Assessment of fishing effort and catch performance in the drift gillnet fishery for mackerel and tuna in Ho Chi Minh city
Abstract
The study employed interview surveys and fishing logbook records from 30 drift gillnet vessels targeting mackerel and tuna operating in Ho Chi Minh City (formerly Bà Rịa – Vũng Tàu) during the period from July 2023 to June 2024. Based on the collected dataset, descriptive statistical methods were applied to determine key indicators for assessing the fishing performance, thereby supporting sustainable fisheries management.
The results showed that the fishing effort (E) of the drift gillnet fleet ranged from 191.8 to 509.7 vessel-days, with an average of 14.8 vessel-days per vessel per month. Catch per unit effort (CPUE) varied between 399.6 and 502.8 kg/10,000 m², averaging 447.9 kg/10,000 m². Both effort and CPUE exhibited clear seasonal variability. The linear regression model between CPUE and fishing effort was determined as CPUE = 1.65E + 208.76 (R² = 0.06), indicating a positive but weak relationship. An incremental increase of 1 vessel-day resulted in only a 1.65 kg/10,000 m² increase in CPUE, suggesting that fishing effort is not the primary driver of catch rates. Instead, CPUE appears more strongly influenced by seasonal dynamics, fishing grounds, tuna school behavior, and operational techniques. Monthly catch estimates ranged from 379.7 to 478.4 tons, peaking between October 2023 and March 2024, highlighting pronounced seasonality. Overall, the findings reveal that the tuna gillnet fishery operates under a seasonal-driven pattern in which fluctuations in resource availability exert stronger effects on fishing performance than variations in effort.