Assessment of Habitability of O-Age Red Sea Bream by Index Expression

Abstract

This study is to propose that comparative assessment is performed on the habitability of 0-age red sea breams as expressed in terms of unified indices. Relative condition index y₁ and density index y₂ are calculated using degree of fatness and distribution density in red sea bream caught by the fixed station. Habitability index y₃ is determined to y₁+y₂. The habitability at two bays of Hirado Island is assessed according to three kinds of indices. The inner bay areas in both the bays are ranked high in good agreement with past ecological studies. A multiple regression analysis is undertaken using y₁, y₂ and y₃ as criterion variables, and bottom materials, organic matter and feed biomass as explanatory variables. A considerable correlation is observed between three indices and the feed biomass variables, especially gammarids as a main food for red sea bream young.