Stock assessment of Newfoundland and Labrador Atlantic Salmon in 2022 (SFA 1– 14B)

Abstract

Twenty-one populations of Atlantic Salmon (Salmo salar) were monitored in 2022. Returning adult salmon were counted on 20 rivers using monitoring fences or fishways, and returns were estimated on one river using a combination of a fish counting fence and snorkel survey. Stock status was estimated for 19 of 21 monitored populations. In 2022, 16 rivers had sufficient time series data to compare adult returns to the previous generation. Of these 16, nine (one in Labrador and eight in Newfoundland) showed declines in total returns with five having declines over 30%. Thirteen rivers had sufficient time series data to compare adult returns to the previous three generations. Of these 13, seven (one in Labrador and six in Newfoundland) showed declines in total returns with five having declines over 30%. Marine survival is considered a major factor limiting the abundance of Atlantic Salmon in Newfoundland and Labrador (NL), with adult returns in any given year determined primarily by marine survival rather than smolt production. In 2022, estimated marine survival on monitored rivers ranged from 5.4% to 10.7% excluding rivers in Salmon Fishing Area (SFA) 11, where survival rates were lower (1.2%–3.9%). In 2022, estimated spawning escapements (eggs) on Labrador rivers were in the Critical Zone on Southwest Brook, the Cautious Zone on Sand Hill River, and the Healthy Zone on English River and Muddy Bay Brook. Of the 15 assessed rivers in Newfoundland, nine were in the Critical Zone, one was in the Cautious Zone, and five were in the Healthy Zone. Preliminary estimates of harvest in the 2022 Labrador Indigenous and subsistence fisheries were inferred from logbooks and were similar to the previous generation average. Preliminary estimates of catch in the 2022 recreational Atlantic Salmon fishery were inferred from angler log returns. Estimates of retained salmon were similar to the previous generation average in Newfoundland and lower in Labrador. Estimates of released salmon were lower than the previous generation average in both Newfoundland and Labrador. In 2022, record high sea surface temperatures during ice-free months were observed on the Newfoundland shelf. Water temperatures from an inshore thermograph network on the island of Newfoundland also suggested that 2021 and 2022 were the two warmest years on record since 1989. However, the effects of higher marine temperatures on Atlantic Salmon are uncertain. In 2022, hourly water temperatures across 12 Newfoundland rivers were above 20°C for 58.9% of August and above 24°C for 7.5% of August, with higher temperatures in the Avalon and Central regions. In Labrador, temperatures were above 20°C for 1.2% of August across three rivers. Temperatures exceeding 20°C can have negative impacts on Atlantic Salmon physiology and behaviour. Overall conditions of the past three years are indicative of improved productivity at lower trophic levels along the NL bioregion (2HJ3KLNOPs). This includes earlier phytoplankton blooms, higher chlorophyll concentrations, and increased zooplankton biomass with a higher abundance of larger, more energy-rich Calanus copepods. Marine ecosystem conditions indicated overall limited productivity of the fish community. Total biomass of the entire fish community remained below pre-collapse levels with minor recovery up to the early 2010s, followed by subsequent declines. In recent years (2019–21), ecosystem indicators have suggested that conditions could be improving from the lows in the mid-late 2010s. However, the lack of offshore multi-species surveys in 2022 prevented an updated evaluation of these trends. Aquaculture associated genetic impacts (i.e., hybridization and introgression) continued to be documented in southern Newfoundland wild salmon populations, with probable impacts on wild population size and persistence. Recent detection of unauthorized European ancestry in aquaculture salmon and escapees in the region elevates the uncertainty and potential magnitude of these impacts. In addition to genetic interactions, there remains significant uncertainty as to the role of aquaculture associated disease or parasite transfer and ecological interactions (i.e., competition or predation) on wild populations in the region.