Varying growth rates of a marine eel, the whitespotted conger (Conger myriaster), are explained by the interaction between seasonal temperature and prey availability

Whitespotted conger (Conger myriaster) is a commercially important species in East Asia; however, the fisheries stock has drastically declined in recent years. Environmental changes are assumed to have profound impacts on the growth of this species, yet the mechanisms that regulate growth remain poorly understood. Here, we used otolith measurements to establish a 9-year growth chronology for whitespotted conger in the Yellow Sea and evaluated the effects of environmental variables on inter-annual variability in growth. Linear mixed-effects models were used to explain growth variation with abiotic and biotic variables, including seasonal water temperature, prey availability, and population density, and to assess age-dependent responses in growth and the interactions between abiotic and biotic factors. The results indicated that the growth of whitespotted conger was positively correlated with seasonal water temperature (except autumn) and prey abundance per capita, and the contribution of sea water temperature was more important than prey availability to explain growth variation. The model detected significant negative interactions between spring sea temperature and prey availability, indicating a higher degree of temperature-dependent growth when prey availability was low. Our findings imply that the growth of whitespotted conger is less influenced by food availability. This study provided the first evidence for the joint effects of abiotic and biotic factors on the growth variation of whitespotted conger, and the information is key to understanding population dynamics, and will help shape the sustainable management of fisheries.