Survival and passage of ingested New Zealand mudsnails through the intestinal tract of rainbow trout

North American Journal of Aquaculture
By: , and 



We conducted laboratory trials to determine the transit time and survival of New Zealand mudsnails Potamopyrgus antipodarum in the gastrointestinal tract of rainbow trout Oncorhynchus mykiss. To assess the rate of snail passage, we force-fed groups of fish a known quantity of snails and then held them in tanks. At selected intervals we removed individual fish from the test tanks and recorded the number of snails, their condition (live or dead), and their location in the gastrointestinal tract (stomach, anterior intestine, and posterior intestine). Feces were removed from tanks and examined for live snails. We repeated evaluations of passage rate and snail survival to determine the effects of varying the number of snails ingested, fish size, snail size, and feeding a commercial diet to fish after snail ingestion. We plotted and modeled gut evacuation using a stochastic model for ordinal data to consider each test variable. Snail passage rates were faster in fish that were fed smaller snails. Surprisingly, fish fed snails and then administered rations of commercial fish feed retained the snails longer in their stomach than did fish that were not administered fish feeds after being fed snails. Increased retention time of snails in the stomach decreased the probability of snail survival when voided in fecal material. Snails that passed through the gastrointestinal tract within 12–24 h of ingestion were often recovered live in fecal samples. However, no live snails were recovered from the posterior intestine or fecal material collected 24 h after ingestion. Using our results we propose potential management options that could reduce the risks of introducing live snails into new locations when stocking fish from infested hatcheries.

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Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Survival and passage of ingested New Zealand mudsnails through the intestinal tract of rainbow trout
Series title North American Journal of Aquaculture
DOI 10.1577/A08-033.1
Volume 71
Issue 4
Year Published 2009
Language English
Publisher Taylor & Francis
Contributing office(s) Idaho Cooperative Fish and Wildlife Research Unit
Description 15 p.
Larger Work Type Article
Larger Work Subtype Journal Article
Larger Work Title North American Journal of Aquaculture
First page 287
Last page 301
Country United States
State Idaho
Other Geospatial Hagerman National Fish Hatchery
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