Demographic assessment of the blue crab (Callinectes sapidus) in Chesapeake Bay using extractable lipofuscins as age markers

The blue crab (Callinectes sapidus) plays an important economic and ecological role in estuaries and coastal habitats from the Gulf of Mexico to the east coast of North America, but demographic assessments are limited by length-based methods. We applied an alternative aging method using biochemical measures of metabolic byproducts (lipofuscins) sequestered in the neural tissue of eyestalks to examine population age structure. From Chesapeake Bay, subsamples of animals collected from the 1998–99 (n=769) and 1999–2000 (n=367) winter dredge surveys were collected and lipofuscin was measured. Modal analysis of the lipofuscin index provided separation into three modes, whereas carapace-width data collected among the same individuals showed two broad modes. Lipofuscin modal analysis indicated that most adults (carapace width >120 mm) were <2 years old. The results indicate that use of extractable lipofuscin can provide a more accurate and better resolved estimation of demographic structure of blue crab populations in the field than size alone.

Final report of the Fisheries Catch Assessment Survey in the Ugandan waters of Lake Victoria for the May 2011 survey

This report presents findings of the CAS conducted in the Ugandan waters of Lake Victoria in May 2011. The results of the previous eleven CASs conducted under the IFMP of the LVFO programme in July, August, September and November 2005; in March, August and December 2006; in March and August 2007; in February and December 2008; and March 2010 are included to show the emerging trends. The report also presents annual catch estimates for the Ugandan part of the lake from 2005 to 2011. Through these CASs, information is building up to show the emerging picture of fish production in the Ugandan waters of the lake. Similar surveys are conducted in the Kenyan and Tanzanian parts of the lake, which provide the lake wide perspective of fisheries production but this time not simultaneously as under the LVFO effort due to different sources and timing of funding. These data can now be utilised together with other Resource and Socio-economic Monitoring survey data for a stock assessment of the lake to provide a firm basis for planning and management of the fisheries resources.

A report on frame and catch assessment surveys on Nabugabo lakes, north west, Lake Victoria Basin, Uganda

The Nabugabo lakes are an important source of affordable protein food in the form of fish, income, water for domestic and commercial purposes (aquaculture farm and Hotels), handcraft materials (mats, hats, roof thatch) and fishing floats and rafts. Nabugabo lakes provide employment, income and export earnings to Uganda that flow from the act of harvesting the fish. In Uganda the fisheries sector directly employs 350,000 people and indirectly 1.2 million people. In 2005, it is estimated that about 370,000 mt fish export (97-98% Nile perch) earned Uganda US $ 143 Million up from US $ 103 million in 2004 .and up from US $ 45 million in 1996. , making it almost become the first non' traditional export commodity. The Nabugabo lakes are also import for cultural values and fish species from these lakes are important in evolutionary studies. The fishery sector is therefore very important in Uganda's socio-economic life. Despite the above values to the communities and global biodiversity roles, the amount of fish caught and the number fishing fleets operating on the Nabugabo lakes to guide management of the lake are lacking. The fishery that exists in these lakes is largely for subsistence and commercial purposes specific for Lake Nabugabo based on introduced species (Nile perch and Nile Tilapia). The fish is caught using mainly gill nets and long line hooks.

Impact of dead and sunken water hyacinth on biotic communities, the aquatic environment and socio-economic activities

The mobile water hyacinth, which was produced in growth zones, especially Murchison Bay, was mainly exported to three sheltered storage bays (Thruston, Hannington and Waiya). Between 1996 and May 1998, the mobile form of water hyacinth occupied about 800 ha in Thruston Bay, 750 ha in Hannington Bay and 140 ha in Waiya Bay). Biological control weevils and other factors, including localised nutrient depletion, weakened the weed that was confined to the bays and it sunk around October 1998. The settling to the bottom of such huge quantities of organic matter its subsequent decomposition and the debris from this mass was likely to have environmental impacts on biotic communities (e.g. fish and invertebrate), physico-chemical conditions (water quality), and on socio-economic activities (e.g. at fish landings, water abstraction, and hydro-power generation points). Sunken water. hyacinth debris could also affect nutrient levels in the water column and lead to reduction in the content of dissolved oxygen. The changes in nutrient dynamics and oxygen levels could affect algal productivity, invertebrate composition and fish communities. Socio-economic impacts of dead sunken weed were expected from debris deposited along the shoreline especially at fish landings, water abstraction and hydropower generation points. Therefore, environmental impact assessment studies were carried out between 1998 and 2002 in selected representative zones of Lake Victoria to identify the effects of the sunken water hyacinth biomass

Stock assessment of the demersal offshore fishery resources off the Karnataka coast

The total biomass of the demersal stocks in the depth range of 30-200m between 12°401 and 15°N latitudes in the Indian Exclusive Economic Zone is estimated to be a:round 1,23,000 metric tons (t). There is scope for doubling the present catch of about 40,000 t from demersal resources by extending exploitation to 50-200m depth zone. About 78% of this increase is expected to come from four species, namely, Nemipterus japonicus, Priacanthus macracanthus, Saurida tumbil and Arius spp.

Transboundary diagnostic analysis. Vol. 2. Background and environmental assessment

The Transboundary Diagnosis Analysis(TDA) quantifies and ranks water-related environmental transboundary issues and their causes according to the severity of environmental and/or socio-economic impacts. The three main issues in BOBLME are; overexploitation of marine living resources; degradation of mangroves, coral reefs and seagrasses; pollution and water quality. Volume 2 contains background material that sets out the bio-physical and socio-economic characteristics of the BOBLME; an analysis of the legal,policy and administrative context; and an assessment of the status of marine living resources and marine environment in coastal areas

Catch assessment survey of Uganda waters

The Artisanal Fisheries Rehabilitation Project (AFRP) Uganda Freshwater Fisheries Research Organisation (UFFRO) Survey was conducted during January - March 1989. The aim of the survey was to evaluate the impact of the AFRP on the national fisheries, assessing the current catch levels, and determining the socio-economic position of the fishermen. On the catch assessment, the survey collected information more specifically on the following: (i) Fish production in Uganda by major species groups. (li) Size structure of the harvested fish. (iii) Catch per unit of effort (CPUE) for the major fish species.

Final report of the fisheries catch assessment survey in the Ugandan waters of Lake Victoria for the May 2014 survey

This report presents findings of the CAS conducted in the Ugandan waters of Lake Victoria in December 2015. The results of the previous thirteen harmonized CASs conducted since July 2005 (July, August, September and November 2005; in March, August and December 2006; in March and August 2007; in February and December 2008; March 2010; May 2011 and May 2014) are included to show the emerging trends. The report also presents annual catch estimates for the Ugandan part of the lake from 2005 to 2015. This information together with other fish stock assessment and socio-economic monitoring survey data can now be utilized in the planning and management of the fisheries resources of Lake Victoria. The 2014 CAS results were very vital in the development of the Lake Victoria Fisheries Management Plan 2014.