2014 Seminar Series - USGS EcoLunch
Date: April 15th
Time: 12:00 pm MDT
Speaker: Adam Sepulveda, USGS Biologist
Title: Are introduced Northern pike driving salmon declines?
Abstract: Introduced Northern pike (Esox lucius) are hypothesized to be a driver of salmonid fish declines across the globe. Pike are renowned piscivores that favor soft-rayed fish, like salmonids. Concern over introduced pike is especially high in southcentral Alaska, where pike were illegally introduced to the Susitna River and Kenai River basins in the 1950s and have since spread to > 100 lakes and 70 drainages. Chinook salmon, coho salmon, sockeye salmon, and rainbow trout populations have declined in lakes and drainages where pike occur– presumably because of pike predation. To test the hypothesis that pike predation has caused declines in salmonids, we applied field-derived diet data, water temperature data and population abundance data to estimate pike consumption of salmonids and other prey species in Alexander Creek and the Deshka River, tributaries to the Susitna River. Data were collected in the summers of 2011, 2012, and 2013. We found that juvenile anadromous salmonid dominated pike diets throughout the summer, especially pike < 500 mm total length. Bioenergetics modeling estimated that an individual pike < 500 mm consumed up to 400 grams (≈ 250 fish) of juvenile anadromous salmonids each summer, while larger pike consumed up to 350 grams (≈ 200 fish) per individual. We estimated a minimum of 2600 pike < 500 mm and 1740 pike > 500 mm in Alexander Creek and 700 pike < 500 mm and 250 pike > 500 mm in the Deshka River. When individual bioenergetics estimates are put in the context of pike abundance, it becomes readily apparent that pike can drive salmonids to low abundance and possible extirpation.
Location: First Floor Conference Room "Madison Room"- NOROCK, 2327 University Way, Suite 2
(Click HERE for directions)
Webinar Info: If you can not attend in person, you can still listen and watch from afar!
Access code: 294333#
April 29: Megan Layhee, USGS - Spread and occupancy of introduced American bullfrog (Lithobates catesbeianus) in Yellowstone River floodplain
May 13: Bahram Farokhkish, USGS - Yellowstone Lake Trout Telemetry Project
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USGS EcoLunch is a forum for students, researchers, visiting scientists and collaborators in the environmental sciences to present their current and past work. Presentations will range from brown bag discussions of ongoing projects to more formal and polished seminar presentations.