Capelin stocks in Newfoundland and Labrador have improved since 2021, but are nowhere near where they need to be.
While delivering its latest technical briefing on capelin stocks, the Department of Fisheries and Oceans (DFO) announced a new limit reference point (LRP) for capelin stocks, indicating their biomass needs to be over 640 kilotonnes (kt). This LRP is based on cod stocks and how much available capelin they would need to sustain a healthy population.
“We’re considering capelin not just on its own, but how important it is to the rest of the ecosystem. Particularly for seabirds, marine mammals, halibut, Greenland halibut, American plaice and particularly Northern cod,” said capelin stock lead Hannah Murphy. “A lot of research coming out of the Newfoundland region has directly related capelin to cod biomass and cod condition.”
For 2022, the reported biomass of capelin was 262kt, which is well within the “critical zone” of the LRP. By the time of the 2023 acoustic biomass index, capelin is expected to be at or above the numbers seen in 2022.
While the stock is well below the period previous to the stock collapse in 1991, where capelin was recorded in the thousands of kilotonnes, 2022 has nonetheless shown some improvement from the previous assessment, with the exception of 2013–2014, where capelin momentarily rebounded to above the 640kt reference point.
Stocks are assessed based on a “spring biomass index,” which is a measurement of capelin in spring-time spawning grounds.
“This is an index because the acoustic survey occurs mainly in division 3L and southern 3K,” said Murphy. “We’re limited by ice in the spring, and we go out in May. And this survey targets mainly a nursery area, so for juvenile fish — mainly age two.”
Since the stock collapse, capelin have also undergone a change in biology due to the limited population. With a maximum age of six, a majority of the capelin population in the past was in the upper age limit, while the population today is mostly comprised of capelin aged two to three. This has also caused the forage fish to spawn at a later date as well as having a lower rate of recruitment, which is the process of younger fish surviving into their next stage of life.
“Capelin now are longer in length at age one and age two than they were in the 1980s. This, again, is linked to this earlier maturation,” said Murphy. “These fish are growing faster at these younger ages and reaching a size of maturity at a younger age… Post-collapse, you’re seeing a very high proportion of age-two fish maturing, sometimes up to 75 per cent. The consequences of this is that these age-two fish come into spawn and a majority die. So, we have very few age classes, mainly ages two and three in the population, which is not ideal for fish stocks. We want a broad range of ages.”
The abundance of capelin larvae was significantly higher than in the past four years, but still markedly lower than in the early 2000s and mid-2010s. According to DFO, this slight upshoot is still well within the average of the post-collapse period.
“The larval index from our Bellevue Beach index is the highest we observed in nearly a decade, which is good news since larval survival is linked to recruitment in year-class strength for capelin, but average compared to the post-collapse time series. These two indices suggest that 2022 was a relatively weak year-class,” said Murphy.
Larval capelin, however, are experiencing a decent environment to mature in. Studies have shown that zooplankton, which capelin feeds on, are larger. Despite the increased larval abundance as well as the higher prevalence of food for said larvae, DFO notes that it’s, “still concerned for the capelin stock.”
Murphy says that while the 2022 levels are quite a way off from DFO’s LRP of 640kt, achieving that level in the near future is feasible.
“The environmental signs are positive for capelin. We’re seeing increased production, and we have been above 640 kilotonnes in the past decade, in 2013–2014. But, this is a bottom-up controlled species, so we need good environmental conditions for good recruitment, good survival of those larvae, earlier spawning and just general food availability in the ecosystem.”
While DFO has painted a picture that this slight uptick in the capelin population is nothing to get excited about, the Fish, Food and Allied Workers Union (FFAW-Unifor) insists that the population has shown signs of good health, and the “doom and gloom” of their technical briefing is unwarranted.
Given the fact that capelin is a bottom-up driven species, FFAW-Unifor points to the increased zooplankton productivity, larger capelin and warmer waters as good indicators for capelin health.
The union also posited that fish harvesters have asked for increased surveying of off-beach, deep-water spawning, which they insist is an important piece of determining the capelin biomass. They also insist that given the new LRP’s focus on the health of cod stocks, other species should have a similar LRP to account for the entire ecosystem.
“FFAW-Unifor would like to see more priority given to understanding the capelin stock prior to the high levels of the late 1980s,” said Erin Carruthers, FFAW-Unifor Science Director.
“We believe that empirical data, meaning data showing the levels from which stock recoveries have occurred, should be a key consideration in setting limit reference points.”
