Science Notes 2019, Volume 14, Number 3

2019·1.4 MB·English

by  Missouri Department of Conservation, Resource Science Division

MDC Resource Science

Surveying Fish and Amphibians in Missouri
Wetlands: Active vs Passive Methods
What season are you considering sampling for amphibians?
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at net at Single sweeps at at net at Single
6-7 sites trap at 9-10 sites 10 sites 6-7 sites trap at
10 sites 10 sites

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What season are you considering sampling for fish?
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sweeps at at net at Single sweeps at at Single Single
9-10 sites 10 sites 6-7 sites trap at 9-10 sites 10 sites trap at
10 sites 10 sites
30-35%
Estimated fish species detected based upon season, available sampling time, and method
Missouri Department of Conservation (MDC) 2019 VOLUME 14 NO. 3
Surveying Fish and Amphibians in Missouri Wetlands: Active vs Passive Methods
By: Julia G. Kamps, University of Missouri; Craig. P. Paukert, USGS Missouri Cooperative Research Unit; Elisabeth B. Webb,
USGS Missouri Cooperative Research Unit; Frank Nelson, Missouri Department of Conservation
Background Information: • Affordability: Method costs vary.
Monitoring cryptic species, like fish and amphibians, helps Dipnet cost ~$45
reduce uncertainty and informs management decisions of a Seine cost ~$80
broader range of wetland dependent taxa. However, the time Minnow trap ~$30
and effort required for monitoring are limited, so knowing the Mini-fyke net ~$350
trade-offs of different survey methods, site selection, and
timing can help managers determine best surveying practices Survey Site Selection:
based on monitoring objectives. The following guidelines are • Distance from Shore: Fish were more frequently detected
based on extensive sampling of 29 wetlands across three closer to shore.
ecoregions in Missouri during 2015-2016. Sampling compared
• Water Depth: Amphibians were detected in greater
two active methods (dipnets and seines) and two passive
numbers in shallower depths with most methods.
methods (minnow traps and mini-fyke nets). See Kamps
• Vegetation: Mesh components of active methods can
(2017) for detailed methods, results, and discussion.
snag on suspended plant debris and erect vegetation or

clog with algae, enabling individuals to escape.

Sampling Timing: Timing of sample collection depends on

monitoring objectives. Amphibians that use wetlands for

reproduction or during specific life history stages may be more

detectable at specific times of the year. Likewise, fish species

may have a greater likelihood of being detected during or after

a flood due to connection with adjacent rivers or streams.

Sampling Method Strengths:

• Minnow Traps: Are affordable and catch unique

amphibians, even in vegetation.

• Dip nets: Are cheap, quick, and easy to use by one
person in shallow water without thick vegetation. They may
A seine is an active gear suited for deeper locations. also detect unique amphibians.
• Seines: Can quickly catch fish in deeper water habitats
Comparison of Active and Passive Methods that is still wadeable.
• Skill and repeatability: Active methods rely on the • Mini-fykes: Can catch a wide range of fish and amphibian
equipment and the skill of the observer. Passive methods species in high numbers, including unique fish species.
rely more on the design and efficacy of the net/trap.
• Effort: Active methods require constant operation over Species Identification: Using field guides and documenting
time. Passive methods are set and left overnight. species with photographs is a good first step. Monitoring
provides an opportunity for biologists to collaborate outside
• Man-power: Active and passive methods may require 1 or
their expertise.
2 people. It’s often easier to sample both methods with 2,
with active sampling requiring 2.
• Time: Active methods can be done in a single day.
Passive methods require setting nets on one day and
checking them the next.
• Species Selectivity (size and behavior): Active methods
tend to capture smaller, less mobile individuals. Passive
methods will capture a larger range of individual sizes and
may target nocturnal species and individuals that are in a
mobile life history stage.
• Habitat Constraints: Overall, active methods may be
limited to shallow open water settings as vegetation and
deeper water restrict observer mobility and reduce method
A mini-fyke net is a passive gear checked after leaving it overnight.
efficiency. Passive methods can be set in or along the
edge of vegetation. Adjustments can be made to passive
Implications: Identifying a project's objectives are first and fore-
methods to account for deeper water but require a
most. Once this has been decided, there are a series of trade-offs
minimum water depth to submerge trap openings.
to consider when selecting appropriate and efficient methodolo-

gies for sampling fish and amphibians. The findings of this study

should help inform this process.

For more information, contact: Keywords: wetland sampling, monitoring, fish,
Missouri Department of Conservation amphibians
Resource Science Division
2901 West Truman Blvd.
Jefferson City, MO 65109
573-751-4115 2019 VOLUME 14 NO. 3
[email protected]