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The An announcement by the Department of Fisheries and OceansAs the fishing season opened, it was decided to suspend fishing for Atlantic mackerel or spring herring in southern Gulf of St. Lawrence.
The decision will have many repercussions on the fishing sector at multiple levels. These species are fished not only commercially but also as bait for the Atlantic halibut, lobster, and snow crab fisheries. The right decision to close the fishery is made due to the precarious condition of the adult population that can be exploited (also called stocks).
As scientists in fisheries ecology, our research is focused on the dynamics of commercially exploited stocks. This article explains the reasons behind the suspension of mackerel and springherring fishing in the southern Gulf of St. Lawrence. It also discusses the implications for the fishing sector.
High adult mortality
The latest stock assessment Atlantic mackerelAnd Spring herring in the southern Gulf of St. LawrenceHigh mortality rates were observed in adult fish. Despite substantial reductions in commercial catch over the past 20-years, with quotas dropping down to 4,000 tonnes from 75,000 tons for mackerel and to 500 tonnes from 16,500 tons for springherring, fishing mortality was too high to promote stock growth. Particularly for mackerel.
(Pablo Brosset), Author provided
In addition to increased fishing pressure, natural mortality due to predation also increased quickly. A phenomenon that is well-detailedIn the herring of southern Gulf of St. Lawrence.
The Grey sealThe main predator of herring is now 16 times more common than in the 1960s.
Bonaventure Island’s northern gannet population and Rocher aux Oiseaux’s (Bird Rock) are also important consumers. HerringAnd mackerelThese are the best. Also at very high levels.
(Shutterstock)
Bluefin tunaAnother top predator is responsible for the high mortality rate of adult herring. Over the past decade, its numbers have risen rapidly in Gulf waters.
Unfavorable environmental conditions
A decline in the recruitment of these stocks could also explain the record lows of spring herring and mackerel.
Recruitment refers to the addition of a new cohort to the adult stock each year. It has remained relatively stable for herring and mackerel in the 2000s. Most likely, this is due to a decrease in recruitment strength Unfavorable environmental conditionsFor the larvae. In fact, the survival of young fish in the first weeks of their lives, when they are only a few millimetres tall and are at high risk of death, is directly dependent on their ability to feed on microscopic crustaceans called Zooplankton.
(Claude Nozères), Author provided
The However, Rapid warming of the southern Gulf of St. LawrenceThe distribution, composition, and development span of zooplankton species have changed over the past 20 years. This has resulted in a Spatial and temporal shiftBetween the emergence mackerel larvae and spring herring larvae and the production their preferred prey. This discrepancy led to a decrease in larval survival rates and recruitment failure, which prevented the recovery or improvement of fish stocks.
Part of stock recovery will depend on conditions that allow for larval survival and recruitment. Unfortunately, our short-term climate projections don’t allow us to see a return of colder years that favor larvae survival.
Bait shortage expected
The impact of the mackerel and spring herring fishery closures goes far beyond the commercial fishing of these two stocks. These species are the main bait for lobster and snow crab traps and hooks that target Atlantic halibut or bluefin tuna.
These fisheries, which are some of the most lucrative in the Gulf have enjoyed good times and brought in more that $1.3 billion to Québec and Atlantic fishers in 2020.
This will only increase the demand for bait. The increased costs of bait supply may increase the demand. Rapid increase in prices of the most valuable resources in the Gulf of St. Lawrence.
What are the options?
The best way to solve the current crisis is for us to continue to implement strict management measures for mackerel and herring stocks that have been affected by the suspension in fishing. We want to preserve enough spawners while we wait for the right environmental conditions to allow them to recover. These species do not reach the minimum size for capture at three to four years old so we cannot expect any immediate effect from management measures. We must be patient.
In the short term, the southern Gulf of St. Lawrence fisherman will need to make up for the lack of bait by sourcing mackerel abroad. The stock in Europe, for instance, is healthier. It is not an ideal long-term solution due to the environmental and direct costs. The fall herring fishing season, which is still open, might allow fishermen stock up later in a season.
However, there is an innovative solution. Alternative baits could be created to replace mackerel and herring in shellfish traps.
Researchers are currently trying to develop a recipe for such baits. Marine byproducts — materials derived from seafood processing that can be used for purposes other than human consumption.
The production of alternative baits using species such as redfish is expected to resume soon in the Gulf of St. Lawrence after the Rapid increase in its numbersIt is worth looking into.
