Small in scale big in contribution: evaluating the stock status of indian mackerel (Rastrelliger anagurta) fishery using cmsy and lbb approaches from pakistan, northern arabian sea

Abstract

Overfishing remains a global concern, however effective management from well valuation of fisheries may efficiently reduce the impact of fishing. Therefore, it is important to evaluate the biomass of Indian Mackerel fishery in order to maintain the stock. Catch-based Monte Carlo maximum sustainable yield (CMSY) method and Length-based Bayesian Biomass (LBB) methods are frequently used to evaluate fish stock. Eighteen years effort-catch and length frequency data from commercial fishing were utilize to estimate the current biomass. The calculated biological reference points from Bayesian state-space Schaefer production model (BSM) at r = 0.618, k = 68,700, maximum sustainable yield (MSY) = 10,600. However, CMSY at r = 0.662, k = 6800, MSY = 11,200. Biomass in 2021 at maximum sustainable yield 2021 (B₂₀₂₁/B_MSY) = 0.436 (< 1) and fishing rate F₂₀₂₁/F_MSY = 1.94 (> 1) values explain the Indian Mackerel fishery is at exploited state. However, results using LBB model defines as B/B_MSY = 0.65 (< 1.0) and fishing rate F/F_MSY = 3.33 (> 1.0) and mean length/optimum length (L_mean/ L_opt) obtained at 1.3 and L_95th/ L_inf at 0.95. Based on suggested prior biomass range (B/B_MSY =0.5–0.8) for stock assessment also indicates that the Indian Mackerel fishery is in unsustainable state from the study area. Monitoring of illicit fishing practices in the area is recommended. Measures need to be implemented for the protection of these valuable resources.