The feasibility of using otolith microchemistry to trace movements of rainbow trout and common smelt in lakes Rotoiti and Rotorua

Abstract

Otolith microchemistry can be used to determine the natal origins of fish. Our feasibility study using single water samples has determined that the water chemistry around Lakes Rotorua and Rotoiti, have different elemental compositions warranting further investigation. We have shown that juvenile trout populations from spawning tributaries around lakes Rotorua and Rotoitit, Rotoua lakes district, New Zealand, could be grouped by using the ¹³⁷Ba:⁴³Ca isotopic ratio obtained from otolith laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) analysis. The ⁸⁸Sr:⁴³Ca isotopic ration further distinguished between different sample locations when combined with the the ¹³⁷Ba:⁴³Ca isotopic ratio. Laser ablation analysis across common smelt otoliths provided information related to the movements between different chemical habitats across the fishes life and some distinct resident and migratory pattern are presented although further investigation into migration is required. Our preliminary results indicate that we will be able to distinguish natal steam for juvenile rainbow trout and probably lake of origin for common smelt.