Western Indian Ocean journal of marine science最新文献

{"title":"Effects of different types of manure on the culture of marine plankton as a potential source of food for mariculture hatcheries","authors":"Fadhili M. Malesa, M. Kyewalyanga, R. Masalu, M. Mtolera","doi":"10.4314/WIOJMS.V20I1.8","DOIUrl":"https://doi.org/10.4314/WIOJMS.V20I1.8","url":null,"abstract":"The study examined different types of organic manure on the culture of marine plankton as a potential source of food for rabbitfish, Siganus stellatus, larvae. Cow dung showed significantly higher species abundance and diversity of cultured marine plankton followed by chicken and finally mixed media manure (p<0.05). A total of 36 genera of phytoplankton (21) and zooplankton (15) were identified in all culture media. Class Bacillariophyta was the most abundant and diverse group which accounted for 41.3 % of the total phytoplankton. Calanoida was the dominant group of the identified zooplankton, accounting for 51.7 %. It was observed that the organic manure used favoured the growth of commercially important species of phytoplankton such as Chaetoceros sp., Skeletonema sp., Chlorella sp., Isochrysis sp., Nannochloropsis sp. and Spirulina sp., and zooplankton such as Eurytemora sp., Calanus sp., Oithona sp., Branchionus sp., Moina sp. and ostracods. The growth performance and survival rate of early stage rabbitfish larvae fed with live marine zooplankton performed better compared to those fed with Artemia spp. and commercial dry feed. This indicates that zooplankton have the potential to enhance growth performance and survival rate, hence increasing productivity and the development of mariculture.","PeriodicalId":200681,"journal":{"name":"Western Indian Ocean journal of marine science","volume":"31 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-08-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127139511","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}

{"title":"Growth, mortality, exploitation rate and recruitment pattern of Octopus cyanea (Mollusca: Cephalopoda) in the WIO region: A case study from the Mafia Archipelago, Tanzania","authors":"M. Silas, M. Kishe, J. Mshana, M. Semba, S. Mgeleka, B. Kuboja, B. Ngatunga, Muhaji A. Chande, Patroba Matiku","doi":"10.4314/WIOJMS.V20I1.7","DOIUrl":"https://doi.org/10.4314/WIOJMS.V20I1.7","url":null,"abstract":"Octopus cyanea is a commercially important cephalopod in the Western Indian Ocean (WIO) region, but scientific information to inform management strategies for the species is limited. A study was conducted in 2014, 2015, 2017 and 2018 to investigate biological parameters including growth, mortality, exploitation rates and recruitment patterns in the sea around Mafia Archipelago, Tanzania. Virtual population analysis (VPA) indicated differential mortality between two sampling sites; the lowest and highest fishing mortality of F = 1.5yr-1 and F = 2.7yr-1 were observed in Bwejuu (Dorsal mantle length, DMT = 18-20 cm) and Jibondo (DMT = 8-12 cm) fishing villages, respectively. The maximum exploitation rate (Emax), which gives the maximum relative yield per recruit, was estimated at 0.380 and 0.379 for Jibondo and Bwejuu, respectively. The exploitation rates E 0.5, which corresponded to 50% of the unexploited stock relative biomass per recruit, were estimated at 0.248 for Jibondo and 0.247 for Bwejuu. These values differ greatly from the exploitation rates of 0.53 and 0.41 for Jibondo and Bwejuu, respectively, suggesting that the stock of O. cyanea is probably being overfished both in terms of yield per recruit and biomass per recruit. The stock-recruit pattern was observed to be continuous year-round, with the peak being between May and July. Since the peak in recruitment of both areas coincides with the south-east monsoon (SE Monsoon) and the level of maximum sustainable yield has been overshot, it is recommended that management plans are implemented that will reduce effort while increasing biomass, for example, implementing temporal octopus fishery closures at a village level.","PeriodicalId":200681,"journal":{"name":"Western Indian Ocean journal of marine science","volume":"116 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-08-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121327289","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}

{"title":"Quick and cost-effective mapping of subsistence and artisanal fishing areas within and adjacent to a marine protected area","authors":"Marcos A. M. Pereira, T. Pereira, C. Louro, C. Litulo, Raquel S. Fernandes","doi":"10.4314/WIOJMS.V20I1.6","DOIUrl":"https://doi.org/10.4314/WIOJMS.V20I1.6","url":null,"abstract":"Spatial information on artisanal fisheries is largely lacking, making subsequent management and threat or impact assessments difficult. Local knowledge, current and readily available mapping software and Global Positioning System (GPS) techniques were used to map small-scale (subsistence and artisanal) fishing areas within and adjacent to the western boundary of the Ponta do Ouro Partial Marine Reserve in southern Mozambique. Data on habitat types were collected in the field and combined with available literature. Thirty-one fishing areas were identified and mapped resulting in a total area of 293.1 km2 with a perimeter of 396.7 km, from the Inhaca Island lighthouse in the north to the Maputo River mouth in the south. Habitats within the fishing areas included isolated intertidal sand banks, seagrass beds, estuarine channels, as well as intertidal muddy areas adjacent to the coast. The fishing areas covered on average 9.5 km2 (SD=12.0) and varied immensely in size (0.3–50.1 km2). Overall, 58.4 % (171.2 km2) of the total fishing area mapped was located inside the reserve. Costs associated with data collection equated to an average of U$D 3.61 per mapped km2 or U$D 2.63 per km tracked. The method was found to be quick, cost-effective and easily replicable elsewhere.","PeriodicalId":200681,"journal":{"name":"Western Indian Ocean journal of marine science","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-08-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132295092","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}

{"title":"Efficacy of Lactobacillus plantarum and Saccharomyces cerevisiae on growth improvement of hybrid Nile and Rufiji tilapia populations","authors":"L. L. Mapenzi, M. Mtolera, D. D. Koning, A. Mmochi","doi":"10.4314/WIOJMS.V20I1.4","DOIUrl":"https://doi.org/10.4314/WIOJMS.V20I1.4","url":null,"abstract":"An investigation of the role of Lactobacillus plantarum and Saccharomyces cerevisiae on growth performance of hybrids from Oreochromis niloticus and Oreochromis urolepis urolepis was carried out in plastic tanks at 10 fish/m3 density and a salinity of 25 units. The probiotic treatments were 2, 4 and 6 g/kg feed while the control feed did not include any probiotics. Growth parameters were measured fortnightly and water quality parameters monitored every day. Survival rate and water quality factors revealed non-significant variations (p > 0.05). Final weight differed significantly among the treatments (p 0.05) between the control and 2 g/kg treatments. However, the 4 and 6 g/ kg feed treatments showed significant differences (p 0.05) among the treatments. Results of this study indicate that increasing the quantity of commercial probiotics in feeds improved growth rates. Condition factor observed in the treatments could be due to the role of the tested probiotics in improving the water quality of tanks. Therefore, probiotics could potentially be used to enhance coastal aquaculture development.","PeriodicalId":200681,"journal":{"name":"Western Indian Ocean journal of marine science","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-08-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114036486","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}

{"title":"Stock assessment of the Tigertooth croaker, Otolithes ruber (Bloch & Schneider, 1801) from the commercial prawn trawl fishery by-catch in coastal Kenya","authors":"F. Mzingirwa, Jane M. Nyamora, J. Omukoto, Paul M. Tuda","doi":"10.4314/WIOJMS.V19I2.11","DOIUrl":"https://doi.org/10.4314/WIOJMS.V19I2.11","url":null,"abstract":"Commercial bottom prawn trawling has been reported to generate a higher proportion of by-catch of up to 70% in Kenya. The Tigertooth croaker, Otolithes ruber is one of the species caught in large quantities as commercial by-catch and also by artisanal fishers. This has led to growing concern that the species could be at risk of over-exploitation. The purpose of this study was to carry out a stock assessment of O. ruber. Stock assessment parameters were estimated using ELEFAN with the generic algorithm as included in the R package TropFishR. The length-converted catch curve and the length-based yield per recruit model were employed. The exploitation rate (F/Z = 0.71) indicates that the stock is overfished based on the length-converted catch curve. The current fishing mortality (F = 2.3) based on the catch curve is larger than the reference level ( = 1.1) based on the yield per recruit analysis and also indicates that the stock is overfished (= 2.09). To reverse the current trend of exploitation, improved management of the stock is required, which should include further studies on other by-catch species and the generation of data to capture the whole fishery for a better estimation of stock status.","PeriodicalId":200681,"journal":{"name":"Western Indian Ocean journal of marine science","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114643801","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}

{"title":"Nematodes as bio-indicators of physical disturbance of marine sediments following polychaete bait harvesting","authors":"M. Wafula, A. Muthumbi, V. Wang'ondu, C. Kihia, J. Okondo","doi":"10.4314/WIOJMS.V19I2.9","DOIUrl":"https://doi.org/10.4314/WIOJMS.V19I2.9","url":null,"abstract":"Sediment disturbance in marine environments is caused by activities including polychaete bait harvesting, trawling, dredging, sediment erosion and treading. These activities affect the benthic communities by changing the densities, community assemblage and diversity. The aim of this study was to evaluate the potential of nematodes as indicators of sediments disturbance following polychaete bait harvesting. The study was conducted in three sites experiencing different bait harvesting intensities in Mida Creek, Kenya. Sediment samples were collected from the mudflats during low tide, preserved in 5% formalin and transported to the laboratory for processing and identification of nematodes. The highly disturbed site recorded the lowest nematode genus richness while the less disturbed sites had the highest. Overall, the most abundant nematode genera in the non-disturbed (Dabaso) and less disturbed sites (Kirepwe) were selective deposit feeders (Spirinia and Terschellingia), while most disturbed sites (e.g. Mayonda) had predators/omnivores (Pheronus, Aporcelaimellus) and selected members of the genus Spirinia. The disturbed site was characterised by low nematode diversity (H’) and low dominance (D) while the non-disturbed and less disturbed sites had higher diversity and dominance. Clearly, nematode community assemblage, diversity and feeding guilds changed following disturbance to a low diversity that favoured higher proportions of predator/omnivore taxa.","PeriodicalId":200681,"journal":{"name":"Western Indian Ocean journal of marine science","volume":"59 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125013908","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}

{"title":"Movement patterns and growth rate of cavebass Dinoperca petersi (Pisces: Dinopercidae) in the iSimangaliso Marine Protected Area, South Africa","authors":"B. Mann, G. Jordaan, R. Daly","doi":"10.4314/WIOJMS.V19I2.4","DOIUrl":"https://doi.org/10.4314/WIOJMS.V19I2.4","url":null,"abstract":"Dinoperca petersi is a relatively common fish species caught in the line-fishery in KwaZulu-Natal (KZN), South Africa. Yet, little is known about the biology and ecology of this species. Movement patterns and growth rate of this species were studied based on data obtained from a long-term tag-recapture study conducted in the iSimangaliso Marine Protected Area in northern KZN between 2001-2019. Results showed that D. petersi is a highly resident species with a linear home-range size of 290-405 m. While most fish showed high site fidelity, 8.8 % of the tagged fish showed wider ranging movements of 2.4-90 km. However, only 5 fish showed movements out of no-take zones into adjacent exploited areas, suggesting limited adult spillover. Growth rate of tagged fish was found to be reasonably slow compared to other sympatric predatory reef fish with an average growth rate of 61.76 mm y–1 for smaller fish (gα = 300) and 9.58 mm y–1 for larger fish (gβ = 550). Based on these life history characteristics, options for the future conservation and management of this species are discussed.","PeriodicalId":200681,"journal":{"name":"Western Indian Ocean journal of marine science","volume":"157 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114907754","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}

{"title":"Conservation of cultural heritage for community socio-economic prosperity: The case of Lamu East and West Sub-Counties, Lamu County, Kenya","authors":"S. M. Bunu, A. H. Ong'ayo, H. Shauri","doi":"10.4314/WIOJMS.V19I2.5","DOIUrl":"https://doi.org/10.4314/WIOJMS.V19I2.5","url":null,"abstract":"Worldwide, cultural heritage has become both an element and a tool for achieving socio-economic prosperity.This study assessed the contribution of conservation of cultural heritage as a resource for the development of Lamu County. A descriptive survey design was used to conduct the study. Proportionate and systematic random sampling procedures were used to sample key informants and households selected from a sampling frame obtained from Lamu West and East Sub-Counties. An interview schedule and a semi-structured questionnaire were used to collect data from key informants and households respectively. Data were analysed using descriptive statistics and narratives. The results revealed that cultural heritage conservation contributes to job creation both directly and indirectly. However, cultural barriers contributed to observed exclusivity in benefitting from income generated from tangible and non-tangible activities. Revenue gains from the cultural heritage are also limited by the poor state of sites such as Pate and Ishakani ruins. The study recommends development and implementation of training programmes in cultural heritage conservation activities to ensure the community is educated and empowered to utilize cultural heritage for socio-economic development. The Government should also institute proper revenue sharing mechanisms to enhance socio-economic development of the Lamu County community.","PeriodicalId":200681,"journal":{"name":"Western Indian Ocean journal of marine science","volume":"12 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121121163","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}

{"title":"A socio-ecological system perspective on trade interactions within artisanal fisheries in coastal Kenya","authors":"John Ndarathi, Cosmas Munga, J. Hugé, F. Dahdouh-Guebas","doi":"10.4314/WIOJMS.V19I2.3","DOIUrl":"https://doi.org/10.4314/WIOJMS.V19I2.3","url":null,"abstract":"Assessments of coastal artisanal fisheries are progressively adopting a social-ecological system (SES) approach as an effective means to accumulate knowledge and integrate findings on different aspects of the fisheries. Ostrom’s SES framework was used to guide assessment of interactions between and within the harvesting and supply-chain processes and the effect of external drivers, seasonal monsoons and tourism, on both processes in a coastal artisanal fishery system in Gazi Bay, Kenya. Specific analyses focused on seasonal catch composition, key resource user groups involved in the fish trade and the resource units traded by each user group. The snowball method was used to identify key resource user groups within the fishery sector, who were then interviewed using semi-structured questionnaires (n = 60). Additionally, existing annual shore-based catch assessment and monthly fish landings data for the years 2014 and 2015 were incorporated for analysis of artisanal catch properties (species composition and weight). Comparison of seasonal catch composition was carried out using sample-based rarefaction curves. Higher fish landings and higher species diversity were recorded during the North-East Monsoon season. Further, a simple fish harvesting-supply network comprising of six key resource user groups (i.e. hotels, fish processing companies, dealers, small-scale fish processors (mama karanga), fish mongers and fishers) was outlined. The tourism industry, through hotels, creates a high demand for fish coinciding with a higher catchability and supply during the calm North-East Monsoon season and consequently, dealers hire migrant fishermen to target pelagic fish. Evidence of interactions within and between different fishery sub-systems, as well as the effect of monsoon seasons and tourism on the exploitation and market dynamics of the multispecies fishery, highlight the need for comprehensive management plans to strengthen self-organization among resource users and to increase adaptive capacity within the fishery system.","PeriodicalId":200681,"journal":{"name":"Western Indian Ocean journal of marine science","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127769008","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}

{"title":"The influence of habitat preference on longitudinal population composition and distribution of Groupers (Serranidae) in Chumbe Island Coral Park, Zanzibar, Tanzania","authors":"Caroline Daley","doi":"10.4314/WIOJMS.V19I2.1","DOIUrl":"https://doi.org/10.4314/WIOJMS.V19I2.1","url":null,"abstract":"Kiswahili) Uchunguzi wa aina sita za kawaida za chewa (Serranidae) zilifanyika kwenye miamba ya magharibi iliyohifadhiwa na mashariki inayozunguka kisiwa cha Chumbe. Aina, inakadiriwa ukomavu, na upendeleo mazingira asilia ambapo aina za chewa huishi ulirekodiwa kwa kutumia vigawanyo sanifu vinavyolingana. Msingi wa viumbe kuweza kukaa katika mazingira na kupedelea kutoweka kwa mazingira ya kiikologia ya jumla ulifanywa kwa ziada kulingana kukisia na kuangalia pamoja na kutambua viumbe kuweza kukaa katika mazingira naeneo ambalo viumbe kukukua, kupata chakula na kuweza kuishi, kina, mteremko mkali , na miamba. Wingi na Uzito wa idadi jamii ya chewa walilinganishwa miongoni mwa maeneo wanayoishi kwenye miamba na ucgaguzi maeneo ya kimazingira na kuzingatia jinsi gani mazingira yanavyoathiri ueneaji na ubora wa maeneo kimazingira. Matokeo ya utafiti huu yametowa taarifa za kina juu ya utafiti uliofanywa kwenye mwamba uliohifadhiwa na zinaonyesha mabadiliko muhimu kati ya mwaka 2014 na 2018 inazifanya aina chache zinazoishi kwenye maeneo maalum Utafiti wa miamba ya karibu isiyohifadhiwa ya mashariki ya Chumbe inaonyesha kiwango cha chini aina za viumbe, utafiti huu huthibitishan matokeo ya muundo kimazingira usiofaa, kuongezeka kwa shughuli za uvuvi, na kupungua kwa ubora wa kimazingira kwa eneo hifadhi ya bahari. Hatimaye, utafiti huu unashauri ufuatiliaji wa aina za viumbe wingi haziwezi kupima ubora wa idadi ya viumbe na kushindwa, kufafanua, mabadiliko katika katika bahari yanaohusishwa kwa sababu ya tishio ambayo hawezi kushughulikiwa hata na MPA mabadiliko ya tabia nchi.","PeriodicalId":200681,"journal":{"name":"Western Indian Ocean journal of marine science","volume":"29 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131244010","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}