FISH FACTOR: Another study shows ocean acidification bad for crab stocks
Increasingly corrosive oceans are raising more red flags for Bering Sea crab stocks.
Results from a first ever, two year project on baby Tanner crabs show that higher ocean acidity (pH) affects both their shell production and the immune systems. Bairdi Tanner crab, the larger cousins of snow crab, are growing into one of Alaska’s largest crab fisheries with a nearly 20 million pound harvest this season.
“We put mom crabs from the Bering Sea in a tank, and allowed her embryos to grow and hatch in an acidified treatment,” explained project leader Bob Foy, director of the NOAA Fisheries laboratory at Kodiak.
“We took the tiny crab and put them in different levels of pH to represent acidification and let them grow. We then took the moms and mated them and ran them again for another year. What that means is the full reproductive development of those females occurred in acidified conditions,” he said.
The first year of exposure didn’t show many effects, he said, but the second year really had an impact on the tiny crabs’ ability to molt, which they do weekly or monthly depending on their growth stage. It takes five to seven years for a Bairdi Tanner to reach its mature, two-pound size.
“Those larval and juvenile animals are constantly going through physiologically stressful times to build a shell,” Foy said. “And that’s where we are seeing the effects.”
Researchers also studied the baby crab blood cells, which bring calcium to the shell and also help fight off illnesses. Those functions went down as well.
“The bottom line is long-term exposure to acidified seawater negatively impacts Tanner crabs’ ability to grow and survive, and likely impacts their ability to defend against disease,” Foy said.
Based on population modeling, which managers use to set annual catch limits, researchers can predict potential impacts the increasing corrosion will have on the crab stocks.
“We can take data collected from surveys, such as the abundance and size of adult crab, and estimate how many crab will survive and recruit to a fishery seven years later,” Foy explained. “To estimate the effects of climate change and ocean acidification, we include the mortality of larval and juvenile crab we observed in the laboratory.”
Based on global estimates of ocean acidification, the Bering Sea may reach a pH level of 7.5 to 7.8 in the next 75 to 100 years if not earlier, Foy said.
Once that level is reached, the crab stocks are likely to begin a countdown.
“For Tanner crab, the timeline for estimated effects on fishery yields and profits is on a scale of 20 years, but only if all life stages of Tanners are exposed to corrosive lower pH water,” Foy explained.
He added that studies on red king crab from Bristol Bay show a double whammy from higher acidity and warming oceans.
“Once the Bering Sea reaches those pH levels,” Foy said, “there will be significant decreases in survival and subsequent fishery yields and profits within 20 years.”
The last pots are being pulled in the Bering Sea crab fisheries and crews can count on good prices for their catch.
“It’s been a really good year for crab all around,” said Jake Jacobsen, executive director of the Inter-Cooperative Exchange, a harvester group that catches 70 percent of the Bering Sea crab quota.
Boats are finishing off the Tanner and snow crab fisheries, and final prices won’t be settled for a few months after sales are made. But advances of $2 per pound for snow crab and $2.20 for Tanners were on par with ending prices last season.
“We expect to see a substantial increase when we complete negotiations for final prices,” Jacobsen said. “Prices for snow crab started to climb significantly last fall when it was announced the quota would be slashed 40 percent to just over 40 million pounds. And prices are still going up.”
Snow crab sales are usually split between Japan and U.S. markets, whereas nearly all of the Bairdi Tanners are sold at home, where it’s really starting to catch on.
“We’re really excited about it,” Jacobsen said. “We’d like things to go more to the domestic side, so our countrymen can appreciate this crab. It’s just got such a great, distinct flavor.”
The red king crab fishery at Bristol Bay last fall also yielded a better payday. Crabbers averaged $8.18 per pound for their catch, compared to $6.86 the previous year.
“That was due primarily to the crackdown on illegal fishing in Russia, which resulted in a reduced influx of Russian crab into the U.S. As supplies diminished, the price rose and it became a very favorable market for us. It’s been a long effort and it’s very satisfying to see some payoff,” Jacobsen said.
Fish brush off
When it comes to Alaska lawmakers cutting fishing related budgets, little discussion takes place on the trickle down effects to local communities.
So claims Gunnar Knapp, a fisheries economist and director of the Institute of Social and Economic Research at the University of Alaska Anchorage. Knapp also has been an advisor to the Alaska Legislature this session.
“The kinds of conversations are not rational, careful considerations of the implications various cuts have on the industry,” he said during a visit to Kodiak. “Nobody says if you cut Fish and Game, they are going to close this counting tower and this research program, and they’re not going to not have these managers. There is no discussion as to whether cuts are penny wise and pound foolish, as I think a lot probably are.”
Knapp pointed to the folly of gutting funds for the state’s lone seafood marketing arm, the Alaska Seafood Marketing Institute, as an example.
“ASMI increases the value of Alaska fish products, and taxes are based on the value of the fish. There is likely a direct trade-off between funding for ASMI and fish value and fish taxes. But no one is thinking about that,” he said.
With Alaska’s commercial catches on the order of 5 to 6 billion pounds per year, adding just one penny per pound to fish prices makes a difference of nearly $1 million dollars for state and local governments each.
Knapp also called it “maddening” that lawmakers think of the seafood industry as a single entity.
“It drives me nuts when people say ‘the fishing industry.’ Our industry is very diverse, from small skiffs to huge floating processors, and what it costs to manage them varies widely,’ he said.
Rep. Louise Stutes (R-Kodiak), chair of the House Fisheries Committee, agreed.
“They just don’t get it. It is the most bizarre thing I have ever seen. Some legislators are just anti-commercial fishing, and it is so apparent. It’s really bad. What do they think held this state up before oil?” Stutes said during a recent trip home.
To Knapp, the most important point lawmakers miss is that Alaska’s fishing industry maximizes community and cultural objectives more than any other.
“We have never in Alaska managed fisheries for the purpose of making it a cash cow of the state, as with oil,” Knapp said. “The Constitution says the ‘legislature shall manage natural resources for the maximum benefit of the people.’ For fisheries, we try to maximize employment, fishing income and a variety of social objectives.”