Atlantic Salmon Smolt Assessment – Terra Nova River

Description: The Atlantic salmon population on Terra Nova River enjoyed significant growth after the marine commercial fishery closed in 1992. Since 2020, however, the trend has turned in the opposite direction. The 2021 return of 2,325 adults was the lowest in 14 years. The average return from 2021 to 2023 was 2,990, in comparison to an average of 5,023 from 2015 to 2020 and the record run of 6,607 in 2019. Linked to climate change, this downturn has highlighted the need for an integrated place- based watershed management plan.

A plan is currently being developed but before it can be completed, more information is needed in order to better understand salmon population demographics, location of critical habitat needs and if there are issues with in-river survival and spawning success. In 2024, this project carried out by the Freshwater-Alexander Bays Ecosystem Corporation (FABEC) will address these needs and enhance efforts to understand the cause(s) of the recent decline by quantifying smolt production and providing a first-time estimate of marine survival. While adult counts on Terra Nova River date back to 1956, little information has been collected on population demographics and other life stages that could provide insight into critical habitats, ecosystem health, and limiting factors. There has never been an estimate of how many smolts leave the river. Hence, there is no baseline of smolt numbers to compare against adult returns.

Currently smolt counts in Newfoundland and Labrador rely on 100% counts at traditional smolt fences. High costs have limited such operations to only a few rivers. In recent years this approach has been undermined by increasing flood events, associated with climate change, that wash out fence structures and result in incomplete counts.

To provide insights on the health of the Terra Nova River smolt population and a realistic estimate of Atlantic salmon survival during the marine stage in their life history FABEC, working with project partners, will utilize a Rotary Screw Trap (RST), or smolt wheel, combined with the mark recapture technique.  As well as determining how many smolts are leaving Terra Nova River and comparing this to the number of adult returns the following year, biological data will be collected from a representative sample of captured smolts to determine size, weight, age, and genetic qualities. A side benefit of the RST may be the capture of resident and sea-run brook trout, sea lamprey and American eel, providing additional valuable insights into ecosystem health

This will be the first time the RST-mark recapture method will be used on a Newfoundland river to estimate smolt population and will test the feasibility of using RST’s as an alternative method to provide population estimates in Newfoundland and Labrador. The final report will include findings and conclusions on whether the project provides a reasonably accurate estimate of smolt population, lessons learned in RST operation and mark recapture and a detailed accounting of human resource and equipment costs. This will aid future RST operations in other rivers in the province.