The corpses of newborn lambs are piling up in their tens of thousands as cold weather continues to hit Southland.

Boaties are being asked to check their vessels for hitchhiking seaweed, after a noxious Japanese kelp turned up in Fiordland.

Bad weather has put a damper on the start of the Bluff oyster season but it has not stopped Auckland's restaurants and retailers getting them on to plates in the thousands.