# Linking Biological Parameters to Fishery Management: Stock Assessment of Green Tiger Prawn, Penaeus semisulcatus De Haan, 1844 Along the Red Sea Coast of Saudi Arabia

## TL;DR

This study assesses the green tiger prawn population in the Red Sea to guide sustainable fishing practices.

## Contribution

The study provides new stock assessment data for Penaeus semisulcatus in the Red Sea, revealing overexploitation and recommending management actions.

## Key findings

- Females of Penaeus semisulcatus grow larger than males, with high growth rates.
- Exploitation rates exceed optimal levels, indicating overfishing and reduced spawning stock biomass.
- Recommendations include gear modifications and seasonal closures to improve sustainability.

## Abstract

Penaeid shrimps, highly prized in global seafood markets, form the main target of marine shrimp fisheries. Their ecological and commercial importance underscores the necessity of conducting robust stock assessments to guide and ensure sustainable management. The present study investigates important population characteristics of the green tiger prawn Penaeus semisulcatus along the southeastern Red Sea coast. Growth analysis showed that the asymptotic carapace length is higher in females than in males, with both sexes exhibiting rapid growth rates. The estimated exploitation rates exceeded the optimum level for both sexes, raising concerns about the sustainability of the shrimp trawl fishery. Notable presence of juvenile prawns in the catch, coupled with excessive fishing mortality, strongly suggests that the stock is overexploited. To mitigate this situation, a transition from traditional diamond mesh codends to square meshes with improved selectivity is recommended to decrease juvenile catches and enhance sustainability. Additional measures, including limiting fishing days, curbing the active trawling fleet, setting catch limits, and prolonging seasonal closures, should be implemented to protect spawning and recruitment periods. Strengthening data collection for ongoing monitoring, incorporating climate-related factors into management, and integrating all actions into an ecosystem-based management framework created in partnership with key stakeholder groups are essential to ensure the long-term sustainability of shrimp stocks and fisheries.

Penaeus semisulcatus is the dominant commercial prawn species along the Saudi Arabian coast in the southeastern Red Sea, yet its population dynamics remain poorly understood. This study examined growth, maturity, and mortality using fishery-independent samples obtained during trawl surveys off Jizan and Al Qunfudhah between October 2022 and September 2023. A total of 85,909 individuals were examined, exhibiting carapace lengths (CL) between 1.29 and 56.14 mm and weights (W) ranging from 0.91 to 94.99 g. The sex ratio (1:1.06) was slightly male-biased. The CL–W relationships were W = 0.00427·CL2.50 for females and W = 0.01274·CL2.16 for males. The von Bertalanffy growth parameters were CL∞ = 60.16 mm, K = 1.03 year−1 for females and CL∞ = 48.10 mm, K = 1.02 year−1 for males. Females first matured at a CL of 22.09 mm. Exploitation rates (0.63 for females and 0.69 for males) and spawning potential ratio analysis indicated severe overfishing, with spawning stock biomass reduced to 19% of its unexploited level. These results highlight the necessity for immediate management intervention. Reducing fishing effort by half, extending seasonal closures, and improving the selectivity of trawl gear are advised to facilitate stock recovery and support sustainable exploitation in the region.