Species composition and abundance of cast net fishery of a tropical lotic freshwater ecosystem

Okoh, F.; Eyo, Joseph Effiong; Ezenwaji, Henry Maduka Godfrey

doi:10.4314/br.v5i1.28630

Cited by 3 publications

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“…The FAO-ICL-ARM Fish Stock Assessment Tools (FISAT II) software (Okoh, Eyo, and Ezenwaji 2007). (Gayanilo, Sparre, and Pauly 2005) was used to analyze the monthly length-frequency data.…”

Section: Estimation Of Growth Parametersmentioning

confidence: 99%

“…The Cross River originates from the Cameroon high mountains and flows through Ebonyi State and Cross River State into the Atlantic Ocean. The river ( Figure 1; Okoh, Eyo, and Ezenwaji 2007) lies in an area between 5°57″-5°30′20″ N and 7°58″-5°30′20″ E. The approximate surface area of the Cross River is 3,900,000 ha (Ita et al 1985). The rainy season and the dry season are the two main seasons of the area.…”

Section: Introductionmentioning

confidence: 99%

“…The Cross River is a major component of the inland waters of south-eastern Nigeria, and its role to the fishery of the area is quite significant (Okoh, Eyo, and Ezenwaji 2007). The Cross River originates from the Cameroon high mountains and flows through Ebonyi State and Cross River State into the Atlantic Ocean.…”

Section: Introductionmentioning

confidence: 99%

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Stock assessment ofTilapia zilli(Gervais, 1848) (Osteichthyes: Cichlidae) in a Nigerian tropical river basin

Uneke

Nwani

2014

Zoology and Ecology

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With limited information on quantitative predictions to provide advice on the optimum exploitation of aquatic living resources, the stock assessment of Tilapia zilli (n = 4044) in the mid-Cross River basin was studied. Monthly samples were collected from commercial artisanal fishermen from January 2010 to June 2011. The FAO-ICLARM Stock Assessment Tool (FiSAT II) software was used for data analysis. Growth parameters for T. zilli were as follows: asymptotic length L ∞ = 27.83 cm TL and growth curvature K = 0.46 yr −1 . The mortality parameters for T. zilli were: total mortality Z = 3.16 yr −1 , natural mortality M = 1.14 yr −1 , and fishing mortality F = 2.02 yr −1 . T. zilli exhibited a bimodal continuous recruitment pattern. Length at first capture (L c ) was 11.86 cm TL. The selection ogive procedure for relative yield and biomass per recruit showed that E max was 0.70 for T. zilli. The stock was not overexploited, since E < E max ; however, the exploitation rate (E) was 0.64 and given that E > 0.50 is considered to be excessive for some fisheries, precautionary management is warranted in this instance.Rekomendacijoms dėl optimalaus vandens gyvūnų eksploatavimo kiekybinių duomenų nepakanka, todėl Nigerijoje, Kryžiaus upės (Cross River) baseino vidurupyje buvo įvertinti Tilapia zilli ištekliai. Nuo 2010 m. sausio iki 2011 m. birželio kiekvieną mėnesį iš žvejų (smulkiųjų verslininkų) laimikio buvo imami mėginiai (n = 4044). Duomenys apdoroti naudojant FAO-ICLARM išteklių vertinimo programą FiSAT II. Nustatyti šie T. zilli augimo parametrai: asimptotinis ilgis L ∞ = 27,83 cm, augimo kreivės koeficientas K = 0,46 per metus. Taip pat nustatyti T. zilli mirtingumo parametrai (per metus): bendras mirtingumas Z = 3,16, natūralus mirtingumas M = 1,14 ir mirtingumas dėl žvejybos F = 2,02. Rūšiai būdingas nuolatinis bimodalinis išteklių atsinaujinimas. T. zilli ilgis pirmo sugavimo metu (L c ) buvo 11,86 cm. Taikant 'Selection Ogive' santykinio gausumo ir biomasės prieaugio apskaičiavimo metodą nustatyta, kad T. zilli išteklių eksploatavimas (E max = 0,70; E = 0,64) neviršijo normos, nes E < E max . Tačiau kai kurioms rūšims E > 0,50 yra laikoma normos viršijimu, todė T. zilli žvejybai reikia taikyti prevencines kontrolės priemones.

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“…The FAO-ICL-ARM Fish Stock Assessment Tools (FISAT II) software (Okoh, Eyo, and Ezenwaji 2007). (Gayanilo, Sparre, and Pauly 2005) was used to analyze the monthly length-frequency data.…”

Section: Estimation Of Growth Parametersmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%