Stock assessment of the river prawn, Macrobrachium caementarius, in the Majes-Camaná river, Arequipa region, southern Peru

Osodein O.A.; Zavaleta-Flores J.; Taylor M.; Wolff M.; Romagnoni G.; Del Solar A.; Tam J. · Crustaceana (2026) · DOI: 10.1163/15685403-bja10563

Resumen

Macrobrachium caementarius (Molina, 1782) is the only freshwater prawn that sustains an artisanal fishery in Peru. This study assessed its stock in the Majes-Camaná river by analysing length-frequency data collected by the Peruvian Marine Research Institute. Growth parameters were estimated using the TropFishR and fishboot packages, with asymptotic length ( L ∞ [jls-end-space/]) fixed at 130 mm for males and 106 mm for females. Total (Z) and natural (M) mortality were estimated from the linearised length converted catch curve and the Tanaka and Sekharan empirical relationship, respectively. Yield-per-recruit (YPR) and spawning potential ratio (SPR) analyses were performed. The larger specimens are predominantly males, while females dominate the smaller sizes. Growth coefficient (K) and growth performance index ( Φ ′ [jls-end-space/]) differ between sexes (males: K = 0.44 year−1, Φ ′ = 4.01[jls-end-space/]; females: K = 0.67 year−1, Φ ′ = 3.82[jls-end-space/]), with males reaching larger sizes, while females grow faster and mature earlier. M was slightly higher in females (0.935 year−1) compared to males (0.63 year−1), while Z, fishing mortality (F) and exploitation rates (E) were higher in males (1.77 year−1, 1.14 year−1, 0.64 year−1, respectively) than in females (1.32 year−1, 0.39 year−1, 0.29 year−1). The SPR values suggest that current fishing pressure does not adversely affect the spawning stock, likely due to the limitations imposed by the current closed season and minimum size regulations. The YPR analysis suggests that the current F and E rates are below rates associated with maximum YPR ( F max and E max [jls-end-space/]). Despite these indications of sustainable exploitation, our results suggest that males may become more vulnerable in the future if effort increases, and sex-dependent minimum capture sizes should be established. Furthermore, YPR may be increased by raising the minimum size at first capture for males from 70 to 80 mm through minimum size regulations. © Oluwayemisi A. Osodein et al., 2026. Published with license by Koninklijke Brill BV. This work is published by Koninklijke Brill BV. Koninklijke Brill bv incorporates the imprints Brill, Brill Nijhoff, Brill Schöningh, Brill Fink, Brill mentis, Brill Wageningen Academic, Vandenhoeck & Ruprecht, Böhlau and V&R unipress. Koninklijke Brill BV reserves the right to protect the publication against unauthorized use and to authorize dissemination by means of offprints, legitimate photocopies, microform editions, reprints, translations, and secondary information sources, such as abstracting and indexing services including databases. Requests for commercial re-use, use of parts of the publication, and/or translations must be addressed to Koninklijke Brill BV.