Preliminary results of several 2019 acoustic-trawl pollock surveys conducted in and around Kodiak indicate strong numbers of one and two-year old fish, suggesting a positive future for the fishery.
A team from the National Oceanic and Atmospheric Administration conducted pollock surveys in the Shelikof Strait, around the Chirikof Shelfbreak and in Marmot Bay from March 7-16. While the final results of these surveys have yet to be compiled, some preliminary findings were presented to a room full of local trawlers and other industry figures by Darin Jones, a Fisheries Biologist with the National Oceanic and Atmospheric Administration, on March 21.
Jones said that the overall biomass was similar to last year, but the surveys indicated far more juvenile fish than were observed last year. Last year, a moderately-sized 2017 year class was observed; this year, it became apparent that a large 2018 year class is present.
“This year, we saw vastly more numbers of age-ones. There’s a large year class from last year that are out there right now,” Jones said. “There’s a good number of age-ones and age-twos.”
This bodes well for the fishery which did not see much recruitment between 2012-2017. According to Julie Bonney, executive director of the Alaska Groundfish Data Bank, trawlers have been fishing off an extremely large 2012 year class over the past several years.
“The recruit to the fishery is age-fours, typically. So 2016 was the first year they were fishing that year class (the 2012),” said Bonney, explaining that the juvenile fish recently would likely come of age in time for the 2021 or 2022 seasons.
Bonney added, however, that there are a lot of unknowns that could impact those fish in the interim. It isn’t yet clear whether the 2018 year class is comparable in size to the 2012 year class. Bonney also noted that, when the 2012 year class came of age, the fish were unusually small.
“There was a problem with the size. The market didn’t want small fish like that,” Bonney said. “We don’t know whether it was the warm blob (2015 Gulf of Alaska warm water anomaly) that caused the smaller fish or whether it was because it was one of the largest year classes they’d ever seen.
“They don’t know when those 2017s and 2018s will come of age –– we just don’t know whether the recruitment to fishery will be age four,” Bonney continued.
That said, Bonney referred to the preliminary results as “good news,” adding that the survey also showed that the adult pollock in the fishery are living longer than typically expected, which means that the fleet will continue to have fish to catch in the immediate future.
“It’s good news in terms of the future of the fishery,” Bonney said. “The 2012s are persisting in the population longer than what is considered normal.”
This year’s Shelikof pollock survey differed from those in the past in a number of ways. Most notably, the surveys were conducted earlier than usual to address changes in the fishery that appear to have been caused by warming waters.
A NOAA Fisheries study published in November indicated that climate change is affecting the spawning time of Alaska pollock. The study, titled “Effects of climate and demography on reproductive phenology of a harvested marine fish population” states that the average spawning time has varied by over three weeks over the past three decades, concluding that changes in water temperature and fishing both affected when the species spawned. Specifically, one of the primary findings of the study are that warmer waters means pollock spawn earlier and for longer.
According to Jones, an unusually large percentage –– 68 percent –– of female pollock observed in the 2018 survey were already in the spawning or spent stage of maturity.
“This year, overall we were a week earlier for the entire survey –– but for the northern Shelikof Strait area, which is where we find most of the spawning fish, we were actually two weeks earlier than last year,” Jones said. “This year, we saw 75 percent of the fish in a pre-spawning state. Surprisingly, there was still about 25 percent spawning or spent, so we feel we were at a better time this year, but I was very surprised that there were still that many spawning and spent fish.”
Overall, he said the surveys were conducted “at a good time” and “didn’t miss any of the fish.”
The survey methods also differed somewhat from those in recent years. Notably, surveyors made greater use of recapture nets, designed to catch juvenile fish that escape from the main trawl net, which helps to provide a more accurate estimate of numbers of juveniles.
“That division of the agency is so proactive in terms of trying to stay ahead of the science and the needs,” said Bonney, who also praised the agency for providing a replacement vessel in lieu of the R/V Oscar Dyson.
Bonney explained that the Dyson was scheduled to go in for maintenance, but its time in the shipyard was extended. Following letters from Kodiak Island Borough and the City of Kodiak asking for a replacement, the R/V M. Bell Shimada was made available for the survey.
“The Dyson also had a power problem … it took them six months to fix it. People were nervous that it wouldn’t come out of the yard in time and we wouldn’t have a survey,” Bonney said. “The only reason it happened is dedicated government staff. It’s a big deal. I just don’t think that ‘Joe Public’ realizes how big government came in and helped us.”
Two additional surveys are due to take place this summer: a summer bottom-trawl survey in the Gulf of Alaska for all groundfish stocks and a gulf-wide hydroacoustic survey specifically for pollock. These two surveys are only conducted once every two years. Bonney said that this will result in a very robust stock assessment, despite a funding cut, which has led to the loss of one of the survey vessels.
“Typically, in the past, the bottom-trawl survey has been three vessels for the Gulf,” Bonney said. “Because of reduced funding, we’re only getting two this year. We are getting additional days at sea available for those vessels.”