Population productivity of wedgefishes, guitarfishes, and banjo rays: inferring the potential for recovery

Abstract

Recent evidence of widespread and rapid declines of wedgefishes, guitarfishes, and banjo ray populations (Order Rhinopristiformes), driven by a high demand for their fins in Asian markets and the quality of their flesh, raises concern about their risk of over-exploitation and extinction. Using life history theory and incorporating uncertainty into a modified Euler-Lotka model, maximum intrinsic rates of population increase (rmax) were estimated for nine species from the four families of rhinopristiforms. Estimates of median rmax varied from -0.04 to 0.60 year-1 among the nine species, but generally increased with increasing maximum size. In comparison to 115 other species of chondrichthyans for which rmax values were available, the families Rhinidae and Glaucostegidae are relatively productive, while most species from Rhinobatidae and Trygonorrhinidae had relatively low rmax values. If the demand for their high value products can be addressed, then population recovery for this species is likely possible but will vary depending on the species.