Sea Watch: Recruitment up for Tanner crabs

Crab fishermen in Kodiak may be poised to reap the rewards of a crash in groundfish populations, as the bairdi Tanner crab fishery is set to get underway in January with an increased quota and an abundance of tiny crab moving up through the ranks, hopefully ready to reach harvestable size in 3-5 years.

The Tanner quota for the fishery which opens at noon January 15, weather permitting, is 500,000 pounds in the Eastside section and 115,000 pounds in the Southeast section.

Kodiak area management biologist Nat Nichols talked about recent recruitment events.

“We do our survey every year, and we saw a big recruitment event this year, the fourth time we’ve seen one of these really big recruitment events here in Kodiak,” he said. “The first one was in 2001, then 2006, and 2013 was the most recent one until this year. This year we saw another big event, so we have the highest estimate in the survey time series this year for the number of crab in the water.”

Nichols said the increase is driven by the smallest size class, crab about the size of a quarter.

However, the latest recruitment event may not be the boon of other year classes.

“It’s encouraging,” he said, “but we don’t seem to have a recruitment issue — we have a survival issue. Our previous biggest estimate was in 2013. We saw them in the survey. We tracked them through the population. We saw them every year after that. There’s just a lot fewer of them, and by the time they got to the legal size for the first time — that was last year — there weren’t really all that many of them left.”

He said there were enough left to provide a surplus to have a small fishery last year, but given that it was the biggest recruitment they had ever seen, it would have been expected to turn into more than just the bare minimum, which at 400,000 pounds just met the regulatory limit.

Those numbers seemed out of whack, Nichols said.

“In earlier recruitments we had about 7 to 9 percent of the male portion of those crab when we first saw them translated into legal males four to five years later. That was about what we would expect. That’s what we saw in 2001 and 2006. In the 2013 group, we only saw 2 percent of them turn into legal males.”

Nichols said there are several competing theories about what has influenced the change in survivability,

“Ocean acidification is certainly a part of the conversation, but more just a larger conversation about disturbance. You had a lot of really warm water, everything is changing. Looking back and using information from 20 years ago, it used to be predictive. We could say ‘each time we saw this, this is what would happen.’ Those relationships seem to be less useful lately, just with ocean conditions changing pretty fast.”

Another contributing factor, Nichols said, may be that in the years those small crab from 2013 were in the water, there were a lot of cod near shore, plus a lot of small halibut and arrowtooth flounder.

“There was a higher than normal rate of predation on that group of crab,” he said. “Everything likes to eat a baby tanner crab, and there were a lot of those predators around those years, so there may be a number of things contributing to that.”

He said that while it is not good to be excited about the lack of cod, that certainly can’t hurt the crab population.

“If we can get some of these crab to bigger size before the cod come back, if they can kind of out-pace the mouths of the cod, that could be good for the crab, so we are cautiously optimistic. We’ll be watching this group move through the population. I think the earliest time we could see them legal and move into the fishery potentially would be 2022. Obviously that’s a long way out and a lot can happen in the interim, but it certainly is encouraging that we’re continuing to have these recruitment events.”

Nichols said the pattern of recruitment events is being seen all through the Southern Alaska Peninsula and out as far as Unalaska, albeit not as strong nor on the same timeline.

“The signal gets a little weaker the farther out you go, and it tends to lag a little bit, so we’ve seen the South Peninsula have its peak events in the survey a year after we see them in Kodiak, but we do see the same trends, which is really interesting. It’s not localized; it’s not just the east side of Kodiak. We see the same trends over on the west side, the mainland, and to a lesser degree the Shelikof side of the island, which seems to have its own thing going on.”

Nichols did not have positive news for the cod fleet, saying that the North Pacific Fisheries Management Council groundfish plan team just wrapped up in Seattle on Friday, and since they only do the cod trawl survey every other year, in the off-survey years such as this the quotas do not tend to move that much.

However, there are other measures that factor in the decision such as some observer size frequency sampling, the International Pacific Halibut Commission longline survey, and the Alaska Fisheries Science Center longline sablefish survey.

“They do encounter cod on those surveys. They do put those numbers into the model, but they don’t weight them very heavily because those aren’t surveys that are targeting cod,” he said. “They take that into account. They also take our trawl surveys that we do for Tanner crab. We catch a lot of cod in that survey as well, and we do that survey every year, so they feed those numbers into the models too.”

Nichols stressed that the numbers are very preliminary — the Council has to approve them, and there are a number of steps before quotas are put into regulation.

However, he said, “It’s looking like there might be another 5 percent reduction in the Gulf, or something like that. But the numbers are so small now that when you’re looking at 5 percent, it doesn’t turn into a whole lot of pounds. That’s the unfortunate part about it. Like in Kodiak, the cod GHL was 1.1 million (pounds) last year, so this year it’s looking like it’s going to be 1.05. It doesn’t move the needle that much when you’re dealing with really small numbers.”

Cristy Fry can be reached at

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