Terms of Reference

Assessment of Atlantic Mackerel in Subareas 3-4

Regional Peer Review - Quebec Region

March 5-7, 2019
Mont-Joli, QC

Chairperson: Mathieu Desgagnés

Context

Atlantic mackerel (Scomber scombrus) from the Northwest Atlantic are a highly migratory transboundary population with two distinct spawning contingents. The Southern contingent has historically spawned in the Mid-Atlantic Bight from April to May whereas the Northern contingent spawns primarily in the Southern Gulf of St. Lawrence from June to July. Both contingents overwinter in deeper waters on the continental shelf. The U.S. fishery takes place during the winter along the New England coast and catches both Northern and Southern contingents, whereas catches in Canadian waters are thought to consist entirely of mackerel from the Northern contingent. Canada evaluates the northern contingent every two years, and as of the last assessment in 2017 this stock was still in the Critical Zone according to the Precautionary Approach.

Mackerel are fished commercially throughout the Atlantic Provinces and Québec. This is a primarily inshore fishery where a variety of gear types are used (gillnets, mechanical jiggers, seines, weirs, and traps) which vary by region and time of year. Mackerel are also harvested through bait as well as recreational fisheries. While each fishery has its own regional harvest control rules, mackerel are managed on a national level. There is a minimum legal size in place of 26.3 cm. In 2017 and 2018, the commercial Total Allowable Catch (TAC) was 10 000 t. However, total Canadian catches of mackerel are grossly underestimated, as not all catches from the bait fishery are reported, dockside monitoring program coverage varies among the provinces, and catches from the recreational fishery are not quantified. In addition, the discards of mackerel (including undersized fish) are not known.

The mackerel fishery in the USA occurs primarily in the winter months in the Gulf of Maine. In contrast to Canada, the USA assesses both contingents. Their last full stock assessment occurred in 2017 and DFO scientists were in attendance to contribute to their peer review process. Based on their commercial landings, estimated recreational catches, estimated discards, egg survey and other biological indicators the American mackerel stock assessment model showed that the stock was overfished with overfishing occurring. This is in concordance with the Canadian model and there is consensus that an unknown proportion of mackerel belonging to the Northern contingent are captured in the American fishery.

The spawning stock biomass of the Northern contingent of mackerel is calculated using a censored statistical catch-at-age model with input from data collected from an annual egg survey in the Southern Gulf of St. Lawrence, catch- and weight-at-age data, as well as the proportion of mature individuals sampled in the population. The uncertainty in undeclared catches is explicitly accounted for by providing a lower and upper limit to the total catches. Closed loop simulations in support of a Management Strategy Evaluation (MSE) approach are currently being developed within the framework of a mackerel stock Rebuilding Plan Working Group with members from Fisheries and Oceans Canada Management and Science, provincial governments, First Nations, commercial mackerel harvesters, and environmental non-governmental organisations.

The last assessment of mackerel in Canada took place in March of 2017. The Fisheries Resource Management Branch has requested scientific advice on Atlantic Mackerel in Canadian waters for the 2019 and 2020 fishing seasons and to support the development of management measures for a Rebuilding Plan under the Precautionary Approach Framework.

Objective

Provide scientific advice on the management of the Atlantic mackerel in NAFO Subareas 3-4 (Canada’s East coast) for the 2019 and 2020 fishing seasons and to support the development of a Rebuilding Plan.
This advice will include:

• An update of knowledge on Atlantic mackerel, including:
• A review of the population structure in the North Atlantic, migratory patterns, habitat preferences, and biology.
• An analysis of the environmental variables that could explain mackerel recruitment, condition, and the distribution of catches in the Northwest Atlantic.
• An analysis of the commercial fishery statistics following the 2014-2018 fishing seasons (Distribution of landings, breakdown by date, province, NAFO subarea, fishing gear, etc.).
• Genetic analyses comparing Atlantic mackerel caught in Northeast Newfoundland with those caught in the Gulf of St. Lawrence.
• A discussion on the quality of the fishery statistics and a review of the main sources of uncertainty, particularly unreported, undeclared or otherwise missing catches, and updated estimates of missing catches from 2015-2018.
• A presentation of updated U.S. catches since their latest egg survey, model outputs, and management decisions.
• Impact of U.S. catches on the northern contingent biomass.
• An analysis of the biological data collected by port samplers, at sea observers, and samples collected by fishery independent surveys (size structure, catch-at-age, and calculation of biological indicators).
• An analysis of the egg survey index up to 2018 including the timing of spawning.
• An analysis of spawning habitat suitability across the Northwest Atlantic.
• An analysis of larval and young-of-the-year growth and survival in the face of predation as a predictor of recruitment strength.
• An assessment of the status of Atlantic mackerel, including:
• A presentation on the results of operating models (censored statistical catch-at-age model). These results will include fishing mortality, abundance and spawning biomass, stock trajectory, and projections over 3, 5, 10 and 20 years.
• Identification or updates of a limit reference point, potential upper stock and target reference point(s), the stock status in relation to the reference points, and fishing rates in relation to a removal reference (Fmsy), taking uncertainty into account.
• An evaluation of the performance of different candidate management strategies (MSE), that set commercial TACs under feedback simulation, through:
• The identification of different sources of uncertainty in the base operating model (including both model fitting and projections).
• Evaluation of candidate management procedure performance against rebuilding and stock objectives  over 3, 5, 10 and 20 years.
•  An analysis of the proposed management procedures under the defined uncertainties and management objectives.
• An evaluation of the impact, or potential impact, of other new or potential management measures for Atlantic mackerel apart from Total Allowable Catches, including:
• Changes to fishing gear (mesh size, hook size)
• Changes to minimum fish size
• Changes in recreational bag limits (recreational catches)
• Changes in monitoring of unreported commercial catches in Gulf region
• Changes to the timing of the fishing season (over all regions, and for each DFO region)
• Specific elements related to the update of the relevant data to the management of Atlantic mackerel such as:
• The determination of the process to provide advice during the interim years, including a description of conditions that may warrant a full stock assessment earlier than originally planned
• Identification and prioritization of research projects to be considered for the future
• Perspectives and advice for 2019 and 2020 and a Rebuilding Plan based on available information

Expected Publications

• Science Advisory Report
• Proceedings
• Research Documents

Expected Participation

• Fisheries and Oceans Canada (DFO) Science and Fisheries Management
• Fishing industry
• Provincial government representatives
• Aboriginal communities/organizations
• Academia
• Environmental NGOs