FitzGerald Jennifer L.

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FitzGerald
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Jennifer L.
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Elemental signatures in otoliths of larval walleye pollock (Theragra chalcogramma) from the northeast Pacific Ocean

2004 , FitzGerald, Jennifer L. , Thorrold, Simon R. , Bailey, Kevin M. , Brown, Annette L. , Severin, Kenneth P.

The objectives of this study are to determine if larval walleye pollock from different geographic localities can be distinguished based on elemental signatures in their otoliths. By analyzing sagittal otoliths with both EPMA and laser ablation ICP-MS, we hoped to identify greater differences among locations than would have been possible by using either technique in isolation. If successful, the study may provide a powerful tool for determining stock structure and tracing migration pathways of walleye pollock in the north Pacific. These data could then be used by managers of one of the world's largest single species fisheries to direct the sustainable harvest of this considerable natural resource.

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Spatial and temporal variation in elemental signatures of statoliths from the Patagonian longfin squid (Loligo gahi)

2004-09-09 , Arkhipkin, Alexander I. , Campana, Steven E. , FitzGerald, Jennifer L. , Thorrold, Simon R.

We quantified elemental signatures in statoliths of 718 Patagonian longfin squid (Loligo gahi) collected in the vicinity of the Falkland Islands (southwest Atlantic) and at sites on the Patagonian Shelf and coastal Peru. All squid were assigned to a spawning cohort by size, spawning condition, and back-calculated spawning date based on daily increments in statoliths. The remaining statolith was then analyzed for six elemental ratios (Mg/Ca, Mn/Ca, Sr/Ca, Cd/Ca, Ba/Ca, and Pb/Ca) using high-resolution inductively coupled plasma mass spectrometry (ICP-MS). Elemental concentrations in the statoliths were broadly similar to other biogenic aragonites. Differences in Sr/Ca ratios in statoliths among geographic locations were generally consistent with a negative correlation between Sr/Ca and temperature. Variations in statolith Cd/Ca and Ba/Ca values confirmed that during winter months, the squid were foraging deeper in the water column. Both Mg/Ca and Mn/Ca ratios in statoliths decreased with squid size, probably corresponding to a decrease in the contribution of the organic component of the statolith. Elemental signatures in the statoliths of L. gahi varied significantly geographically and between spring- and autumn-spawned cohorts, which must therefore have spent significant portions of their life histories in different environments.

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