Identification of Two Ecological Forms of Chum Salmon by Analyzing Microstructure of Otoliths

摘要

We analyzed otoliths (sagitta) of chum salmon caught in 2002 in the Taui River, the largest river of the Taui Gulf on the continental coast of the Sea of Okhotsk. While conducting biological analyses, we sampled otoliths from 818 individuals of chum salmon caught with a drag seine during controlled test fishing. Otoliths were removed during biological analysis and stored dried until processing. Some otoliths were rejected due to indistinct micro-increments (aberrant otoliths). Thermoplastic cement (Buehler, USA) was used to prepare sections. Sections were polished with "Mark-52" polisher (USA) using aluminum oxide abrasive paper disks with different particle sizes (Struers, Copenhagen/Denmark).