Walleye were once plentiful across the Great Lakes region, and were thefocus of a major sport fishing industry. But heavy over-fishing andotherproblems such as pollution depleted the walleye population. Now,researchersare trying to increase walleye stocks by drastically improving thesurvivalrate of small walleye stocked in lakes. The project focuses on teachingyoung fish how to use their sense of smell to avoid predators. Researchers say that if they are successful, the effect on themulti-million dollar sport fishing industry could be staggering. TheGreat Lakes Radio Consortium’s Bob Reha reports:
Walleye were once plentiful across the Great Lakes region, and were the
focus of a major sport fishing industry. But heavy over-fishing and other
problems such as pollution depleted the walleye population. Now, researchers
are trying to increase walleye stocks by drastically improving the survival
rate of small walleye stocked in lakes. The project focuses on teaching
young fish how to use their sense of smell to avoid predators. And
researchers say that if they are successful, the effect on the multi-million
dollar sport fishing industry could be staggering. The Great Lakes Radio Consortium’s Bob Reha reports.
(sound of gulls over head)
Doctor Brian Whizenden and his students sit in front of the Detroit
Lakes Fish Hatchery waiting for a DNR tank truck loaded with walleye
fingerlings to show up.
(Sound of truck backing into fishers)
As DNR workers back the vehicke into a stall Doctor Whizenden and his
crew spring into action. Rubber containers are filled with water.
(Sound of cross fade up water sound into containers)
Oxygen is then pumped into the containers to make sure the fish will
survive the 45 minute drive back to the MSU campus.
(Sound of oxgen bubbling into the water spiked and then faded cross
fade of walleyes being dumped in containers, Dr. Whizenden counting fish)
Finally fifty walleyes, ranging from 6 to 8 inches in length
are transported by hand held nets into the containers, loaded and driven
back to the Moorhead campus and they’re new home in Doctor Whizenden’s lab…
(Sound from lab)
All of this effort is part of an experiment to determine if young
walleye can be taught to use their sense of smell to avoid predators in the
wild. If successful, Doctor Whizenden believes the survival rate of
fingerlings, fish that are stocked in lakes will rise. This could mean lowering the costs of keeping catchable populations of fish in lakes. Better
populations of catchable fish mean more anglers and tourism dollars
pouring into walleye country. Doctor Whizenden has done research that shows
some fish, like minnows have an alarm cell in their skin, when attacked the
cell releases a signal or scent, this acts like an alarm bell to other
minnows that a predator is in the area.
“For example minnows can smell not only their predator but the diet of the predator when they smell a predator when they smell the predator they know not only that its a pike or something but they can tell what that pike has been eating lately.”
Whizenden says not only do minnows have a great sense of smell, they’re quick learners.
“But at the same time they learn to associate fear or an anti-predator response with anything else they encounter at the same time so if they encounter both the skin extract and the predator odor at the same time they learn to associate fear with the predator odor and this association, this pairing takes only one exposure for them to learn that just one time.”
Whizenden says research indicates that while walleye don’t share the
same genetic makeup as minnows, they do react to the chemical or scent
release of other walleyes when attacked by a predator.
“So what we’re trying to do is see if we can use this research
that has been quietly being done on minnows now for a number of years to
see if we can apply it to this walleye situation where we take naive walleye,
train them to be afraid of pike odor which is a dominate predator and
see if that training translates into increased survival once they’re
stocked into the big lakes.”
Whizenden concedes there are a lot of ifs remaining to be answered and
that tracking the success of the theory in the wild will be difficult. But
the potential rewards has gotten the attention of DNR officials. Dave Friedal
is the area fisheries manager for the Detroit Lakes district.
“It could be a means of getting better survival on the fish we’re
stocking in lakes and it could mean a fairly easy treatment if all
it takes is some very dilute smells in the water in order to educate or
train or if their behavior is changeable by a simple exposure to a smell
that might be pretty easy to do it might be something we could put in our
fish tanks on the way out to the lakes.”
If the project shows that Walleyes can be trained to avoid predators
before being stocked in lakes, it could reduce the cost
of the stocking program. Wildlife managers say higher survival rates of
fingerlings in the wild mean more fish for the same amount of money. It
could also mean more fish for anglers, which in turn could mean more
business for resort owners and other tourist related businesses across
the Great Lakes. Doctor Whizenden says if preliminary experiments in the lab
are successful the next step will be to do a field test some time next
year. For the GLRC I’m Bob Reha in Moorhead Minnesota.