Tributary use and large-scale movements of grass carp in Lake Erie

Movement and Space Use of Grass Carp in the Sandusky River, Ohio: Implications for Lake Erie Eradication Efforts

“…Given these descriptions, we anticipated that Grass Carp would be mostly located in the Sandusky River between mid‐spring and early summer and then would move into Muddy Creek Bay, Sandusky Bay, or Lake Erie during the remainder of year. Contrary to our expectation and as first reported by Harris et al (2021), we found that adult Grass Carp remained in the Sandusky River throughout the year and moved widely throughout the river. Similarly, Chapman et al (2013) reported that juvenile Grass Carp caught in the Sandusky River likely spent their entire lives in the Sandusky River based on otolith microchemistry analysis.…”

“…We observed mean daily total movements ranging from 0.00 to 19.67 km and daily ranges of movement from 0.0 to 2.2 km. The mean daily total movement found in this study (1.17 km) was somewhat higher than the mean daily total movement of 0.76 km reported by Harris et al (2021) for all of Lake Erie, but results were still fairly consistent between the two studies. Both movement rates are higher than what has been reported from telemetry studies conducted on stocked Grass Carp in reservoirs and other impoundments.…”

“…Data collection.-This study evaluated acoustic tag detection data from Grass Carp (n = 70) that were captured from Michigan and Ohio waters of Lake Erie between 2014 and 2019 by either commercial fishing operations or state/federal agency removal efforts and subsequently implanted with acoustic telemetry transmitters (Model V16H; Vemco, Halifax, Nova Scotia; hereafter, "transmitters"). Grass Carp collection and the procedures used to implant transmitters are described in detail by Harris et al (2021) but are summarized here. Prior to surgery, fish were anesthetized to stage 4, as recommended by Bowzer et al (2012), using a portable electroanesthesia system (Smith-Root, Vancouver, Washington) set to pulsed DC at 30 V, 100 Hz, and a 25% duty cycle for 3 s, similar to the process described by Vandergoot et al (2011).…”

“…Not accounting for these potential tag fates could lead to negatively biased detection rates because of excess zero detections. Grass Carp were considered to have emigrated from the Sandusky River if they were detected on the lowest RKM receiver and then either were never detected again or were detected on another acoustic telemetry receiver outside the Sandusky River (Harris et al 2021). The identification of tagged Grass Carp that possibly died or shed their tags in the Sandusky River was informed by fitting a state‐space SCR model to the encounter history data (described below).…”

“…For targeted removal to be an effective response method, knowledge of areas where Grass Carp aggregate and how these aggregation areas change temporally is needed. Using detections of Grass Carp implanted with acoustic telemetry transmitters, Harris et al (2021) identified four areas in Lake Erie that were heavily used by Grass Carp: the Sandusky River, Plum Creek, the Maumee River, and the Detroit River. Of these areas, the Sandusky River was the most used system, with telemetered fish remaining in the river throughout the year.…”