The colourful Portuguese man-of-war is more commonly seen in warmer waters. Their painful stings can be fatal to some.

Researchers from the University of Washington used 80 years of data to figure out how much warming fish could withstand. They discovered fish in the tropics are already living in water at the upper end of their threshold.

Opalescents, also known as market squid, are showing up in waters previously considered too cold for them, and fishermen are paying attention.

NOAA and NASA satellites measured an average sea-surface temperature of 68.93 degrees Fahrenheit in the Gulf of Maine on Aug. 8, only 0.05 degrees below the all-time record high of 68.98 set in 2012. It is the epicenter of the U.S. lobster fishing industry, an important feeding ground for rare North Atlantic right whales .