Resource carrying capacity diagnosis and evaluation of small yellow croaker based on traffic light approach

The traffic light approach as a technical procedure was first developed for evaluating the status and level of risk faced by a fish population.It has also facilitated stock management and conservation.This paper introduced the construction procedure of traffic light approach, and applied fuzzy logic to deal with the uncertainty of boundaries and observation values.Red, yellow and green lights in traffic lights were defined as overload, critical overload and loadable respectively.Taking the stock of small yellow croaker from 2000~2015 in East China Sea as an example, the inter-annual variation and carrying state of small yellow croaker were explored in terms of the characteristics of abundance and productivity, and these indicators were integrated into traffic light system, more than 30% red within one year was classified as the serious overload.The results showed that the serious overload years for recruitment was in 2005 and 2011, for spawning stock was in 2002, 2003 and 2012, and for the abundance at the beginning season was in 2002~2004 and 2006.According to the integrated traffic light index, there were 12 years existed overload states during 2000~2015, and the years which had serious overload states was 2002, 2003, 2004 and 2006.Loadable states had occurred in 9 years; Critical overload state was the dominant state which had appeared in every year, and the proportion in every year ranged from 29.14% to 91.56%.The analysis method and results can enrich the evaluation system of fishery resources carrying capacity and provide theoretical reference for fishery resources management.