Nonlinear effects in finfish aquaculture: A panel threshold analysis of stocking density and water temperature in Korea

Abstract

This study applies the fixed-effects threshold model (FETM) to examine nonlinear dynamics and threshold effects in Korean finfish aquaculture using panel data from 2010 to 2023. The analysis identifies a critical threshold in current biomass (log-transformed 13.9483, approximately 1,142,010 fish), beyond which the marginal productivity of stocking density declines due to resource competition, oxygen depletion, and metabolic stress. Among key production inputs, feed input exhibits the highest elasticity (0.4717), confirming its dominant role in production efficiency, whereas water temperature shows a significant negative elasticity (-1.3301), highlighting the adverse impact of rising water temperatures on fish growth and survival. Additionally, many finfish aquaculture regions in Korea face severe constraints due to overuse of water surface areas, leading to diminishing marginal returns and heightened ecological stress. These findings highlight the urgent need for comprehensive environmental assessments, real-time monitoring systems, and adaptive management strategies to enhance sustainable aquaculture practices. Particularly, optimizing stocking densities based on the identified current biomass threshold and implementing spatial planning policies can balance ecological sustainability and production efficiency. This study demonstrates the effectiveness of FETM in detecting nonlinear relationships and production thresholds in aquaculture systems, providing insights for evidence-based policymaking and sustainable resource management aligned with global sustainability goals.