Question Period Note: Atlantic Mackerel Consumption by Predators

• The Fisheries Act requires rebuilding plans for all depleted fish stocks that are prescribed by regulation under the fish stocks provisions such as Atlantic mackerel.
• Our Government is committed to accomplishing this work. That is why Budget 2024 announced $33 million over the next five years to support sustainable fisheries.
• Departmental and US scientists have investigated levels of predation on mackerel by various predators. Their results pointed to an overall increase in level of mackerel mortality from predation over time.
• Analysis of predation helps Fisheries and Oceans Canada to include ecosystem considerations into stock assessments and advice.
• At current low levels of mackerel abundance, predators are likely to take a larger share of the remaining stock.

• Atlantic Mackerel are a schooling pelagic fish that form dense aggregations and stick to a narrow temperature range (7-16°C). They are highly migratory, moving into the Gulf and then northward throughout the year to spawn and feed. Accordingly, Atlantic Mackerel tend to move to Newfoundland waters later in the season relative to other parts of Atlantic Canada.
• Because of this high degree of local aggregations, mackerel are easy to harvest at very low levels and high overall population abundance cannot be inferred from high catches in localized areas.
• The commercial and bait fisheries were closed in 2022, while recreational and Food, Social, and Ceremonial (FSC) fisheries remained open. A limited personal use bait fishery of 470t will be open in 2024.
• The Canadian portion of the Atlantic Mackerel stock (predominantly NAFO subareas 3 and 4) is in the Critical Zone of the precautionary approach framework.
• The 2023 stock assessment showed that the spawning stock biomass (SSB) for mackerel declined to its lowest values in 2021 and 2022 (40 per cent and 42 per cent of the Limit Reference Point; LRP), relative to 79per cent and 56 per cent of the LRP in 2019 and 2020, respectively.
• The age structure remains truncated and this erosion has increased over time. There were very few fish over age 5 in 2021 and 2022 (3 per cent or less).
• The available evidence indicates the stock rebuilding potential is currently limited by a truncated age structure, low recruitment, and high predation pressure.
• In response to industry concerns about predation, DFO Science conducted an investigation of predation pressure on mackerel by various predators in Canadian and US waters for the 2023 assessment, which suggests an overall increase in predation-induced mackerel mortality over time. Prior to publication, the results of this work were presented to the Atlantic Mackerel Advisory Committee in February 2024. This study has now been published by the department and has gathered media interest.
• Although mackerel do not to make up a significant portion of the diet of seals, there has likely still been an increase in the mackerel consumed by seals, given the increase in seal abundance. However, Northern Gannets are likely having a larger impact on predation induced mortality of mackerel.
• There is currently no evidence that natural mortality had a key role in causing the stock decline. However, at current low mackerel biomass, predators are likely to remove a relatively larger proportion of the stock. Although an effort was made to estimate the minimal biomass removed by predators for the 2023 assessment, this information had high uncertainty. Natural mortality is considered overall and was increased in 2023, but it was not possible to explicitly incorporate predation into the assessment model.
• Atlantic mackerel are an important part of the ocean ecosystem. They are an important prey for northern gannets and also consumed by other species for seabirds, seals, groundfish, tunas and cetaceans.
 

If pressed on seal predation on mackerel
• Mackerel are a key prey source in the Northwest Atlantic ecosystem. They are an important prey species for Northern gannets and consumed by other seabirds, seals, groundfish, tunas and cetaceans.
• As such, several predators are contributing to total natural mortality.
• Mackerel is a minor prey source for grey seals, contributing only up to 4 per cent of their diet.
• Given the current size of the grey seal population, the annual consumption by grey seals was estimated to be between 7,000 and 13,000 t.
• However, other predators take more mackerel than seals. Seal consumption of mackerel was found for example to be less than consumption by northern gannets.
 
If pressed on the 2024 mackerel bait fishery

• On April 25th, I announced the opening of a 470 tonne (t) Atlantic mackerel personal-use bait fishery this spring, along with the continued closure of the Atlantic mackerel commercial fishery in Atlantic Canada and Quebec for the 2024 season.
• We understand the hardship the ongoing closure of the mackerel fishery is having on harvesters and the local communities they live in, and that purchasing mackerel for bait from other sources has become very expensive.
• We believe that this bait fishery will be beneficial for harvesters without jeopardizing the ongoing rebuilding of this stock.
• Fish caught under a bait licence are intended for personal-use and are not permitted to be sold, traded or bartered.