All three Marine Stewardship Council-certified herring fisheries in Atlantic Canada have lost their MSC-sustainability certification as the forage fish continues to struggle.

Last week, the Seafood Producers Association of Nova Scotia voluntarily suspended its MSC certification on behalf of the 10 companies that operate an 11-vessel fleet of herring purse seiners primarily out of southwestern Nova Scotia.

The suspension means product can no longer be sold with the MSC blue check mark, which assures consumers the fisheries are sustainably managed.

The Seafood Producers Association did not respond to a request for comment on its decision to suspend its MSC certification.

In 2015, herring fisheries in P.E.I. and Nova Scotia were the first gillnet herring fisheries in the world to achieve the certification.

$20M fishery in Nova Scotia

In 2017, companies landed 37,000 tonnes of herring from the Scotian shelf worth nearly $20 million.

"I'm hoping what that means is that industry is actually going to take action toward rebuilding the stock because it's been in a cautious or critical zone since about 2001," said environmentalist Katie Schleit of Oceans North.

"I think it's pretty indicative of the precarious state of the herring stocks in Atlantic Canada."

The Nova Scotia purse seiner fleet is not alone in losing eco-sustainability certification.

The Marine Stewardship Council's eco label indicates a product has come from a certified sustainable fishery. (Marine Stewardship Council)

In April, the Gulf of St. Lawrence fall herring gill-net fishery in the Northumberland Strait was notified its certification would be suspended because the fishery failed to meet MSC standards.

Third-party auditors said the stock has declined to the point where it is "now considered to be depleted."

The sustainable fisheries certificate, held by the Gulf Nova Scotia Herring Federation, will be formally suspended on May 8.

Earlier this year, the 19-vessel purse seiner herring fishery off western Newfoundland, led by the Barry Group Inc. of St. John's, withdrew from MSC certification after auditors warned it was taking too many fish from the spring spawning stock biomass.

Herring in decline

Known as a pelagic, or open-ocean fish, herring are in decline, according to Fisheries and Oceans Canada.

"Herring stocks in southwest Nova Scotia/Bay of Fundy had been relatively stable at a low level for many years," federal fisheries spokesperson Debbie Buott-Matheson said in an email to CBC News.

"Over the last three years, the stock has been experiencing a decline and recent science information suggests that the stock is likely now in the critical zone."

In 2017, the total allowable catch was reduced by 15 per cent due to the lack of stock rebuilding.

"We remain committed to supporting the eco-certification of Canadian fisheries," Buott-Matheson said.

Why herring matters

Herring provide a critical link in the marine food web.

They eat tiny animal organisms called zooplankton and are in turn eaten by larger species, including bluefin tuna, cod, halibut, sharks, whales and seabirds.

A recent federal fisheries report on the health of the Atlantic Ocean noted the suspected connection between lower zooplankton production due to sea ice melt caused by climate change and declines in herring and other forage fish.

The fish is also capable of bursts and collapses.

In the 1980s, the spawning stock jumped in the Gulf of St. Lawrence and plunged off the Scotian Shelf.

Big quota cut in New England

Amid sustainability concerns, United States authorities announced a 70 per cent reduction in the New England herring quota for 2019 — down by almost 16,000 tonnes.

Herring is the favoured bait in the Maine lobster fishery.

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