• W. O. ABDUL



Recruitment pattern, stock assessment, Tilapia zillii, Ogun state.


A study was carried out on the stock parameters, recruitment pattern, and probability of capture of T. zillii in Ogun estuary, Ogun State, Nigeria using length-frequency and catch-at-length data. The fish stock was assessed using the methods of ELEFAN 0- III of the FiSAT II software. Results showed that the stock has a continuous recruitment pattern. L25, L50 and L75 were 13.82cm, 15.50cm and 17.19cm respectively. Fish population decreased with increase length class. Average mortality rate was 1.16/year, and exploitation rates were lower in length class 11-12cm to 26-27cm and large size, 34-35cm, and equal or greater than optimum in others. Steady biomass also increased with length class until 24-25cm. The fishery would attain MSY if the present effort level is raised by 1.6.



Abdul, W.O., Omoniyi, I.T. 2003. An investigation of ‘Iken’ brush park fish aggregating device in Iwopin lagoon, Ogun State, Nigeria. Asset series A, 3(3): 69 – 177.

Abdul, W.O. 2009. Stock assessment of Tilapia zillii in the freshwater ecotype of Ogun estuary, Ogun State, Nigeria. PH.D thesis, University of Agriculture, Abeokuta, 189p.

Barry, J.P., Tegner, M.J. 1989. Inferring demographic processes from size-frequency distribution: simple models indicate specific patterns of growth and mortality. US Fish. Bull. 88: 13 – 19.

Fagade, S.O., Olaniyan, C.O. 1974. Seasonal distribution of the fish species of the Lagos Lagoon. Bill de IFAN. Jan. I.T. Ser. A: 45 – 67.

Galucci, V.F., Amjoun, B., Hedgepeth, J., Lai, H.L. 1996. Size-based methods of stock assessment of small-scale fisheries. In: Gallucci, V.F., S.B. Saila, D.J. Gustafson and R.J. Rothschild (Eds.). Stock assessment: quantitative methods and applications for small-scale fisheries. Lewis Publ., Boca Raton, Florida, 9-81.

Gayanilo, F.C. Jr., Soriano, M., Pauly, D. 1988. A draft guide to the COMPLEAT ELEFAN. ICLARM Software Project 2: 65 p. and 10 diskettes (5.25 inches, 360K).

Gayanilo, F.C. Jr., Pauly, D. 1987. Announcing the release of version 1.10 of the Complete ELEFAN. ICLARM software 2: 65p.

Gayanilo, F.C. Jr., Sparre, P., Pauly, D. 1996. FAO-ICLARM stock assessment tools (FiSAT). User’s manual. FAO computerized information series (Fisheries), No. 8 Rome, FAO, 126p.

Gayanilo, F.C. Jr., Sparre, P., Pauly, D. 1997. FAO-ICLARM stock assessment tools (FiSAT). Reference manual. FAO computerized information series (Fisheries), No.8. Rome, FAO, 262p.

Gayanilo, F.C., Jr., Sparre, P., Pauly, D. 1997. FAO-ICLARM stock assessment tools (FiSAT). Reference manual.
FAO computerized information series (Fisheries), No.8. Rome, FAO,262p.

Gayanilo, F.C., Jr., Sparre, P., Pauly, D. 2002. FiSAT II user’s guide version 1.2.0. FAO Rome. 81p.

Gulland, J.A. 1968. The concept of the maximum sustainable yield and fishery management. FAO Fisheries Technical Paper No. 70, 265p.

Hay, C .J., Naeseje, T.F., Breistein, J., Harsaker, K., Kolding, J., Sandlund, O.T., van Zyl, B. 2000. Fish populations, gillnet selectivity and artisanal fisheries in the Okavango River, Namibia. Recommendation for a sustainable fishery. NINA. NIKU project Report No. 010, 105p.

Hilborn, R., Walters, C.J. 1992. Quantitative stock assessment choice, Dynamics and uncertainty. Chapman and Hall, London, 570p.

Huiskes, T. 1998. Virtual population analysis with the adjoint method. Fishery stock assessment models. Lowell Wakefield Fisheries Symposium Report No. 98-01

Isreal, D.C., Banzon, C.P. 2004: Overfishing in the Philippine marine fisheries sector. Economy and Environment Program for Southeast Asia, document 59 of 63, 35p.

King, R. P., Etim, L. 2004: Reproduction, growth, mortality and yield of T. mariae Boulenger 1899 (cichlidae) in Nigeria rainforest wetland stream. J. of Applied Ichthology, 20(6): 502-510

Lablanche, G., Carrara, G. 1988. Population dynamics of Emperor Red Snapper (Lutjanus sebae) with notes on the demersal fishing on the malie Platem, Seycheles. Paper presented at the FAO/DANIDA follow-up training. FAO Fisheries Tech. Pap., 171 – 192.

Larkin, P.A. 1978: Fisheries management - an essay for ecologists. Ann. Rev. Ecol. Syst. 9: 57-73.

Mess, C.C., Rausean, J.A. 1997. The potential yield of the Lutjanid fish Pristipomoides filamentous from the Malie Plateau, Seychelles: managing with uncertainty. Fisheries Research 33:73 – 87.

Onazi, E.M. 2000. The thermal loading of the Lagos lagoon at Egbin: Implications on the fish community. M.Sc. Thesis, University of Lagos, Nigeria. 70p.

Pauly, D. 1981. Tropical stock assessment package for programmable calculators and micro-computers. ICLARM Newsl., 4(3): 10-3

Pauly, D. 1984. A mechanism for the juvenile to adult transition in fishes. Journal du Conseil Permanent international pour l’Exploration de la Mer 41: 280-284

Polacheck, T., Preece, A., Betlehem, A., Klaer, N. 1998. Treatment of data and model uncertainties in the assessment of southern bluefin tuna stocks. In: Funk, F., T.J. Quinn II, J. Heifetz, J.N. Lanelli, J.E. Powers, J.F. Schweigert, P.J. Sullivan and C.I. Zhang (Eds.). Fishery stock assessment models. Lowell Wakefield fisheries symposium Report No. 98-01

Sikoki, F.D. 2000. The challenges of sustainable fisheries development in Nigeria. In: FISON proceedings- A keynote address at the 20th annual conference of FISON held at Port Harcourt from 14-19th Nov. 2005. Ansa, E.J., P.E. Anyanwu, B.W. Ayonoadu, E.S. Erondu and S.N. Deekae (Eds.), 5-14

Solarin, B.B., Udolisa, R.E.K. 1993. An investigation of brush park fishing in Lagos lagoon. Nigeria Fisheries Research International Journal, 15: 331-337

Sparre, P., Venema, S.C. 1992. Introduction to tropical fish stock assessment. Part 1. Manual. FAO Fisheries Technical Paper No. 306. 1, Rev. 1. Rome, FAO. 1992, 376 p.

Ssentongo, G.W., Ajayi, T.O., Ukpe, E.T. 1983. Report on a resource appraisal of the artisanal and inshore fisheries of Nigeria. FAO, Rome FI: DP/ NIR/ 77/ 001, 43p.

Vaugham, D.S., Zhao, B., Collins, M.R., McGovern, J.C., Meister, H.S. 1998: Evaluation of multiple survey indices in assessment of Black Sea Bass from the U.S. South Atlantic Coast. In: Funk, F., Quinn II, T.J. Heifetz, Sullivan, P.J. and Zhang, C.I. (Eds.) Fishery Stock assessment models. Lowell Wakefield Fisheries Symposium, Report No. 98-01.

Williams, N.V. 1962. The seasonal distribution of the teleost fish fauna in Lagos Habour, Creek and lagoon in relation to salt tolerance. M.Sc. thesis, University of Lagos, Nigeria






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