Local distribution and abundance of swimming crabs (Callinectes spp. and Arenaeus cribrarius) on a tropical arid beach

Distribution, abundance, and several population features were studied in Ensenada de La Vela (Venezuela) between 1993 and 1998 as a first step in the assessment of local fisheries of swimming crabs. Arenaeus cribrarius was the most abundant species at the marine foreshore. Callinectes danae prevailed at the estuarine location. Callinectes bocourti was the most abundant species at the offshore. Abundances of A. cribrarius and C. danae fluctuated widely and randomly. Ovigerous females were almost absent. Adults of several species were smaller than previously reported. This study suggests that fisheries based on these swimming crabs probably will be restricted to an artisanal level because abundances appear too low to support industrial exploitation.

Textural and compositional variations in beach sands along Karachi coast

The texture of clastic sediments is a fairly reliable index of the erosional history and energy conditions of the depositional environment, while its mineralogy reflects the composition of the source rocks. The beach sands of Clifton, Sandspit, Hawkesbay and Paradise Point were studied to determine their erosional history, depositional environment and their source

Ceylon's beach seine fishery

Setting a net in the water and hauling it up onto the beach manually by its two ends is one of the oldest methods of catching fish and it is still employed in several parts of the world: Ceylon is one of these. Here there are several hundreds of beach seines operated by several thousands of fishermen and they contribute 35-40% of Ceylon's total annual fish catch. This means that beach seining been and still is Ceylon's most important single method of fishing. In recent years the beach seine fishery has encountered difficulties which threaten its existence and the seiners have appealed repeatedly to the Department of Fisheries to undertake remedial action. There have been many and conflicting representations as to what this action should be, and the Department is seeking for a wise course through the confusion. As part of its search it asked its Research Division in April 1953, to undertake a study of the seine fishery to describe it, study the nature of its problems and to present any recommendations that seemed appropriate and consistent with the welfare of the fishing industry as a whole. The following is a report on the preliminary phases of that study.

Status of the beach seine fishery in the Hambantota District during 1995-97

Beach seine fishery is one of the oldest fishing methods practiced in Sri Lanka. In the recent past several modifications were observed in the structure of the net and the material used in the construction of nets. beach seine nets made of nylon material were also reported at 4 operating sites out of 17-beach seine landing centers in the Hambantota District. However, traditional beach seine nets made of coir and kuralon were the common nets used in the area. Fishing season extends from September to April of the following year. However, beach seining at Mawella was carried out throughout the year. The estimated average annual effort for the entire study area was about 4250 operations. The mean annual catch rate at Mawella, Kalametiya and Welipatanwila were estimated as 81.8, 290.7, and 167.3 kg/operation respectively. The mean annual catch rate for the entire study area was estimated as 157.3 kg/operation. The beach seines recorded an estimated annual production of 662mt in the Hambantota district. Stoleophorous sp. has made the major contribution to the beach seine catches and it was about 31.7% of the total beach seine production. Leiognathus sp. Carangids and Trichuras sp. have produced 11.5%, 9.5% and 8.5% respectively while Amblygaster sirm and other Sardinella sp. have produced 5.5% and 4.9% respectively. A sirm was found during the months of November, February, March and July. The size range of A. sirm caught by beach seine during February –March period was in the range of 5-12cm (total length). Contribution by Rastrelliger sp. and Sphyreana sp. were 2.9% and 2.6% by each category. Average income of a beach seine operation at Mawella, Kalametiya and Welipatanwila were Rs. 3330/=, 10250/= and 6222/= per operation respectively.

Nutrient profile of pond water in north-eastern state of Tripura and impact of water acidity on aquaculture productivity

Physicochemical parameters of 31 fish pond water samples of Tripura were studied to ascertain the nutrient profile of acidic soil zone and the impact of water acidity towards aquaculture productivity. The pH was acidic (mean 6.63±0.44) with high Fe (mean1.04±0.40 mglˉ¹) and AI (mean 2.67±2.41 mglˉ¹) contents. These were mostly responsible for pond water acidity and poor productivity with low nitrogen, phosphate and total alkalinity. The study also showed strong negative relationship between water pH and redox potential (R²=0.5251). However, pH was positively significant with electrical conductivity. The roles of redox potential and electrical conductivity in water acidity were found highly important. Available calcium content was also found low (mean 2.91±2.96 mglˉ¹). Elevating level of pH of pond water could be the possible management practices in acidic water so that such unproductive water might be productive enough with higher phosphate and nitrogen levels for better biological production.

Effect of dietary supplementation of tocoferol acetate alone and with varying combinations on growth, survival and fatty acids profile of Macrobrachium rosenbergii larvae through Moina micrura enrichment

A study was carried out to determine the effect of tocopherol acetate along with cod liver oil astaxanthin enriched Moina micrura (MC- control, Ml- tocopherol acetate enriched, M2-tocopherol acetate combined with cod liver oil (CLO) enriched and M3- tocopherol acetate combined with astaxanthin enriched) on growth, survival and fatty acid composition of M. rosenbergii (de Man) larvae (TC- unenriched Moina fed larvae, Tl- tocopherol acetate enriched Moina fed larvae, T2- tocopherol acetate + CLO enriched Moina fed larvae to T3 – tocopherol acetate+ astaxanthin enriched Moina fed larvae). Growth was expressed as the time taken in to the settlement of 95% post larvae. Maximum growth i.e., the lowest time taken to the 95% PL settlement (40 days) and the maximum survival percentage (61%) was observed in both T2 and T3 treatments fed with M2 and M3 Moina respectively. Minimum growth and survival was observed in unenriched Moina fed larvae (TC). In larval treatments T2, (larvae fed with (M2) vitamin E + CLO enriched Moina), showed a higher percentage of EPA, DHA and higher HUFA level than other treatments.

Supply of Astaxanthin and its combinations through live feed (Moina micrura) enrichment affects the growth, survival and fatty acid profile of Macrobrachium rosenbergii larvae

A study was carried out with three replicates to determine the effects of feeding Moina micrura enriched with astaxanthin alone (M1) or astaxanthin in combination with either vitamin E (M2), vitamin D (M3) or Cod Liver oil (M4) on the growth, survival and fatty acid composition of giant fresh water prawn Macrobrachium rosenbergii (de Man) larvae. Growth rate was expressed as the time taken to the settlement of 95% post larvae. Maximum growth, the lowest time taken to the 95% PL settlement (38.5±0.50 days), was observed in larvae fed with M3 Moina. The highest survival rate (66.0±1.00%) was observed in those fed with M4 Moina and the second highest survival (61.0±1.00%) and growth rates (40.0±0.00 days) were shown with M2 Moina. The minimum values for both growth (42.5±0.50 days) and survival (33.0±1.50%) were observed in the group fed un-enriched Moina. Results also showed that the survival of prawn larvae increased as the quantities of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) increased in the dietary Moina. The highest levels of EPA (5.57±0.21%), DHA (3.50±0.21%) and highest total Highly Unsaturated Fatty Acids (HUFA) (13.87±0.68%) were seen in the Moina fed on astaxanthin and Cod Liver Oil (CLO). The results of the study showed that the nutritive quality of Moina, with respect to important fatty acids, can be increased by enrichment and will influence the growth, survival and the fatty acid composition of fresh water prawn larvae fed on them.

Fisheries profile mapping of coastal districts in Maharashtra state through GIS

In recent times, GIS is being increasingly used as a decision support system for management of fisheries and aquaculture. It provides new innovative approaches of the dynamic relations that characterize this sector. In this context, a study is conducted based on the secondary data of a major maritime state, Maharashtra, where mapping of fisheries profile of coastal districts in the state is performed through GIS tool having critical geographic dimensions. This paper aims to map information of the state which can be used for the purpose of planning and decision making as each aspect of map has a different component involved. For this purpose, at the core of the system, the data were accessed and integrated from different sources mainly from the five coastal districts of Maharashtra state. Data were brought in tabular form through Microsoft Excel and then joined to Map info Professional version 8.0 GIS software was used with the digitized map of Maharashtra state to enable mapping. This was further synchronized and integrated to generate four thematic maps searchable on several criteria. Map 1 contains the searchable criteria as regards to the fish growth for the year 1997-2004 and fish seed production for the year 2003-04. Map 2 contains fisher population along with their occupation for the year 1992. Map 3 contains brackish water and shrimp farming production and culture area. Map 4 contains infrastructural facilities which include type of boats etc. With this mapping, planners and various stakeholders have accessible information as regards to the various components of fisheries in the state of Maharashtra.

Assessment of the performance of beach management units (BMUs) on Lakes Victoria, Albert, Kyoga and George

Until the late 1990s the fisheries of Ugandan lakes had been managed by government where stakeholders were excluded from the decision-making process. In order to involve other stakeholders, co-management was adopted. Operationalising Co-management on landing sites has led to the formation of BMUs at gazetted landing sites. A BMU is made up of a BMU assembly and the BMU committee that it elects. A BMU committee should be: 30% boat owners; 30% boat barias 30% including fish processors, boat makers, local gear makers and repairers, fishing input dealers and managers and 10% fish mongers/traders; and if possible, 30% women. To operate at a particular landing site, one must be registered with the BMU. The BMU assembly is the supreme organ of a BMU empowered to elect, approve and remove the BMU committee