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Tuesday, January 30 • 6:00pm - 9:00pm
Poster Display. Tracking Grass Carp Spawning and Egg Development in the Sandusky River

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AUTHORS: Madeline Tomczak, Ohio Department of Natural Resources Division of Wildlife and The University of Toledo Department of Environmental Sciences and Lake Erie Center; Nicole King, The University of Toledo Department of Environmental Sciences and Lake Erie Center; Patrick Kocovsky, US Geological Survey Lake Erie Biological Station; Christine Mayer, The University of Toledo Department of Environmental Sciences and Lake Erie Center; Song Qian, The University of Toledo Department of Environmental Sciences and Lake Erie Center

ABSTRACT: Invasive Grass Carp (Ctenopharyngodon idella) have been present in the Great Lakes since the 1980s, and were thought to be sterile individuals stocked in ponds for weed control. However, in 2015 eight eggs were collected from the Sandusky River, OH, establishing that spawning occurs in a Great Lakes tributary. Sampling continued in 2016, but no eggs were found. In 2017, two high flow events resulted in the collection of 7,000+ eggs. In 2017 the Sandusky River was sampled from Fremont, OH, the current location of a dam, to the river mouth at Sandusky Bay. Five-minute bongo net tows were used to collect eggs at the surface and at 1.8m on both sides of the river. During the first spawning event (May 30-June 1) egg catch peaked at 105, 490, and 11 per site on days one through three respectively. The presence of eggs over multiple days suggests a prolonged spawning event. During the second event (July 12) we carried out adaptive sampling once eggs were detected, sampling downstream to upstream and then back downstream to encounter the egg mass at different locations through time. Eggs were detected throughout the eight hour sampling period, with peak catch at a single site being 1,993. The duration of egg presence again suggests a prolonged output of fertilized eggs that likely involved multiple spawning individuals. Developmental stages of eggs increased with downstream distance. Eggs ranged from stage 3 to 25 (stage 1=no development to stage 30=hatching). Variability in developmental stage increased downstream. This may have resulted from differences in transport rates due to hydraulic variability. More developed eggs are more likely to hatch, whereas un-hatched eggs that reach Sandusky Bay are likely to sink and not hatch. Therefore, the likelihood of successful hatching, a necessary precursor to recruitment, likely depends on specific flow conditions.

Tuesday January 30, 2018 6:00pm - 9:00pm CST
Ballroom C & Foyer

Attendees (1)