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Researchers breaking new
ground in knowledge of Black River sturgeon
by L. Scott Swanson
Historic research is taking place on a prehistoric species
of fish in the Black River. Fisheries researchers are not only
tagging sturgeon, they're also taking fin samples for DNA research
and checking larvae during the sturgeon's annual spawning run.
While there's been some research done on sturgeon in Wisconsin,
past research on Lake Sturgeon in Michigan, particularly in the
Black River system has been minimal. Back in the '70s some research
was done on sturgeon growth and size, but that's been about it.
Research currently taking place is much more extensive and will
provide a foundation for future research.
Kraig Smith, a graduate student from Central Michigan University,
is leading the research, which is funded by a grant through the
Department of Natural Resources. Pat DeHaan, a graduate student
from Michigan State University, is handling the genetic research
portion of the project.
Smith said that since the Black River sturgeon population hasn't
been studied much in the past there really isn't any literature
to refer to from past studies. Research currently taking place
will provide not only answers, but also questions and lay the
groundwork for future research.
In the first phase of the project, Smith and a partner, either
DeHaan or Tom Trayban of the DNR Fisheries Division, wade into
the river and capture and tag the fish.
Researchers use long-handled landing nets to capture the fish.
They usually net the fish in deeper holes and then bring them
into shallow water to work with them. Although some of the fish
weigh more than 100 pounds, they normally don't thrash and fight
the process too strenuously. Smith says the smaller fish tend
to fight more than the larger fish.
Once in the shallows, researchers place two tags in the fish.
One is a brightly colored external tag. That lets fishermen and
other researchers know that the fish is one on which data is
being gathered. There's also an internal pit tag inserted beneath
the fish's skin. That tag is numbered and researchers read the
number by waving an electronic wand.
Researchers also clip a piece, about the size of a thumbnail,
from one of the fish's fins. DeHaan uses that for DNA research.
By checking the DNA of adult fish against DNA from larvae fish,
researchers can determine what percentage of adult fish are successfully
reproducing.
While they have the fish, researchers also measure the fish's
length and girth and weigh it.
As of Tuesday, researchers had tagged approximately 70 fish.
It's difficult to say what percentage of the overall Black River
system that number constitutes. Female sturgeon spawn only every
four to seven years. Male sturgeon spawn every other year. Unlike
some other species of fish, sturgeon don't die after spawning.
Sturgeon can live to be up to 100 years old.
After tagging is completed, Smith will also be doing larvae studies.
He will be looking at both eggs and the larvae sturgeon. Among
the things researchers would like to get a handle on are egg
mortality rate and if there are places in the Black River system
that serve as nursery areas for small sturgeon.
Fishermen and fisheries researchers have a pretty good idea of
how adult sturgeon function and there's information available
about spawning. When it comes to how and where sturgeon grow
between the time they're eggs and the time they're adults, there
are more questions than answers.
At the same time research is taking place, the Sturgeon For Tomorrow
group is working on the annual Sturgeon Patrol with the DNR and
volunteer individuals and organizations. This is the third year
for an organized Sturgeon Patrol effort and it has grown to include
nearly 300 people. That effort and changes in fishing seasons
and limits are designed to keep adult sturgeon populations from
declining.
The research may provide ideas as to how to reverse the decline
and increase sturgeon populations. The research may indicate
that improving the riverbed to allow for better egg attachment
and hatch is needed. It could indicate that perhaps there's a
need to create some type of nursery area. It also could indicate
any number of other things.
At this stage of the game questions are easy to come by. Answers
are more difficult. This year's research is like opening the
first page of a book. The twists and turns the plot takes from
here remain to be seen.
TOP PHOTO:
Fisheries researcher Kraig Smith holds onto one of more than
70 sturgeon that have been tagged this spring in the Black River.
This large female could be as much as 60 to 70 years old. Research
being done this spring on sturgeon size, reproduction, genetics
and survival rates will provide a data base for future research
and sturgeon population management.
BOTTOM PHOTO:
Kraig Smith and Tom Trayban tag a large female sturgeon Tuesday
on the Black River. The fish received both a brightly colored
external tag and a small internal tag that is inserted under
the sturgeon's skin. The internal tag has a number researchers
can read later with an electronic wand.
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