Wednesday, May 7, 2014

Climate Change Affects Alaska’s Fisheries

A new federal report on "human-induced" climate change released May 6 claims acidifying changes in ocean chemistry have potentially widespread impacts on the marine food web, including commercially important species.

The National Climate Assessment claims that the effects of global warming are not something of the future, but already having an impact, with Alaska in particular being heavily impacted.

Those engaged in commercial fisheries in Alaska should take special note of the section on the 49th state, within document, which is online at

Current and projected increases in Alaska’s ocean temperatures and changes in ocean chemistry are expected to alter the distribution and productivity of Alaska’s marine fisheries, a leader in commercial value, the report says.

Ocean acidification, rising ocean temperatures, declining sea ice and other environmental changes interact to affect the location and abundance of marine fish, including those commercially important, those used as food by other species and those used for subsistence.

Researchers found that these changes have allowed some near-surface fish species, including salmon, to expand their ranges northward along the Alaskan coast. Non-native species meanwhile are invading Alaskan waters more rapidly, primarily through ships releasing ballast waters and bringing southerly species to Alaska, the report said. The introduction of these non-native species could affect marine ecosystems, including the feeding relationships of fish important to commercial and subsistence fisheries, the report said.

Overall habitat extent is expected to undergo change too. Reductions in seasonal sea ice cover and higher surface temperatures may open up new habitat in polar regions for some species, including cod, herring and pollock. But continued presence of cold bottom-water temperatures on the Alaskan continental shelf could limit northward migration into the northern Bering Sea and Chukchi Sea off northwestern Alaska.

Warming might cause reductions in abundance of some species, such as pollock, in their current ranges in the Bering Sea and reduce the health of juvenile sockeye salmon, potentially resulting in decreased overwinter survival.

Should ocean warming continue, current fishing pressure on pollock cannot likely be sustained, and frequency of early Chinook salmon migrations will likely increase, making management of the fishery by multiple user groups more challenging.

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