An investigation to determine origin: age and otolith chemistry of a brown bullhead catfish (Ameiurus nebulosus) found at Okawa Bay, Lake Rotoiti

Abstract

Some time between 10 and 15 January 2009, a brown bullhead catfish(Ameiurus nebulosus) was found washed up on the shore of Okawa Bay, Lake Rotoiti. The elemental signature of the otolith was measured using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) in order to determine the origin of the catfish. The otolith elemental signature of the Rotoiti catfish was compared to the otolith elemental signatures of catfish caught at Tokaanu Bay, Lake Taupo. Because otolith chemistry is largely determined by water chemistry, fish sharing a common origin should show similar otolith elemental signature.