The outlook is bleak for the spring spawning herring stock in the southern Gulf of St. Lawrence, with the most recent stock assessment projecting it could be close to extinction in 10 years.
“In the projections it doesn’t reach zero but goes pretty close to zero,” said Francois Turcotte, Department of Fisheries and Oceans (DFO) marine biologist based in Moncton, N.B.
There is “a lot of uncertainty” around the projection which is based on the declining biomass, said Turcotte. “We don’t know if predation or recruitment will change,” he said, but no matter how you look at it, the prognosis is not good.
“For this stock, natural mortality is high” due to predation, the average fish size is smaller than it used to be and recruitment is very low, said Turcotte.
“Spring spawners need cold water to have good recruitment,” he said, noting the temperature of the Gulf waters is warming gradually. Colder water temperatures are also needed for zooplankton, which is “not in abundance in the southern Gulf anymore. Recruitment is not good because of that.”
Combined with high fishing mortality from the mid 1990s to early 2000s, the stock has been in the critical zone since 2002.
“The spring stock I’m afraid the environment is just not good enough for them anymore,” said Turcotte.
As for the fall spawners, “this stock is doing better but is still in bad shape,” said Turcotte. The stock has been in a fast decline since 2010, it currently is in the cautious zone, with projections that it is likely to be in the critical zone by 2025,” said Turcotte.
“Recruitment is low too and natural mortality is high for that stock too,” said Turcotte. “It’s about the same for both stocks. There is a constant fishing pressure on that stock also.”
Landings for the 2019 fall fishery totalled 15,500 tonnes. In 2018, 16,000 tonnes were landed. In the spring fishery for 2019, 500 tonnes were landed. In 2018, 800 tonnes were caught.
Turcotte said the only positive thing going for the fall stock is “that stock should be able to have good recruitment in warm waters” but there’s uncertainty around that due to the Gulf’s changing environment. “Theory says that stock should do better in warm waters. It’s not happening now but could happen in the future.”
The news is no better for the Bay of Fundy herring stock, where the decreasing spawning biomass put the stock in the critical zone last year.
Similar to other herring stocks, “we’ve seen relatively low recruitment and lower individual growth relative to how the stock was in 1980s,” said DFO biologist Ken Smedbol. “We’re not seeing any large year classes.”
In Scotia Fundy, scientists are working on a different approach borrowed from the west coast herring fishery called management strategy evaluation to better build a solid population model of the stock, said Smedbol.
“We’re about halfway through the process now,” he said. “We have been working closely with industry and resource managers to come up with some of the objectives. We have had two major meetings for this framework so far and are planning another one for late spring. The final piece, the key thing is to have industry and resource managers agree on what those objectives are for the fishery and what are the most appropriate management objectives and we will undertake that analysis to inform management on the likelihood some methods may turn out to be better recovery than others… it’s a little different than saying we have 250,000 tonnes out there and we can harvest 20 per cent. It’s the early days yet. We have to see how it performs. It seems to have worked reasonably well in other fisheries around the world.”
