Study: Is development harming our fisheries?
Deerwood, Minn. Participants at the 2004 Lakes and Rivers
Conference held at Ruttger’s Bay Resort in Deerwood last week were
one of the first public audiences to hear DNR Fisheries biologist
Paul Radomski’s presentation on how cumulative affects of shoreline
development have damaged fish habitat.
The presentation was based a on 3-year-old study by Radomski and
fellow biologist Tim Goeman called Consequences of Human Lakeshore
Development on Emergent and Floating-Leaf Vegetation Abundance.
Native aquatic plants such as hard stem bulrush, yellow water
lily, white water lily, and cattail are commonly found on Minnesota
lakes and provide habitat for a variety of fish species. However,
these plants often are removed by shoreline property owners seeking
to improve their beach area. For each developed lake lot, the study
found an average reduction of 66 percent of the adjacent near-shore
floating leaf vegetation. On 531 walleye/sunfish lakes in
north-central Minnesota, the biologists calculated that 20 to 28
percent of emergent vegetation has been lost to development.
How important is this habitat loss to fish?
“With this research we saw correlations between plant occurrence
and total biomass of fish,” Radomski says. “The link isn’t strong,
but it is significant.”
Other research suggests the vegetation is very important to some
fish species. One Minnesota study found most crappie spawning
occurred in the vicinity of hardstem bulrush. Other members of the
sunfish clan also rely on bulrush habitat. Studies elsewhere have
documented how the loss of vegetation affects northern pike
reproduction and survival.
Although Radomski and Goeman’s study was the first in Minnesota
to quantify the effects of shoreline development on fish habitat,
the DNR never issued a press release about the findings.
“It was bad news,” explains Radomski. “There was internal debate
about how to handle it. I think a lot of people in the agency would
rather cite the positive aspects of habitat restoration than cite
the amount of habitat we’ve lost.”
The DNR has a program to restore aquatic habitat and publishes a
habitat-friendly landscaping book for shoreline property owners. To
get the word out about the consequences of fish habitat loss,
Radomski has made his presentation to state and regional fisheries
biologists. He has also shared the information with the media and
with local lake associations, to whom he points out that aquatic
plants help stabilize shorelines and absorb nutrients. Radomski
says there is a growing audience for fish habitat restoration,
which gives him some hope for improving conditions on Minnesota’s
many developed lakes.
“Cumulative impacts go both ways,” he says. “We can have a bunch
of people doing bad things or turn it around so people are doing
good things for habitat.”
Identifying high-priority areas for restoration, finding a
source of plants, and learning the best transplanting methods
challenge habitat improvement efforts. Minnesota DNR researchers
intend to further study shoreline development and fish habitat
loss. In this regard, the state lags behind neighboring Wisconsin
and Ontario. In Wisconsin, research into the ecological changes
associated with development is guiding policy decisions regard
shoreland regulations. Ontario has a “no net loss of fish habitat”
policy in place.
In Minnesota, as Lakes and Rivers conference participants
pointed out, those habitat losses continue to occur.