Preliminary results of trans-generational marking of larval marine fish otoliths

Preliminary results of trans-generational marking of larval marine fish otoliths

R.M. Buckley, L.L. LeClair, E.C. Volk, and S.L. Schroder

Preliminary results of trans-generational marking of larval marine fish otolithsThis is part of Biology, Assessment, and Management of North Pacific Rockfishes
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Description

Dispersal, connectivity, and retention of larval fish are key ecological processes affecting populations of marine fishes. Quantification of these parameters is vital for effective use of marine reserves and other resource management options, and yet these determinations are among the greatest challenges facing marine ecologists today. A major impediment is the lack of a reliable technique for marking extremely small marine fish larvae. Extensive testing with captive rockfishes (Sebastes spp.) and surfperches (Embiotocidae) has validated that trans-generational mass marking of larvae in vivo occurs with the transfer of elemental strontium to otoliths of developing larvae via matrotrophic viviparity. The mark is induced by intramuscular injection of up to 30,000 ppm strontium chloride into gestating females in situ. The marks are permanent, and can provide unique identifiers for cohort and location. Laser ablation inductively coupled plasma mass spectrometry detects marks in juvenile otoliths as a zone of significantly increased ratio of strontium to calcium. The first field test of trans-generational marking used brown rockfish (S. auriculatus) on Pt. Heyer reef in Puget Sound, Washington. Post-settlement juveniles were captured for otolith recovery only from Pt. Heyer reef. To date, 127 otoliths from marked-cohort juveniles have been analyzed and one strontium-marked otolith recovered.

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