Assessment of aquatic ecosystems, the fishery and socio-economics of a coastal area in the Shama District, Ghana

Abstract

The study provides requisite scientific and socio-economic data for sustainable management of the fishery and aquatic ecosystems at Anlo Beach in the Shama District, Ghana. Physico-chemical conditions, macrozoobenthic fauna, and the fish and fishery characteristics of River Pra Estuary, the associated wetlands and marine waters were studied from February 2012 to December 2013. Economics of the fishery, governance and other livelihood activities were also investigated. Data were partly analyzed with quantitative (FiSAT and Ecopath with Ecosim) and qualitative (loop analysis) fishery modeling tools. High turbidities (> 500 ppm), low dissolved oxygen (< 5 mg/l) and high nitrate and phosphate concentrations were recorded in the estuary especially in 2012 possibly emanating from illegal mining activities upstream. Densities of pollution indicator animals, such as Nereis, Capitella spp. (Polychaeta), and Tubifex spp. (Oligochaeta) were below 1000 individuals/m2 suggesting the ecosystems had low organic pollution. A total of 65 fish species from 38 families were found, with the highest diversity (H'= 3.42) occurring in the sea, followed by the estuary (H'= 2.63), and wetland (H'= 1.75). Results indicate the fishery may have exceeded the maximum sustainable yield, with over-exploitation (E > 0.05) of barracudas and small pelagic fishes. About 70% of the fishermen were classified as poor, earning below Ghana’s 2013 minimum wage of GH¢ 5.24 (≈US$ 1.87) per day. Model predictions showed that fish stocks could be revamped by eliminating undersized mesh nets and introducing pots to exploit shrimps. Recommendations to improve water quality, fisheries management and diversified livelihood are provided.