Research Document 2023/005

Assessment of proposed harvest decision rules for the Atlantic Salmon recreational fishery: Miramichi River case study

By Breau, C. and Chaput, G.

Abstract

Fisheries and Oceans Canada (DFO) is developing a precautionary approach (PA) framework for the management of the Atlantic Salmon recreational fisheries for DFO Gulf Region rivers. A DFO Fisheries Management-led working group (DFO-WG) convened over the previous year to discuss and develop candidate harvest decision rules (HDRs) for the Atlantic Salmon recreational fishery using the Miramichi River as a case study. The candidate HDRs for the recreational fishery are evaluated for compliance to the PA policy and supporting science advice. The candidate HDRs specify management measures for different levels of abundance prior to recreational fisheries rather than being specific about exploitation rates. There is insufficient information to determine the extent to which the described management measures will change the exploitation rates and losses due to fishing. Using historical exploitation rates and assumed catch and release mortality rates from the Miramichi River, the management measures in the candidate HDRs are translated into the proportion of the total eggs lost from recreational fishing. The losses for similar management measures are higher in the Northwest Miramichi compared to the Southwest Miramichi because of differing biological characteristics and seasonal catch profiles between the two rivers. Several elements of the candidate HDRs, such as adjusting losses for three status zones and maximum losses being less than the removal rate reference, comply with the PA policy. Other elements of the candidate HDRs may not comply with the PA policy, subject to interpretation. One key element is the interpretation of the PA statements that removals be kept to the lowest level possible and no tolerance for preventable decline when the stock is in the critical zone. Both candidate rules would allow a directed catch and release recreational fishery when the abundance is in the critical zone; directed fisheries would only be closed if the abundance before fishing was < 15% or < 25% of the Limit Reference Point (LRP), dependent on the rule. The losses from a catch and release fishery in the critical zone would be approx. 1% of the eggs prior to the fishery but could be as high as 4 to 7% if the season-adjusted catch and release mortality rate was in the range of 16 to 25% as indicated from a wider meta-analysis of studies and mean water temperatures in the Miramichi, rather than 3% mortality rate that has been used to date. The implementation of the candidate HDRs requires a forecast of expected abundance prior to the fishery. The performance of the candidate HDRs and compliance to the PA policy will need to be re-evaluated to take account of the uncertainties and biases of the forecast model and the decision making process.

Research Document 2023/005 (PDF, 4,658 KB)

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