Assessment of the Selective Properties and Optimization of Mesh Size of Pelagic Trawl Codends, Used for Fishing Mackerel (Trachurus Spp) in the Gulf of Guinea

作     者：Njomoue Pandong Achille Ebeku Ngomo Christopher Tcham Leopold 

作者机构：Department of Fisheries Faculty of Industrial Engineering University of Douala Douala Cameroon 

出 版 物：《Open Journal of Marine Science》 (海洋科学期刊（英文）)

年 卷 期：2013年第3卷第2期

页      面：103-111页

学科分类：1002[医学-临床医学] 100214[医学-肿瘤学] 10[医学] 

主　　题：Codend Selectivity Mesh Size Gulf of Guinea Selectivity Models 

摘      要：Over the past few decades, it has become widely recognized that the management strategies of world fisheries must ensure sustainability of target species. The intervening years have seen many improvements to the concept of gear selectivity and methods for measuring the selectivity of fishing towed gears. Improved understanding of the principles of the selection of fish by gears has changed the list of parameters which are known to have a significant effect upon selection. The recent development of new mathematical models and the increased availability of powerful computers have resulted in improvements in the analysis procedures for the data produced to measure a gear’s selectivity. The catch of mackerel in the gulfofGuineahas steeply declined during the last two decades, and resource management is clearly required. Therefore, the need for evaluation of trawl codends used in this fishery and the potential improvements to their selectivity are of prime importance. In this paper, we use semi-empirical models to define selective properties of pelagic trawl codends targeting black mackerel (Trachurus spp) in theGulfofGuinea. These properties are determined using the experimental and theoretical methods of assessing the parameters of the selectivity curve, and by plotting the curve. Selection parameters were obtained by fitting a logistic equation using a maximum likelihood method. Trawl codend selectivity is estimated for 17 internal diamond mesh sizes in the range 47 - 79 mm. Using the basic selectivity equations, we determine the needed mesh size A = 58 mm for fishing mackerel in the gulf of Guinea. This nominal mesh size gives room for nj = 0.1 catch of juveniles, which not exceeds the allowable proportion [nj] = 0.1. To provide resource conservation, there is the need to make amendments in the fishery regulations for more rational exploitation of mackerel stoks, because the currently use nominal mesh size A = 56 mm is rather unselective.