NANAIMO -- Large numbers of dead herring that washed ashore this week on a Vancouver Island beach have both fishery officials and local fishermen looking for answers.

Will Meeks, who works close to Cedar's North Beach where the fish washed ashore, said he knew something was amiss when he saw unusually large numbers of birds congregating on the beach Thursday morning.

He said he was surprised to find "thousands" of dead herring washed ashore, a scene he can't recall ever seeing before on local beaches.

Meeks said the dead herring appear to localized to North Beach because he and friends checked nearby beaches and found nothing similar.

Lisa Mijacika, a spokeswoman with the Department of Fisheries and Oceans, said DFO officers are being sent to North Beach to determine what killed so many herring.

"It appears to be a very rare occurrence and we hope to know more once our officers have a look."

Paul Kershaw, a commercial herring fisherman, speculated that the fish could have ended up in an area of the ocean close to the beach that was low in oxygen, which could have caused the deaths.