IMPACTS OF CLIMATE CHANGE ON FISHERIES

American fishermen catch or harvest five million metric tons of fish and shellfish each year. U.S. fisheries contribute more than $1.55 billion to the economy annually (as of 2012). Many fisheries already face multiple stresses, including overfishing and water pollution. Climate change may worsen these stresses. In particular, temperature changes could lead to significant impacts.

  The ranges of many fish and shellfish species may change. In waters off the northeastern United States, several economically important species have shifted northward since the late 1960s. The three species shown in [the figure to the left]  (American lobster, red hake, and black sea bass) have moved northward by an average of 119 miles. 

·          Many aquatic species can find colder areas of streams and lakes or move north along the coast or in the ocean. Nevertheless, moving into new areas may put these species into competition with other species over food and other resources, as explained on the Ecosystems Impacts page.

·         Some marine disease outbreaks have been linked with changing climate.  Higher water temperatures and higher estuarine salinities have enabled an oyster parasite to spread farther north along the Atlantic coast.  Winter warming in the Arctic is contributing to salmon diseases in the Bering Sea and a resulting reduction in the Yukon Chinook Salmon, Finally, warmer temperatures have caused disease outbreaks in coral, eelgrass, and abalone.

·         Changes in temperature and seasons can affect the timing of reproduction and migration. Many steps within an aquatic animal's lifecycle are controlled by temperature and the changing of the seasons. For example, in the Northwest warmer water temperatures may affect the lifecycle of salmon and increase the likelihood of disease. Combined with other climate impacts, these effects are projected to lead to large declines in salmon populations.

In addition to warming, the world's oceans are gradually becoming more acidic due to increases in atmospheric carbon dioxide (CO₂). Increasing acidity could harm shellfish by weakening their shells, which are created by removing calcium from seawater. ^[10] Acidification also threatens the structures of sensitive ecosystems upon which some fish and shellfish rely.