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| Format: | Artículo científico |
| Language: | en |
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Universidad de Costa Rica
2015
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| Online Access: | https://www.redalyc.org/articulo.oa?id=44939781017 https://www.redalyc.org/journal/449/44939781017/ https://www.redalyc.org/journal/449/44939781017/html/ https://www.redalyc.org/journal/449/44939781017/44939781017.epub https://www.redalyc.org/journal/449/44939781017/movil |
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Table of Contents:
- Stock assessment of fishery target species in Lake Koka, Ethiopia Gashaw Tesfaye Matthias Wolff Biología mega Growth spawners mortality size indicators Effective management is essential for small-scale fisheries to continue providing food and livelihoodsfor households, particularly in developing countries where other options are often limited. Studies on the popula-tion dynamics and stock assessment on fishery target species are thus imperativeto sustain their fisheries andthe benefits for the society.In Lake Koka (Ethiopia),very little is known about the vital population parametersand exploitation status of the fishery target species:tilapiaOreochromis niloticus,common carpCyprinus car-pioandcatfishClarias gariepinus.Our study, therefore,aimed at determining the vital population parametersand assessing the status of these target speciesin Lake Koka using length frequency data collected quarterlyfrom commercial catches from 2007-2012.A total of 20 097 fish specimens (distributed as 7 933 tilapia, 6025 catfish and 6 139 common carp) were measured for the analysis.Von Bertalanffygrowth parameters andtheir confidence intervals were determined from modal progression analysis using ELEFAN I and applying thejackknife technique. Mortality parameters were determined from length-converted catch curves and empiricalmodels. The exploitation status of these target species were then assessed bycomputing exploitation rates (E)from mortality parameters as well as from size indicators i.e., assessing the size distribution of fish catchesrelative to the size at maturity (Lm), the size that provides maximum cohort biomass (Lopt) and the abundance ofmega-spawners. The mean value of growth parametersL∞,Kand the growth performance index ø’were 44.5cm, 0.41/year and 2.90 forO. niloticus, 74.1 cm, 0.28/year and 3.19 forC. carpioand 121.9 cm, 0.16/year and3.36 forC. gariepinus, respectively.The 95 % confidence intervals of the estimates were also computed.Totalmortality (Z) estimates were1.47, 0.83 and 0.72/yearforO. niloticus,C. carpioandC. gariepinus, respectively.Our study suggest thatO. niloticusisin a healthy state, whileC. gariepinusshow signs of growth overfishing(when both exploitation rate (E) and size indicators were considered). In case ofC. carpio, the low exploitationrate encountered would point to underfishing, while the size indicators of the catches would suggest that toosmall fish are harvested leading to growth overfishing. We concluded that fisheries production in Lake Kokacould be enhanced by increasingEtoward optimum level of exploitation(Eopt) for the underexploitedC. carpioand by increasing the size at first capture (Lc) toward theLoptrange for all target species. Rev. Biol. Trop. 63(3): 755-770. Epub 2015 September 01. 2015 artículo científico 0034-7744 https://www.redalyc.org/articulo.oa?id=44939781017 https://www.redalyc.org/journal/449/44939781017/ https://www.redalyc.org/journal/449/44939781017/html/ https://www.redalyc.org/journal/449/44939781017/44939781017.epub https://www.redalyc.org/journal/449/44939781017/movil en http://www.redalyc.org/revista.oa?id=449 Revista de Biología Tropical application/pdf Universidad de Costa Rica Revista de Biología Tropical (Costa Rica) Num.3 Vol.63