Pennsylvania Angler & Boater - July/August - 15

Silver
Bullet
by Rob Criswell

Streamline Chub

photo by the author

If any Pennsylvania fish deserves the name Silver Bullet, it is
the Streamline Chub, Erimystax dissimilis. It is the right size,
shape and color. This elongate minnow is 31/2- to 5-inches long,
nearly cylindrical and glitters brilliant silver in the sunlight.
The Streamline Chub exhibits a protruding snout and
possesses a small, horizontal mouth replete with diminutive
barbels at the corners. Its base colors are olive dorsally (upper
half of body) and whitish ventrally (lower half of body).
A narrow lateral band extends from the tail to the snout,
with a slight interruption at the eye. This distinctive stripe
is light green, silver or straw-colored, and sports a dozen or
so regularly-spaced spots that may be dark to electric blue,
making this species easy to distinguish from Pennsylvania's
other minnows. It is most similar to the Gravel Chub
Erimystax x-punctatus, which lacks the lateral spots.
The Streamline Chub occurs in the Ohio River basin from
Alabama and Tennessee northward to Indiana and New York
but is generally uncommon and localized, and absent from
much of this range. It is difficult to determine how common it
originally was in Pennsylvania. It was undoubtedly common
prior to the extensive pollution and damming that impacted
our western rivers in the 1800s and early- to mid-1900s, but
there is only a handful of older records. What is clear, however,
is that the Streamline Chub has made quite a comeback in
Pennsylvania recently. In the past two decades, its numbers
have expanded almost explosively in French Creek and the
free-flowing section of the Allegheny River, and it can now be
found in the lock-and-dam section of the Allegheny River and
the Ohio River.
The primary reasons for this dramatic return include
improvements in water quality in our larger rivers and an
increase in water clarity. The Streamline Chub occupies large
streams and rivers, where it prefers the faster velocities of riffles
and the areas above and below the riffles, and is generally
found in water less than 4 feet in depth. It also requires clear
water and a clean sand or gravel bottom. In sections of Ohio
www.fishandboat.com 		

streams where the bottom became silt-covered, this chub
promptly disappeared.
Spawning usually occurs in April and May and is thought to
be triggered by high water levels and warming temperatures.
A single female may produce 225 to 1,200 eggs, depending on
length. Offspring reach maturity in 1 year, but this species is
rather short-lived, rarely making it to age 3.
Streamline Chubs often patrol feeding grounds in compact,
roving groups of glittering silver, feeding mainly on aquatic
insects and some aquatic vegetation and bottom material.
Prior to 1927, Streamline Chubs and Gravel Chubs were
considered the same species and occupied similar habitat,
although the latter can tolerate cloudier conditions. An Ohio
ichthyologist observed rather keen competition during feeding
periods where the two species occurred together, and as our
waters cleared, it is likely conditions favored the Streamline Chub
and facilitated its expansion. It is possible that the Streamline
Chub's ability to outcompete its close relative for food and habitat
resources signaled the death knell for the Gravel Chub, which is
now believed to be extinct in Pennsylvania.
With its nearly continuous occupation of the entire lengths
of French Creek and the free-flowing Allegheny River, as
well as its occurrence in other nearby waters, we host a
significant portion of the global population of this minnow.
As with other fishes, such as the Redside Dace, Clinostomus
elongatus, and Longhead Darter, Percina macrocephala, the
2015-2025 Pennsylvania Wildlife Action Plan recognizes the
Streamline Chub as a responsibility species. This blueprint for
the management of our species of greatest conservation need
reinforces the importance of Pennsylvania's Streamline Chubs
to the overall well-being of the species. The responsibility
designation reinforces the need to monitor and maintain the
conditions that now occur in the rivers within its range and
provide protection into the future.
The rebound of the Streamline Chub is a cause to celebrate,
and continued efforts at reducing pollution and improving
water quality will result in schools of glittering Silver Bullets
rushing through the riffles of even more Pennsylvania rivers in
the future.

Pennsylvania Angler & Boater * July/August 2019

15
http://www.fishandboat.com
Pennsylvania Angler & Boater - July/August

Table of Contents for the Digital Edition of Pennsylvania Angler & Boater - July/August
