Age compositions of flatfish stocks as determined by a new otolithometric method, its application in the estimation of growth, spawning potential and fisheries management

Satoshi Katayama, Masayuki Yamamoto, Shigeaki Gorie

Research output: Contribution to journalArticle

11 Citations (Scopus)

Abstract

We developed an ageing methodology and examined age composition of three flatfish stocks inhabiting the Seto Inland Sea, Japan. Ages were difficult to determine for three-lined tongue sole (Cynoglossus abbreviates) and ridged-eye flounder (Pleuronichthys cornutus) because the first year annulus ring was often indistinct; therefore, we used directional change in otolith growth to distinguish it. Sectioning and etching methods were powerful tools for identifying annual checks for red tongue sole (Cynoglossus joyneri). Using these ageing methods, we determined age-length relationships and growth curves. The age composition of the populations studied and of the landings showed that a large proportion of the latter consisted of individuals under the mean age of sexual maturity, thereby reducing the percent spawning potential ratio (%SPR) to ≈ 20% for all species. These findings suggest that fishing pressure on immature fish is leading to overfishing of these flatfish stocks.

Original languageEnglish
Pages (from-to)451-456
Number of pages6
JournalJournal of Sea Research
Volume64
Issue number4
DOIs
Publication statusPublished - 2010 Nov 1
Externally publishedYes

Keywords

  • %SPR
  • Directional Change
  • Red Tongue Sole
  • Ridged-eye Flounder
  • Sectioning and Etching Methods
  • Three-lined Tongue Sole

ASJC Scopus subject areas

  • Oceanography
  • Ecology, Evolution, Behavior and Systematics
  • Aquatic Science

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