Science Advisory Report 2022/031

Stock Assessment of Newfoundland and Labrador Atlantic Salmon in 2020

Summary

• Seventeen populations of Atlantic Salmon (Salmo salar) were assessed in 2020. Returning adult salmon were counted on 16 rivers using monitoring fences or fishways, and returns were estimated on one river using a combination of a fish counting fence and snorkel survey (Little Barachois Brook, Salmon Fishing Area [SFA] 13).
• COVID-19 public health measures in 2020 resulted in disruptions and delays to Atlantic Salmon monitoring activities. There were no smolt counts in 2020 and adult fences were not installed on Harrys River (SFA 13) and Sand Hill River (SFA 2). Counting fences were installed later than normal on six rivers. The proportion of the 2020 salmon run prior to counting facility operations was estimated using available run timing data on each of these rivers since 2005.
• In 2020, eight of 16 monitored rivers with information over the previous generation showed declines in total returns. This included one river in Labrador (English River, SFA 1) and seven rivers in Newfoundland, six of which declined by >30% relative to the previous generation. Five of six of the rivers were located on the south coast of Newfoundland.
• The status of the three monitored Atlantic Salmon populations in SFA 11 on the south coast of Newfoundland were deep in the critical zone (less than 20% of the Limit Reference Point [LRP]). Returns to Conne River in 2020 were the lowest on record over the available time-series, and returns to Little River were the second lowest, with both populations near local extinction. Estimated marine survival in 2020 (adult return year) on Conne River was <1%.
• Garnish River had historically large reported angling catches (approximately 1,000 to 2,000 fish landed in the late-1970s and 1980s) and, while monitoring data were limited (2015–20), the pattern of decline (>60%) was similar to neighbouring rivers. Estimated marine survival in 2020 (adult return year) on Garnish River was <1%.
• Marine survival was considered a major factor limiting the abundance of Atlantic Salmon in Newfoundland and Labrador, with adult returns in any given year determined primarily by marine survival rather than smolt production. Inter-annual estimates of marine survival were lower than the previous generation and three generation averages on most rivers where estimates were available.
• Of 13 rivers with information on adult returns over the previous three generations, total returns in 2020 were lower on six rivers (all in Newfoundland), five of which declined by more than 30%.
• In 2020, estimated spawning escapements (eggs) on Labrador rivers were in the critical zone (below the river-specific LRP) on Southwest Brook (SFA 2) and were in the healthy zone (above the Upper Stock Reference Point [USR]) on English River and Muddy Bay Brook.
• In 2020, estimated spawning escapements (eggs) on Newfoundland rivers were in the critical zone on seven of the 14 assessed rivers in 2020. Of the remaining rivers, five were in the healthy zone and two were in the cautious zone (between the LRP and USR).
• Preliminary estimates of harvest in the 2020 Labrador Indigenous and subsistence fisheries were inferred from logbooks (63% returned) to be 13,713 salmon in 2020 (7,558 small, 6,155 large), which was 3% lower than the previous seven-year average (2013–19).

Recreational Fisheries

• Estimates of catch and effort for the 2020 recreational fishery were unavailable at the time of the assessment. Mean catch values over the previous generation were used to calculate 2020 total returns and spawning escapements, and involved 20,574 retained and 25,704 released salmon for Newfoundland rivers and 1,288 retained and 6,302 released for Labrador rivers.

Genetics

• Juvenile surveys and genetic analysis indicated that the proportion of first-generation wild-escapee hybrids in southern Newfoundland in 2019 and 2020 were the lowest since monitoring began in 2014. Despite this, first-generation hybrids were detected in both years in Fortune Bay, and samples from smaller rivers continued to be dominated by hybrids. Both experimental evidence and increases in the detection of the offspring of first-generation hybrids and wild salmon supported a role for precocial male hybrid maturation in ongoing introgression.
• Genomic analysis of Atlantic Salmon throughout the Conne River watershed suggested that:
1. despite genomic evidence of declines in abundance since the mid-1980s, there was still significant differentiation between the main stem and tributaries, and
2. introgression with farmed escaped salmon occurred in lower parts of the watershed.
• Population genomic analysis exploring European introgression into North American farmed salmon indicated that some farmed Atlantic Salmon had been interbred with European-origin salmon, and that individuals escaped and hybridized in the wild in southern Newfoundland.

Environment

• Marine ecosystem conditions in the Newfoundland-Labrador Bioregion remained indicative of overall limited productivity of the fish community. Total biomass of the entire fish community remained much lower than prior to the collapse in the early-1990s. It showed some recovery up to the early to mid-2010s, when some declines where observed. Current total biomass of the fish community remained below the early-2010s level, but with some positive signals in 2020. Since the mid-2000s, this assemblage reverted to a finfish-dominated structure, though 2019–20 data suggested small increases in the proportion of shellfish.
• Mean annual air temperature in Newfoundland and southern Labrador was near the 1991-2020 long-term average in 2020, characterized by a cold winter/spring and a warm summer. Summer sea surface temperatures (SST) were above average and sea ice was below average for the first time since 2014 and 2013, respectively. The amplitude and duration of the warmest SST conditions in the shallower areas around Newfoundland has increased since the 1980s, in agreement with climate change projections.
• Chlorophyll concentrations and zooplankton biomass were below normal in the early and mid‑2010s, but have increased to values above the long-term (1999–2020) average since 2016–17. Changes in zooplankton community structure over the past decade resulted in fewer large and more small copepods although the abundance of large, energy-rich calanoid copepods increased to above-normal levels in some areas since 2017. Additionally, changes in zooplankton seasonality (weaker spring and stronger summer and fall zooplankton signals) may have changed the quality and timing of food availability for upper trophic levels.

This Science Advisory Report is from the March 2–4, 2021 Regional Peer Review Process on the Assessment of Atlantic Salmon in Newfoundland and Labrador. Additional publications from this meeting will be posted on the DFO Science Advisory Schedule as they become available.

Science Advisory Report 2022/031 (PDF, 3891 KB)

Accessibility Notice

This document is available in PDF format. If the document is not accessible to you, please contact the Secretariat to obtain another appropriate format, such as regular print, large print, Braille or audio version.