Fish heavily impacted by a three-year marine heatwave in the Gulf of Alaska may be headed for round two. Commonly referred to as the blob, warmer waters between 2014 and 2017 were blamed for a dramatic decline in Pacific cod and are thought to have negatively impacted other species such as pollock.
The North Pacific Fishery Management Council set catch limits for several groundfish species in the Gulf of Alaska Thursday afternoon. Before members set those limits, Stephani Zador with the Alaska Fisheries Science Center updated the council on the latest trends in the Gulf.
“Importantly, starting in September, we are officially in another heatwave in the Gulf of Alaska,” she explained.
Pacific cod populations in the Gulf plummeted as their food source decreased during the blob, but after waters returned to somewhat normal temperatures in 2017, Zador said cod body conditions improved.
“All the groundfish in our survey that we sampled, except for cod, had poor body condition. So, they were skinnier per length than average,” Zador said. “That was a sign we saw consistently through the heatwave and indicates that cod were able to pop back up.”
The council slashed the total allowable catch by 80 percent last year and lowered it slightly again this year in order to allow the species to rebound. Pacific cod populations in the Gulf are expected to stabilize in the coming years, but another marine heatwave, or blob 2.0, could hamper any progress.
Pollock have also suffered poor recruitment in recent years, but Zador said larva abundance was above average in 2017. However, much like cod, another heatwave is not a good sign.
“This has some implications. I was talking about all those positive signs for age 0 pollock for 2017, but we know when we get into really warm conditions, we think that’s not as positive,” Zador added.
In response to that information and poor recruitment numbers in the past, the council lowered the total allowable catch for pollock in the Gulf by about 25,000 tons.
On the other side of the coin, sablefish fared well during the blob years. Next year’s catch limits were set at roughly 12,000 tons, a minuscule decrease compared to 2018.
Managers say a large number of younger fish are moving into the fishery, but fishermen and others at Thursday’s meeting cautioned against any increase in catch limits.
Some fishermen fear an increase could lead to sperm and killer whales eating more fish off longlines. Managers say whale depredation is decreasing, but some fishermen argued it’s worse than ever.
Others also expressed concern about pulling too many young fish from the water before they can replace larger, older fish, which have been depleted in recent years.