Ocean researchers in the United States say spring is coming earlier every year as sea temperatures rise in the northeastern Atlantic.

The latest ecosytem advisory released by the Northeast Fisheries Science Center predicts that by the end of the century, summer will increase to 240 days.

"For the northeast shelf, that summer half of the year will increase on the order of two months," said Kevin Friedland, an oceanographer with the National Oceanic and Atmospheric Administration's National Marine Fisheries Service in Narragansett, R.I.

Scientists measure the arrival of spring when water temperatures reach the mean average. For many years, that benchmark stayed the same.

Not anymore.

"Over the last decade it's changed quite dramatically," Friedland told CBC News.

The Northeast Fisheries Science Center projections suggest the transition to spring will shift from mid-May to early April, and the fall transition from mid-November into December.

"Although we anticipate only on the order of 2 C or 3 C change in the temperature, that date will change by many weeks," said Friedland.

The question is what effect that will have on species whose behaviour and enzymes revolve on optimum ocean temperatures.

Scientists are actively investigating another potential effect of warmer temperatures happening right now — a dramatic dip in the spring bloom of phytoplankton in the Gulf of Maine.

In 2013, the spring bloom was so poorly developed it was below detection thresholds used by scientists.

"Many marine species reproduce around a spring bloom timetable. They spawn in the winter and so the young can enjoy the benefits of the spring bloom," said Friedland.

The lucrative Georges Bank fishing grounds — straddling the boundary between Canada and the U.S. — actually experienced a well developed phytoplankton bloom this spring.

Freidland said U.S. researchers are also reporting that a sporadic fall bloom on Georges Bank may be responsible for the bank's exceptionally high haddock productivity.