Observations on movement patterns of <i>Tilapia</i> spp. in Nyanza Gulf, Lake Victoria, East Africa

Rinne, John N.; Wanjala, B.

doi:10.1111/j.1095-8649.1982.tb04713.x

Cited by 6 publications

(4 citation statements)

References 4 publications

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“…In salmonids, the proportion of red muscle is approximately 5–10% of the total muscle mass (Webb, ), whereas the proportion of red muscle in Nile tilapia is only approximately 1.6% of the total muscle mass. These tilapia are relatively less strong swimmers and typically travel short distances of <1 km in the field (Rinne and Wanjala, ). Thus, with regular exercise, lipid catabolism increased in salmonids and decreased in tilapia.…”

Section: Discussionmentioning

confidence: 99%

Effects of exercise training on carbohydrate and lipid catabolism in the swimming muscles of Nile tilapia (Oreochromis niloticus)

Wei

Lin

et al. 2015

Animal Physiology Nutrition

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This study aims to determine the effects of exercise training on carbohydrate and lipid catabolism in the swimming muscles of Nile tilapia (Oreochromis niloticus) by measuring the levels of related enzymes, lipids and free fatty acids. We designed one control group and two training groups of fish that were exercised at different training intensities [0, 1 and 1.5 body lengths per second (bl/s)]. The fish in the experimental groups were trained for 12 h/day for 4 weeks. Compared with the control group, the 1 and 1.5 bl/s groups showed significantly increased hexokinase and pyruvate kinase activities in red muscle (p < 0.05). In white muscle, pyruvate kinase activity was significantly higher in the 1.5 bl/s group than in the control group (p < 0.05), and hexokinase activity did not significantly differ between the groups. The activities of hormone-sensitive lipase and carnitine palmitoyltransferase I in both muscle types were significantly lower in the training groups than in the control group (p < 0.05). The plasma-free fatty acid level decreased (p < 0.05), while the lipid percentages increased in red muscle (p < 0.05) after exercise training. These findings clearly indicated that with exercise training, glycolysis increased and lipid oxidation decreased in the swimming muscle of tilapia.

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Section: Discussionmentioning

confidence: 99%

Effects of exercise training on carbohydrate and lipid catabolism in the swimming muscles of Nile tilapia (Oreochromis niloticus)

Wei

Lin

et al. 2015

Animal Physiology Nutrition

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“…Management measures imposed by the riparian governments, via their respective fisheries department/divisions, do not appear to have succeeded in reducing the overexploitation of Nile tilapia. Nile tilapia travel <5 km in the lake (Rinne & Wanjala 1985), meaning that intense localized overfishing could easily deplete its stocks. The shallow nearshore areas of Lake Victoria, in which Nile tilapia generally dwell, are apparently the most heavily exploited areas in the lake (Balirwa 1998; Njiru et al .…”

Section: Discussionmentioning

confidence: 99%

Management of the Nile tilapia (Oreochromis niloticus (L.)) fishery in the Kenyan portion of Lake Victoria, in light of changes in its life history and ecology

et al. 2008

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This study reports on the population parameters, catch distribution and feeding ecology of Nile tilapia (Oreochromis niloticus) from bottom trawls and commercial catches obtained in the Kenyan portion of Lake Victoria during 1997-2006. The population parameters were analysed using the FAO-ICLARM stock assessment tool (FISAT). The fish biomass and the food ingested by the fish were estimated using the swept area and point methods, respectively. Immature fish comprised ഠ70% of the total fish population. The asymptotic length, maximum weight, maximum age, exploitation rate (E) and length at 50% maturity of Nile tilapia have decreased, whereas the growth curvature and fishing mortality have increased. The commercial catches increased from 13.93 t in 1997, to 23.70 t in 1999, decreasing thereafter to 18.73 t in 2005. The bottom trawl catches increased from 46.90 kg ha -1 in 1997, to 401.48 kg ha -1 in 2000, decreasing thereafter to 15.57 kg ha -1 in 2006. The major food items ingested by the fish were algae, insects and other fish. Population parameters, and the catch and diet of O. niloticus, have changed over the years in Lake Victoria. The population characteristics suggest a population under stress, attributable to intense catch exploitation. Even under intense exploitation (E = 0.68), however, the mature fish constituted ഠ30% of the population. The commercial catches are still high, indicating a very resilient fishery. Nevertheless, despite this resilience, the future of Oreochromis fishery is threatened by increased fishing capacity in the lake, and there is need to re-evaluate the effectiveness of current fishery management measures, with the goal of possibly adopting new measures. Enactment of new fishery policies also should provide for co-management to enhance the management process. Furthermore, there is a need to reduce fishing capacity and illegal fishing methods, and to seek alternative livelihoods for lake fishers and other stakeholders.

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“…Catches were dominated by males, possibly attributable to differential migration of sexes (Rinne & Wanjala 1982; Njiru et al. 2006).…”

Section: Discussionmentioning

confidence: 99%

Some aspects of the biology and life‐history strategies of Oreochromis variabilis (Boulenger 1906) in the Lake Victoria Basin

.J¹,

Njiru²,

Okeyo-Owuor

et al. 2012

Lakes & Reservoirs

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Oreochromis variabilis (Boulenger), a fish species endemic to Lake Victoria, was abundant, forming an important component of the indigenous fisheries stocks before and up to the late-1950s. Catches declined drastically thereafter, and only sporadic catches are currently found in Lake Victoria. Remnants population of the species, however, are found in several small waterbodies (SWBs) within the lake basin. The life-history characteristics of O. variabilis in Lake Victoria, including, sex ratio, reproduction and length-weight relationship, were compared to those in selected three SWBs in the lake basin. Fish samples were collected by monofilament gillnets of 30-255 mm between 2001 and 2005. Males predominated over females from all the sampled sites (sex ratio 1.00:0.33). Length at first maturity (Lm 50 ) had mean (±SE) of 18.48 ± 1.50 cm TL for males, and 16.87 ± 0.95 cm TL for females, and did not exhibit any significant differences between habitats. Fecundity ranged between 73 and 14 800 eggs for fish of 13.5-18.6 cm TL, respectively. Absolute fecundity of O. variabilis was proportional to the body weight, but nearly proportional to the cube of the fish length. Egg diameter varied from 0.3 to 5.19 mm, with a mean (±SE) of 3.44 ± 0.08 mm. Growth was allometric in both male and female, being significantly different from the expected value of 3 (P < 0.05). The life-history strategy of O. variabilis is discussed within the context of changes in the lake and the SWBs.

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Observations on movement patterns of Tilapia spp. in Nyanza Gulf, Lake Victoria, East Africa

Cited by 6 publications

References 4 publications

Effects of exercise training on carbohydrate and lipid catabolism in the swimming muscles of Nile tilapia (Oreochromis niloticus)

Effects of exercise training on carbohydrate and lipid catabolism in the swimming muscles of Nile tilapia (Oreochromis niloticus)

Management of the Nile tilapia (Oreochromis niloticus (L.)) fishery in the Kenyan portion of Lake Victoria, in light of changes in its life history and ecology

Some aspects of the biology and life‐history strategies of Oreochromis variabilis (Boulenger 1906) in the Lake Victoria Basin

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