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Going Green: Weather report

Unusual, extreme climate conditions have various impacts on fisheries

By Lisa Duchene
May 02, 2012

In Josh Keaton’s 11 years of keeping tabs on Alaska fishing boats working the Bering Sea, he has never seen the Bering Sea ice cover extend as far south and remain as long as it has this year. Keaton, an in-season manager with the Alaska Regional Office of NOAA Fisheries in Juneau, says the ice cover is likely to prevent fishermen from catching the entire 88.9-million-pound snow crab quota. 

In warmer years, there is no ice. Even in cooler years — relatively speaking for Alaska, that is — the ice edge may extend as far south as the Pribilof Islands by the end of the winter. But this year, says Keaton, the extreme cold, snowfall and wind that marked an exceptionally harsh Alaska winter meant the Bering Sea ice reached the islands by early January, and that area of the sea was still frozen in early April, blocking fishermen from reaching productive fishing grounds. Ice covered tens of thousands of square miles typically fished.

By March, the snow crab season is usually winding down. But quota still remained in early April. The ice also prevented fishermen from reaching yellowfin sole hot spots near Bristol Bay, which was nearly all iced in. The ice did not affect the overall Pacific cod and pollock harvest, says Keaton, but it made it more difficult for fishermen to reach.

The situation couldn’t be more different back east. In the Chesapeake Bay, a mild winter and early, warm spring led to blue crabs emerging from their muddy winter homes early and a plentiful harvest marked the usually slow beginning of the blue crab season.

Anyone who buys fish for a living is well aware that weather affects harvest and supply. Storms prevent boats from heading out to fish and temperature changes often signal changes in fish and shellfish. A warming Gulf of Maine may lead lobsters to molt earlier this summer, for example.

But extreme weather events are becoming more common and — since extreme weather is consistent with predicted effects of climate change — may be here to stay.

A heat wave made for the warmest March on record (since 1895) in the eastern two-thirds of the United States, and 15,000 warm-temperature records were broken, according to NOAA. 

Last year was the 11th-warmest since record-keeping began in 1850, according to the World Meteorological Organization’s (WMO) Annual Statement on the Status of the Global Climate. The year was also the warmest on record with a La Niña, an ocean-atmosphere phenomenon that has a cooling influence, says the WMO.

Climate change accelerated from 2001 to 2010, which was the warmest decade ever recorded in all continents of the globe, according to the WMO.

“Climate change is happening now and is not some distant future threat,” says WMO Secretary-General Michel Jarraud.

No single weather event can be accurately linked to climate change. Experts, however, are tracking weather patterns.

“Single weather extremes are often related to regional processes, like a blocking high pressure system or natural phenomena like El Niño,” says Stefan Rahmstorf, as reported by Reuters News Service. Rahmstorf is a scientist at Germany’s Potsdam Institute for Climate Research and co-author of a study that found extreme weather events in the past decade were “very likely” caused by human industrial activity. The study was published in the journal Nature Climate Change. “These are complex processes that we are investigating further. But now these processes unfold against the background of climatic warming. That can turn an extreme event into a record-breaking event.”

Of course, unusual weather is not always bad news for fish stocks — effects can be a mixed bag.

In Alaska, for example, the pollock fishery benefits from cooler-than-normal winters like the recent one.

“The odds are better to have a good [pollock] year-class when it’s cold,” says Mike Sigler, a marine biologist with the Alaska Fisheries Science Center in Juneau. “But it is not guaranteed by any means.

“These cold years often bring better year-classes,” adds Sigler, “which we really needed because the recruitment was very low in 2004-2005 and it was these recent years that have let the population recover and start to [approach] its former abundance.” 

The 2009 and 2010 pollock quotas were around a low of 800,000 metric tons, while the 2011 and 2012 quotas were 1.2 million metric tons. Peak quotas in the last several years were 1.3 to 1.4 million metric tons. Pollock spawn January to March and reach harvestable size in their 4th or 5th year.

In the Chesapeake Bay, an extended warm period will likely be a good growing season for blue crab. But for striped bass, there are concerns that the early warmth triggered any of the migratory fish that had reached the Bay to spawn. The worry, says David Secor, professor at the University of Maryland Center for Environmental Science, is that striped bass larvae may not survive the April return to cooler, seasonable temperatures. Air temperatures in the 50-degree (Fahrenheit) range and below would cool shallow waters enough to jeopardize striped bass larvae, says Secor.

Off the coast of California and Oregon, salmon runs are predicted to be abundant this year, due to good river conditions and excellent ocean conditions, according to the Pacific Fishery Management Council. The adult fall chinook salmon run to the Sacramento River is predicted to be 819,400 fish, and adult fall chinook to the Klamath River is predicted to be 1,567,600 fish, which is four times more than last year and would be the highest observed number on record.

But with salmon abundance comes weather-related worries. Recent drought conditions in the region have managers worrying about whether there will be enough water in the Klamath River system. Salmon share the fresh water with the irrigation needs of farmers. In 2002, large salmon returns combined with a low-water year led to disease outbreak and the loss of 35,000 to 60,000 salmon, says Jennifer Gilden, council spokeswoman.

“There was an expectation of a drought in California and that’s still up in the air, but we got a lot of rain in March and those fears have mellowed a bit,” says Gilden. In March, the snowpack was 61 percent of normal, but several storms pushed it to 84 percent of normal.

The council’s habitat committee has drafted a letter to the U.S. Department of the Interior, asking it to “pursue all necessary measures to ensure additional water will be available for release from the Trinity and/or Upper Klamath basins.” The Trinity is the biggest Klamath River tributary. 

Contributing Editor Lisa Duchene lives in Bellefonte, Pa.

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