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By SCOTT BOWLEN
Daily News Staff Writer
Those fishermen’s nets flooded by record pink salmon catches in 2013 might feel a bit empty next year if the state’s harvest forecast is correct.
The Alaska Department of Fish and Game is predicting a catch of around 22 million pink salmon in Southeast Alaska in 2014, based on past harvest trends and data from annual federal trawl surveys of juvenile pink salmon abundance in the Upper Chatham and Icy straits.
The forecast harvest would be in the average range, according to Fish and Game. The department’s "confidenceinterval" in the forecast in 80 percent, indicating the actual harvest is likely to be between 8 million and 36 million pink salmon.
Although a catch of 22 million pink salmon would be far less than the astounding 2013 catch of about 94 million pinks, it would be neither unusual nor the lowest-on-record for Southeast Alaska.
In 2012, commercial fishermen landed about 21.3 million pinks in Southeast Alaska. And, the average pink catch during the past five even-numbered years (2012, 2010, 2008, 2006 and 2004) has been right around 22 million fish.
As for the all-time lowest catches since statehood, fishermen landed about 2.7 million pinks in 1960, 3.1 million in 1967, and 3.9 million in 1975, according to department data.
The lowest catch in recent years was about 11.6 million pinks in 2006.
That year — 2006 — has been a pivotal factor in the department’s forecasts of late.
Part of the reason is that pink salmon have a lifecycle of two years.
For example, a pink salmon that was spawned in 2006 would have traveled into the open ocean in 2007 and then returned to its home streams to spawn and die in 2008.
The number of pinks able to spawn in a given year is usually a good indicator of how weak or strong the return of pink salmon might be two years later.
Looking at actual harvest trends in recent years, pink salmon catches in Southeast Alaska have been higher in odd-numbered years than in even-numbered years.
The 2002 catch of 45 million pinks was followed by about 52 million in 2003, 45 million in 2004, and 59 million in 2005.
Then, in 2006, the catch plummeted to about 11.6 million pink salmon.
"Before 2006, our odd- and even-year pinks were both mostly performing at high levels," said Andy Piston, the research biologist who serves as the department’s pink and chum salmon project leader for Southeast Alaska.
"In 2006, we had kind of an anomalous poor return of even-year pink salmon," he said. "And since then, we’ve seen this extreme odd-even year pattern."
So, what happened to the pink salmon "class of 2006?"
Fish and Game notes that the Gulf of Alaska was unusually warm in 2005 — the year that pink salmon set to return in 2006 were out in the open ocean.
Along with the warmer temperatures that year, there were a lot of predators in the Gulf of Alaska that usually aren’t there.
Piston said other factors could have been involved, but whatever affected the pink salmon survival also affected other salmon species.
"Not only did our pink salmon returns come back poor the next year (2006), but we also saw real poor survival rates for the sockeye that went to sea in 2005, and also chum salmon that went to sea in 2005," Piston said.
But unlike sockeye and chum, which can return to spawn at different ages (chum can return as 3-, 4- or 5-year-old fish), pink salmon only return as two-year-olds.
"Our pink salmon, they're all the same age, so there's no buffer," Piston said. "Like with sockeye and chum salmon, you have multiple age classes returning, so you have some buffer against having one really bad year of survival. But for pink salmon, the odd and even runs are isolated from each other, so when we had that downturn in 2006, we’ve seen some pretty relatively weak pink salmon returns since then."
While the odd-year harvests have stayed robust — ranging from 38 million pinks in 2009 to this year’s record-smashing haul of 89.2 million fish — the even-year catches have remained relatively low.
The 2008 catch was about 15.9 million pinks, followed by harvests of 24 million fish in 2010 and 21.3 million in 2012.
In looking forward, Fish and Game uses the harvest trends from past years as the basic component of its forecast of the upcoming year’s catch of pink salmon in Southeast Alaska.
The other big factor is the annual trawl-survey data gathered by the National Oceanic and Atmospheric Administration’s Auke Bay Laboratories.
The trawl-survey data that’s collected in June and July provide a good picture of the abundance of juvenile salmon in the northern region of Southeast Alaska.
"(It’s a) snapshot of what survived all of the fresh-water and early marine portion of the life cycle — and that's where a good portion of the mortality occurs," Piston said. "So rather than having to guess at an infinite number of variables that could affect salmon survival, you're just basically getting a snapshot of what survived all of that."
As such, the trawl-survey data is "highly correlated" with the harvest of adult pink salmon in the following year."
This year’s trawl-survey data did not result in a large change to the final forecast.
"The (trawl survey) catch of pink salmon leaving inside waters really didn't change our forecast much from just what we had predicted with the trend in harvest," Piston said.
The pink salmon that will be returning next year were spawned in 2012.
Piston noted that escapements — the amount of fish reaching the streams and thus potentially able to spawn — were quite strong in southern and outer coast areas of Southeast Alaska in 2012, although there was some stock weakness in some of the northern inside areas.
The departments top fishery management priority is meeting escapement goals.
No matter what the forecast is, Fish and Game bases its in-season management on the actual returns of fish.
"They make sure it looks like there are adequate numbers to meet escapement needs," Piston said.
There weren’t many — if any — escapement concerns for 2013 as pink salmon flooded into every corner of Southeast Alaska for a return and harvest that far surpassed the department’s forecast.
Fish and Game had forecast an "excellent" catch of around 54 million pink salmon for this year. As of early this month, the total stood at about 94 million — and counting, according to Piston.
‘"Everyone was expecting a big return of fish, but nobody had any idea it would be that big," he said. "If our forecast model had told us there was going to be a harvest of 94 million, nobody would have even believed it. ... It’s kind of hard to forecast something that's never occurred in the history of pink salmon in Alaska."