|Reclamation bio technician Jon Nelson deploys a remote PIT tag scanning unit at Lake Mohave. Photo by Reclamation.||Briana, a Lake Havasu City resident, holds an adult male razorback sucker which had been at large since it was stocked March 5, 2009. Photo by Reclamation.||View of the Topock Gorge area. Photo by Reclamation.|
ASU Students Gain Hands-on Experience with Native Fish Conservation at Lake Havasu
By Nathan Lenon, a general biologist in the LCR MSCP
Five students from Arizona State University Colleges at Lake Havasu City got up close and personal with endangered fish conservation efforts during this year’s “razorback roundup” on Lake Havasu. Lake Havasu is home to three native Colorado River fish, including the razorback sucker, bonytail, and the flannelmouth sucker.
The “roundups” are annual lake-wide sampling events which allow biologists to collect information on the abundance of Federally Endangered razorback sucker relative to the many species of introduced sport fishes that dominate the lake. Participating agencies this year include Reclamation, U.S. Fish and Wildlife Service, California Department of Fish and Wildlife, U.S. Bureau of Land Management, and Arizona Department of Game and Fish. Reclamation is the implementing agency for the Lower Colorado Multi Species Conservation Program (LCR MSCP), which includes Razorback Sucker among its list of 31 species it seeks to conserve.
During the roundups, biologists deploy trammel nets to capture fish, and then perform species identification and measure the length and weight for each fish. Razorback suckers and other native fish are scanned for microchip tags, called passive integrated transponder (PIT) tags. The microchips contain unique identifiers that associate an individual fish with when, where, and how large it was when it was last contacted or stocked.
“Prior to the initiation of this roundup,” said Jeff Lantow, Reclamation fishery biologist, “the Lake Havasu native fish population was unknown and virtually undetectable. This was due to the low numbers of (native) fish and the expanse of habitats between Davis and Parker Dams. Since the late 90s, we have been able to compare annual data which has shown a slow and steady rise in the razorback population. This increase has coincided with fish augmentation programs initiated by the Lake Havasu Fishery Improvement Program and the LCR MSCP. The current population is now believed to be over 3,000 razorback suckers.”
During the morning hours on February 12th and 14th, the students and Reclamation biologists met at the boat launch at Moabi Regional Park, which is located on the Colorado River south of Needles, California. The students and biologists, who were paired into crews of about four per boat, set out to retrieve a series of 300-foot long trammel nets set in place the previous afternoon to fish overnight.
“Experiential learning opportunities like this are invaluable to our life science students,” said instructor Dr. Kerrie Anne Lloyd, “…meeting agency biologists and learning about volunteer opportunities helps students determine career paths by finding out more about each field.”
While pulling in the third of four nets Thursday morning, one biologist noticed the distinctive dorsal keel behind the head of a large entangled fish. The crew gently brought the 525 mm (approximately 21 inches) long fish onboard, working quickly to remove the net and transfer it to the live well.
“I did not expect to see that many fish,” said Briana of Lake Havasu City, “and handling a razorback sucker was certainly exciting! Though I didn’t grow up in a household with much money, my dad always advised me to ‘do what you love’ when it came to choosing a career. This experience confirmed my interest in the field of aquatic biology.”
Besides roundups, new technologies are allowing biologists to study native fish without capturing them. Remote scanners which use underwater antennae are being used in some studies to continuously scan for tagged fish along shoreline areas and in swift moving currents. These remote sensors can generate large datasets with less human labor and reduced fish handling stress, when compared to traditional netting.
When fisheries biologists seek to answer detailed questions about the movement patterns and the habitat use of stocked fish, they can use a technique known as sonic telemetry. Acoustic transmitters are implanted into a known number of fish just prior to release. As the fish disperse from the stocking location, the transmitters emit a signal that is recorded by a series of logging devices, known as submersible ultrasonic receivers, placed throughout the lake. The acoustic transmitters can also allow biologists to follow an individual fish, which can identify migration patterns or previously unknown spawning locations.
Reclamation bio technician Jeff Anderson, who frequently works with remote PIT tag scanners on Lake Mohave, explains, “In the last 5 years remote sensing technology has come a long way. The necessary gear and batteries to power it has been condensed to make it easier to deploy and retrieve in the field. Now we can program them to record at certain intervals to maximize deployment time with the minimal amount of power usage.”
Annually, approximately 4,000 bonytail and 10,000 razorback suckers are stocked into Lake Havasu to meet the goals of the LCR MSCP. Razorback Suckers mainly occupy the portions of Lake Havasu between Davis Dam and the Lake Havasu Delta, while bonytail contacts are concentrated near the Bill Williams River inflow to Lake Havasu.
Following an inquiry by Professor Kerrie Anne Lloyd, who sought field experiences for her life sciences students, the ASU University Colleges at Lake Havasu City opened in the fall of 2012 and has already participated in several LCR MSCP wildlife monitoring projects.
Updated December 2, 2013