Environmental Effects on the Spatiotemporal Variability of Fish Larvae in the Western Guangdong Waters, China

Yuting Feng,Lijun Yao,Zhaojin Lin,Hui Zhao,Jing Yu

doi:10.3390/jmse9030316

Abstract

Spawning grounds occupy an important position in the survival and reproduction of aquatic life, which plays an important role in the replenishment of fishery resources, especially in the China coasts where fishery resources are depleting. This study investigated environmental effects on the spatiotemporal variability of fish larvae in the western Guangdong waters (WGWs), on the basis of generalized additive models (GAMs) and center of gravity (CoG). Satellite data including sea surface salinity (SSS), sea surface temperature (SST), and in situ observations for fish larvae from April to June in 2014–2015 were used. Results showed that 40.3% of the total variation in fish larvae density was explained. SST, SSS, and depth showed positive effects in 23–24 °C and 27–30 °C, 24–32 PSU, and 0–60 m, and showed negative effects in 24–27 °C, 32–34.2 PSU, 60–80 m. Based on the stepwise GAMs, the most important factor was month, with a contribution of 10.6%, followed by longitude, offshore distance, depth, and latitude, with contributions of 7.0%, 7.0%, 6.3%, 4.2%, 3.9%, and 1.3%, respectively. Fish larvae CoG shifted northward by 0.6° N and eastwards by 0.13° E from April to June. The distribution of fish larvae in the WGWs was affected by complex submarine topography in the Qiongzhou Strait, coastal upwelling in the WGWs, and runoff from the Pearl River.

Highlights

The western Guangdong waters (WGWs), extending from the west of Pearl RiverEstuary (PRE) to the northeast of Hainan Island, is rich in fish resources and critical to the spawning, feeding, breeding, and migration of many commercial fishes [1]
The spatiotemporal and environmental variables selected by the model included month (Month), longitude (Lon), sea surface salinity (SSS), water depth (Depth), latitude (Lat), offshore distance (Distance) and sea surface temperature (SST)
The results showed that fish larvae density was the highest when the depth was less than 40 m and the slope is >0.3◦, indicating that the fish population tended to spawn in shallow waters with a small slope

Summary

Introduction

The western Guangdong waters (WGWs), extending from the west of Pearl RiverEstuary (PRE) to the northeast of Hainan Island, is rich in fish resources and critical to the spawning, feeding, breeding, and migration of many commercial fishes [1]. As an important place to the survival and reproduction of aquatic lives, the WGWs plays an important role in the replenishment of fish resources [2]. The early life history of fish is mainly divided into three stages: the embryonic stage, the larval stage, and the juvenile stage. The strength of this generation and the abundance of fish resources depend on the early replenishment quantity and survival rate [3,4]. Research on larvae is essential and fundamental to the study of fish population dynamics and marine ecology. Studies have shown that there is a strong link between the natural and predatory mortality of larvae

Objectives

Results

Discussion

Conclusion