The Coastal Post - August, 1997

El Nino And Next Year's Fish

Scientists studying rockfishes off the Central and Northern California coast have found unusually warm ocean temperatures during May and June, a major indicator of the presence of an El Nino event. The warm water was associated with low catches of juvenile rockfishes during the research cruise, while sardines, which favor warmer waters, were very abundant.

"We've never seen anything like this in our previous sampling, even in the El Ninos of 1983 and 1992," said National Marine Fisheries Service biologist Dr. Alec MacCall. "There was warm water everywhere from Monterey to Pt. Arena. The warmest water was off Pt. Arena, about 35 miles south of Fort Bragg, where it measured 64 degrees. That's more than 14 degrees above normal for this time of year."

MacCall said that during the late spring and summer months, this area is normally a center of intense upwelling of cold, nutrient-rich ocean water which supports fishes and other marine life. Northwesterly winds, which normally drive this upwelling system, were absent during most of the survey. This decreased upwelling condition could well be a product of the strong El Nino that is currently forming in the Eastern Pacific.

El Ninos are believed to be triggered by shifts in atmospheric pressures on both sides of the Pacific Ocean. This particular El Nino caught oceanographers by surprise, however, because it was not preceded by these atmospheric shifts. Also, only five years have passed since the last El Nino, an unusually short interval between events.

* * *

Fishery biologists from the Southwest Fisheries Science Center's laboratory in Tiburon conducted the month-long research cruise aboard the National Oceanic and Atmospheric Administration's research vessel David Starr Jordan. The researchers used a midwater trawl to survey the marine waters off the California coast to determine the distribution and abundance of oceanic juvenile rockfishes.

Rockfishes, commonly called rock cod or Pacific red snapper, comprise a valuable resource utilized by both sport and commercial fishermen. Only a few hundred juvenile rockfish were caught during the survey this year, compared to nearly a hundred thousand caught during years with more productive water conditions.