Observations on the Bottom-Set Gillnet Fishery and Fishery Biology of Selected Species at Three Locations off the Central Region Coast of Ghana

Abstract

Studies were conducted at three coastal stations in the Central Region of Ghana, namely Apam, Egyaa and Cape Coast from February 2017 to July 2018 to assess the characteristics of the bottom-set gillnet fishery, the biology and exploitation of some species of economic importance. Canoe sizes were mainly 7 to 10 m long and mesh sizes were dominated by 7.9 and 8.9 cm. Mean catch per unit effort was 44.59±23.40 kg/day at Apam, 57.97±46.69 kg/day at Egyaa and 36.93±24.55 kg/day at Cape Coast. Landings were dominated by the spotted box crab Calappa rubroguttata (Calappidae) at Apam and Egyaa, and by the cassava croaker Pseudotolithus senegalensis (Sciaenidae) at Cape Coast. By-catches were mostly corals and crustaceans at Apam and Egyaa and crustaceans at Cape Coast. The asymptotic lengths of C. rubroguttata, P. senegalensis and Cynoglossus senegalensis (Senegalese tonguesole) were 13.13 cm carapace width, 48.83 cm and 60.38 cm total length respectively but were being landed at 7.4 cm carapace width, 27.8 cm and 39.4 cm total length respectively. Mortality in C. rubroguttata was largely due to fishing activities and the stock was being exploited above the optimum level. With stocks being exploited below optimal levels, mortality in P. senegalensis and C. senegalensis was mainly due to natural causes. The operations of the fishery negatively impacted on the marine ecosystem and artisanal fisheries in Ghana. Enforcement of the regulation on the use of monofilament gillnet in the marine waters of Ghana was recommended to minimize its negative ecological impacts. Recommendation was as well made for regular studies on gear specific fisheries to provide and update information critical for their management.