstrate that \Bond_{tip}\propto\Weber, explaining both why the transition to crown splash can be characterized in terms of the impact Weber number and why this transition occurs for $We_{crit}\simeq 140$. Next, including the effect of air, we have developed a theory which predicts the time-varying thickness of the very thin air cushion that is entrapped between the impacting solid and the liquid. Our analysis reveals that gas critically affect the velocity of propagation of the splash wave as well as the time-varying force on the disc, $F_D$. The existence of the air layer also limits the range of times in which the self-similar solution is valid and, accordingly, the maximum deceleration experienced by the liquid rim, what sets the length scale of the splash drops ejected when We>\Weber_{crit}

CIFE contribution to marine fisheries R & D

The CIFE contributions to marine fisheries R&D are mainly In the areas of stock assessment, brackish water farming, fishing and product diversification, fishery socio-economics and technology transfer. Stock assessment studies, limited to the west coast and particularly to the northwest coast Include the stocks of Co///a dussumleii, Otolilhus cuvleri, Johnlus glaucus, Polynemus heptadactylus, Harpodon nehereus, Arius thalasslnus, Nemlpterus japonlcus, all-northwest coast Inshore species, penaeid prawns, Rastrelllger kanagurta, Sardlnella longiceps and xancus pyrum. In respect of brackish water fisheries, R & D acclivities are concerned with prawn hatcheries, seed banks, low Input culture, live feed culture and fishery estates. Simple techniques for making laminated Bombay duck, fish wafers and minced meat have been developed for the purpose of product diversification. High opening bottom trawling has been experimentally proven to be more productive than the traditional bottom trawling, and Is being popularised. Studies on profitability of mechanised fishing indicate some prospects for additional Investment. Small private owned brackish water farms are more profitable than large government owned farms, Indicating thereby the need to privatize the farm sector. The fisherie