Contribution of walleye pollock eggs to the Gulf of Alaska food web in spring

Pulsed resources are prevalent phenomena in nature that can have disproportionally large and long-lasting effects on ecosystem production. Many fishes aggregate and spawn at high densities and release large amounts of resources to the environment in the form of eggs. These spawning events can provide pulsed dietary resources for a range of consumers; however, this is still an understudied topic particularly in the Gulf of Alaska food web. Here we assessed the magnitude and timing of eggs from walleye pollock Gadus chalcogrammus and their energy contribution to a highly productive ecosystem in Shelikof Strait, Gulf of Alaska. Our results show that aggregate spawning events of walleye pollock contribute considerably to the resource fluxes of this coastal food web in spring. Walleye pollock egg resources constituted on average 18.9% of April and 5.8% of May copepod production in the Shelikof Strait marine food web. In addition, the resource contributions from eggs appear 1 to 3 wk earlier than the spring peak rates of zooplankton production and thus occur at a time when equivalent dietary resources are still limited for many consumers. Our analysis showed that spawning events of walleye pollock provide an important pulsed resource subsidy in the Gulf of Alaska ecosystem.