Growth, mortality, recruitment, yield-per-recruit and present rate of exploitation of the African river prawn Macrobrachium vollenhovenii were studied in the Cross River Estuary, Nigeria. The research was based on length-frequency data collected between January 1997 and June 1998, and FAO-ICLARM Software (FiSAT) routine runs. Growth parameters obtained from the seasonalized von Bertalanffy growth function were L∞ 213.63 and 198.99 mm, K = 1.24/year and 1.24/year; C = 0.95 and 0.95; WP = 0.6 and 0.45, for M. vollenovenii males and females, respectively. Using the seasonalized length-converted catch curves, the instantaneous rate of total mortality Z was estimated as 3.93/year and 6.85/year for males and females. Natural mortality M, fishing mortality F, and exploitation rate E of both sexes were 2.21/year and 2.27/year, 1.72/year and 4.58/year, and 0.44 and 0.67, respectively. The length at first capture L c estimated from the probability of capture routine was 44.25 mm and 73.41 mm for males and females. One recruitment peak was observed for males, and two of unequal strength for females. Length-weight relationship gave 'b' values of 3.483 and 3.329 for males and females, respectively. The relative yield-per-recruit analysis predicted maximum exploitation rates (E max ) of 0.42 and 0.47 as against current exploitation rates of 0.44 and 0.67 for males and females and suggest that only female M. vollenhovenii are being over-exploited. Hence, it is proposed that fishing on females during the reproductive season is reduced, and that the return of egg-bearing females into the waters is enforced.
The Cross River Estuary, Nigeria, is an important shrimping area for artisanal fishermen of the coastal communities. The multi-species Macrobrachium fishery is exploited with three main gears, namely beach seine, push net and trap. Studies on species composition of this fishery recorded thirteen shrimp species, one swimming crab (Callinectes amnicola) and two fish species (Eleotris sp. and Pellonula leonensis). The shrimp species identified included Macrobrachium macrobrachion (83.39% and 55.69% by number and weight, respectively), M. vollenhovenii (9.66% and 37.18%), M. equidens (3.8% and 2.87%), juveniles-sub-adults of Penaeus notialis (1.11% and 1.3%), M. dux, M. felicinum, Palaemonetes africanus, Palaemon maculatus, Palaemon elegans, Desmocaris sp., Leander sp., Nematopalaemon hastatus and Alpheus pontederiae. While the selectivity index for trap was 0.25, beach seine and push net had a lower index of 0.063. The results present the first comprehensive and representative report for the Estuary shrimp fishery and will assist in the management of the biodiversity of this ecosystem.
Nigeria's fisheries sector is gender biased in terms of prominence in participation. The male counterparts dominate the scene, occupying prominent positions such as ownership, control and access to productive resources of aquaculture production systems, ownership of the fishing vessels and equipment in the capture fisheries sector. These roles confer on them pecuniary benefits such as investment opportunities, loan facilities, importing and exporting licences, among others. Despite women's economic potentials in small-scale fisheries and aquaculture, investments by women in both the aquaculture, artisanal and industrial sectors are at abysmally low levels. The female counterparts play the second-fiddle role of processing and marketing while depending on the male counterparts for major decisions. Underlying socio-cultural norms and gender relations accentuated by intersectionality are factors which most often impede the opportunities to own, access to or control productive resources and other inputs. Apparently, gender mainstreaming in the fisheries sector is very nascent in Nigeria. Our objective in this review is to re-orient women particularly in the small-scale fisheries sector including capture and aquaculture for active and strong participation in ownership, productivity and policy/decision making contributions. Secondary data and inferences from previous studies, particularly reports and reviews from across the globe were compared with what is obtainable in Nigeria. We therefore propose improving social-entrepreneurship, bootstrapping and social-capital based empowerment initiatives among other interventions that would boost women's participation in Nigeria's fisheries sector.
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