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.

Determination of biological characteristics and blood groups of hilsa shad (Tenualosa ilisha) in the north of Persian Gulf (Bushehr coastal waters)

Hilsa shad, Tenuolosa ilisha, belongs to Clupeidae family and Alsinae subfamily is an euryhaline pelagic and anadromous species living in marine and freshwater waters. Regarding to study the biological characteristics of this species, this study was carried out in the Northern Persian Gulf within Bushehr province waters during years 2006-7. A total of 344 specimens were collected and transported to the laboratory for further different biological measurements consist of: reproduction (GSI, fecundity, maturity stages), feeding (stomach contents, food preference ...), aging; 58 morphometric and ٧ meristic measurements. The results indicate that minimum, maximum and mean body weight are 203, 953 and 481.35±147.64 g, respectively and this values for total length are 26.5, 45.1 and 35.99±3.98 cm. For food regimes, the most abundant phytoplankton foods belong to Bacillariophyta (83.74٪) and zooplanktons of Arthropoda (51٪). The mean RLG was measured about 1.53±0.22 and the mean feeding intensity was about 51.79±38.13. Also, the aging of studied fishes showed that they have 2 to 4 years and most of the samples had 2+ years. The reproduction studies showed that Indian shad is a batch spawner species. The average gonadosomatic index (GSI) is 1.64±1.382 and the main spawning season was determined for April-May.

Assessing potential of production in Lake Choghakhor

Phytoplankton productivity is the common and important factor being considered in determining the overall status of a given body of water. This is because they are found at the base of an energy or food chain, being the basic source of primary food in a given aquatic system. Hence, information on their contribution is essential in indicating how much biomass energy will be available to all other living resources in the system. Though the primary productivity of shallow lakes is characterized by mixed populations of phytoplankton and submersed aquatic vegetation in the open water. Lake Choghakhor, is a shallow lake, located in Chaharmahal-Bakhtiyari Province. This lake is the most important ecosystem in the region especially for waterfowl populations, has a recreational value and supports tourism and fisheries. During last decade Choghakhor has been influenced by some man-made impacts such as water level fluctuation, agricultural discharge and fish (Cyprinids) introduction causing a serious problem in its trophic states. So water quality for physical, chemical and biological was monitored in five sampling stations, from April 2003 to March 2004. As biological parameters we studied phytoplankton, epiphytic algae, and zooplankton and macrobenthose community structure. Chlorophyll a content for phytoplankton and epiphytes was measured to estimate production of these groups (biomass over time). Also we determined biomasses of submersed macrophytes and macrobenthose and primary production of phytoplankton (dark and light bottles technique) to estimate fish production. The results of this study showed Lake Choghakhor did not undergo stable thermal and oxygen stratification, and the lake water was mixed throughout the study (the lake mixing regime is polymictic). Now submerged plants especially Myriophyllum spicatum has covered almost the entire lake and dense macrophyte beds (Polygonom amphibium), located on the east southern end of the lake appear to act as a sink for these nutrients. Lake Choghakhor appeared to be in a macrophyte dominated clear water state with low TP (annual mean: 24± 15μg.l-1) and chlorophyll a (annual mean: 3±1.28μg.l-1) concentrations and very high Secchi depth. The grazing pressure of dominant pelagic filtering zooplankton Daphnia longespina did not seem to be significant in determining the low phytoplankton crop expressed as chlorophyll a. We expect that sequestering of nutrients by submerged plants and associated epiphytes are the dominant stabilizing mechanisms suppressing the phytoplankton crop of Lake Choghakhor.

Transboundary diagnostic analysis: executive summary

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.

Education and awareness programme on marine protected area management, Bar Reef Marine Sanctuary, Sri Lanka

The objectives of the education programme included: making the fishing community and the younger generation aware of the importance of conserving marine resources; to obtain their suggestions and opinions; and to identify gaps and needs to strengthen local participation.

Meeting on BOBLME engagement in the International Indian Ocean Expedition 50th anniversary initiative (IIOE-2), Bangkok, Thailand, 17-18 March, 2015

Objectives included; a contribution to understanding large-scale processes affecting the Bay of Bengal Large Marine Ecosystem Project (BOBLME) and it's living resources; and to align with International Indian Ocean Expedition (IIOE-2) (2015-2020) which will extensively explore and study the Indian Ocean to improve understanding of the ocean and coupled climate processes.

Our mother ocean: enclosure, commons, and the global fishermen's movement [book review]

The book is written by Mariarosa Dalla Costa and Monica Chilese; translated by Silvia Federici; Common Notions; NY.2014. It is a vigorous critique of where globalization and industrialization in fishing have led global water resources to, and the direct role that humankind has played in this destructive relationship.

Geographic and economic setting of Lake Victoria

Lake Victoria, besides being the second largest in the world after Lake Superior, is the largest tropical lake. Its waters are shared by Kenya (6% of the surface area), Uganda (43%), and Tanzania (51%). Before dramatic structural and functional changes manifested in the lake's ecosystem especially in the 1980s, fish life flourished in the lake's entire water column at all times of the year. Currently, the situation is much more different from what it was in the past. The exponential increase in the introduced Nile perch (Lates niloticus) and Nile tilapia (Oreochromis niloticus) stocks, siltation, wetland degradation and eutrophication have characterised the lake ecosystem. The two exotic species and the small native cyprinid (Rastrineobola argentea) form the basis of the commercial fishery that was once dominated by two native tilapiines (Oreochromis esculentus and Oreochromis variabilis) and five other large-bodied endemic fishes. Severe deoxygenation observed at shallow depths (Ochumba 1990; Hecky et al., 1994) indicates that a large volume of the lake is unable to sustain fish life. The Lake Victoria catchment is one of the most densely populated areas in East Africa, encompassing a population of about 30 million people. Widespread poverty resulting from high inflation rates, lack of opportunities and general unemployment have characterised the lakeside communities over much of the last two decades. The biophysical environment in which Lake Victoria exists makes the lake particularly susceptible to changes that occur as a result of human modification to the watershed or the lake itself, thus rendering benefits from the lake unsustainable.

Composition, biomass, distribution and population structure of the fish stocks

Until the 1970s, Lake Victoria had a multi-species fishery dominated by the tilapiine and haplochromine cichlids. There were important subsidiary fisheries for more than 20 genera of non-cichlid fishes, including catfishes (Bagrus docmak, Clarias gariepinus, Synodontis spp and Schilbe intermedius), the lungfish (Protopterus aethiopicus) and Labeo victorianus) (Kudhongania and Cordone 1974). Stocks of most of these species declined and others disappeared following the introduction of four tilapiines (Oreochromis niloticus, Oreochromis leucostictus, Tilapia rendalli and Tilapia zillit) and Nile perch (Lates niloticus) during the 1950s. Since then the commercial fishery in the Uganda portion of Lake Victoria has been dominated by the Nile perch, Nile tilapia (Oreochromis niloticus) and the native cyprinid species, Rastrineobola argentea (Mukene).

Evolution of the tilapia fishery with specific reference to the Nile tilapia (Oreochromis niloticus Linne)

As a fishery, the immensely large (c. 68,800 km2 ) Lake Victoria is a unique ecosystem which together with a riverine connection to the Lake Kyoga basin share a common endemic "Victorian" fish fauna (Greenwood 1966). Until the 1950s, the single socio economically most important species of fish in these two lakes was the native Oreochromis esculentus Graham (Graham 1929) even though the lake also contained a second native tilapiine, 0reochromis variabilis , and over 300 other fish species (Beauchamp, 1956).

Evolution and management of the mukene (Rastrineobola argentea) fishery

Rastrineobola argentea locally known as mukene in Uganda, omena in Kenya and dagaa in Tanzania occurs in Lake Nabugabo, Lake Victoria, the Upper Victoria Nileand Lake Kyoga (Greenwood 1966). While its fishery is well established on Lakes Victoria and Kyoga, the species is not yet exploited on Lake Nabugabo. Generally such smaller sized fish species as R. argentea become important commercial species in lakes where they occur when catches of preferred largersized table fish start showing signs ofdecline mostly as a result of overexploitation. With the current trends of declining fish catches on Lake Nabugabo, human exploitation of mukene on this lake is therefore just a matter of time. The species is exploited both for direct human consumption and as the protein ingredient in the manufacture of animal feeds.

Implications of changes in trophic diversity and food webs on fisheries and the environment

Most of the earth's ecosystems are experiencing slight to catastrophic losses of biodiversity, caused by habitat destruction, alien species introduction, climate change and pollution (Wilcove et al., 1998). These human effects have led to the extinction of native fish species, the collapse of their populations and the loss of ecological integrity and ecosystem functioning (Ogutu-Ohwayo & Hecky, 1991; Witte et al. , 1992a; Mills et al., 1994; Vitousek et al., 1996). Food webs are macro-descriptors of community feeding interactions that can be used to map the flow of materials and nutrients in ecosystems (Jepsen & Winemiller, 2002). Comparative food web studies have been used to address theoretical questions such as 'does greater trophic connectivity increase stability?' (Cohen et al., 1990), and 'does the number of trophic levels increase with productivity?' (Briand & Cohen, 1987). Answers to such questions have obvious applications for natural resources management. From a multi-species fisheries standpoint, there is a need to understand consumer-resource dynamics within complex trophic networks.

Changes in phytoplankton communities and primary production

Lake Victoria is the second largest lake in the world (69000km2) by surface area, but it is the shallowest (69m maximum depth) of the African Great Lakes. It is situated across the equator at an altitude of 1240m and lies in a shallow basin between two uplifted ridges of the eastern and western rift valleys (Beadle 1974). Despite their tropical locations, African lakes exhibit considerable seasonality related to the alteration of warm, wet and cool, dry seasons and the accompanying changes in lucustrine stratification and mixing (Tailing, 1965; 1966; Melack 1979; Hecky& Fee 1981; Hecky& Kling,1981; 1987; Bootsma 1993; Mugidde 1992; 1993). Phytoplankton productivity, biomass and species composition change seasonally in response to variations in light environment and nutrient availability which accompany changes in mixed layer depth and erosion or stabilization of the metalimnion / hypolimnion (Spigel & Coulter 1996; Hecky et al., 1991; Tailing 1987). Over longer, millennial time scales, the phytoplankton communities of the African Great Lakes have responded to variability in the EastAfrican climate (Johnson 1996; Haberyan& Hecky, 1986) which also alters the same ecological factors (Kilham et al., 1986). Recently, over the last few decades, changes in external and or internal factors in Lake Victoria and its basin have had a profound inlluence on the planktic community of this lake (Hecky, 1993; Lipiatou et al., 1996). The lake has experienced 2-10x increases in chlorophyll and 2x increase in primary productivity since Tailing's observations in the early 1960s (Mugidde 1992, 1993). In addition to observed changes in the lake nutrient chemistry (Hecky & Mungoma, 1990; Hecky & Bugenyi 1992; Hecky 1993; Bootsma & Hecky 1993), the deep waters previouslyoxygenated to the sediment surface through most of the year are now regularly anoxic(Hecky et al., 1994).

The status and significance of invertebrate communities

Invertebrates constitute a major link in energy flow culminating into fish production in aquatic ecosystems. In tropical water bodies relatively little research has been done on invertebrate ecology especially their role in fishery production. European scientists through periodic expeditions to Africa in the last quarter of the 20th century carried out the earliest research on zooplankton. Rzoska (1957) listed these early workers including Stuhlmann (1888), Weltner (1897) and Mrazek (1897-1898). Daday (1907), Verestchagin (1915) and Delachaux (1917) undertook further work during the early twentieth century. These earlyworks provide a useful basis for tracking community changes by comparison with modem investigations. Worthington (1931) provided the first quantitative account of the zooplankton of Lake Victoria along with information on diurnal vertical migrations, compared to a temperate lake. The establishment of the East African Freshwater Fisheries Research Organisation (EAFFRO) at Jinja in 1947 enabled investigations on the fisheries, algae, invertebrates and water quality aspects of the lake (EAFFRO Annual Reports 1947-1977) to be regularly carried out. Macdonald (1956) made the first detailed observations on the biology of chaoborids and chironomids (IakefJies) in relation to the feeding of the elephant snout fish, Mormyrus kannume. A detailed study of the biology of the mayfly, Povilla adusta Navas with special reference to the diurnal rhythms of activity was carried out by Hartland-Rowe (1957). The search to unravel the ecological role of aquatic invertebrates in the production dynamics of the lake has taken invertebrate research to greater heights through recent investigations including Okedi (1990), Mavut

Implications of the industrial fish processing growth for the commercial fishery and fishers in Uganda

The study was undertaken to generate socio-economic information on fish market systems and performance of the industrial processing industry, which will guide the processes leading to modernization of the fisheries sector and, sustainability of Lake Victoria fisheries. The main objective of this study was to evaluate the socio-economic implications of the fish marketing systems with particular emphasis on fish export market in Uganda. The study thus, analysed the socio-economic characteristics of fishers and examinined fish marketing systems and the impacts on the fishing activities, food security, employment opportunities and incomes of fisher-folk communities.