Distribution and abundance of Coilia nasus larvae and juveniles in the southern branch of Yangtze River Estuary

Abstract:

To clarify the distribution and abundance of Coilia nasus larvae and juveniles, 8 stations were set along the southern branch of Yangtze River Estuary from March to September 2014 . A total of 1270 individuals of C. nasus were collected at the spring tides by a larval net(1.3 m mouth-diameter, mesh aperture 0.5 mm). The body length ranged from 3.56-50.88 mm, with developmental stages from yolk-sac larvae to juveniles. A total of 1 013 individuals of C. nasus were collected at flood tide. The average density was 0.27 ind/m³, the average body length was 10.00 mm. The highest average density was 0.268 ind/m³ at station 8, average body length was 9.44 mm. St. 6-8 were simultaneously sampled at ebb tide, and a total of 163 individuals of C. nasus were collected. The average density was 0.01 ind/m³, the average body length was 20.08 mm. At St.8, a total of 94 individuals of C. nasus were collected at night time. The average density was 0.056 ind/m³ at flood tide and 0.003 ind/m³ at ebb tide, both smaller than the day time. The average body length at flood tide was 13.86 mm, the average body length at ebb tide was 22.01 mm. Compared with the study on the surf zone, the average body length of C. nasus larvae and juveniles in the southern branch of Yangtze River estuary was smaller,and it is necessary to protect the early resources of C. nasus.