This year, the model successfully predicted a poor year even though many fishery biologists – including Martino – thought it would be good.
But that predictability may contain a hint of problems on the horizon for striped bass. Although the coastwide population remains above target levels, striped bass recruitment in Maryland has been below average for three consecutive years, largely because the weather hasn’t cooperated.
“The Bay is full of spawners, but we are seeing a real reduction in recent years in reproduction,” Martino said. “So I think it’s pretty obvious that something else is going on in the environment.”
That “something else” may be found in work done by Bob Wood, the NOAA scientist in charge of the Oxford Lab. Wood suggests that a broader, long-lasting climate pattern called the Atlantic Multidecadal Oscillation may be affecting striped bass and other fish.
The Atlantic Multidecadal Oscillation is an alternating pattern of warming and cooling over large areas of the Atlantic Ocean, similar to the El Nino, La Nina patterns in the Pacific. The shifts, in turn, affect climate over large regions of North America. Various AMO phases, during which different parts of the Atlantic are warmed or cooled, persist for decades.
During certain AMO phases, which promote wetter winters, cool springs and more frequent nor’easters, the prevailing climate pattern seems to promote improved reproductive success for anadromous fish, such as striped bass, which live most of their lives at sea but return to freshwater to spawn.
During other AMO phases, which promoted drier, warmer springs, the situation is reversed, with fish that spawn on the coastal shelf and whose larvae use estuaries for nurseries, such as menhaden, getting a boost in recruitment. During those times, striped bass reproduction takes a hit.