Fisheries Research 137 (2013) 71–80 Contents lists available at SciVerse ScienceDirect Fisheries Research jou rn al hom epage: www.elsevier.com/locate/fishres Growth and mortality parameters of P. senegalensis and P. typus (Sciaenidae) in nearshore waters of Benin (West Africa) and their implications for management and conservation E. Sossoukpe a,∗ , F.K.E. Nunoo b , P.K. Ofori-Danson b , E.D. Fiogbe a , H.R. Dankwa c a Departement de Zoologie et Génétique, Université d’Abomey-Calavi, Benin b Department of Marine and Fisheries Sciences, University of Ghana, Legon, Ghana c Water Research Institute, CSIR, Ghana a r t i c l e i n f o Article history: Received 17 March 2012 Received in revised form 17 August 2012 Accepted 17 August 2012 Keywords: Pseudotolithus Benin nearshore waters Growth Mortality Fisheries management a b s t r a c t Most fisheries in Africa are overexploited or are at the peak of exploitation. A key contributor to this overfishing is poor data on fisheries, inefficient management strategies and unenforced policies. Pseu- dotolithus species off Benin nearshore waters are mainly fished by beach seining. Unfortunately, since 1994, the production of these species has been decreasing, with more small-sized fishes appearing in catches, and little is known about the species’ population dynamics. Therefore, the growth and mortal- ity parameters of two commercially important Sciaenids (Pseudotolithus senegalensis and Pseudotolithus typus) off Benin’s nearshore waters were investigated using length–frequency data of 2019 specimens sampled from beach seine hauls over a period of 18 months. The length–weight relationship was com- puted from linear regression analysis. P. senegalensis exhibited isometric growth while P. typus exhibited negative allometric growth. The von Bertalanffy growth constants for P. senegalensis were TL∞ = 51.4 cm, K = 0.24 yr -1 , and t 0 = -0.60 yr with a derived growth performance index of ϕ ′ = 2.753. The corresponding estimates for P. typus were TL∞ = 56.2 cm, K = 0.19 yr -1 , t 0 = -0.73 yr and ϕ ′ = 2.652. The growth patterns determined by the growth performance index (ϕ ′ ) were higher for P. senegalensis than for P. typus of similar sizes. The total mortality rate, Z, for P. senegalensis was estimated as 4.39 yr -1 , with the fishing mortality, F, being calculated as 3.70 yr -1 . The mortality estimates for P. typus were Z = 4.12 yr -1 and F = 3.70 yr -1 . The exploitation rate of the two fish species was higher than the optimum exploitation criterion, which is indicative of over-fishing. Several immediate management actions, such as size-limit regulation by gradually increasing beach seine mesh size and time-limit regulation by restricting fishing outside the spawning season, are considered necessary for sustainable exploitation of these stocks. Crown Copyright © 2012 Published by Elsevier B.V. All rights reserved. 1. Introduction Many of the world’s fish populations are overexploited, probably to meet the fish consumption requirements of the human popula- tion (Milton et al., 2002; Nunoo et al., 2006; Fazli et al., 2007; Narges et al., 2011). Apart from being a cheap source of highly nutritive pro- tein, fish contain essential nutrients required by the body (Sikoki and Otobotekere, 1999). The fisheries sub-sector is important to Benin on many fronts. For example, as a source of foreign income, the sub-sector con- tributed US$12 million to Benin’s total receipts of agricultural non traditional export products in 2008 (INSAE, 2009). Fish are also a preferred source of animal protein in the Beninese diet ∗ Corresponding author at: P.O. Box 526, Cotonou, Benin. E-mail address: esossoukpe@yahoo.fr (E. Sossoukpe). (approximately 55%), with a consumption of approximately 12 kg per person per annum (FAOSTAT, 2005). The fish requirement for the population (8 millions, INSAE, 2003) was estimated to be approximately 96,000 metric tons. The fishery sector supports an informal workforce of 1.5 million people (approximately 18% of the population), which includes fishermen, fish processors and traders, most of whom are women (Anato, 1999). The dependence of the Beninese on fish has resulted in a demand that far outstrips the total local production from capture fish- eries (both marine and inland waters). In 2008, for example, the total production was 43,000 metric tons, while the demand was approximately 80,000 metric tons (Direction des Pêches, 2009). In 2005, the total value of fish imports into Benin was US$80 mil- lion. Approximately 33% of the local fish production is from a marine source. The marine fisheries in Benin are dominated by arti- sanal fisheries, which contribute approximately three-quarters of the total marine production (Gbaguidi, 2000). The species of high 0165-7836/$ – see front matter. Crown Copyright © 2012 Published by Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.fishres.2012.08.020