Friday, October 9, 2015

Who You Callin’ “Chubby?” Eastern Creek Chubsucker Erimyzon oblongus (Mitchill 1814) by Don Orth



The Eastern Creek Chubsucker occurs throughout many of the Atlantic slope drainages of the United States.   It is typically found in small streams and riverine wetlands, hence the “creek” descriptor.    It is very seldom caught by anglers because of its small mouth and is also infrequently observed by fisheries biologists.    Adults are olive-brown above grading to a more golden color on the sides and a white or silvery belly.  Fins are olive-gray and may be yellow at times.  The scales are darkly edged with pigments, which gives the fish a cross-hatched appearance on the sides.      The genus name, Erimyzon, derives from the Greek word eri  meaning "very much" or "a lot," and myzo "to suck.The specific name, oblongus, refers to the oblong body shape, because  it is longer than the Lake Chubsucker.  The Lake Chubsucker was the “chubby” one, first described by the French naturalist, Bernard Germain de Lacépède in 1803.     

Adult male Eastern Creek Chubsucker (top, photo by Jason Emmel) and juvenile (bottom)
Eastern Creek Chubsucker is a member of the sucker family (Catostomidae) and has a small, slightly oblique, nearly terminal sucker-type mouth with fleshy plicate lips.  It is a small sucker, generally less than 20 cm.   The body is thick and round, hence the “chubby” descriptor.   During spawning the males are dark brown above and pink to yellow below with orange paired fins and yellow median fins.    Breeding males also develop 3 large tubercles on each side of the snout.    Young Eastern Creek Chubsuckers are distinguished by a faint yellow stripe above black stripe that extends from the snout to the caudal fin base. 

Three large tubercles on snout of breeding male (left, photo by Todd Crail); Ventral view of mouth of Eastern Creek Chubsucker showing plicate lips, which meet at nearly right angles (right).
The genus, Erimyzon, consist of four species, the Eastern Creek Chubsucker E. oblongus, Western Creek Chubsucker C. claviformis, Lake Chubsucker E. sucetta, and the Sharpfin Chubsucker E. tenuis.  Older literature recognizes two disjunct forms, or subspecies of Creek Chubsuckers, one along the Atlantic slope drainages and one in Mississippi and Gulf Slope drainages.  However, today these are considered Eastern Creek Chubsucker and Western Creek Chubsucker.  All members of the genus are similar in body shape and have no lateral line.   They are distinguishable by scale counts.  The lateral line is a system of sense organs used to detect movement and vibrations in surrounding water, very useful adaptation.   The loss of the lateral line is a derived trait but raises the question "Why lose a lateral line organ?"  No one has ever investigated that evolutionary question.     

Creek Chubsucker may be important pioneer fishes, among the first to ascend small creek newly flowing in the springtime.  Creek Chubsuckers spawn in spring (March through May) over sand and gravel.   The very large tubercles on the snout are formidable looking weapons and one can only speculate about the nature of agonistic encounters among breeding male Creek Chubsuckers.  Larry Page and Carole Johnston do describe males defending territories by head butting.   After males establish breeding territories, they court females and lead them to the territory.  The female digs in the gravel with her snout presumable to indicate spawning readiness.   To view these activities click here.  

Although the Eastern Creek Chubsucker is widely distributed, there have been few studies that examine the role(s) that it plays in the aquatic ecosystem.   Databases on fishes will categorize its feeding mode as invertivore, but its feeding behavior and preferences in the dynamic creeks and riverine wetlands are largely unexplored.   Even Wikipedia has conflicting entries regarding the invertivore and/or herbivore-detritivore classification.  More research is needed on this question!  One study examined 16 specimens in a Virginia stream; of the 13 that had food materials, 61% contained digested plant matter and animal food items were entomostracans (a subclass of Crustaceans).    

Some other observations provide hints to the role of this species. During breeding, the scattering of thousands of eggs for each spawning females attracts many egg predators.  The mortality is likely very high and, therefore, the Creek Chubsucker with its high fecundity likely feeds many carnivorous animals. The Eastern Creek Chubsucker is often associated with warm-water, sluggish streams that also support Brown Bullhead Ameiurus nebulosus, Pumpkinseed Lepomis gibbosus,  Yellow Perch Perca flavesens, and either the Chain Pickerel Esox niger or the Redfin Pickerel Esox americanus.    It is likely the Eastern Creek Chubsucker is a frequently encountered prey item in the diet of the black bass and pickerels.    Along with Golden Shiner Notemigonus crysoleucas and Fathead Minnow Pimephales promelas, chubsuckers are highly acceptable baits for fishermen.   In fact, many lure makers have patterned artificial lures to resemble the chubsuckers. 

Chubsucker fishing lure sold by bigbitebaits.com (top)   Creek Chubsucker by Uland Thomas (bottom).
The unfortunate reality is that there are few studies that examine the status of populations of the Eastern Creek Chubsucker or other species of chubsuckers throughout their range.   Milton Trautman, author of “The Fishes of Ohio” described the detrimental effect of heavy erosion on Western Creek Chubsucker.  He wrote that “upon several occasions I found many dead chubsuckers in a stream section whose water contained much clayey silt.  This silt had been washed into the stream from recently cultivated cornfields during a brief summer shower.  The sticky silt had packed about the gills of the chubsuckers, suffocating them.”    As far as I know there are no "Save the Chubsucker" associations anywhere.   So keep a look out for these "chubby" suckers and see what they might be telling you.

References

Page, L.M. and C.E. Johnston. 1990.   Spawning in the Creek Chubsucker, Erimyzon oblongus, with a Review of Spawning Behavior in Suckers (Catostomidae). Environmental Biology of Fishes 27:265-272

Trautman, M.B. 1981. The fishes of Ohio. Ohio State Univ. Press, Columbus. 782 pp.  

Wagner, C.C. and E.L. Cooper.1963.  Population density, growth, and fecundity of the Creek Chubsucker, Erimyzon oblongus.  Copeia   1963:350-357.


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