Gillnet fisheries targeting grey mullets Mugil cephalus are an important part of small-scale fisheries in

the coastal areas of China. However, in fishery production, the catch efficiency of gray mullet is low and the

number of catches is out of proportion to the fishing effort, which leads to a low economic benefit for the fishery.

Improving the catch efficiency of gray mullets has become an urgent problem that needs to be solved. In recent

years, light-emitting diodes (LEDs) have been widely used to improve the catch efficiency of target species. It

mainly uses the phototaxis of the target species to attract, gather, and trap fish. Many studies have shown that the

gray mullet has phototaxis and may have different phototaxis for different lights. Therefore, the application of

LEDs in gray mullet gillnet fisheries may effectively improve catch efficiency; however, their specific impact

needs to be systematically assessed. In this study, sea trials were conducted in the northern sea area of Rongcheng

from May to June 2023 to test the effects of different LED light colors (red, white, yellow, blue, and green) and

amount (2, 4, 6) on the catch efficiency of gray mullet. A total of 1549 specimens of grey mullet were caught. The

generalized linear mixed effect model (GLMM) was used to evaluate the effect of LEDs on the catch efficiency of

gray mullets. When building the model, CPUE (catch amount per unit of fishing effort) and WPUE (catch weight

per unit of fishing effort) were taken as dependent variables, LED color and quantity as fixed effects, and voyage

time as random effects, according to the Akaike Information Criterion (AIC) and Bayesian Information Criterion

(BIC), to judge the fitting degree of the normal, gamma, Poisson, and negative binomial distributions. The gamma

distribution was selected as the optimal fit to analyze the influence of LED color and quantity influence the catch

efficiency of gray mullets. Compared with LEDs of different light colors, the CPUE of mullet with 2/4/6 green

lights significantly increased by 50.72%, 97.46%, and 98.07%, whereas the WPUE significantly increased by

39.38%, 80.54%, and 84.63%, respectively. The CPUE and WPUE of gray mullets in the test nets with 4 and 6

LEDs were not significantly different (P>0.05). In addition, LEDs improve the catch efficiency of bycatch in sea

bass (Lateolabrax maculatus) and black rockfish (Sebastes schlegelii). Based on the results of this study, green

LEDs are recommended in grey mullet gillnet fisheries to improve the catch efficiency of grey mullet, and the

recommended number is four per net.