7014

• UCREFRP Catalog Number: 7014
• Author: Valdez, R. A. and A. Wasowicz.
• Title: Non-Lethal Stomach Pumping Technique To Recovery Gut Contents of Roundtail Chub ‎(
• USFW Year: 1992.
• Copyright Material: NO

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METHODS

Stomach pumps were designed and constructed for this study based on Gengerke's
modification of the original Seaburg design (Gengerke 1973, Seaburg 1957). Flexible plastic tygon
tubing was connected to both ends of a clean, hand-held, rubber bulb, commonly used as an in-line
gasoline pump for outboard motors. The clear outlet tube was inserted into the buccal cavity of the
fish and a stream of water pumped through the inlet tube and into the stomach. Food items are
subsequently flushed out of the digestive tract through the vent of the fish and into a collecting jar.
Flexible tubing minimized the chance of damage to the esophagus, and the hand-held rubber pump
allowed for precision in dictating water flow and pressure. Different sized, interchangeable tubes
allowed for efficient flushing of various sized fish. .

Tests were conducted on forty roundtail chub collected by electrofishing on the mainstem of
the Colorado River, upstream of Westwater Canyon near Utah/Colorado state line, from August 5 -
6, 1992 (Table 2). Twenty adult roundtail chub were collected, pumped, and euthanized with MS-
222, before dissection of the fish to quantify untlushed remains in the stomach, and to examine the
condition of the pharyngeal teeth subsequent to pumping. Twenty randomly-selected adult roundtail
chubs were used as the control group; these were handled in the same manner as the experimental
group, but not pumped. After euthanizing the control group, the condition of the pharyngeal mill
of "un-pumped" chubs was compared to those of pumped fish to assess the amount of damage, if any,
inflicted by the stomach pump. Each fish was photographed to photodocument each individual and
record any evidence of external effects of electrofishing.

The head of each fish (test and control) was dissected using a pair of sharp scissors. The first
cut was made longitudinally through the dorsal aspect of the cranium from the tip of the maxillary
to the posterior end of the cranium. A second cut was made transverse to the first that extended
circumventrally to the base of the gill arches. Care was taken not to damage the gill arches or
pharyngeal arches. The neurocranial cavity was carefully exposed, and the otoliths (sagittae) were
extracted for aging (scales were also taken to determine if they were useable for aging this species).
The pharynx was then exposed in order to examine the pharyngeal teeth. Photographs were taken
of select pharyngeal mills to photodocument the condition of the teeth.

The pharyngeal teeth of each experimental and control fish was examined in the field, with
detailed notes taken on their condition and any existing damage. Specifically, the number of teeth
on each side of the pharyngeal mill was counted and examined for alignment, and each tooth was
inspected for loosening or breakage.

Following stomach pumping of experimental fish, the volume of all flushed prey items was
measured using a graduated cylinder. Following examination of the pharyngeals, the entire gut of
the individual was removed, cut open, and the volume of residual remains not flushed by the stomach
pump was measured. Efficiency was expressed as the percentage (by volume) of food items recovered
from the fish by stomach pumping. The volume of the stomach contents of untlushed chubs (the
control group) was not measured. All stomach contents, both flushed and dissected, were labeled and
preserved in alcohol in whirl-packs for later identification of food items.

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