A Preliminary Assessment of the Spawning Potential Ratio of Five Target Species of the Coastal Gillnet Fishery in Guyana and Suriname

Abstract

Data—limited stock assessment methods have the potential to positively impact livelihoods of fishermen around the world by providing management recommendations that aim to optimize sustainable yields from fisheries. Some years ago, a novel length— based (LB) method was developed for the assessment of spawning potential ratio (SPR), a measure of the reproductive capacity of fish stocks. We applied the LB—SPR method to 5 important target species of the coastal gillnet fishery in Guyana and Suriname. Nebris microps (Smalleye Croaker; 32% SPR) and Macrodon ancylodon (King Weakfish; 34% SPR) had the highest spawning potential, but remained below the 40% target level needed to ensure sustainable exploitation. Cynoscion acoupa (Acoupa Weakfish; 13% SPR), C. virescens (Green Weakfish; 11% SPR) and Hexanematichthys proops (Crucifix Sea Catfish; 14% SPR) had SPR values below the 20% limit reference point, indicating severe and potentially long—term population depletion. There are several sources of potential bias in our SPR estimates, including concerns over the length frequency dataset, potential violation of LB—SPR model assumptions and the poor estimation of certain life—history parameters. Based on our experiences, various recommendations are formulated to be considered in future stock assessment efforts in the region. While our results are preliminary and need careful interpretation, they are in line with anecdotal evidence that the demersal gillnet fishery in Guyana and Suriname is overexploiting the resources it depends upon. We recommend to implement precautionary fisheries management measures that aim to rebuild the stocks and improve their spawning potential.