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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pharynx and develop on modifications of lower elements of the last gill arch. The pharyngeal teeth
that characterize minnows and suckers are on the fifth pair of the ceratobranchials or gill arches, and
are known as the pharyngeal arches or pharyngeal bones. New World cyprinids have one to three
rows of pharyngeal teeth on each arch, depending on the species. The greater or primary row usually
has four or five teeth, and the minor or secondary row one or two teeth. Many cyprinids exhibit
bilateral asymmetrical counts with greater numbers of teeth on the left primary arch. The pharyngeal
teeth formula for most Gila sp. is 2,5-4,2 (left secondary, left primary - right primary, right secondary).

Cyprinoid pharyngeal teeth are unusual among vertebrate teeth in that the "enamel organs"
are of endodermal rather than ectodermal origin (Eastman 1977, Edwards 1929, Harder 1975). Each
develops from the deeper columnar layer of the pharyngeal epithelium representing the endoderm
of the primitive foregut. The sites for this tooth formation in the epithelium are known as anlagen;
the number of anlagen equals the number of pharyngeal teeth on the primary row. The crowns of
the teeth are probably composed entirely of dentin. The teeth first appear as tooth buds ("enamel
organs") in the dental lamina in a process similar to that descnbed for lower vertebrates such as
reptiles (Eastman and Underhill 1973, Edmund 1960). The developed tooth buds ankylose to the
pharyngeal arch where they are surrounded by connective tissue. The bony ankyloses serve to unite
the crowns to the pharyngeal bone. The ankyloses are partially resorbed by osteoclasts prior to tooth
loss and reformed during tooth replacement.

The pharyngeal teeth of cyprinids and catostomids are deciduous or polyphyodont. Each
definitive crown ankylosed to the pharyngeal arch has, in the surrounding mucosa, tooth buds that
are destined to form its replacement cap. There are the same number of anlagen on the dental
lamina producing tooth buds as there are major-row teeth (Eastman and Underhill 1973). Thus,
pharyngeal teeth patterns are often species or genus-specific. There is, however, great variation in
tooth counts, probably caused by either recently-shed teeth or teeth that have not yet ankylosed.

The pharyngeal teeth of Gila robusta and Gila ~ are described as having thick bases,
pointed and hooked, and with a weak grinding surface (Miller 1946, Jordan and Everman 1896). The
teeth observed on G. robusta used in this study ranged in size from about 1 mm to about 7 mm, and
were consistent in appearance with previous descriptions.

CONCLUSIONS

The preliminary results of this study show that the non-lethal stomach pump technique used
on roundtail chub is an efficient and safe method for recovering stomach contents, and can be
recommended for use with endangered humpback chub. Further analyses will be performed on the
data to statistically support these conclusions.

The stomach pump used on roundtail chub was 100% efficient at removing gut contents
through the anal vent, rather than through the buchal cavity. This method of anal evacuation had
not been tested before. Although the long-term effect of stomach pumping on round tail chub was
not evaluated in this study, the immediate lack of stress or disorientation by the test fish indicated
that no long-term ill effects can be expected from the procedure. Also, no evidence of damage to
the pharyngeal teeth was found following stomach pumping. Since the pharyngeal teeth are naturally
deciduous, damaged teeth would be replaced immediately, resulting in no long-term ill effects, even
if there was damage to the pharyngeal mill.

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