839 resultados para Murray cod - Reproduction


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Developing guidelines for sustainable freshwater aquaculture planning in Vietnam. Aquaculture production, certification and trade: Challenges and opportunities for the small-scale farmer in Asia. The successful development of backyard hatcheries for crustaceans in Thailand. Alternate carp species for diversification in freshwater aquaculture in India. Genetic and reproduction technologies for enhanced aquaculture and fisheries management of Murray cod. Effluent and disease management in traditional practices of shrimp farming: A case study on the west coast of Sabah, Malaysia. Status of sahar domestication and its development in the Himalayan Region of Nepal. Vaccination benefits highlighted as Schering-Plough reinforces commitment to Asian aquaculture. Comparative advantage analysis of shrimp production in Asia. Strategies to improve livelihood of the rural poor: A case study in two small reservoirs in Binh Phuoc Province, Vietnam. Cambodian Government ban on snakehead farming enforced. Marine finfish aquaculture developments at ‘Indonesian Aquaculture 2007’. Production update – marine finfish aquaculture in the Asia-Pacific region. Body size of rotifers from estuaries in North Sulawesi. NACA Newsletter.

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Eel tailed catfish, silver perch and Murray cod are three key recreational fishing species that have declined in the Murray-Darling Basin region. This research project will be an important step towards developing methods to restore and enhance stocks of these fish.

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The reproduction biology of cod is one of the main re-search topics of the Institute of Baltic Sea Fisheries at Rostock. It was defined 10 years ago when the Institute was formed. Since then results have been published in a number of publications. This paper summarizes the main results of the past decade ant outlines necessities for future research in cod reproduction biology in the Baltic Sea.

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This study evaluated the effects of two lipids sources of fish residue (tilapia and salmon) compared with a vegetable oil source (soybean oil) on the fatty acid profiles of male and female lambari. This experiment was developed in a completely randomized experimental design in a 3 x 2 factorial arrangement, totaling 6 treatments resulting from the combination of the three experimental diets for both sexes, with four replications for each treatment. This study involved 120 male (2.58 +/- 0.13 g) and 72 female lambari (4.00 +/- 0.09 g), fed the experimental diets twice a day until apparent satiation for a period of 60 days. Oleic, linoleic, palmitic and stearic fatty acids were found at higher concentrations in all experimental oils and diets, as well in the muscle of male and female lambari. The low amounts of arachidonic, eicosapentaenoic and docosahexaenoic acids in the experimental diets and subsequent greater concentrations in muscle tissue, suggested that lambari are able to desaturate and elongate the chain of fatty acids with 18 carbons. The fish of both sexes that received the diet with soybean oil showed high levels of n-6 fatty acids, especially of C18: 2n-6 and low levels of eicosapentaenoic and docosahexaenoic acids. The diet with salmon residue oil promoted higher levels of fatty acids of the n-3 series and resulted in the best n-3/n-6 ratio in the muscle of male and female lambari. The oils from fish residues can be a substitute for traditional fish oil and its use in the lambari diets does not impair its growth.

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Ocean acidification, caused by increasing atmospheric concentrations of CO2 (refs 1-3), is one of the most critical anthropogenic threats to marine life. Changes in seawater carbonate chemistry have the potential to disturb calcification, acid-base regulation, blood circulation and respiration, as well as the nervous system of marine organisms, leading to long-term effects such as reduced growth rates and reproduction(4,5). In teleost fishes, early life-history stages are particularly vulnerable as they lack specialized internal pH regulatory mechanisms(6,7). So far, impacts of relevant CO2 concentrations on larval fish have been found in behaviour(8,9) and otolith size(10,11), mainly in tropical, non-commercial species. Here we show detrimental effects of ocean acidification on the development of a mass-spawning fish species of high. commercial importance. We reared Atlantic cod larvae at three levels of CO2, (1) present day, (2) end of next century and (3) an extreme, coastal upwelling scenario, in a long-term (2; months) mesocosm experiment. Exposure to CO2 resulted in severe to lethal tissue damage in many internal organs, with the degree of damage increasing with CO2 concentration. As larval survival is the bottleneck to recruitment, ocean acidification has the potential to act as an additional source of natural mortality, affecting populations of already exploited fish stocks.

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Barents cod spawn in the Motovsky Bay during the periods of warming in the Arctic when proportion of mature fish in the population is high enough. Cod spawning is most likely to occur in the Motovsky Bay when large cod forage in southeastern waters, and prespawning fish migrate close by the Murmansk coast. Under such conditions cod spawn in the Motovsky Bay, but low water temperature and slow egg drift toward Murmansk coastal waters delay development of cod eggs. As a result the eggs remain at the first stage for a long time; this causes high egg mortality before hatching. Larvae that survive and become pelagic and then bottom juveniles nevertheless have little chance to survive in winter because they are not biologically ready for overwintering. Thus, delay in egg development at the first stage delays subsequent stages of fish ontogeny, and strongly impairs survival of cod juveniles from the Motovsky Bay.

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Vol. 2-3 published : London : Philip Lee Warner; New York : G.P. Putnam's Sons

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The exponential growth of studies on the biological response to ocean acidification over the last few decades has generated a large amount of data. To facilitate data comparison, a data compilation hosted at the data publisher PANGAEA was initiated in 2008 and is updated on a regular basis (doi:10.1594/PANGAEA.149999). By January 2015, a total of 581 data sets (over 4 000 000 data points) from 539 papers had been archived. Here we present the developments of this data compilation five years since its first description by Nisumaa et al. (2010). Most of study sites from which data archived are still in the Northern Hemisphere and the number of archived data from studies from the Southern Hemisphere and polar oceans are still relatively low. Data from 60 studies that investigated the response of a mix of organisms or natural communities were all added after 2010, indicating a welcomed shift from the study of individual organisms to communities and ecosystems. The initial imbalance of considerably more data archived on calcification and primary production than on other processes has improved. There is also a clear tendency towards more data archived from multifactorial studies after 2010. For easier and more effective access to ocean acidification data, the ocean acidification community is strongly encouraged to contribute to the data archiving effort, and help develop standard vocabularies describing the variables and define best practices for archiving ocean acidification data.

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Ocean acidification, caused by increasing atmospheric concentrations of CO2, is one of the most critical anthropogenicthreats to marine life. Changes in seawater carbonate chemistry have the potential to disturb calcification, acid-base regulation, blood circulation and respiration, as well as the nervous system of marine organisms, leading to long-term effects such as reduced growth rates and reproduction. In teleost fishes, early life-history stages are particularly vulnerable as they lack specialized internal pH regulatory mechanisms. So far, impacts of relevant CO2concentrations on larval fish have been found in behaviour and otolith size, mainly in tropical, non-commercial species. Here we show detrimental effects of ocean acidification on the development of a mass-spawning fish species of high commercial importance. We reared Atlantic cod larvae at three levels of CO2, (1) present day, (2) end of next century and (3) an extreme, coastal upwelling scenario, in a long-term ( 2.5 1/2 months) mesocosm experiment. Exposure to CO2 resulted in severe to lethal tissue damage in many internal organs, with the degree of damage increasing with CO2 concentration. As larval survival is the bottleneck to recruitment, ocean acidification has the potential to act as an additional source of natural mortality, affecting populations of already exploited fish stocks.

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The accumulation of carbon dioxide in the atmosphere will lower the pH in ocean waters, a process termed ocean acidification (OA). Despite its potentially detrimental effects on calcifying organisms, experimental studies on the possible impacts on fish remain scarce. While adults will most likely remain relatively unaffected by changes in seawater pH, early life-history stages are potentially more sensitive, due to the lack of gills with specialized ion-regulatory mechanisms. We tested the effects of OA on growth and development of embryos and larvae of eastern Baltic cod, the commercially most important fish stock in the Baltic Sea. Cod were reared from newly fertilized eggs to early non-feeding larvae in 5 different experiments looking at a range of response variables to OA, as well as the combined effect of CO2 and temperature. No effect on hatching, survival, development, and otolith size was found at any stage in the development of Baltic cod. Field data show that in the Bornholm Basin, the main spawning site of eastern Baltic cod, in situ levels of pCO2are already at levels of 1,100 µatm with a pH of 7.2, mainly due to high eutrophication supporting microbial activity and permanent stratification with little water exchange. Our data show that the eggs and early larval stages of Baltic cod seem to be robust to even high levels of OA (3,200 µatm), indicating an adaptational response to CO2.

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Jean Anyon’s (1981) “Social class and school knowledge” was a landmark work in North American educational research. It provided a richly detailed qualitative description of differential, social-class-based constructions of knowledge and epistemological stance. This essay situates Anyon’s work in two parallel traditions of critical educational research: the sociology of the curriculum and classroom interaction and discourse analysis. It argues for the renewed importance of both quantitative and qualitative research on social reproduction and equity in the current policy context.