Science Advisory Report 2024/013

Update on the Status of American Eel and Elver Fisheries in Maritimes Region and Science Advice on Available Regional Indices

Summary

• Based on reported landings from the large eel fishery, the number of commercial licenses that are active has decreased over the past decade. In recent years, it appears that the fishery has been prosecuted by a small (9% to 11% of the total licenses), consistent group of license holders. As a result, significantly fewer eels are now landed than in the past when participation, in terms of both participants and deployed gear, was much higher.
• There is a large number of commercial eel licences that are not actively fished at present, which represents a high level of latent gear. There is known to be a high level of unauthorized harvesting directed towards elvers at present. These factors represent sources of potential and realized eel exploitation, respectively, in the Maritimes Region not reflected in the reported catches for eel and elver, and are sources of uncertainty for this assessment.
• East River-Chester (ER-C) elver index was completed in three of the five years since the last assessment. This index suggests that the average elver run size is above the 1996-2018 reference level median run size estimate of 320 kg (2.33 kg/km²) and either approximately equivalent to or greater than the 75th quantile run sizes for the 1996–2018 time period (466 kg, 3.40 kg/km²).
• Catch and catch per unit effort (CPUE) were evaluated as potential alternative or supplemental sources of information. While a CPUE index may provide some useful supplemental information to help with interpretation of other indices, or assisting interpretation of years for which other indices are not available, there are issues related to the ability to standardize and to the impact of external factors such as market and price. It is not a replacement for fishery-independent indices.
• Two other current and former regional elver abundance indices were evaluated, and while they could provide supplemental information for comparison with the ER-C index, they were not considered to be an immediate alternative to the ER-C index, as they were either not correlated with the ER-C index (e.g., West Harbor Pond (WHP)) or have been discontinued (Eel Pond Brook (EPB)).
• Analyses of the Maritimes Salmon Electrofishing Database provide some information on eels and have been reported previously as indices of standing stock. Analysis of the existing data for the LaHave, St. Mary’s and Nashwaak rivers show differing trends from 2002–2022, with an increasing trend in LaHave and no trend in St. Mary’s or Nashwaak. Estimates of eel densities for 2021 and 2022 were above the 50th quantile for all three rivers.
• There are no indications that silver eel escapement from either Eel Pond Brook or Oakland Lake Stream has changed appreciably since the inception of monitoring in 2014 and 2011, respectively. Adult production in both catchments is approximately one adult per hectare of catchment area.
• Directed monitoring of young migratory yellow eels at fixed locations has potential to provide information to supplement the ER-C elver index and the electrofishing-based estimates of eel standing stock, with lags of several years (the duration of which may be dependent on distance from the head of tide). However, the episodic nature of high catches of juveniles both within and among years indicates that uninterrupted monitoring for an extensive period of time beginning in the spring and extending into the autumn may be required.
• This assessment demonstrated the importance of having consistent and accurate time series of information for analysis, and the importance of accounting for removals, including the implications of high levels of unauthorized harvesting directed towards elvers.

This Science Advisory Report is from the regional peer review on October 11-12, 2023, on the Updated Science Advice on Status of American Eel and Elver Fisheries in Maritimes Region. Additional publications from this meeting will be posted on the Fisheries and Oceans Canada (DFO) Science Advisory Schedule as they become available.

Science Advisory Report 2024/013 (PDF, 1,596 KB)

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