DFO says warming ocean temperatures likely a factor in boom that led to about 1 million fish
The spawning population of striped bass tripled between 2016 and 2017 and is now estimated at one million fish. (Meghan Wilson/DFO)
The remarkable recovery of striped bass in the southern Gulf of St. Lawrence reached unprecedented levels in 2017, according to the latest assessment from the federal Department of Fisheries and Oceans.
Department scientists say the spawning population tripled between 2016 and 2017 and is now estimated at one million fish — a 100-fold increase from the 1990s.
In addition to the population rebound, tagged striped bass from the Gulf were recovered from Rimouski, Que., north to Labrador for the first time in 2017.
In the Forteau Bay area of Labrador, catches of tens of thousands were reported.
“I think this is unusual,” said Trevor Avery, a marine biologist at Acadia University who is tracking the expanded range of Gulf striped bass. “This seems to be a first-time sighting in, let’s use the term, in living memory.”
Until last summer, the northern limit of the confirmed distribution for southern Gulf striped bass had been the Gaspé Peninsula.
‘Something changed in 2017’
The Department of Fisheries and Oceans said the most significant finding was a large movement of striped bass in the Gulf beyond their normal distribution north to the Quebec and Labrador coasts.
“Something changed in 2017 that motivated striped bass to swim [farther] north during the summer months than previously known,” Moncton-based DFO scientist Scott Douglas said in an email statement.
Douglas, one of 11 scientists who contributed to the report, has no explanation as to why this happened but said ocean temperatures are likely a factor.
“There has been some suggestion that it may be linked to climate change and warming waters which ‘opened’ habitat which was previously too cold for the fish to occupy,” he said in the statement.
Avery said a combination of variables can contribute, including survival of larvae, a healthier ecosystem and more bait fish. He too points to a warming ocean.
“It allows things to produce faster, grow larger in shorter seasons. There are all kinds of things that are tied to temperature,” he said.
The comeback story
When the spawning population collapsed in the 1990s, DFO started closing fisheries.
The commercial fishery was shut down in 1996, followed four years later by recreational and Indigenous fisheries.
In 2004, Gulf striped bass was listed as a threatened species by federal authorities.
But the population came back and in 2012, First Nations food, social and ceremonial fisheries were reinstated and a recreational fishery reopened in 2013.
2017 marked the seventh straight year striped bass met species recovery targets.
Trap nets overwhelmed
For several weeks every year, the epicentre of the Gulf striped bass population is the northwest Miramichi River, where hundreds of thousands return to spawn in May and June.
That’s where scientists count them, tag others and make population estimates based on models.
In 2017, modelling produced estimates ranging from 450,000 spawners up to two million. The department settled on an estimate of 994,000.
The run coincides with a commercial gaspereau trap net fishery on the northern Miramichi which is used to monitor striped bass.
‘Something strange going on’
Nathan Wilbur, New Brunswick program director for the Atlantic Salmon Federation, said the striped bass explosion was part of a bizarre 2017 off New Brunswick.
“Last year there was something strange going on in the Gulf of St. Lawrence,” he said, pointing to the appearance of endangered North Atlantic right whales in large numbers. “Fishermen in Newfoundland were seeing species they’d never seen before.”
Wilbur argues striped bass are now so numerous it’s time for a small, First Nations commercial fishery in the Miramichi. He said striped bass entering the system were already taking a toll on Atlantic salmon smolts on their way out to sea.
“With the population of spawning bass tripled, our fear is predation may have increased quite a bit as well,” Wilbur said.
Recreational fishery worth millions
Jeff Wilson co-hosts the Striper Cup, an annual striped bass tournament in the Miramichi.
He said reinstatement of a commercial fishery is premature and could jeopardize a recreational fishery that he said generates millions of dollars in the Miramichi area.
“We have to be careful. The population could crash quickly,” Wilson said. “We have to make small adjustments to our harvest program in order to make sure we have this fish for years and years to come.”