Annual Young-of-the-Year Redhorse Survey in the Richelieu River : Main Approach to Measure the Achievement of the Objectives of Protection and Recovery of the Copper Redhorse (Moxostoma hubbsi)

The Copper Redhorse is an endangered species unique to Québec. Its recruitment is extremely low and considered insufficient to offset natural mortality. Among multiple recovery actions, a supportive breeding program is applied since 2004 to rebuild the ageing spawning stock. Near 3.5 millions larvae et 204,000 fingerlings were stocked in the Richelieu River. A YOY (young-of-the-year) Redhorse survey is carried out in September almost annually since 1998 in the same sectors of the Richelieu River. This monitoring is an invaluable source of knowledge on the early life history of the five sympatric Redhorse species of the Richelieu River. The survival of specimens stocked at the larval and fry stages was demonstrated up to second year by chemical marking and genetic analysis. The relative contribution of stocked YOY to wild ones is very significant (9:1). In nearly 50% of cases, one or both parents of natural YOY Copper Redhorse can be identified by parentage assignment genetic analysis, which highlights the very low abundance of spawners. More concrete results are expected within 5-10 years since the Copper Redhorse reaches its sexual maturity at around 10 years.