A bedform morphology hypothesis for spawning areas of Chinese sturgeon

Abstract

Results from previous research suggested that geomorphic characteristics may be important controlling factors among other microhabitat variables for spawning fish. We investigated the bedform morphology of seven spawning areas (five historic and two present spawning areas) of Chinese sturgeon (Acipenser sinensis) by analysis of relief maps of the riverbed and by field surveys. We conclude that the topographic characteristics of the spawning areas include rocky or gravelly substrate river bend, large variations in water depth and river width and a slope with moderate length and slope. The turning structure and the adverse slope may be the most important topographic characteristics for the spawning areas. Combined with the reproductive occurrence of the fish in these spawning areas, we tentatively propose a bedform morphology hypothesis for the spawning areas. We consider that a spawning area of A. sinensis should consist of three functional areas: Mating area (M), Dispersal area (D) and Incubation area (I). M, D and I are distributed along the water current and their bedform characteristics are clearly different. M is the place for mature fish to mate and spawn. It is usually below a riffle with rolling terrain. D is the place for fertilizing and dispersing fertilized eggs. It is usually in a river bend with sharp variations in terrain, such as deep pools or steep slopes. I is the place for dispersal of fertilized eggs. It is usually in long point bars or broad shallow areas with rocky substrate. This hypothesis could serve as a guideline for improving the present spawning areas or constructing new spawning areas, so as to rehabilitate the wild stock of the sturgeon.

Migrations and movements of adult Chinese sturgeon Acipenser sinensis in the Yangtze River, China

“…1). This reach has the topography of a sharply adverse slope and a substratum dominated by cobble and gravel (Wei, 2003; Zhang et al , 2008; Zhang 2009).…”

“…Watanabe et al (2008) employed an acoustic transmitter to monitor depth utilization, tail‐beating activity and swimming speed. Du et al (2011), Zhang et al (2007 a , b , 2008, 2011) and Zhang (2009) described the spawning environment, including depth, topography, velocity and substratum type. All results revealed the environment influenced spawning, and even determined whether spawning was successful.…”

If you build it, will they come? Spawning habitat remediation for sturgeon

“…While spawning downstream of migratory barriers is widely observed, such locations might not provide the biological benefits associated with upstream spawning locations (see below). For example, lost migratory access concentrates spawning in tailrace areas of hydroelectric facilities, which can contain either unsuitable habitats (Cooke & Leach, ; Terraquatic, ) or a much reduced area of potential spawning habitat (Chebanov & Savelyeva, ; Khodorevskaya et al., ; Zhang et al., ). Maintaining the existing connectivity is thus preferred (see Rupert River case study) in the absence of understanding how to fully mitigate the benefits accrued by migrating (see Brown et al., ).…”

Impact of the Three Gorges Dam on the spawning stock and natural reproduction of Chinese sturgeon in Changjiang River, China

“…The environmental conditions of the spawning ground of the Chinese sturgeon, fast-fl owing, turbid, and with rock and gravel (Zhang et al, 2009;Wang et al, 2012b ), make fi eld observation to count the eggs scattered on the river bottom almost impossible. Under these conditions, investigation for the eggs in the alimentary canal of the benthic fi shes off ered the only feasible approach to estimate the quantity of the eggs.…”