Fish species composition and size structure exploited by gill net fishery in The New Calabar River, Nigeria

Olaniyi Alaba Olopade, Henry Eyina Dienye, Ogheneforon Oderhohwo


The purpose of this study was to investigate the species composition and size selectivity of gillnets commonly used by the artisanal fishers in the New Calabar River, Rivers State, Nigeria. The data was collected during February-July 2018 from 3 sampling stations: SI Choba, S2 Ogbogoro, and S3 Iwofe all along the stretch of the river. Twenty-eight fish species were found belonging to 15 families. The prevalent families were Cichlidae, Mugilidae and Clupeidae representing 32.22%, 30.36% and 10.23% of the total catch, respectively. The most dominant species in terms of number were Liza falcipinnis (12.58%) and Mugil cephalous (12.26%) while in terms of biomass, the most abundance species were Xenomystus nigri (24.12%) and Lutjanus agennes (12.50 %). The girth and total lengths of the fishes ranged from 5.20±0.20 to 21.00±0.00 cm and 8.85±0.15 to 28.19±1.13 cm respectively. The length at first capture (L50%) for the most abundant species (Liza falcipinnis) was calculated to be 14.13 cm while that of L25% and L75% were 12.70cm and 15.25cm respectively. It was concluded that the gill nets used in the New Calabar River exploit fish species of small sizes and few medium sized specimens relative to species potential maximum size. It is therefore recommended that for an improved and sustainable exploitation fish stock of the New Calabar River, the use of gillnets of less than 25 mm-mesh sizes and “other gears” should be prohibited.

Keywords: gill nets; species composition; mesh size; selectivity; New Calabar River

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Adesulu, E. A., Sydenham, D. H. J., 2007. The fresh water and fisheries of Nigeria. Macmillan Nigeria Publishers, Lagos. 397 pp.

Baranov, F. I., 1948. Theory and assessment of fishing gear. Pishchepromizdat, Moscow, 436 p. (In Russian). (Translated by Dept. of Lands and Forests, Maple, Ontario, Canada.)

Dickson, W., 1989. Cod gillnet simulation model. Fish. Res. 7: 149–174

Fröese, R., 2004. Keep it simple: three indicators to deal with overfishing. Fish Fisheries, 5:86-91.

Gayanilo, F. C., Pauly D. 1997., The FAO-ICLARM stock assessment tools (FiSAT). Reference manual. Rome, FAO, 262 p.

Hamely J. M. 1975. Review of gillnet selectivity. Journal of the Fisheries Research Board of Canada 32:1943–1969.

Hickford, M. J. H., Schiel,D. R., Jones, J. B., 1977. Catch characteristics of commercial gill-nets in a near shore fishery in central New Zealand New Zealand Journal of Marine and Freshwater Research, 37:249-259.

Huse, I., Lokkeborg, S., Soldal, A.V., 2000. Relative selectivity in trawl, long line and gillnet fisheries for cod and haddock. Ices Journal of Marine Science 57: 1271–1282.

Ibim, A. T., Gogo, O. O., Igbani, F., 2016. The ichthyofaunal Assemblage of the Lower and Upper Reaches of New Calabar River, Rivers State, Niger Delta, Nigeria. J. Environ. Earth Sci. 6(9): 186-197.

Ita, E. V., Machili, M., 1997. The current status of fish stock and fisheries in Kainji Lake. Consultancy reporton fish stock assessment in Kainji Lake; To the Nigeria- German (gt29) Kainji lake fisheries promotion project, New Bussa pp.128.

Inland Fishing Act., 1992. Inland Fishing Regulation. Act Federal Government of Nigeria Extract- Ordinary Gazelte, 1.

Matsuoka, T., Sbaganei, T., Kasu J., 1990. A comparison of selectivity of gill-net and trammel net. Science in New Guinea 16: 100-108.

Marais, J. F. K., 1985. Some Factors Influencing The Size of Fishes Caught in Gillnets in Eastern Cape Estuaries. Fish. Res. 3: 251–261.

Millar, R. B., Holst, R., 1997. Estimation of gillnet and hook selectivity using log-linear models. Ices Journal of Marine Science 54: 471–477.

Molles, Jr. M.C., 2008. Ecology: concepts and applications.5th ed., Mc Graw-Hill companies, Inc,New York 562pp.

Nedelec, C., Prado, J., 1990. Definition and classification of fishing gear categories Fisheries Technical Paper, No. 222, Revision 1: 92 pp.

Olopade, O. A., Rufai, O. P., 2014. Composition, Abundance and Diversity of the Family Cichlidae in Oyan Dam, Ogun State, Nigeria, BioDiversitas Journal, 15, 2: 195-199 DOI: 10.13057/biodiv/d150211

Olopade, O. A., Taiwo, I. O., Dienye, H. E., 2017. Management of Overfishing in the Inland Capture Fisheries in Nigeria. LimnoFish. 3(3):189-194. doi: 10.17216/LimnoFish.335549

Olopade, O. A., Dienye, H. E., Eyekpegha, A., 2018. Length frequency distribution, length-weight relationship and condition factor of cichlid fishes (Teleostei: Cichlidae) from the New Calabar River, Nigeria. Iranian Journal of Ichthyology 5(1): 74-80.

Pinkas, L., 1971. “Food habits study”, in “Food Habits of Albacore, Blue-fin Tuna, and Bonito in California Waters” (Ed. L. Pinkas, M. S. Oliphant and I. L. K. Iverson), The California Department of fish and Game’s Fish Bulletin No. 152, pp.5-10

Pinkas, L., Oliphant, M.S., Iverson I. L. K., 1971. Food habits of albacore, bluefin tuna and bonito in Californian waters. Fish. Bull. Calif. Dep. Fish and Game 152: 1-105.

Solarin, B. B., Kusemiju, K., 2003. Fish Shelters as Fisheries Enhancement Techniques int he Lagos Lagoon, Nigeria. Nig. J. fish, 1: 57-61.

Van Dyke, F., 2002. Conservation Biology: Foundation, Concepts, Applications. Mcgraw-Hill Companies, New York, USA.

Valdez-pizzini, M., Acota, A., Griffith, D.C., Riiz-peres, M., 1992. Assessment of the socio economic impact of fishery management options upon gillnets and trammel nets fishermen in Puerto Rico: an interdisciplinary approach (Anthropology and fisheries biology) for the evaluation of management alternatives. Final report NOHA/NMFS, pp: 96.


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