FISH FACTOR: Arrowtooth flounder study focused on food competition
Fish stomachs could help solve the mystery of why Alaska halibut are so small for their age.
Halibut weights are about one-third of what they were 30 years ago, meaning a halibut weighing 120 pounds in the late 1980s is closer to 40 pounds nowadays.
One culprit could be arrowtooth flounders, whose numbers have increased 500 percent over the same time to outnumber the most abundant species in the Gulf: pollock.
Fishermen for decades have claimed the toothy flounders, which grow to about three feet in length, are blanketing the bottom of the Gulf, and many believe they are out-competing halibut for food.
A study being done by researchers in Southeast Alaska aims to find out.
“People think that potentially arrowtooth is competing with halibut for space and/or prey which is limiting the growth of Pacific halibut,” said Cheryl Barnes, a PhD student at the University of Alaska Fairbanks who is working out of the National Oceanic and Atmospheric Administration’s Auke Bay lab in Juneau.
Since last summer, Barnes and her adviser Dr. Anne Beaudreau have been studying spatial and dietary overlaps between the two species. Along with analyzing Gulf of Alaska bottom trawl data, the team is doing field studies in fishing areas around Juneau where no trawling occurs.
Barnes said they are looking at two things: space use and the composition of prey within their stomachs to try and get answers using a concept called “resource partitioning.”
“The thought is that if you see areas where halibut and arrowtooth are overlapping in space, you might expect to see that they are not eating the same things as a way to alleviate competitive effects. They are partitioning their resources in that way,” she explained.
“Whereas if they are in an area where there is not much spatial overlap between the two, they might be eating roughly the same things because they are part of the same niche and the goal is to eat those prey items that are more optimal for their growth. And they are more able to do that if both species are not found in the same location.”
Barnes is studying the contents of over 1,000 halibut and arrowtooth stomachs collected last year from sport anglers, and she hopes to collect at least that many through September. She said her diet study dovetails with other others being done that focus on environmental factors and impacts of fishing.
“Especially size selective fishing — the idea that we have been removing the larger, faster growing individuals, and it just kind of brings that average size at age down,” she said.
If the project proves that the two species are competing for food, it will fall to managers to find creative solutions. That could prove problematic in terms of increasing arrowtooth catches to leave more food for halibut.
“One of the problems is that arrowtooth aren’t really marketable because when you heat them up the flesh turns into a mushy fish smoothie. The other is that there is a lot of bycatch associated with arrowtooth catches since they share the same habitat,” Barnes explained.
Meanwhile, Barnes wants to get more donated stomachs of both species, either fresh or frozen, along with information that includes fish length, body weight, and where it was caught.
While the project, which is funded by the Pollock Conservation Cooperative Research Center, now centers on fishing areas around Juneau, it could expand to other regions.
“We are considering it a pilot project,” Barnes said, “and if we find that we are able to find some answers on the potential for competition around Juneau, there is opportunity to expand it to other areas of the Gulf of Alaska.”
Got stomachs? Contact Barnes can be at (907) 957-4893 or [email protected].
Salmon sales slump
Salmon sales data from last year show what everyone already knows: lower prices across the board. The Alaska Department of Revenue’s Tax Division tracks sales of six different salmon product forms by region, including frozen, fresh, roe and cans. The latest report shows data from the busy sales season from September through December. Here’s a sampler:
By far, the bulk of Alaska’s salmon goes to market in frozen, headed and gutted form. The average wholesale price for sockeye was $2.40 per pound, compared to $3.13 last year. For cohos, the price was $2.20 compared to $2.53 per pound; pinks averaged $1.07, down 26 cents, chums sold at $1.25, down 23 cents, and frozen chinook salmon averaged $3.85 a pound, compared to $4.28 at the same time last year.
Fresh and frozen sockeye fillets wholesaled for $5.73 on average, down from $6.19 a pound.
Pink salmon roe averaged $4.16 per pound, down from $6.95; chum roe at $10.30 was a drop of $2.50 per pound from 2014.
Cases of 48 tall cans of sockeye took a huge nose dive to $126.53 per case, a drop of nearly $70. Cases of canned pinks were wholesaling at $76.86, down $4.
The market could get some relief from less salmon being available to buyers this year.
A toxic algae bloom continues to kill millions of farmed salmon from Chile, where production is pegged to fall way below expectations.
“The upshot is that Chile’s production may fall by 40,000 to 50,000 tons, or 13 percent below what was expected from the inventory of fish in the water taken at the end of December,” said market expert John Sackton.
Salmon catches on the West Coast also are projected to be down by half at Puget Sound and on the Columbia River due to low coho numbers. Likewise, chinook salmon populations along the coast are in even worse shape, and fishing will be severely restricted this year.
Officials blame the overall declines on record warm ocean temperatures and poor river conditions following years of drought.
Lower salmon numbers also are projected for several Alaska fisheries – notably, for pink salmon in Southeast and at Prince William Sound. Bristol Bay’s sockeye forecast calls for a catch just under 30 million fish, well below harvests of the past two years.
March means a couple thousand Alaska fishermen will start gearing up for halibut, which opens a bit later this year on the March 19. For the first time in decades the total coastwide catch increased by 2.3 percent to just under 30 million pounds. Alaska gets the lion’s share at about 21.5 million pounds, a boost of 200,000 pounds from last year.
The year’s first roe herring fishery at Sitka Sound could kick off around the same time. A quota of nearly 14,941 tons is a 70 percent increase. Last year the Sitka fishery opened on March 18 and managers planned to begin surveys this week.
Fishing for cod, pollock, flounders and other groundfish continues in the Bering Sea and Gulf of Alaska.
Likewise for crab: Bering Sea snow crabbers have taken 70 percent of the 36.5 million pound quota with less than 11 million pounds left to go. Less than 3 million pounds remain in the Tanner crab quota of nearly 18 million pounds.
A new law requiring life rafts for fishing boats has been delayed. The new rules would have applied to any vessel operating more than three miles from shore, even small hand trollers or halibut skiffs. Currently, only boats 36 feet or larger, or those carrying four or more people, are required to have so called ‘buoyant apparatus.’
Word came after the Feb. 26 deadline that Congress chose to repeal the requirement, and opted instead to go through the formal rule making process before implementation. That could take at least a year, said Steve Ramp, a Coast Guard Commercial Fishing Vessel Examiner in Sitka.