Biology of lanternfish Ceratoscopelus warmingii in waters of the northern slope in South China Sea

YANG Yu-yan;YING Yi-ping;ZHAO Xian-yong;WANG Xin-liang;ZHANG Jun;CHEN Zuo-zhi;TANG Yong;College of Marine Science and Environment,Dalian Ocean University;Key Laboratory of Sustainable Development of Marine Fisheries,Ministry of Agriculture,Yellow Sea Fisheries Research Institute,Chinese Academy of Fishery Sciences;South China Sea Fisheries Research Institute,Chinese Academy of Fishery Sciences;

Ceratoscopelus warmingii;;diurnal vertical migration;;body length;;reproduction;;feeding habit;;mesopelagic fish

The distribution and biological characteristics of lanternfish Ceratoscopelus warmingii as an important species were studied based on the catches of mesopelagic fish survey conducted in the northern slope in the South China Sea during June of 2015. It was found that the lanternfish had body length from 30 mm to 64 mm and three cohorts with overlapping body length,(37.52±2.39),(44.62±2.84) and(49.80±3.17) mm. The relationship between body length and body weight was expressed as W = 8.418×10-6L3.0985. Over half of the lanternfish with body length of 42.54 mm collected in June had gonads which developed into maturity at stage Ⅱ and stage Ⅲ,with sex ratio of 1 ∶ 0.7( female ∶ male),smaller in male than in female. The average degree of stomach fullness( ADSF) of the lanternfish was found to be increased with time during night,with ADSF of 0.82 at 20:00,1.58 at 22:00,and2.53 at 4:00. No lanternfish were collected at over 600 m depth during the daytime. However,a few lanternfish were caught during evening,and more fish were collected at night at over 650 m depth except one station,indicating that the diel vertical migration is one of important feature of lanternfish and that agrees with the other research results during day time most species aggregated in water deeper than 700 m depth. The findings will help to analyze the biology and distribution of the lanternfish in waters of the northern slope in South China Sea.