Capelin rolling late creates ripple effects, says researcher

They may be small, but the late arrival of capelin in Newfoundland and Labrador this summer has had some mighty biological impacts, according to one researcher. 

• Middle Cove magic: Capelin frenzy begins as fish finally start rolling

"[Birds] had to fly a really long distance … over 200 kilometres to get a single fish for their chick and return to the colony," said Gail Davoren, an associate professor at the University of Manitoba, who is studying capelin.

"So what that translated into was when the chicks were actually leaving, they were leaving a lot later and they were a lot smaller — they didn't have as much body mass."

Davoren and her team's study area was the northern part of Bonavista Bay. She said the capelin didn't arrive there until the first week of August, about six weeks later than the average arrival for the last 15 years. 

"Not 100 per cent sure [why]," she said. "Through talks with people at DFO, like Fran Mowbray, she mentioned in her May survey, that the fish just weren't developing."

Davoren isn't sure why that is, but one possible cause is this year's heavy ice cover,  which had other dramatic impacts. 

"It actually caused massive breeding failure of a whole bunch of gulls species … so that was another really strange thing that happened this year," she said.

Variety is the spawn of life 

Not only were the capelin later than normal this year, their spawning habits were a bit different, too. 

"It's interesting that the fish are sometimes spawning on the beach up in our area and then sometimes they're spawning in deep water ... they're kind of switching back and forth," said Davoren, who said deep water sites are considered less than 40 metres and are all around, including Trinity Bay and Conception Bay. 

"[Spawning] on the beach, they are not as accessible to, you know, whales [and] sea birds," she said, adding that's not good for the capelin's predators who count the small fish as a food source. 

She said the capelin — and the impacts of its arrival as well as spawning cycles — are not to be underestimated and should be watched closely in the years to come, partly because they are considered a key component of the recovery of more valuable fish. 

"Definitely the capelin have been doing some very interesting things ... [They are] very, very important, critical in fact, " said Davoren.