Document Type

Article

Department/Program

Virginia Institute of Marine Science

Publication Date

2001

Journal

Fishery Bulletin

Volume

99

Issue

4

First Page

628

Last Page

640

Abstract

Calcified structures of summer flounder, Paralichthys dentatus, were evaluated to identify the best age determination method. Scales, the currently preferred structure, were compared with opercular bones and to right and left whole and sectioned otoliths for ages 0 to 10. All structures showed concentric rings that were interpreted as annual; however structures differed greatly in the clarity of their presumed annual marks. Right and left otoliths generally gave the same age, although they differed in the clarity of marks. Sectioned otoliths, particularly right ones, were the best aging structure. Right sectioned otoliths consistently showed the clearest marks and had the highest confidence scores, lowest reading times, and highest agreement within and between readers, 97% and 96%, respectively. Left sectioned otoliths took twice as long to prepare and were more difficult to interpret than right sectioned otoliths. Whole otoliths were the second best structure and were adequate to age 4 or 5, after which sectioning greatly improved the clarity of marks. Scales were inferior to, and often did not give the same age readings as, whole and sectioned otoliths. Compared with otoliths, scales tended to overage at younger ages and to underage at older ages. Opercular bones were undesirable for aging summer flounder. They were often unclear and inconsistent, and they had the lowest confidence scores, the highest reading times, and only 46% within-reader agreement. A major source of disagreement in scale and otolith age readings was the presence of an early, presumably false, mark on some structures. We compare the formation of this early mark in summer flounder with early mark formation on otoliths of Atlantic croaker, a species,vith similar life history traits.

Keywords

Micropogonias-Undulatus; Atlantic Croaker; Chesapeake Bay; Coastal Waters; New-Jersey; Age; Growth; Reproduction; Mortality; Scale

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