Growth and maturity heterogeneity of three croaker species in the East China Sea

Abstract

Big head croaker (BC) Collichthys lucidus, Large yellow croaker (LC) Larimichthys crocea, and Yellow croaker (YC) Larimichthys polyactis are important ecological and commercial species along the coastal seas of China. Based on samples collected from seasonal bottom trawl surveys in the southern East China Sea from 2015 to 2018, we analyzed the growth and maturity characteristics of these three croaker species. Simple linear model, mixed-effects model and hierarchical methods were conducted in this study to evaluate the variations in growth and maturity among sexes, seasons and years for each species. Our results showed that, mixed-effects model performed better than simple linear models, while hierarchical methods could reveal variations in different life stages. Female LC and YC tended to gain more weight at the same length and matured earlier than the male for LC and YC. The individuals tended to gain more weight in spring and fall, while all croakers had larger weight at the same length and matured earlier from 2015 to 2017 compared to those in 2018. Results from the hierarchical model indicated that for all captured croakers, individuals with bigger sizes were mostly females, especially for LC. Big head croaker and LC tend to gain more weight in spring, while YC tends to gain less weight in winter. Mixed-effects models and hierarchical methods can be incorporated to provide more information about the heterogeneity of fish life history traits. These results will help provide more insights related to the growth and maturity of these three important species in the East China Sea. Also, the methodology applied in this study may be used on the life history research for species with multiple data sources.