The fishery and population dynamics of groupers from Andaman Islands were studied from Jan 2010 to Dec 2011 with a special emphasis on Malabar grouper, Epinephelus malabaricus (Bloch & Schneider 1801).The average annual catch of Malabar grouper was 1,296 tonnes contributing to 21.6% of annual grouper landings.Length-weight relationship of Malabar grouper showed that growth was allometric (b=2.96) and relative condition factor (Kn) was 1 and the growth parameters viz., L ∞ , K and t 0 were 124.60 cm, 0.80 and -0.05 respectively.The recruitment pattern was unimodal with one major peak during April to July throughout the study period.The natural mortality (M), fishing mortality (F) and total mortality (Z) were 1.05, 1.48 and 2.53 respectively and exploitation rate (E) was 0.58.The M/K ratio (1.31) was found to be well within the normal range of 1to 2.5.Catch per unit effort varied from 4 to16.5 kg.h -1 .The maximum sustainable yield (MSY) was 1,107 tonnes which was lower than the average annual catch (1,296 tonnes), indicating over exploitation.The current study calls for further research in identifying the grouper fishing and spawning aggregation grounds and introduce measures for reducing fishing efforts with input and output controls to sustain the Malabar grouper fishery in Andaman waters.

This study describes the different stages of ovarian development and estimate the fecundity in captive-raised snakehead murrel, Channa striatus. The fish (14.93.9 g) were fed twice daily until satiation from February to September 2010 with a commercial diet. The gonadosomatic index (GSI), gradually increased from the 1 st to the 4 th month, remained unchanged at the 5 th until the 7 th month, and then declined slightly by the 8 th month. However, the hepatosomatic index (HSI) fluctuated as the feeding period progressed. In contrast, HSI increased from the1 st month and peaked by the 3 rd month. However it declined sharply in the 4 th month to a level lower than that in the first 3 months and remained consistently low thereafter. Interestingly, HSI sharply increased in the 8 th month, when GSI declined. The absolute fecundity was found to be 33,9493,388. Oocyte and egg diameters were found to be 1.21mm0.07mm and 1.33mm0.09 mm, respectively. Four different developmental stages were identified and discussed through histological examination: primary, yolk vesicle, vitellogenic and mature oocytes. The results demonstrated that captive-raised fingerling C. striatus came to sexual maturity after 8 months.

An experiment was carried out to determine the combined effects of temperature and salinity on the survival and development of zoea, megalopa and crab instar stages of mud crab Scylla tranquebarica (Fabricius 1798). Salinities of 15, 25, 35 and 45 ppt were tested for each of the zoea stages; 5, 15, 25, 35, 45 ppt for the megalopae and 0, 5, 15, 25, 35 and 45 ppt for crab instar 1 (C1), at temperatures of 20, 26 and 32 o C. Two-way ANOVA showed a significant effect of temperature, salinity and interaction between temperature and salinity on the survival of all stages tested. Larvae at Z1-Z4 stages tolerated 25-35 ppt in 20 o C and 25-45 ppt in 26 and 32 o C. There was successful metamorphosis of Z5 larvae to megalopa at 25-35 ppt in 26 and 32 o C while all larvae died at 15 and 45 ppt, in all temperatures. The megalopae survived and developed to crab instar at 25-35 ppt in 26 and 32 o C. The first crab instar (C1) survived to the second crab instar (C2) at 5-45 ppt in 26 and 32 o C and at 15-45 ppt in 20 o C.

The changes of land area and vegetation cover in the channel segment of the Negombo estuary, Sri Lanka from 1987 to 2009 were assessed with the multivariate alteration detection (MAD) algorithm using multi-temporal satellite images of Landsat TM, ETM+ and ASTER. Changes in chlorophyll a (Chl-a) distribution were also studied using time series Landsat satellite data. The study successfully detected changes in land area and vegetation cover during the study period. Results indicated that the channel area of the Negombo estuary had significantly reduced during the study period with rapid changes from 2000 onwards. A notable increase in land area in urbanised areas around the channel segment and an increase in the density of mangroves around some islets were also detected. New islets have also formed in the channel segment during 1987-2009. The results also indicated that during this period there was a significant increase of Chl-a content especially in water stagnant areas at Kuda Ela and Madabokka, leading to localised eutrophication. This information will be useful to identify the areas with high eutrophication and remedial action could be taken well in advance in order to mitigate sudden fish kills that frequently occur in such areas.

Weedicides bring about adverse effects to non-targeted animal species in the agricultural fields and associated habitats. Among these, Roundup (glyphosate) is one of the commonest that is used all over the world. The present laboratory investigation examined the effects of Roundup on fingerlings of guppies (Poecilia reticulata). In this investigation, the 24-hr and 96-hr LC 50 of Roundup for the guppy fingerlings were determined by exposing them to a series of Roundup test preparations ranging from 3.6 mg . L -1 to 36 mg . L -1 . Further, the behavioural changes of the fingerlings at these test preparations were studied and the histopathological changes of their gills were examined. The results showed that the 24-hr and 96-hr LC 50 for Roundup were 15.1 mg . L -1 and 9.76 mg . L -1 respectively. These values are well below the recommended field concentration of Roundup , which is 2,592 mg . L -1 . Fingerlings preferred to rest more at the surface of test preparations than resting elsewhere in the tanks. In contrast, such a behavioural change was not observed in the control. The histopathological study showed that the fingerlings exposed to all the Roundup concentrations developed gill hyperplasia where its severity was concentration dependent. It is evident that the toxic concentration of Roundup on guppy fingerlings is much lower than its recommended field concentration. At these toxic concentrations, Roundup brings about stress and severe gill damage in guppies.

Growth in crustaceans and other arthropods is interrupted by cyclical moults, in which the old cuticle or exoskeleton is shed, and in the intervening growth phases the soft tissue swells and a new elastic cuticle gradually thickens and hardens. Marine prawns, Penaeus monodon, from a commercial farm in northern Queensland, Australia, were studied alive to assess their growth and moulting stages. The median part of the setae of inner uropods was examined by light microscopy. A finely graded classification of five stages and substages of postmoult, stage A consisting of substages A1 and A2, and stage B (1-16 hours); intermoult, stage C (1 day); premoult, stage D consisting of substages D1, D2 and D3/D4 (2-12 days) and ecdysis, stage E (about one minute) are described and illustrated. Ecdysis took place at night. Rapid and repetitive moult staging in individual prawns can be carried out without sacrificing the prawns.

The expansion of shrimp culture in the Americas has been historically limited by disease epidemics that caused severe production crashes. As intensive culture systems provide almost ideal conditions for the propagation of infectious diseases, the producers are constantly looking for means to manage diseases to minimize losses in production and quality. The most attractive options are exclusion or eradication, breeding for disease resistance and various sanitary measures. On the other hand, low market prices limits the resources invested in shrimp diagnostics and prevention. In this scenario, identification of new pathogens could be restricted to outbreaks with high mortalities, thus making shrimp producers more susceptible to the effect of shrimp pathogens. In this review, we analyzed the main shrimp diseases in the Americas.