The role of protected areas in the conservation and management of fisheries in the Chobe District of Botswana
- Authors: Bakane, Modiegi
- Date: 2017
- Subjects: Cichlids Botswana Chobe District , Protected areas Botswana Chobe District , Fishery management Botswana Chobe District
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/7459 , vital:21262
- Description: This study was aimed at better understanding the function of protected areas as a management strategy for the Chobe District fishery in Botswana, by first investigating the relative abundance in fish communities in and outside protected areas and secondly, by performing an assessment of the biology of commercially important large cichlid species viz threespot tilapia Oreochromis andersonii, greenhead tilapia Oreochromis macrochir and redbreast tilapia Coptodon rendalli. In this study, data and specimens were collected during seasonal surveys between September 2014 and April 2015, using the standard graded fleets of gillnets employed in other programmes in the region, together with D-nets, angling and electro-fishing. The study demonstrated that fish communities in the floodplain ecosystems in the Chobe District of Botswana were representative of the region, containing some 70 species in 14 families. This study also demonstrated that for all the species collected, the mean Catch Per Unit Effort (CPUE) by weight for all the species was significantly higher in protected areas (Kruskal Wallis Test; P<0.05) namely, Zibadianja Lagoon (38 ± 31 kg/net.night"1 and Savuti River/marsh 25 ± 19 kg/net.night"1) than in the fished Chobe River floodplains CPUE (6 ± 3 kg/net.night-1). Biological contributions were estimates of longevity, growth and maturity for O. andersonii, O. macrochir and C. rendalli. Age and growth were estimated using sectioned sagittal otoliths. The Von Bertalanffy growth equation from otolith derived length at age was Lt(mm) =298 (1-e-0 59(t=- 098)) for O. andersonii and Lt(mm) = 337 (1-e-0'20(t=-235)) for C. rendalli. The results indicated that protected areas enhanced fish longevity, and fish in protected areas were larger and older than those in exploited areas. Maturity estimates for the large cichlids were consistent with other research in the region and the length-at-50% maturity was estimated as 250mm Lt for O. andersonii, 225 mm Lt for O. macrochir and 210 mm Lt for C. rendalli. Management recommendations are therefore to retain gill net mesh size regulations that ensure that these fish reach maturity and can breed before being harvested and to assess the possibility of increasing the number of protected areas in the district.
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- Authors: Bakane, Modiegi
- Date: 2017
- Subjects: Cichlids Botswana Chobe District , Protected areas Botswana Chobe District , Fishery management Botswana Chobe District
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/7459 , vital:21262
- Description: This study was aimed at better understanding the function of protected areas as a management strategy for the Chobe District fishery in Botswana, by first investigating the relative abundance in fish communities in and outside protected areas and secondly, by performing an assessment of the biology of commercially important large cichlid species viz threespot tilapia Oreochromis andersonii, greenhead tilapia Oreochromis macrochir and redbreast tilapia Coptodon rendalli. In this study, data and specimens were collected during seasonal surveys between September 2014 and April 2015, using the standard graded fleets of gillnets employed in other programmes in the region, together with D-nets, angling and electro-fishing. The study demonstrated that fish communities in the floodplain ecosystems in the Chobe District of Botswana were representative of the region, containing some 70 species in 14 families. This study also demonstrated that for all the species collected, the mean Catch Per Unit Effort (CPUE) by weight for all the species was significantly higher in protected areas (Kruskal Wallis Test; P<0.05) namely, Zibadianja Lagoon (38 ± 31 kg/net.night"1 and Savuti River/marsh 25 ± 19 kg/net.night"1) than in the fished Chobe River floodplains CPUE (6 ± 3 kg/net.night-1). Biological contributions were estimates of longevity, growth and maturity for O. andersonii, O. macrochir and C. rendalli. Age and growth were estimated using sectioned sagittal otoliths. The Von Bertalanffy growth equation from otolith derived length at age was Lt(mm) =298 (1-e-0 59(t=- 098)) for O. andersonii and Lt(mm) = 337 (1-e-0'20(t=-235)) for C. rendalli. The results indicated that protected areas enhanced fish longevity, and fish in protected areas were larger and older than those in exploited areas. Maturity estimates for the large cichlids were consistent with other research in the region and the length-at-50% maturity was estimated as 250mm Lt for O. andersonii, 225 mm Lt for O. macrochir and 210 mm Lt for C. rendalli. Management recommendations are therefore to retain gill net mesh size regulations that ensure that these fish reach maturity and can breed before being harvested and to assess the possibility of increasing the number of protected areas in the district.
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Assessment of the Lake Liambezi fishery, Zambezi region, Namibia
- Authors: Simasiku, Evans Kamwi
- Date: 2014
- Subjects: Fishery management -- Namibia -- Lake Liambezi , Seines -- Namibia -- Lake Liambezi , Gillnetting -- Namibia -- Lake Liambezi , Fishes -- Namibia -- Lake Liambezi , Fisheries -- Catch effort -- Namibia -- Lake Liambezi
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5366 , http://hdl.handle.net/10962/d1013036
- Description: Lake Liambezi in the Zambezi Region of Namibia, formerly known as the Caprivi Region, is shallow (<6m deep) and characterised by cyclic episodes of filling and drying. When full the lake supports a highly productive fishery and when dry the lake is completely dry and used for agriculture and grazing. In 2000 the lake filled, and between May 2011 and April 2012 was surveyed using beach seine, experimental gillnets and catch landing surveys to obtain information for conservation and management recommendations for the fishery. Littoral fishes in Lake Liambezi and the Kavango floodplain were sampled using seine net and physicochemical properties were measured. Seine net surveys demonstrated that Lake Liambezi littoral zones were dominated by fishes of the family Alestidae (59.7%) while Cichlids constituted the most diverse family. Juvenile Tilapia rendalli and Oreochromis macrochir were among the five most important species in the littoral zone, indicating that these commercially important species use the littoral zone as a nursery ground. Since T. rendalli and O. macrochir are commercially important species, because of this, it is advised that seine nets should not be used. Catch efficiency between monofilament and multifilament gillnets in Lake Liambezi offshore waters were assessed. Catch efficiency experimental fishing trials showed that monofilament gillnets catch per unit effort (CPUE) was three times higher than that of multifilament gillnets for Oreochromis andersonii, O. macrochir, T. rendalli, Serranochromis macrocephalus and Clarias spp. Oreochromis andersonii comprised over 66% of the overall CPUE for both net types combined indicating the importance of this species in the gillnet fishery on the lake. A fishery has been established on the lake with more than 300 canoes and 120 fishermen using monofilament and multifilament gillnets. CPUE was 15 kg/canoe/day and was significantly (P < 0.05) associated with monthly temperature and moon phase parameters indicating that the fishery of Lake Liambezi may be altered by climate and environmental factors. Annual catch from Lake Liambezi was estimated at 3193t with an estimated productivity of 106kg/ha, suggesting that Lake Liambezi makes a significant contribution to the fish supply in the Zambezi Region. Recommendations were made to manage the Lake Liambezi fishery by imposing restrictions on effort (number of fishing boats), gear type, mesh sizes and access. Proper fisheries management and monitoring should incorporate climatic and environmental factors such as temperature and moon phase to meet the challenges of global climatic changes as well as other environmental issues.
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- Authors: Simasiku, Evans Kamwi
- Date: 2014
- Subjects: Fishery management -- Namibia -- Lake Liambezi , Seines -- Namibia -- Lake Liambezi , Gillnetting -- Namibia -- Lake Liambezi , Fishes -- Namibia -- Lake Liambezi , Fisheries -- Catch effort -- Namibia -- Lake Liambezi
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5366 , http://hdl.handle.net/10962/d1013036
- Description: Lake Liambezi in the Zambezi Region of Namibia, formerly known as the Caprivi Region, is shallow (<6m deep) and characterised by cyclic episodes of filling and drying. When full the lake supports a highly productive fishery and when dry the lake is completely dry and used for agriculture and grazing. In 2000 the lake filled, and between May 2011 and April 2012 was surveyed using beach seine, experimental gillnets and catch landing surveys to obtain information for conservation and management recommendations for the fishery. Littoral fishes in Lake Liambezi and the Kavango floodplain were sampled using seine net and physicochemical properties were measured. Seine net surveys demonstrated that Lake Liambezi littoral zones were dominated by fishes of the family Alestidae (59.7%) while Cichlids constituted the most diverse family. Juvenile Tilapia rendalli and Oreochromis macrochir were among the five most important species in the littoral zone, indicating that these commercially important species use the littoral zone as a nursery ground. Since T. rendalli and O. macrochir are commercially important species, because of this, it is advised that seine nets should not be used. Catch efficiency between monofilament and multifilament gillnets in Lake Liambezi offshore waters were assessed. Catch efficiency experimental fishing trials showed that monofilament gillnets catch per unit effort (CPUE) was three times higher than that of multifilament gillnets for Oreochromis andersonii, O. macrochir, T. rendalli, Serranochromis macrocephalus and Clarias spp. Oreochromis andersonii comprised over 66% of the overall CPUE for both net types combined indicating the importance of this species in the gillnet fishery on the lake. A fishery has been established on the lake with more than 300 canoes and 120 fishermen using monofilament and multifilament gillnets. CPUE was 15 kg/canoe/day and was significantly (P < 0.05) associated with monthly temperature and moon phase parameters indicating that the fishery of Lake Liambezi may be altered by climate and environmental factors. Annual catch from Lake Liambezi was estimated at 3193t with an estimated productivity of 106kg/ha, suggesting that Lake Liambezi makes a significant contribution to the fish supply in the Zambezi Region. Recommendations were made to manage the Lake Liambezi fishery by imposing restrictions on effort (number of fishing boats), gear type, mesh sizes and access. Proper fisheries management and monitoring should incorporate climatic and environmental factors such as temperature and moon phase to meet the challenges of global climatic changes as well as other environmental issues.
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