Mass marking of juvenileSchizothorax wangchiachii(Fang) with alizarin red S and evaluation of stock enhancement in the Jinping area of the Yalong River

Abstract

Schizothorax wangchiachii is a key fish species in the stock enhancement program of the Yalong River hydropower project, China. Alizarin red S (ARS) was used to mark large numbers of juvenile S. wangchiachii in the Jinping Hatchery and later used to evaluate stock enhancement in the Jinping area of the Yalong River. In a small-scale pilot study, 7,000 juveniles of the 2014 cohort were successfully marked by immersion in ARS solution, and no mortality was recorded during the marking process. The ARS mark in the fish otoliths remained visible 20 months later. In the large-scale marking study, approximately 600,000 juveniles of the 2015 cohort were successfully marked. Mortalities of both marked and unmarked juveniles were very low and did not differ significantly. Total length, wet mass and condition factor did not differ significantly between unmarked and marked individuals after three months. On 24 July 2015, about 840,000 Jinping Hatchery-produced young S. wangchiachii, including 400,000 marked individuals, were released at two sites in the Jinping area. Recapture surveys showed that (1) marked and unmarked S. wangchiachii did not differ significantly in total length, wet mass and condition factor; (2) stocked individuals became an important part of recruitment of the 2015 cohort; (3) instantaneous growth rate of marked individuals tended to slightly increase; and (4) most stocked individuals were distributed along a 10–15 km stretch near the release sites. These results suggest that the ARS method is a cost-efficient way to mass mark juvenile S. wangchiachii and that releasing juveniles is an effective means of stock recruitment.

Substrate type and brightness preference ofSchizothorax wangchiachiiandPercocypris pingijuveniles

“…Captive‐reared S. wangchiachii and P. pingi have been released into the wild, including the Yalong and Jinsha rivers, to restore the species’ populations to sustainable levels (Deng, Wang, & Gan, 2016; Gan et al, 2016; Yang et al, 2017). However, factors such as water quality and temperature have been considered more important than substrate when creating suitable hatchery environments for S. wangchiachii and P. pingi .…”

Deterministic processes dominate microbial community assembly in artificially bredSchizothorax wangchiachiijuveniles after being released into wild

“…Between March and April 2021, the hatchery‐reared juvenile SW otoliths were marked by immersing in a fluorochrome ARS (C 14 H 7 NaO 7 S) solution (doses ≤100 mg L −1 ; 24 h) to be able to identify these individuals post release (Yang et al. 2017). Prior to release (day 0), five juvenile fishes (body length: 4–6 cm, approx.…”

Effect of predation‐risk and foraging opportunities on substrate choice and strength of brightness preference inSchizothorax wangchiachiiandPercocypris pingijuveniles

“…Red List of Threatened Species and as Endangered (EN) on the Red List of China's Vertebrates (Jiang et al, 2016;Zhao, 2011). At present, hatchery-reared S. wangchiachii and P. pingi have been released into the Jinsha and Yalong rivers for restoring populations in the wild (Deng et al, 2016;Gan et al, 2016;Yang et al, 2017).…”

“…wangchiachii and P . pingi have been released into the Jinsha and Yalong rivers for restoring populations in the wild (Deng et al, 2016; Gan et al, 2016; Yang et al, 2017).…”