A comparative analysis of the ecological impacts of Chinese tuna longline fishery on the Eastern Pacific Ocean

Ecological Risk Assessment (ERA) has been widely applied in data-poor fisheries to identify potentially vulnerable species and prioritize future research. We performed an ERA study using semi-quantitative Produc-tivity-Susceptibility Analysis (PSA) to analyze the relative vulnerability of 24 species caught by the Chinese tuna longline fishery operating in the Eastern Pacific Ocean (EPO). The PSA results in our study were compared with those of all longline fisheries in the EPO and validated by the quantitative vulnerability assessment (EASI) applied to EPO longline and purse-seine fisheries. We conducted a sensitivity analysis of the attributes used in the PSA. Of the 24 species assessed, five species were classified as highly vulnerable, including the target species of Bigeye tuna (Thunnus obesus) and four shark species, with the remaining species being moderately vulnerable. Our findings revealed good concurrence with the PSA study considering all longline fisheries but differed significantly from EASI. There were seven medium vulnerability species in our assessment corresponding to low vulnerability in the EASI study, which is largely attributed to the precautionary attribute scoring and vulnera-bility classification criteria used in PSA. The sensitivity analysis suggested that species vulnerability was more likely to be influenced by susceptibility attributes than productivity attributes, especially Areal Overlap with RMSE value of 0.146. Given these findings, while it is reasonable to adopt the PSA approach until we have more reliable data, there is a need to move further toward quantitative assessment.

Automated summary

In this study, a semi-quantitative PSA approach was used to assess the vulnerability of 24 species caught by the Chinese tuna longline fishery in the EPO, with 5 species identified as highly vulnerable and the rest as moderately vulnerable. The PSA results showed good concurrence with all longline fisheries in the EPO, but differed significantly from EASI, highlighting the need for more reliable data for quantitative assessments.