Acoustic tag study compares
wild/hatchery migration habits
April 13, 2007 Columbia Basin Fish and Wildlife
What are the differences between survival and
migration traits of wild and hatchery steelhead
An Oregon Department of Fish and Wildlife research
project will attempt to answer that question and
others over the next few months.
The Alsea steelhead acoustic project will
determine the migration habits and survival traits
of two groups of hatchery smolts and one group of
naturally-reared steelhead smolts.
Each of the three groups had 75 smolts implanted
with acoustic transmitters. Each transmitter has a
unique code that can be picked up by acoustic
receivers placed throughout the Alsea River and
The receivers will determine when the tagged fish
move through an area in the river or estuary--
ODFW staff placed 15 acoustic receivers in the
Alsea River, 14 receivers in the Alsea estuary,
and 5 receivers in the ocean near the mouth of the
"We are looking at these groups of smolts to see
if they are moving down the river at the same
time, whether they are using the estuary for the
same duration, and whether they are using the same
areas of the estuary for rearing," said Steve
Johnson, ODFW assistant project leader.
"Ultimately, we hope to understand what percentage
of each group survives their journey through the
river and estuary and successfully enter the
According to Johnson, the two groups of hatchery
smolts have been reared under similar conditions,
but differ in their degree of domestication.
One group represents the "traditional" broodstock
line that has been used at the North Fork Alsea
Hatchery for many years.
The second hatchery group represents a new
broodstock line that was developed recently by
bringing naturally reared adults into the hatchery
The migration patterns and survival rates of these
two groups are being compared to smolts that have
reared naturally in a tributary of the North Fork
Alsea near the hatchery.
The acoustic tags have a battery that lasts
approximately 70 days. The ODFW research and
monitoring group that is performing the study will
collect data from the receivers on a weekly basis.
The acoustic tags are used because they can be
detected in both salt water and fresh water and
trace fish that are several hundred yards away.
The $70,000 research project is a collaborative
effort among ODFW and researchers with the
Environmental Protection Agency at the Hatfield
Marine Science Center at Newport, Oregon. Funding
for the research comes through a grant from the
ODFW Fish Restoration and Enhancement Program and
additional funds from the Oregon Hatchery Research