Please use this identifier to cite or link to this item: http://hdl.handle.net/1942/44494
Title: Estimates of life-history and growth parameters of exploited fish species in lakes Edward and George: Implications on exploitation status, population dynamics, management, and conservation of native species
Authors: Musinguzi, Laban
Kamya, Ashiraf
Nsega, Monic
Natugonza, Vianny
Okello, William
Snoeks, Jos
VAN STEENBERGE, Maarten 
Issue Date: 2024
Publisher: WILEY
Source: Journal of fish biology,
Status: Early view
Abstract: Adequate knowledge is essential for responsible inland fisheries. However, many inland fisheries lack monitoring, and therefore, decision-making for fisheries management is not reliable. In this paper, we used data from surveys and literature to estimate the life-history and growth parameters of 16 exploited fish stocks in the Ugandan part of Lake Edward and Lake George (East Africa). The estimated parameters are pivotal indicators of fish stock status, particularly in data-poor fisheries. The estimated parameters included maximum length (Lmax) and mean length (Lmean) as indicators of size structure in experimental and commercial catches, coefficients of length-weight relationships, length at 50% maturity (Lm50), fecundity, von Bertalanffy parameters, total mortality (Z), and natural mortality (M). These parameters were estimated using empirical formulae, statistical methods, and analyses of length frequencies. Only two stocks of semutundu Bagrus docmak exhibited significant and increasing trends in Lmax (Lake Edward) and Lmean (Lake George). The estimates for the remaining parameters were consistent with those in FishBase and other literature resources, either for the same species or related species. This consistency indicates their reliability for application in decision-making and further assessments. Some parameters showed evidence of unsustainable fishing. For example, estimates of Lm50 for four of the assessed stocks belonging to two species (Nile tilapia Oreochromis niloticus and marbled lungfish Protopterus aethiopicus) were lower than baseline estimates in the studied waterbodies. Furthermore, the Lmean in catches for all the stocks were less than the optimum lengths (Lopt), which maximize catches with a minimal impact on biomass and size structure. No significant changes in Lmean, length-frequency distributions, and size at maturity could be attributed to the management changes implemented in 2018, probably because it is too early to observe changes in these parameters. However, there are positive signs attributable to the changes in management as shown by a high proportion of mature individuals in commercial catches for most of the stocks for which the proportion was calculated, and an increase in Lmean and Lmax for some stocks, such as B. docmak, in commercial or experimental catches. New estimates from this study will enhance decision-making and further assessments of fisheries. Routine monitoring is recommended to update and improve the estimates.
Notes: Musinguzi, L (corresponding author), Natl Fisheries Resources Res Inst NaFIRRI, Jinja, Uganda.
labanmusinguzi@firi.go.ug
Keywords: fisheries management;inland fisheries;overfishing;small-scale fisheries
Document URI: http://hdl.handle.net/1942/44494
ISSN: 0022-1112
e-ISSN: 1095-8649
DOI: 10.1111/jfb.15929
ISI #: 001322365300001
Rights: 2024 Fisheries Society of the British Isles.
Category: A1
Type: Journal Contribution
Appears in Collections:Research publications

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