Preliminary Test of an Electrical Barrier to
Prevent the Upstream Movement of New
Zealand Mud Snails Introduction

During the past century, several hundred exotic aquatic plant and animal species have
been introduced into North America (Mills et al. 1993; Ricciardi and Rasmussen 1998). Many of these species
were inadvertently spread through aquacultural practices (Naylor et al. 2001). While not originally documented
in an aquaculture facility, New Zealand mud snails (Potamopyrgus antipodarum; syn. Hydrobia jenkinsi;
NZMS) are an aquatic nuisance species that are now found in many locations in the western United States
(Bowler 1990). Because they can consume a significant portion of stream gross primary production (Hall et al.
2003) and may account for the majority of invertebrate production (Hall et al. 2006), NZMS frequently out-
compete other invertebrates both numerically and through exploitative competition (Hall et al. 2006). Because
of the potential effect they have on wild fish and invertebrate populations, actions should be taken to prevent the
spread of NZMS. Since NZMS can survive passage through the digestive tract of rainbow trout Oncorhynchus
mykiss (Bruce 2006), stocking of fish from NZMS infested hatcheries
could lead to inadvertent spread of the species.

In November 2007, NZMS were identified in the raceways of the Utah
Division of Wildlife Resources (UDWR) Loa State Fish Hatchery.
Several other UDWR hatchery facilities are located upstream of wild
NZMS populations. UDWR officials are concerned that NZMS could
move upstream into these other facilities. In this article, we present
results from preliminary research conducted by the UDWRs Fisheries
Experiment Station to develop an electrical barrier that can be installed
at other hatchery facilities to prevent the upstream movement of NZMS. Methods
To test the effect of electricity on NZMS behavior, four artificial
streams were created. Each stream consisted of two parallel, 150 cm
long sections of housing gutter. The two gutter sections ended in a
common collection basin that was also constructed from housing gutter.
A 2.5 cm wide copper strip was glued 30 cm from the downstream end
of each parallel gutter. A second copper strip was installed 2.5 10.0
cm upstream of the first strip. These copper strips served as electrodes
and the separation between the strips was selected in such a manner than when 24.0 v of direct current (DC) was
applied to the electrodes, four electrical current densities were created (0.7, 1.5, 3.4, and 4.2 mA/in 2 ). The artificial streams were placed into raceways at the Loa Hatchery and siphons were started to provide water for
each stream. A DC power supply (BK Precision Model 1715, set at 24.0 V) was used to electrify the copper
strips in one gutter section of each artificial stream. The other side was not electrified and served as a control. (Continued on page 2) V OLU M E 19, N UM B ER 2 J ULY 2008 The Ichthyogram U T AH D IVIS ION OF WIL D LI FE RES OURC E S
F IS H ERI ES EX PE RIME NT S TATI ON
1465 WE ST 200 NO RTH
L OGA N, U T 84321 Electrical Barriers and
New Zealand Mud Snails 1 RT Egg Disinfection with
H202 and Iodine 3 6 Lethal Effects of Various
Chemicals on New
Zealand Mud Snails INS IDE THIS ISS UE: Biologist Randy Oplinger places New
Zealand Mud Snails in raceway troughs at
Loa hatchery in a previous experiment P AGE 2 V OLUME 19, N UMBER 2 (Continued from page 1) One hundred NZMS were placed into the collection basin of each artificial stream. After 24 h, the number of
snails in the electrified and non-electrified gutters in each
artificial stream was counted. In addition, the number of snails
between and upstream of the copper strips (on both sides) was
counted. Snails were then removed from the gutters and a new
batch of 100 NZMS were added to each collection basin. A total
of four replicate 24 h runs were performed in each artificial
stream.

Results and Discussion
Overall, we found that the presence of the non-electrified copper
strips had no effect on NZMS behavior (Table 1). We found that
on average, 7.5