How blooms of northern anchovies are helping bring more sea life back to Burrard Inlet
Small, flashy fish are huge food draw for predators and may be helping local salmon stocks
It's not easy to spot northern anchovies in murky sea water, but a school of these 10-centimetre-long fish can often set off a frenzy of hungry seabirds and sea mammals that reveals their underwater dance.
The sight of anchovy scales catching the glint of the sun is becoming more common in B.C. waters, marine biologists say, and that could be drawing other, bigger species back to busy waterways like the Burrard Inlet in Metro Vancouver.
Rod MacVicar is convinced the fish helped lure a humpback whale closer to the shores of Port Moody, B.C., than he's ever seen, just a few weeks ago.
MacVicar, a marine biologist and co-founder of the Mossom Creek Hatchery in Port Moody, says he recently spotted a school of anchovies and netted a few of them to be sure — positively identifying the 10-centimetre-long fish by their "inferior shark-like" mouths.
He believes warming sea water is enabling anchovies to re-establish near his home.
Northern anchovies, once a food source for Indigenous people living in what is now the Burrard Inlet, were more common south of B.C. over the past century.
But University of Victoria researcher Will Duguid, who studies chinook salmon ecology, published a study late last year showing the number of anchovies in the Salish Sea increasing in tandem with sea temperatures.
He is not surprised that anchovies are showing up in the Burrard Inlet, Indian Arm and near the shores of Port Moody.
A 10-centimetre-long fish represents an anchovy that's about a year old. MacVicar believes that indicates the fish spawned locally in the pelagic zone, or upper, warmer zone of the seawater.
He says temperatures in the harbour have been rising consistently since 2016. While, generally, rising ocean temperature are seen as negative as the change can bleach coral and jeopardize breeding grounds, MacVicar says the warmer waters in the harbour of the Port Moody arm of Burrard Inlet may be "perfect" for anchovies. He monitors the area and says it's often 17 C.
Light show attracts predators
Anchovies often provide "conspicuous shows" near shore, drawing predators to feed, as seen near the White Rock pier last December.
Duiguid says a school of anchovies is unmistakable because the fish flare their gill covers as they feed on plankton, providing "conspicuous shows" and drawing predators to feed.
"It almost looks like you are looking at the stands at a sports game with all the flash bulbs going off and they are all exactly the same size and shape of flashes," he said.
In Port Moody, MacVicar says the anchovies are attracting dozens of Arctic Sabine's gulls and, this past week, a pigeon guillemot, a bird more common to the open ocean.
He says he's seeing more sea lions and seals in the area, and with them, potentially, come transient, mammal-eating orcas.
But his biggest treat came a few weeks ago, when he got to witness a humpback feed for hours.
"For the first time in my lifetime, I saw a humpback whale feeding in Port Moody," MacVicar said.
MacVicar said a reduction in pollution in the waters off Port Moody may also be helping the fish — as well as other species like sea urchins and sea cucumbers — reappear.
Effect on salmon
Historically, the numbers of anchovies seem to rise as salmon stocks fall, but it's not clear if an increase in their numbers will help or hurt the larger fish. Researchers are hopeful.
"They are an alternative food source for salmon and they increase the diversity of the prey base, so I don't imagine them having a negative effect. It's quite possible they will have a positive effect," said Duguid.
MacVicar says the anchovy "bloom" is likely protecting the salmon fry that swim from the hatcheries into the inlet each year, by distracting predators.
"I notice the seals are just about filled up on anchovies, so it probably is reducing the [predatory] pressure on salmon," said MacVicar.
If northern anchovies re-establish long term, they could potentially feed more than seals. Anchovies sustain the world's largest fishery in South America and could offer an alternative to B.C.'s herring fishery, MacVicar says.
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