2022 Early Hearing Detection & Intervention Virtual Conference

March 13 - 15, 2022

5/22/2018 | 9:15 AM - 9:30 AM | CONSEQUENCES OF SALMON SPAWNING TO RESIDENT FISH IN GREAT LAKES TRIBUTARIES | 321

CONSEQUENCES OF SALMON SPAWNING TO RESIDENT FISH IN GREAT LAKES TRIBUTARIES

In Great Lakes tributaries, introduced Pacific salmon deposit energy and contaminants as carcass and gametic tissue during spawning migrations. Such ecosystem linkages increase both growth and bioaccumulation in resident fish but mechanisms are unclear. Using observational surveys, experimental manipulations, and modeling we assessed the salmon role in resident fish growth and bioaccumulation. In stream reaches with salmon, resident fish had 25-fold higher PCB but marginally lower Hg levels than fish from upstream reaches without salmon. A mesocosm experiment suggested that fish growth did not improve with carcass consumption while isotope and Hg data suggested incorporation of salmon. In a salmon addition to a naïve stream, resident fish increased PCBs by 50-fold whereas Hg did not change. Coincident with increased PCB levels was a shift to salmon egg consumption. Analysis of salmon tissue indicate that eggs have elevated PCBs, lower Hg, and higher energy density than carcasses. A bioenergetic model synthesized our empirical results suggesting that salmon egg consumption controls growth and PCB bioaccumulation of resident fish, and indirectly mediates reduced Hg through growth dilution. Our study identifies mechanisms controlling the transfer of salmon-derived energy and contaminants to resident fish.

Ecotoxicology
Food Webs
Great Lakes

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Presenters/Authors

Brandon Gerig (), Northern Michigan University, bgerig@nmu.edu;