LOS ANGELES (AP) — Three weeks after a huge fish die-off in Southern California, officials have a fish count but still can’t say what drove 175 tons of sardines into a marina.

Dave Caron, professor of biological sciences at the University of Southern California, said Thursday that as many as 2.5 million sardines blanketed the surface and floor of King Harbor Marina.

READ MORE: Bill Clinton Expected To Be Released From UCI Medical Center Sunday

After the fish surfaced on March 8, about 700 volunteers and city workers scrambled to remove the remains to ease the threat to other sea life.

READ MORE: Three Teenagers Critically Wounded At Halloween House Party In Whittier

Redondo Beach City Manager Bill Workman says crews may have gotten some unexpected help from the tsunami in Japan, which caused tidal surges and flushed fish out of rocks and crevices.

Workman estimates the cleanup will cost at least $300,000.

MORE NEWS: Suspect Arrested In Death Of Man At Newport Pier

(©2011 CBS Local Media, a division of CBS Radio Inc. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed. Wire services contributed to this report.)