Open AccessDaily increment formation in otoliths of juvenile skipjack tuna Katsuwonus pelamis
Author(s) -
TANABE Toshiyuki,
KAYAMA Sadaaki,
OGURA Miki,
TANAKA Sho
Publication year - 2003
Publication title -
fisheries science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.412
H-Index - 64
eISSN - 1444-2906
pISSN - 0919-9268
DOI - 10.1046/j.1444-2906.2003.00680.x
Subject(s) - skipjack tuna , otolith , juvenile , diel vertical migration , sagittal plane , morning , fishery , evening , biology , zoology , tuna , anatomy , fish <actinopterygii> , physics , ecology , botany , astronomy
In the present study, we verified daily increment formation within sagittal otoliths of juvenile skipjack tuna Katsuwonus pelamis by analysis of diel changes in marginal increment width. Specimens were collected by midwater trawl in the tropical western Pacific from November to December 1995 and in February 1999. The sagittal plane of the otolith was embedded in enamel resin and polished with lapping films. The otolith‐measuring system was equipped with a light microscope and was used for marginal increment analysis. The index of completion of the marginal increment increased with time of day, approximately 40% at 07 : 00–10 : 00 h, 66% at 13 : 00–16 : 00 h and 80% at 19 : 00–23 : 00 h. Therefore, growth of the marginal increment progressed from morning to evening and was completed during the night. We conclude that increments are formed daily in juvenile skipjack otoliths and these increments have a width of 15–40 µm.