Estimating the total allowable catch and management of Threadfin porgy(Evynnis cardinalis)fisheries in the northern South China Sea based on sampling surveys conducted at fishing ports

In order to develop a method that apply sampling survey data randomly obtained at fishing ports to fish stock assessments,based on fish landing surveys conducted at fishing ports in the northern South China Sea(SCS),19 Threadfin porgy(Evynnis cardinalis)catch per unit effort(CPUE)datasets were collected for fishing vessels with different gear types and engine powers and incorporated into surplus production models.Considering only the fitting performance,the Schaefer model had the best overall goodness of fit,followed by the Fox,CYP,W-H,and Schnute models.Among fishing vessels with different gears and engine powers,the data were best fitted for single-trawl vessels powered by 301-400-kW engines and for gillnet vessels powered by>200-kW engines.Eight model expressions were superior and selected for subsequent analyses based on their goodness of fit and relative residuals.The Kobe plot analysis results showed an optimistic fish stock status when using the four model expressions,required more caution when using three model expressions and output pessimistic estimations using one model expression.Considering the incomplete information acquired,a compromising decision-making method was used to derive a 2017 northern SCS E.cardinalis total allowed catch(TAC)of 44,691.21 t.The different conclusions drawn from estimations using CPUEs reflect variable exploitation and utilization fish stock statuses among fishing vessels with different gears and engine powers.Hence,the fishing operations were grouped according to their CPUE relationship,and recommendations regarding optimum fishing efforts were assigned to the groups following a fundamental principle:to improve fishery TAC management,fishing efforts should be reduced if the fish stock assessment is pessimistic and maintained if the assessment is optimistic.This study providing a feasible technical method for the TAC management of China’s offshore fisheries.

Advancing multispecies fishery management in China:Lessons from international experience

China’s 13th Five-Year Plan elevated the national mandate for environmental sustainability.Chinese fisheries are characterized by full retention of high diversity catch harvested using unselective gears,creating ecological risks.Therefore,China launched pilot projects in management by Total Allowable Catch(TAC)in five coastal provinces in 2017 and 2018 to build experience with output controls.Fujian province launched an important pilot in its swimming crab fishery,the first to adopt a multispecies approach.To guide Fujian and other provinces in multispecies management,a workshop in April 2018 shared international experience.The workshop considered 13 case studies spanning a wide range of underlying scientific models and types of harvest controls.Multispecies harvest controls based on simple survey-or index-based models that aggregate trends for many species are typically operationally easier for managers and fishers.However,inadequate management can cause declines of individual species,sometimes leading to adoption of species-specific models and then species-specific harvest controls.This transition often incurs economic costs through scientific and management demands,and constraints on harvest of co-occurring species.The lessons revealed by the case studies suggest multispecies TACs might be effective in the Fujian swimming crab fishery given the modest number of species with similar and productive life history traits,and the market demand for all species.Continued experimentation with different management approaches through pilot projects can enable China to maintain progress toward sustainable fisheries goals under the 14th Five-Year Plan.

Estimation of age and growth and mortality parameters of the sea cucumber Isostichopus fuscus (Ludwig, 1875) and implications for the management of its fishery in the Galapagos Marine Reserve

The fishery of the sea cucumber Isostichopus fuscus was the most important one in the early 2000s in the Galapagos Marine Reserve.Its overexploitation leads to its total closure from 2016 to 2021.At the end of this period,if the co-management system of the Galapagos Marine Reserve decides to open this fishery,a total allowed catch must be established using the methodology of Wolff,Schuhbauer,and Castrejón(2012).The objective of this paper is to evaluate this methodology and improve the total allowed catch calculation.We replicated Wolff et al.‘s methodology that uses the Cadima equation of Maximum Sustainable Yield(in Troadec,1977).We determined the age and growth parameters of I.fuscus to estimate total mortality and improved the calculation of the area of fishing and habitat of this species in Galapagos to estimate its abundance.We found inconsistences in Wolff et al.‘s estimations of mortality and abundance and we recommend that the Maximum Sustainable Yield be used not as the total allowed catch,but as a limit reference point for this fishery.We propose,instead,to use a dynamic abundance model that is capable of estimating a variety of reference points,including the fishing mortality for optimal fishing that is recommended to use to establish a total allowed catch.In addition,for the first time,the age and growth parameters of I.fuscus for Galapagos and the eastern-central region of the Pacific Ocean are determined(L∞=42.5 cm;K=0.21/year).