Biomass particle size spectrum of fish in the Jiaozhou Bay

In order to understand the grain size structure characteristics of fish communities in the Jiaozhou Bay, in this study, we constructed the biomass particle size spectrum of fish in this area based on the data collected from the four submarine trawl surveys performed during 2016 to 2017. The heterogeneities of the characteristic parameters of biomass particle size spectrum of fish in four seasons were analyzed and compared. The results showed that the Sheldon-type biomass particle size spectrum of fish in the Jiaozhou Bay displayed the unimodal pattern, with the fish particle sizes being ranged from −3 to 10 grain size, showing a relatively uniform particle size distribution spectrum and the highest peak was on the 5-6 grain size. It is mainly composed of small fish, such as Hexagrammos otakii and Sebastiscus marmoratus. There was a significant difference in the degree of curve and curvature of the normalized biomass particle size spectrum of each season. Among them, the spring curvature was the largest and the curve was gentle whereas the summer curvature was the smallest and the curve was relatively steep. The degree of curve and curvature of the curve were mainly related to the presence of a large number of endemic perennial species, such as Liparis tanakae, Ammodytes personatus, and Cryptocentrus filifer as well as the seasonal migratory fish, such as Thrissa kammalensis, and Argyrosomus argentatus. The ABC curve indicated that the spring was in an undisturbed state, the winter was in a moderately disturbed state whereas the summer and autumn were in a state of severe disturbance. These results indicated that the fish biomass spectrum in Jiaozhou Bay was unimodal, and the particle size structure was mainly small-sized fish. The number and size of supplementary populations such as local perennial and seasonal migratory fish affected the peak type and curvature of the biomass particle size spectrum of fish in the Jiaozhou Bay.