Federal, state and tribal officials are attempting to track a large dock that was reported drifting off the coast of Washington state.

NOAA spokeswoman Keeley Belva said Monday the object has not been relocated or confirmed since it was initially reported Dec. 14. Fishermen aboard a vessel reported seeing a large object floating off the coast, about 16 nautical miles northwest of Grays Harbor.

Spokesman Robert Lanier says the Coast Guard has been broadcasting alerts to mariners about the floating debris. Helicopter crews have also conducted five searches, covering about 317 square miles.

NOAA has received about 1,400 debris reports in the past year. It says 17 of those reports have been confirmed as definite debris from the earthquake and tsunami that struck Japan on March 11, 2011.