The warming ocean has been in the news lately as the most powerful Atlantic hurricanes ever recorded — Harvey’s rain and Irma’s wind — slammed into Texas, the Caribbean, and Florida. The ocean is hotter now than any time since record keeping began in the 1880’s and, though hotter water doesn’t cause hurricanes we’ve learned it makes them worse. Uh oh!
There’s another sign the ocean is warming. Fish are on the move. A wide variety of species including sole, haddock, herring, and black sea bass have left places too warm for them and migrated to cooler water.
For example an enormous Atlantic sailfish (Istiophorus albicans), normally off the coast of Florida above, was caught in the Cape Cod Canal in August 2013. It was the first Massachusetts record.
It’s not just temperature that makes fish move. Warm water has less oxygen, so it’s harder to breathe, and more carbon dioxide so it’s more acidic. Acidic water holds less calcium carbonate, the building block of sea shells including those of tiny copepods. With fewer tiny organisms there’s less food all the way up the food chain.
Fish swim away from these “deserts” but some animals can’t move very far. Think of lobsters, now gone from Long Island Sound.
The changes in species affect both fishermen and nesting seabirds. The old catch limits refer to fish that can’t be found because they’ve moved north, and baby puffins starve because the new species are too big for them to swallow.
From more powerful hurricanes to fish leaving home, we’re in hot water!
Read more in this article from Yale e360: Feeling the Heat: How Fish Are Migrating from Warming Waters
(photo from Wikimedia Commons; click on the image to see the original)