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Variation in stable isotope (δ18O and δ13C) signatures in the sagittal otolith carbonate of king threadfin, Polydactylus macrochir across northern Australia reveals multifaceted stock structure

journal contribution
posted on 2023-05-19, 12:24 authored by Newman, SJ, Allsop, Q, Ballagh, AC, Garrett, RN, Gribble, N, Meeuwig, JJ, Mitsopoulos, GEA, Bradley MooreBradley Moore, Pember, MB, Rome, BM, Saunders, T, Skepper, CL, Stapley, JM, van Herwerden, L, Welch, DJ
Otoliths of king threadfin, Polydactylus macrochir were collected from 2007 to 2009 at nine locations across northern Australia representing most of their distributional range and areas where fisheries are active. Measurement of the stable isotope ratios of δ18O and δ13C in the sagittal otolith carbonate from assemblages of P. macrochir revealed location-specific signatures and indicated that adult fish sampled from representative sites across their range were significantly different. The significant differences in the isotopic signatures of P. macrochir demonstrated that population subdivision is evident and there is unlikely to be substantial movement of fish among these distinct adult assemblages. The stable isotopic signatures for the fish from the different locations were persistent through time, and therefore it could be concluded that they comprise separate stocks for many of the purposes of fisheries management. The spatial separation of these populations indicates a complex stock structure across northern Australia with stocks of P. macrochir associated with large coastal beaches and embayments on a fine spatial scale. These results indicate that in order to achieve optimal fisheries management, the current spatial management arrangements need to be reviewed, particularly the potential for localised depletion of stocks on small spatial scales. This study has provided further evidence that measurement of the stable isotopes ratios in teleost sagittal otolith carbonate can be a valuable tool in the delineation of fishable stocks or fishery management units of adult fish and that widely distributed fish can nonetheless show strong localised population structure.

History

Publication title

Journal of Experimental Marine Biology and Ecology

Volume

396

Pagination

53-60

ISSN

0022-0981

Department/School

Institute for Marine and Antarctic Studies

Publisher

Elsevier Science Bv

Place of publication

Po Box 211, Amsterdam, Netherlands, 1000 Ae

Rights statement

Crown Copyright © 2010 Published by Elsevier B.V. All rights reserved.

Repository Status

  • Restricted

Socio-economic Objectives

Wild caught fin fish (excl. tuna)

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