STUDIES ON SOME ASPECTS OF REPRODUCTION OF FEMALE ANABAS TESTUDINEUS ( BLOCH )

Department of Marine Biology, Microbiology and Biochemistry

Some studies on the reproductive endocrinology of tiger prawn Penaeus monodon Fabricius

The growing demand for quality prawn seed from the farmers‘ and entrepreneurs, coupled with uncertainity of their availability from nature at the appropriate time in required quantities has prompted‘ research on problems connected with prawn seed production. Endocrine control of reproduction in the penaeid shrimp _P_. monodon has been investigated in detail by adopting a comprehensive approach to the problem. The major aspects of the study included in depth investigations of the cytological details of the reproductive and neuroendocrine organs in correlation with the process of gonadal maturation. Based on the conclusions drawn from such ultrastructural studies various endocrine manipulations were carried out to see their effects on gonadal maturation. Besides that studies on the reproductive quality of male P_. monodon and the cryopreservation of spermatophores form a part of the present investigation. The shrimp 3; Inonodon used in the present study were collected from the offshore waters of Cochin, Madras and Mandapam and from the culture ponds of Vypeen Island near Cochin (Kerala) . The entire investigation on the cytological aspects were carried out using standard histological and electron-microscopic methods. Endocrine manipulations and cryopreservation studies is also carried out using the standard methods.

Studies on some aspects of the reproductive physiology of the female grey mullet mugil cephalus l.

Aquaculture is the dynamic pursuit of production of organisms from water a process analogous to agriculture on land. The field of aquaculture is an emerging bioindustry, based upon the culture and husbandry of economically utilizable aquatic organisms. Of late, there has been a global upsurge for aquaculture, the main reasons for which include the requirement of protein source for the increasing world population, the decision by various world nations to increase the fish yield by developing unutilized or partially utilized water bodies and depletion of natural stock which is evident in recent years due to excessive exploitation .The present study has been taken up on the reproductive physiology of the female grey mullet, M. cephalus. The thesis is presented in seven chapters. In the present study, variations in the major biochemical parameters namely, moisture, proteins, lipids, carbohydrates cholesterol, carotenoid, ash, calcium and iron in four tissues E. muscle, liver, ovary and bloodserum of cephalus have been analysed at different maturity stages.

Studies on the female reproductive physiology of the prawn, Macrobrachium idella (Hilgendorf, 1898)

’l‘he reproductive physiology of the female palaemonid prawn M. idella has been investigated by adopting a comprehensive approach to the problem. The major aspects of the study included investigations on breeding biology and process of oogenesis, variations in the biochemical components in relation to maturation, neuroendocrine relations and control over reproduction, and artificial insemination. The prawns used in the present study were procured from Vembanad Lake at Panavally village - a place nearly 20 km. away from Cochin. The studies were carried out using standard histological and biochemical methods. The modern technique of electroejaculation was adopted for extrusion of spermatophores in artificial insemination experiment.

“Population Characteristics, Fishery and Post larval distribution of Macrobrachium rosenbergii (de Man) and M. idella (Hilgendorf) of Vembanad lake”

Macrobrachium rosenbergii (de Man) and M.ide77a (Hilgendorf) form two commercially important Palaemonid prawns of the Vembanad lake (9 28' and 10 10’ N and 76 13' and 76 31' E). Both of them were known to have contributed to a very lucrative fishery during the sixties, however, in recent years these natural resources have badly depleted owing to the impact of many man made alterations brought about in the ecosystem such as habitat reduction, physical obstruction imposed in the migratory pathway of these species, pollution hazards, etc,. Changed environmental conditions and increased fishing pressures caused persistent alterations in the stock size of these prawns during the past so many years, however, no serious attempt was made to monitor the stock size from time to time and also to bring out the resource characteristics. Though, the morphotypic differentiation in grow out male population of M.rosenbergii has been documented, no similar studies were conducted with regard to natural male and female population. Based on the data collected during fishery cruise surveys conducted in Vembanad lake from March '94 to February '96, population characteristics. postlarval distribution, fishery and population dynamics of M.rosenbergii and M.ide77a of the lake were studied in detail.

Form-invariant bivariate weighted models

In this paper the class of continuous bivariate distributions that has form-invariant weighted distribution with weight function w(x1, x2) ¼ xa1 1 xa2 2 is identified. It is shown that the class includes some well known bivariate models. Bayesian inference on the parameters of the class is considered and it is shown that there exist natural conjugate priors for the parameters