Comparison of otolith microchemistry between juvenile steelhead cohabitant resident fish species
Grant: # 1552
Grant Amount: $119,268.13
Board Decision Year: 2015
Central Michigan University - Department of Biology and Institute for Great Lakes Research (Mt. Pleasant)
Department of Biology and Institute for Great Lakes Research
Pangle, Kevin (email@example.com) 989-774-3185
2015 Ecosystem Health and Sustainable Fish Populations: Ecological and Biological Research to Inform Management - Ecological and biological fisheries research to inform management
Fish populations in the Great Lakes are generally comprised of different stocks that originate from distinct natal locations. Effective management of such populations requires an explicit consideration for how stocks (i.e., locations) differentially contribute individual fish. Salmon and trout, which are comprised of mixed-stock populations including stocked and naturally produced fish, are economically and ecologically important, to the Lake Michigan community and its watershed, representing millions of dollars in value to the region.
Conventional techniques for assessing survival of fish to adulthood, such as mass marking programs, are impractical to implement for naturalized salmonines, because it is not feasible to collect and mark a large number of wild juveniles in each tributary. The microchemical signature of otoliths offers a more informative diagnostic for the identification of fish origin. This chemical mark on the otolith is naturally imprinted on all fish inhabiting a given water body, thus overcoming the impracticalities associated with artificial marking techniques. Findings from a previous GLFT-funded project on juvenile steelhead in the Lake Michigan basin support the utility of otolith chemistry. This project, led by Pangle and Jonas, has analyzed the otolith chemistry of steelhead collected in 2013 and 2014 from 28 different watersheds throughout the basin and has found unique chemical signatures within a watershed, between watersheds, and between broad regional classifications. One important, but open question is how transferrable are these chemical signatures to other fish species.
Herein, we tested the hypothesis that otolith trace elemental signatures of mottled sculpin Cottus bairdi, slimy sculpin C. cognatus, and juvenile coho salmon Oncorhynchus kisutch were predictive of those of juvenile steelhead O. mykiss across many streams within the Lake Michigan basin. Laser ablation inductively coupled plasma mass spectrometry was used to generate otolith trace elemental signatures for each individual fish. For each species pair, statistical correlations of mean otolith concentrations of Mg, Mn, Cu, Zn, Sr, Ba, and Pb for each site were estimated. Linear equations describing these relationships were used to transform juvenile steelhead otolith chemistry data to those of each of the other species. Transformed otolith chemistry data were subjected to random forest classifications developed for mottled sculpin, slimy sculpin, and juvenile coho salmon to assess interspecific natal source assignment accuracies.
Steelhead otolith concentrations of Sr were significantly correlated with those of each of the other species, whereas otolith concentrations Ba and Mn were significantly correlated among some species pairs, but not others. Natal source assignment accuracies of juvenile steelhead to stream and watershed generally decreased when otolith trace elemental data were transformed to those of mottled sculpin, slimy sculpin, and coho salmon. Miss-assigned fish often classified into nearby watersheds within larger management units, leading to higher assignment accuracies at coarser geographical resolutions (75-97% correct assignment to management unit for each species). These findings suggest that applications of otolith chemistry data may extend beyond the species from which it is collected.
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Same habitat, different species: otolith microchemistry relationships between migratory and resident species support interspecific natal source classification
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