Over the past three decades, pollock spawning times in the Gulf of Alaska have varied as much as three weeks.
That’s potentially deadly for baby fish that are spawned into an environment that’s not ideal.
Now, new research confirms what some scientists have long suspected: Warmer ocean temperatures are playing a role.
Pollock have been a big part of Lauren Rogers’ career. She works as a research fish biologist at the National Oceanic and Atmospheric Administration offices in Seattle, and you could say she takes her work home with her — and straight to the dinner table.
“I’ll go with my most common way. It’s got to be fish sticks,” Rogers said. “I have two little boys and, eating fish [sticks] that would be their preferred method.”
Chances are, those fish sticks could have originated from pollock caught in Alaska. It’s the nation’s biggest fishery.
The fish are caught in the Bering Sea and the Gulf of Alaska. In the Gulf, pollock typically spawn in the spring.
“So if it’s warmer, pollock generally spawn a little bit earlier. If it’s colder, they’re going to hold off and spawn later,” Rogers said.
But exactly when could be a crucial detail that determines the chance of survival for baby pollock. According to NOAA meteorologists, waters in the Gulf of Alaska have been warmer than normal.
Rogers said that warm water, in addition to some other factors, could signal to the pollock it’s time to spawn. Still, that doesn’t necessarily mean the food sources will be there. It could be too early.
For pollock, this could play out in two ways.
“Well, maybe you’ll get really lucky and the spring bloom will also be three weeks earlier, and then your babies are going to hit it right on time,” Rogers said. “They’re going to have lots of food. They’re going to grow up fast.”
They’re going to move out of the house, get their own apartment and go on to be productive members of the aquatic society. Or rather, take the form of those fish sticks mentioned before.
That is, if the pollock spawn their babies around the right time — when food sources are available.
“However, maybe you get it wrong?” Rogers said. “Maybe actually, it’s warm now. But it cools off all a sudden and production is a little bit delayed, and there’s not food available and your babies all die.”
Right now, the catch rate for pollock in the Gulf of Alaska has been consistent.
But scientists like Rogers are trying to understand how much variability exists in the spawn time. To get an idea, Rogers used more than 30 years of information consisting of samples from larval pollock.
“By looking at the ear bones of the larval pollock, you can actually see daily growth rings on there. And you can figure out how old they are,” Rogers said.
With some back calculating, she was able to figure out how spawning for pollock changed over time: a variation of as much as three weeks.
But the big question remains: Could this mean a future with less fish?
“Well, I think it’s not necessarily a doom-and-gloom story,” Rogers said. “But I don’t know if it’s going to be, ‘Everything’s great,’ either.”
Rogers said as the environment continues to warm, with less and less cold years, spawn time may actually become a little more stable from year to year. But that’s only one piece in the complex puzzle that is the ocean.
Scientists are trying to get a handle on how the new normal of climate change is going to affect everything else.