Development of a species identification method for shishamo smelt larvae using whole-mount immunohistochemistry

Abstract

A method for species identification of shishamo smelt (Spirinchus lanceolatus) larvae was developed using whole-mount immunohistochemistry (IHC) to estimate fish stock abundance easily and accurately. Polyclonal antibodies against extracts of shishamo smelt larvae were produced. They were preadsorbed with extracts of rainbow smelt (Osmerus mordax) larvae, purified as IgGs specific to shishamo smelt larvae extract, and labeled with alkaline phosphatase. Shishamo smelt larvae could be distinguished from rainbow smelt larvae by whole-mount IHC using the adsorbed antibody. This simplified species identification and reduced its cost. The body length of smelt larvae caught from the Shin-Kushiro River was gradually smaller during the middle-late period of sampling. Species identification of these larvae by whole-mount IHC and 16S rDNA analysis revealed that shishamo smelt was the dominant species during the early-middle period, whereas rainbow smelt was dominant during the late period. Since both methods exhibited similar abundance ratios for these two species, whole-mount IHC appears to be effective for estimating shishamo smelt stock abundance.