Migration and feeding habits of juvenile Chinese sturgeon (Acipenser sinensis Gray 1835) in the Yangtze Estuary: Implications for conservation

Abstract

Spatial and temporal variation in migration and feeding ecology of juvenile Chinese sturgeon (Acipenser sinensis Gray 1835) is reported for waters around Chongming Island, Yangtze Estuary, between April and August 2015. A migration survey showed that juvenile Chinese sturgeon remained within the Yangtze Estuary for a period of time preceding their onward migration to the sea; upper estuarine reaches were an important transition habitat during April and May, while nearshore coastal areas were foraging habitat during June to August. Stable isotopic analysis revealed (1) significantly lower isotope values in smaller‐sized Chinese sturgeon (≤100 mm) than larger‐ sized fish (>100 mm), which indicated a dietary shift likely occurs at fork lengths greater than 100 mm; (2) the increase in values of δ13C and δ15N from May to August implied an ontogenetic dietary shift from lower to higher trophic‐level prey items; and (3) slight changes in distributional range among different coastal sites implied that individuals fed on similar food items. Coastal shallows represent major foraging areas for juvenile Chinese sturgeon in the Yangtze Estuary. In addition to the conventional conservation measures at the nature reserve, we suggest additional conservation actions to better protect juvenile Chinese sturgeon residing in the estuary; namely: (1) expanding the protected area and adding a seasonal component, from April to August, to afford better protection of juvenile Chinese sturgeon in the whole estuary, but particularly just upstream of the estuary mouth and in nearshore waters; and (2) banning all fishing activities and extending protection to the food resources (such as zoobenthos and small‐sized fishes) of juvenile Chinese sturgeon in coastal shallows.

Growth and feeding ecology of juvenile Chinese sturgeon, Acipenser sinensis , in the Yangtze Estuary

“…The larvae and juvenile A. sinensis migrate to the Yangtze Estuary, where they arrive in mid‐May, and then leave to the East China Sea approximately three months later (Wang et al, ; Zhuang et al, ). Achieving a good growth in the Yangtze Estuary is essential to their subsequent marine life.…”

Optimization of Sampling Effort for Different Fishery Groups in the Yangtze River Estuary, China

“…2011]), as well as migration channels, for many important and rare aquatic species (e.g., for Chinese sturgeon Acipenser sinensis [Wang et al. 2018] and Tapertail Anchovy Coilia nasus [Dou et al. 2012]), playing a key role in the conservation of aquatic biodiversity in the Yangtze River basin.…”

“…The Yangtze River Estuary (YRE) is located where the Yangtze River meets the East China Sea and is sensitive to natural changes and human activities. The YRE and its adjacent waters are important spawning grounds (e.g., for Chinese mitten crab Eriocheir sinensis) and feeding grounds (e.g., for Osbeck's Grenadier Anchovy Coilia mystus [He et al 2011]), as well as migration channels, for many important and rare aquatic species (e.g., for Chinese sturgeon Acipenser sinensis [Wang et al 2018] and Tapertail Anchovy Coilia nasus [Dou et al 2012]), playing a key role in the conservation of aquatic biodiversity in the Yangtze River basin. The habitats of aquatic organisms in the Yangtze River have been deteriorating gradually over many years due to human activities such as river damming (Wang et al 2014), water pollution (M üller et al 2008), and overfishing (Zhu and Chang 2008).…”