C. Kemigabo, J. Kang’ombe, C. Masembe, L. Jere, D. Sikawa
Improving protein digestibility in nutrient poor fish feeds through incorporation of dietary enzymes is expected to be achieved with protease. Understanding the role of other dietary enzymes was therefore evaluated to guide appropriate use for optimal fish growth. Protein digestibility of 30, 35, 50 and 55% crude protein (CP) diets was determined with catfish gut enzyme extract, sprouted sorghum, protease and phytase both singly and in a mixture of 500 units of protease and phytase using the pH drop method in vitro. Significant (p<0.05) digestibilities were recorded in 30 and 35% CP diets incorporated with phytase and in 50 and 55% CP diets incorporated with protease singly. These results showed that protein digestibility was more efficient with protease enzyme in high protein diets while phytase was efficient in low protein diets. This implied that the use of protease was more beneficial in catfish starter feeds and phytase in grower/finisher diets and provided a basis for enzyme selection for production of cost-effective catfish diets. Key words: In-vitro protein digestion, catfish gut enzyme extract, phytase, protease, sprouted sorghum.
{"title":"Effects of protease enzyme supplementation on protein digestibility of legume and/or fish meal-based fish feeds","authors":"C. Kemigabo, J. Kang’ombe, C. Masembe, L. Jere, D. Sikawa","doi":"10.5897/IJFA2017.0620","DOIUrl":"https://doi.org/10.5897/IJFA2017.0620","url":null,"abstract":"Improving protein digestibility in nutrient poor fish feeds through incorporation of dietary enzymes is expected to be achieved with protease. Understanding the role of other dietary enzymes was therefore evaluated to guide appropriate use for optimal fish growth. Protein digestibility of 30, 35, 50 and 55% crude protein (CP) diets was determined with catfish gut enzyme extract, sprouted sorghum, protease and phytase both singly and in a mixture of 500 units of protease and phytase using the pH drop method in vitro. Significant (p<0.05) digestibilities were recorded in 30 and 35% CP diets incorporated with phytase and in 50 and 55% CP diets incorporated with protease singly. These results showed that protein digestibility was more efficient with protease enzyme in high protein diets while phytase was efficient in low protein diets. This implied that the use of protease was more beneficial in catfish starter feeds and phytase in grower/finisher diets and provided a basis for enzyme selection for production of cost-effective catfish diets. \u0000 \u0000 Key words: In-vitro protein digestion, catfish gut enzyme extract, phytase, protease, sprouted sorghum.","PeriodicalId":415026,"journal":{"name":"International Journal of Fisheries and Aquaculture","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130515099","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This study aimed at investigating the haematological profile of Heterobranchus bidorsalis fingerlings fed processed Delonix regia seeds at different inclusion levels of diets. Ten isonitrogenous diets (40% crude protein) were formulated with processed D. regia seed at 0% (Control), 10, 20 and 30% inclusion, respectively. The parameters analysed were pack cell volume (PCV), red blood cell (RBC), white blood cell (WBC), hemoglobin (HB), mean corpuscular volume (MCV), mean corpuscular heamoglobin (MCH) and mean corpuscular heamoglobin concentration (MCHC). Different among the groups were tested using analysis of variance. Raw Delonix regia seed meal had significant effect (P<0.05) on RBC, HB, MCV, MCH and MCHC respectively across the dietary treatments. RBC, MCV, MCH and MCHC differs significantly (P<0.05) across the dietary treatments for fish fed fermented D. regia seeds. All the haematological parameters differ significantly (P<0.05) across the dietary treatments with the exception of PCV, MCV and MCHC respectively for fish fed cooked D. regia seeds. It is therefore concluded that significant variations exist among the processing methods on the health status of the fish. It is recommended that inclusion of D. regia up to 20% will have no deleterious effect on their health status. Key words: Haematological profile, Delonix regia, processing methods, Heterobranchus bidorsalis, inclusion levels.
{"title":"Haematological profile of Heterobranchus bidorsalis fingerlings fed processed Delonix regia seeds at different inclusion levels of diets","authors":"B. Oyegbile, B. Abdullahi, I. Yola","doi":"10.5897/IJFA2017.0619","DOIUrl":"https://doi.org/10.5897/IJFA2017.0619","url":null,"abstract":"This study aimed at investigating the haematological profile of Heterobranchus bidorsalis fingerlings fed processed Delonix regia seeds at different inclusion levels of diets. Ten isonitrogenous diets (40% crude protein) were formulated with processed D. regia seed at 0% (Control), 10, 20 and 30% inclusion, respectively. The parameters analysed were pack cell volume (PCV), red blood cell (RBC), white blood cell (WBC), hemoglobin (HB), mean corpuscular volume (MCV), mean corpuscular heamoglobin (MCH) and mean corpuscular heamoglobin concentration (MCHC). Different among the groups were tested using analysis of variance. Raw Delonix regia seed meal had significant effect (P<0.05) on RBC, HB, MCV, MCH and MCHC respectively across the dietary treatments. RBC, MCV, MCH and MCHC differs significantly (P<0.05) across the dietary treatments for fish fed fermented D. regia seeds. All the haematological parameters differ significantly (P<0.05) across the dietary treatments with the exception of PCV, MCV and MCHC respectively for fish fed cooked D. regia seeds. It is therefore concluded that significant variations exist among the processing methods on the health status of the fish. It is recommended that inclusion of D. regia up to 20% will have no deleterious effect on their health status. \u0000 \u0000 Key words: Haematological profile, Delonix regia, processing methods, Heterobranchus bidorsalis, inclusion levels.","PeriodicalId":415026,"journal":{"name":"International Journal of Fisheries and Aquaculture","volume":"38 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125213330","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
There is evidence that ammonia, hydrogen sulphide and dissolved oxygen are implicated in fish kills occurring on the Lake Malawi shores of Karonga town. Exposure to fish is influenced by strong winds while water temperature differences cause upwelling and fish mortalities in surface waters. The vulnerability of fish in Karonga town to physico-chemical factors was computed from secondary sources data obtained in 2000 to 2016 regarding lethal and sub-lethal limits; this has helped to broaden our understanding of aquatic risk factors in this area. Equilibria relationships of ammonia (NH3 + H2O = NH4+ + OH-; K = 10-4.74; 2.70-4.28 µg.L-1 at depth of 100 to 200 m) and hydrogen sulphide (H2S = HS- + H+; K= 10-7.01; 54.9-82.5 mg.L-1 at a depth of 0-150 m) are imputed to have been implicated in the cause of a spate of fish kills. Uranium fallout might also be implicated but further analysis on actual exposure is needed to confirm this. Inferences of fish vulnerability have been drawn from studies done elsewhere on similar freshwater fish but under controlled conditions. While fish catches temporarily improved in 2007-2008 and 2010-2011, changes in fish diversity have been consistent, such as the disappearance of Ntchila (Labeo mesops), decline of Chambo (Oreochromis species) and the dominance of sardine type Usipa (Engraulicyprus sardella). Therefore, other sources of risks are over-fishing and climate change; the latter is evidenced by warming of the deep water columns, reduced dissolved oxygen and declining Lake Malawi water levels. The significance of fish by-catch recorded as ‘others’ indicates that a high number of fish species remain scientifically undescribed, hence the need for further taxonomic studies. Fish catches as per caput fish supply for Karonga District (19.5-38 kg) are above the current national average of 4.0 go 5.8 kg. Since fish provides Karonga communities with affordable animal protein, it significantly contributes to food security for the town. More than 5,500 people depend directly on fishing, representing 10% of the population of Karonga. Fisheries are a driver to rural commercialization for businesses of up to 22,000 people; hence, it is critical to people’s livelihoods and incomes at the local level. Therefore, this study confirms what has commonly been observed for Karaonga town; that fish as a nutrition and income source should be factored into studies dealing with risks to livelihoods of Karonga town communities; even where this might require indirect methods of assessment. Key words: Fish catches, Karonga town, Lake Malawi, fish diversity, per caput fish supply, thermodynamic concentrations (H2S/HS-; NH3/NH4+).
{"title":"A prognosis of the causes of vulnerability of Lake Malawi fish resources in Karonga town","authors":"O. Msiska, G. D. Kanyere, S. Ngwira, M. Manda","doi":"10.5897/IJFA2016.0587","DOIUrl":"https://doi.org/10.5897/IJFA2016.0587","url":null,"abstract":"There is evidence that ammonia, hydrogen sulphide and dissolved oxygen are implicated in fish kills occurring on the Lake Malawi shores of Karonga town. Exposure to fish is influenced by strong winds while water temperature differences cause upwelling and fish mortalities in surface waters. The vulnerability of fish in Karonga town to physico-chemical factors was computed from secondary sources data obtained in 2000 to 2016 regarding lethal and sub-lethal limits; this has helped to broaden our understanding of aquatic risk factors in this area. Equilibria relationships of ammonia (NH3 + H2O = NH4+ + OH-; K = 10-4.74; 2.70-4.28 µg.L-1 at depth of 100 to 200 m) and hydrogen sulphide (H2S = HS- + H+; K= 10-7.01; 54.9-82.5 mg.L-1 at a depth of 0-150 m) are imputed to have been implicated in the cause of a spate of fish kills. Uranium fallout might also be implicated but further analysis on actual exposure is needed to confirm this. Inferences of fish vulnerability have been drawn from studies done elsewhere on similar freshwater fish but under controlled conditions. While fish catches temporarily improved in 2007-2008 and 2010-2011, changes in fish diversity have been consistent, such as the disappearance of Ntchila (Labeo mesops), decline of Chambo (Oreochromis species) and the dominance of sardine type Usipa (Engraulicyprus sardella). Therefore, other sources of risks are over-fishing and climate change; the latter is evidenced by warming of the deep water columns, reduced dissolved oxygen and declining Lake Malawi water levels. The significance of fish by-catch recorded as ‘others’ indicates that a high number of fish species remain scientifically undescribed, hence the need for further taxonomic studies. Fish catches as per caput fish supply for Karonga District (19.5-38 kg) are above the current national average of 4.0 go 5.8 kg. Since fish provides Karonga communities with affordable animal protein, it significantly contributes to food security for the town. More than 5,500 people depend directly on fishing, representing 10% of the population of Karonga. Fisheries are a driver to rural commercialization for businesses of up to 22,000 people; hence, it is critical to people’s livelihoods and incomes at the local level. Therefore, this study confirms what has commonly been observed for Karaonga town; that fish as a nutrition and income source should be factored into studies dealing with risks to livelihoods of Karonga town communities; even where this might require indirect methods of assessment. \u0000 \u0000 Key words: Fish catches, Karonga town, Lake Malawi, fish diversity, per caput fish supply, thermodynamic concentrations (H2S/HS-; NH3/NH4+).","PeriodicalId":415026,"journal":{"name":"International Journal of Fisheries and Aquaculture","volume":"45 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126416000","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
D. Kassam, W. Changadeya, Hamad Stima, W. Jere, E. Kaunda
Fisheries management continues to be a nightmare due to over exploitation of fish stocks and various anthropogenic activities resulting in a reduction of genetic resources. Opsaridium microlepis, a commercially exploited fish species from Lake Malawi, is no exception, hence it is listed among as endangered species. Opsaridium microlepis stocks from four different rivers, were analyzed using 13 geometric morphometric landmarks and 20 microsatellite loci, to determine if the stocks were morphologically and/or genetically different. AMOVA performed on DNA data revealed a significant (P < 0.001) genetic differentiation with 16.4% of the total genetic variance ascribed to differences among populations, and 83.6% due to differences within population. This finding was supported by higher pairwise FST values (FST = 0.17). MANOVA of morphological data showed significant body shape variation among the stocks (Wilk’s λ = 0.0913; P < 0.0001). Pairwise comparisons using both methods indicated that all pairs were significantly different, except morphologically for Bua and Linthipe (P=0.3311). The morphological differences observed consisted of shorter gape and shorter head were thatof the Bua/Linthipe stock was seen in the North Rukuru and Dwangwa stocks. The morpho-genetic differentiation revealed in this study implies that the populations are distinct and should be considered as separate management and conservation units. Key words: Lake Malawi, Mpasa, procrustes distance, genetic differentiation, endangered species, fish stocks, conservation.
{"title":"Morphological and genetic variability among Mpasa (Opsaridium microlepis Gnther, 1864) populations from the inflow rivers of Lake Malawi","authors":"D. Kassam, W. Changadeya, Hamad Stima, W. Jere, E. Kaunda","doi":"10.5897/IJFA2017.0626","DOIUrl":"https://doi.org/10.5897/IJFA2017.0626","url":null,"abstract":"Fisheries management continues to be a nightmare due to over exploitation of fish stocks and various anthropogenic activities resulting in a reduction of genetic resources. Opsaridium microlepis, a commercially exploited fish species from Lake Malawi, is no exception, hence it is listed among as endangered species. Opsaridium microlepis stocks from four different rivers, were analyzed using 13 geometric morphometric landmarks and 20 microsatellite loci, to determine if the stocks were morphologically and/or genetically different. AMOVA performed on DNA data revealed a significant (P < 0.001) genetic differentiation with 16.4% of the total genetic variance ascribed to differences among populations, and 83.6% due to differences within population. This finding was supported by higher pairwise FST values (FST = 0.17). MANOVA of morphological data showed significant body shape variation among the stocks (Wilk’s λ = 0.0913; P < 0.0001). Pairwise comparisons using both methods indicated that all pairs were significantly different, except morphologically for Bua and Linthipe (P=0.3311). The morphological differences observed consisted of shorter gape and shorter head were thatof the Bua/Linthipe stock was seen in the North Rukuru and Dwangwa stocks. The morpho-genetic differentiation revealed in this study implies that the populations are distinct and should be considered as separate management and conservation units. \u0000 \u0000 \u0000 \u0000 Key words: Lake Malawi, Mpasa, procrustes distance, genetic differentiation, endangered species, fish stocks, conservation.","PeriodicalId":415026,"journal":{"name":"International Journal of Fisheries and Aquaculture","volume":"92 3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-05-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126029716","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The lack of better performing native fish species for aquaculture led the government of Malawi to import the exotic common carp (Cyprinus carpio L.) from Israel in 1976. Growth trials at Domasi and Kasinthula Experimental Stations had shown that common carp grew faster and to a larger size than the indigenous fish species. The government decided to distribute the fish to farmers for grow-out. Barely five years into common carp distribution to farmers, the government reversed its policy and banned the use of the species in aquaculture. The government not only became unpopular but also lost the confidence of the farmers who had begun to see positive impacts of common carp to their livelihoods. The farmers are as unconvinced today as they were before with the reasons behind the banning of common carp. This paper explores the background to common carp farming in Malawi, why the fish was later banned, and the impacts of the fish’s ban on the status of Malawi’s aquaculture. The paper further highlights the farmers’ call for a return of common carp to Malawi’s aquaculture and the research needed to be undertaken to inform government’s policy for the development of a sustainable aquaculture industry in Malawi. Key words: Aquaculture, common carp, fish introduction, exotic fish, Malawi.
{"title":"A review of the farming of common carp (Cyprinus carpio L.) in Malawi: Policy research directions for aquaculture development in Malawi","authors":"E. R. Chirwa, D. Kassam, W. Jere, A. Mtethiwa","doi":"10.5897/IJFA2017.0631","DOIUrl":"https://doi.org/10.5897/IJFA2017.0631","url":null,"abstract":"The lack of better performing native fish species for aquaculture led the government of Malawi to import the exotic common carp (Cyprinus carpio L.) from Israel in 1976. Growth trials at Domasi and Kasinthula Experimental Stations had shown that common carp grew faster and to a larger size than the indigenous fish species. The government decided to distribute the fish to farmers for grow-out. Barely five years into common carp distribution to farmers, the government reversed its policy and banned the use of the species in aquaculture. The government not only became unpopular but also lost the confidence of the farmers who had begun to see positive impacts of common carp to their livelihoods. The farmers are as unconvinced today as they were before with the reasons behind the banning of common carp. This paper explores the background to common carp farming in Malawi, why the fish was later banned, and the impacts of the fish’s ban on the status of Malawi’s aquaculture. The paper further highlights the farmers’ call for a return of common carp to Malawi’s aquaculture and the research needed to be undertaken to inform government’s policy for the development of a sustainable aquaculture industry in Malawi. \u0000 \u0000 \u0000 \u0000 Key words: Aquaculture, common carp, fish introduction, exotic fish, Malawi.","PeriodicalId":415026,"journal":{"name":"International Journal of Fisheries and Aquaculture","volume":"43 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-05-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123055451","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
K. Omolo, A. Onyango, G. Magoma, J. Munguti, K. Ogila
The present study evaluated the impact of varying dietary linseed oil composition on growth, survival and tissue polyunsaturated fatty acids (PUFA) profiles in Nile tilapia (Oreochromis niloticus). Five iso-nitrogenious diets with varying linseed and sunflower oil concentrations were formulated and fish fed twice daily to for 3 months. Commercial diet was used as a control in triplicate tanks set for each diet treatment. Growth parameters were measured from changes in body weight and length. A 75:25 ratio of sunflower oil to linseed oil gave a better survival and specific growth rate than 100% linseed oil or 100% sunflower oil. Tissue PUFA composition were determined using gas chromatography. High dietary linseed oil composition (100%) resulted into significantly high (P 50% reduced growth and survival rate in tilapia, however, it increased tissue accumulation of essential fatty acids which also increased with the length of feeding period. Key words: Growth, Tilapia, n3 fatty acids, linseed oil, polyunsaturated fatty acids (PUFA).
{"title":"Dietary effect of varying linseed oil compositions on growth response, survival and polyunsaturated fatty acid levels in Tilapia (Oreochromis niloticus)","authors":"K. Omolo, A. Onyango, G. Magoma, J. Munguti, K. Ogila","doi":"10.5897/IJFA2017.0621","DOIUrl":"https://doi.org/10.5897/IJFA2017.0621","url":null,"abstract":"The present study evaluated the impact of varying dietary linseed oil composition on growth, survival and tissue polyunsaturated fatty acids (PUFA) profiles in Nile tilapia (Oreochromis niloticus). Five iso-nitrogenious diets with varying linseed and sunflower oil concentrations were formulated and fish fed twice daily to for 3 months. Commercial diet was used as a control in triplicate tanks set for each diet treatment. Growth parameters were measured from changes in body weight and length. A 75:25 ratio of sunflower oil to linseed oil gave a better survival and specific growth rate than 100% linseed oil or 100% sunflower oil. Tissue PUFA composition were determined using gas chromatography. High dietary linseed oil composition (100%) resulted into significantly high (P 50% reduced growth and survival rate in tilapia, however, it increased tissue accumulation of essential fatty acids which also increased with the length of feeding period. \u0000 \u0000 \u0000 \u0000 Key words: Growth, Tilapia, n3 fatty acids, linseed oil, polyunsaturated fatty acids (PUFA).","PeriodicalId":415026,"journal":{"name":"International Journal of Fisheries and Aquaculture","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-04-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125430499","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper revisits and builds on the work of Ishmael Kosamu, Wouter de Groot and Patrick Kambewa who, in 2016, proposed a management system for the Elephant Marsh Wetland Fishery in Malawi, and identified key issues that would help the fishery to be sustainable in the short to medium term. They postulated that a sustainable three-pillared (locally based, weak, and amorphous) institution for the Elephant Marsh Wetland Fishery would rest on: (i) the social reputation of the leaders of local fishery institutions (beach village committee leaders), and (ii) the power dynamics between traditional chiefs and local fishery leaders. This paper suggests additional attributes and new insights which, if included in the design that Kosamu and his colleagues proposed, could make the institution more relevant in the long term. The suggested supplementary priorities embrace both financial and legal issues in the institutional development process. Key words: Elephant Marsh, institutions, Malawi, small-scale fisheries, sustainability, wetlands.
本文回顾了Ishmael Kosamu、Wouter de Groot和Patrick Kambewa的工作，他们在2016年提出了马拉维象沼泽湿地渔业的管理系统，并确定了有助于渔业在中短期内可持续发展的关键问题。他们假设一个可持续的大象沼泽湿地渔业的三支柱(以地方为基础，薄弱和无定形)制度将取决于:(i)当地渔业机构领导人(海滩村委会领导人)的社会声誉，以及(ii)传统酋长和当地渔业领导人之间的权力动态。这篇论文提出了额外的属性和新的见解，如果包括在Kosamu和他的同事提出的设计中，可以使该制度在长期内更具相关性。建议的补充优先事项包括体制发展进程中的财政和法律问题。关键词:大象沼泽，机构，马拉维，小规模渔业，可持续性，湿地
{"title":"Revisiting the three-pillared design of a management system for the Elephant Marsh Wetland Fishery in Malawi","authors":"I. Kosamu","doi":"10.5897/IJFA2016.0588","DOIUrl":"https://doi.org/10.5897/IJFA2016.0588","url":null,"abstract":"This paper revisits and builds on the work of Ishmael Kosamu, Wouter de Groot and Patrick Kambewa who, in 2016, proposed a management system for the Elephant Marsh Wetland Fishery in Malawi, and identified key issues that would help the fishery to be sustainable in the short to medium term. They postulated that a sustainable three-pillared (locally based, weak, and amorphous) institution for the Elephant Marsh Wetland Fishery would rest on: (i) the social reputation of the leaders of local fishery institutions (beach village committee leaders), and (ii) the power dynamics between traditional chiefs and local fishery leaders. This paper suggests additional attributes and new insights which, if included in the design that Kosamu and his colleagues proposed, could make the institution more relevant in the long term. The suggested supplementary priorities embrace both financial and legal issues in the institutional development process. \u0000 \u0000 \u0000 \u0000 Key words: Elephant Marsh, institutions, Malawi, small-scale fisheries, sustainability, wetlands.","PeriodicalId":415026,"journal":{"name":"International Journal of Fisheries and Aquaculture","volume":"216 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130339770","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Oreochromis variabilis Boulenger (1906) is an indigenous and critically endangered fish species of Lake Victoria. It is among the species targeted for stock enhancement and restoration in Kenya. Such mass stock enhancement requires simple and easily applicable techniques to maximize its larviculture. This study investigated the growth potential of O. variabilis from fry to fingerling stages using diets formulated from locally available feed materials during the rearing period. Fish fry reared on formulated diets incorporating Rastrineobola argentea Pellegrin and Caridina nilotica Roux as protein source and cassava as basal feed gave higher growth and survival rates than those maintained on plankton live feed alone. There were significant differences in the final mean lengths and weights of fish fed the three treatment diets. Diet 3 gave significantly higher final mean lengths and weights than Diets 1 and 2. Growth rates of fish fry fed diets 2 and 3 regimens were significantly higher than those fed diet 1. The best food conversion ratio and condition factor were maintained in fry populations reared on Diet 3. The study concluded therefore that, viability of larviculture of O. variabilis using simple formulated diets may be achieved, and that this result provides an important breakthrough in the propagation of its seed stock for mass culture towards stock enhancement and restoration to marketplace. Key words: Oreochromis variabilis, endangered species, rearing techniques, larviculture, stock enhancement, restoration.
{"title":"Growth performance of Oreochromis variabilis larvae: A case study of effect of live and formulated diets on growth and survival rates","authors":"J. Maithya, M. Mbithi N., Wanjala P.","doi":"10.5897/IJFA2016.0553","DOIUrl":"https://doi.org/10.5897/IJFA2016.0553","url":null,"abstract":"Oreochromis variabilis Boulenger (1906) is an indigenous and critically endangered fish species of Lake Victoria. It is among the species targeted for stock enhancement and restoration in Kenya. Such mass stock enhancement requires simple and easily applicable techniques to maximize its larviculture. This study investigated the growth potential of O. variabilis from fry to fingerling stages using diets formulated from locally available feed materials during the rearing period. Fish fry reared on formulated diets incorporating Rastrineobola argentea Pellegrin and Caridina nilotica Roux as protein source and cassava as basal feed gave higher growth and survival rates than those maintained on plankton live feed alone. There were significant differences in the final mean lengths and weights of fish fed the three treatment diets. Diet 3 gave significantly higher final mean lengths and weights than Diets 1 and 2. Growth rates of fish fry fed diets 2 and 3 regimens were significantly higher than those fed diet 1. The best food conversion ratio and condition factor were maintained in fry populations reared on Diet 3. The study concluded therefore that, viability of larviculture of O. variabilis using simple formulated diets may be achieved, and that this result provides an important breakthrough in the propagation of its seed stock for mass culture towards stock enhancement and restoration to marketplace. \u0000 \u0000 Key words: Oreochromis variabilis, endangered species, rearing techniques, larviculture, stock enhancement, restoration.","PeriodicalId":415026,"journal":{"name":"International Journal of Fisheries and Aquaculture","volume":"76 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115963522","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
T. O. Amoussou, A. Toguyéni, I. Toko, A. Chikou, Mivice Bravo, I. Y. A. Karim
Tilapia Sarotherodon melanotheron is naturally adapted to both fresh and brackish environments. In order to improve its farming potential, this study evaluated the growth, survival and reproductive parameters of individuals from three lakes of southern Benin according to their sex and age at experimental fishing. During fry rearing and breeding, fish were fed with commercial feed granulated. The chlorophyll a concentration and the abundance of plankton were determined by molecular absorption spectrometry and under a light microscope respectively. Physico-chemical parameters were within acceptable limits for good survival and growth of S. melanotheron. Together with chlorophyll a, three phytoplankton species and five zooplankton species were also available in the rearing tanks. At the end of the experiment (90 days post nursery), most of the growth parameters did not vary significantly according to the waterway of origin and the sex. However, the age at experimental fishing influenced significantly most of the growth parameters. The individuals from Lake Nokoue and Lake Toho were characterized by higher body weight, total length, standard length, weight gain, average weight gain, daily weight gain, nutritive quotient, survival rate, net biomass, biomass per square meter while Grand-Popo Lagoon individuals were characterized by higher ccondition factor and a weak ponderal and linear specific growth rates. Overall, reproductive parameters were higher in females than males. The majority of males were with empty testicles, while females with ova were expelled by manual pressure. S. melanotheron individuals from the considered lakes can be recommended for selective breeding program in fresh and brackish waters. Key words: Benin, Sarotherodon melanotheron, aquaculture, captivity, growth, reproductive parameters.
{"title":"Evaluation of zootechnical and reproductive parameters of wild populations of Sarotherodon melanotheron Rppell, 1852 of Southern Benin raised in captivity","authors":"T. O. Amoussou, A. Toguyéni, I. Toko, A. Chikou, Mivice Bravo, I. Y. A. Karim","doi":"10.5897/IJFA2016.0594","DOIUrl":"https://doi.org/10.5897/IJFA2016.0594","url":null,"abstract":"Tilapia Sarotherodon melanotheron is naturally adapted to both fresh and brackish environments. In order to improve its farming potential, this study evaluated the growth, survival and reproductive parameters of individuals from three lakes of southern Benin according to their sex and age at experimental fishing. During fry rearing and breeding, fish were fed with commercial feed granulated. The chlorophyll a concentration and the abundance of plankton were determined by molecular absorption spectrometry and under a light microscope respectively. Physico-chemical parameters were within acceptable limits for good survival and growth of S. melanotheron. Together with chlorophyll a, three phytoplankton species and five zooplankton species were also available in the rearing tanks. At the end of the experiment (90 days post nursery), most of the growth parameters did not vary significantly according to the waterway of origin and the sex. However, the age at experimental fishing influenced significantly most of the growth parameters. The individuals from Lake Nokoue and Lake Toho were characterized by higher body weight, total length, standard length, weight gain, average weight gain, daily weight gain, nutritive quotient, survival rate, net biomass, biomass per square meter while Grand-Popo Lagoon individuals were characterized by higher ccondition factor and a weak ponderal and linear specific growth rates. Overall, reproductive parameters were higher in females than males. The majority of males were with empty testicles, while females with ova were expelled by manual pressure. S. melanotheron individuals from the considered lakes can be recommended for selective breeding program in fresh and brackish waters. \u0000 \u0000 Key words: Benin, Sarotherodon melanotheron, aquaculture, captivity, growth, reproductive parameters.","PeriodicalId":415026,"journal":{"name":"International Journal of Fisheries and Aquaculture","volume":"41 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-01-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124520253","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This study was conducted at the coastal villages of Zanzibar Island to investigate changes in fish biodiversity. The methodology mostly involved face-to-face interviews and structured questionnaires. Findings of this research paper revealed that there are twenty seven families of fish species of economically importance in the study area of which Scombridae is the most dominate species. This research study shows that there is no significant difference on the distribution of fish biodiversity in the coastal villages of Kizimkazki vs. Matemwe p>0.86; Matemwe vs. Nungwi p>0.09 and Nungwi vs Kizimkasi p>0.06. Findings of the research study revealed that out of twenty seven families of fish species of economic importance to the household’s income of the fishermen; ten families of those fish species were reported by the highly experienced fishermen to have been depleted over the last four decades. The most devastated fish species perceived by the senior fishermen includes Green hump head parrot fish, Javelin grunter, Rosy dwaft monocle bream, Twinspot red snapper, Green job fish and bicolour. T-test revealed that there is a significant difference on the perception of the fishermen on the changed in fish biodiversity between the three generation. Significant result were found between younger age vs middle age p<0.002; high significant results were found between middle age vs old age p<0.002 and high significant were found between old age vs younger age p<0.000. Findings of the research study revealed that the highly experienced fishermen perceived that the main reasons for the decline of fish biodiversity in the coastal villages of Zanzibar Island were (a) increasing number of fishermen, (b) the uses of destructive fishing gear has devastated marine ecosystem, (c) increasing development of tourism industry have created a new demand for fish market, (d) climate variability and seasonality has contributed negatively on the decline of fish biodiversity. The research study concluded that further decline on fish biodiversity are likely to increase in future unless appropriate enforcement of laws and regulation are established. Key words: Biodiversity, marine fisheries, perception of fishermen changed, fish species.
本研究在桑给巴尔岛的沿海村庄进行，以调查鱼类生物多样性的变化。研究方法主要包括面对面访谈和结构化问卷调查。结果表明，研究区有27科具有经济价值的鱼类，其中以鲭科为优势种。研究结果表明:克孜姆卡兹基与马泰姆韦沿海村庄鱼类生物多样性分布差异不显著(p>0.86);Matemwe vs Nungwi p>0.09, Nungwi vs Kizimkasi p>0.06。研究结果表明，在27个对渔民家庭收入具有经济重要性的鱼类家庭中;据经验丰富的渔民报告，在过去四十年中，这些鱼类的十个科已经枯竭。资深渔民所察觉到的受破坏最严重的鱼类包括绿驼头鹦鹉鱼、标枪鲷鱼、玫瑰色矮鲷鱼、双色鲷鱼、绿工作鱼和双色鱼。t检验显示，渔民对鱼类生物多样性变化的认知在三代之间存在显著差异。青壮年与中年之间有显著差异p<0.002;中年与老年之间有显著性差异p<0.002，老年与青年之间有显著性差异p<0.000。研究结果表明，经验丰富的渔民认为，桑给巴尔岛沿海村庄鱼类生物多样性下降的主要原因是:(a)渔民数量的增加;(b)破坏性渔具的使用破坏了海洋生态系统;(c)旅游业的日益发展创造了新的鱼类市场需求;(d)气候变化和季节性对鱼类生物多样性的下降起了不利的作用。该研究的结论是，除非制定适当的法律和法规，否则鱼类生物多样性的进一步下降可能会在未来加剧。关键词:生物多样性;海洋渔业;渔民观念变化;
{"title":"Investigating changes in fish biodiversity in coastal villages of Zanzibar Island, Tanzania","authors":"John Sebit Benansio, N. Jiddawi","doi":"10.5897/IJFA2015.0529","DOIUrl":"https://doi.org/10.5897/IJFA2015.0529","url":null,"abstract":"This study was conducted at the coastal villages of Zanzibar Island to investigate changes in fish biodiversity. The methodology mostly involved face-to-face interviews and structured questionnaires. Findings of this research paper revealed that there are twenty seven families of fish species of economically importance in the study area of which Scombridae is the most dominate species. This research study shows that there is no significant difference on the distribution of fish biodiversity in the coastal villages of Kizimkazki vs. Matemwe p>0.86; Matemwe vs. Nungwi p>0.09 and Nungwi vs Kizimkasi p>0.06. Findings of the research study revealed that out of twenty seven families of fish species of economic importance to the household’s income of the fishermen; ten families of those fish species were reported by the highly experienced fishermen to have been depleted over the last four decades. The most devastated fish species perceived by the senior fishermen includes Green hump head parrot fish, Javelin grunter, Rosy dwaft monocle bream, Twinspot red snapper, Green job fish and bicolour. T-test revealed that there is a significant difference on the perception of the fishermen on the changed in fish biodiversity between the three generation. Significant result were found between younger age vs middle age p<0.002; high significant results were found between middle age vs old age p<0.002 and high significant were found between old age vs younger age p<0.000. Findings of the research study revealed that the highly experienced fishermen perceived that the main reasons for the decline of fish biodiversity in the coastal villages of Zanzibar Island were (a) increasing number of fishermen, (b) the uses of destructive fishing gear has devastated marine ecosystem, (c) increasing development of tourism industry have created a new demand for fish market, (d) climate variability and seasonality has contributed negatively on the decline of fish biodiversity. The research study concluded that further decline on fish biodiversity are likely to increase in future unless appropriate enforcement of laws and regulation are established. \u0000 \u0000 Key words: Biodiversity, marine fisheries, perception of fishermen changed, fish species.","PeriodicalId":415026,"journal":{"name":"International Journal of Fisheries and Aquaculture","volume":"28 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129563237","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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