 Bull
Trout Tag
Objectives: Students will compare
adfluvial bull trout return rates* as influenced by various natural
and human-caused challenges.
Related Web-Activity: River
Caretakers
Subjects: Ecology, Biology
ELRS: Science 1.2, 1.3
Size: Entire classroom
Setting: Outside grassy field
Duration: Thirty minutes
Materials: 20 feet of rope, clipboard,
paper, pencil, and 5 cones or other markers
Procedure
Teachers, discuss the life cycle of an adfluvial bull trout with
your students. Compare this with the anadromous salmon lifecycle
if you wish. This game of tag should illustrate two concepts: 1)
only a fraction of original juvenile trout return to spawn, 2) natural
challenges make life difficult for bull trout, and human-created
challenges put an extra strain on these fish.
Begin the challenge by laying out a rope for the start/finish line.
Next, design a course of three cones to represent a stream ending
with two cones to represent the lake area. Begin by installing only
natural challenges in the course and one or two adult bull trout
(represented by students or teachers). These people can cover the
entire course and gently tag anyone they can catch.
Each participant represents a bull trout. They must circle the
lake four times before returning, which represents the four to seven
years that it takes for juveniles to reach adulthood. Each session
begins with all the students racing the course and attempting to
make it back to the finish line without being tagged. Chart the
outcome for each session: initial count, final count, return rate
percentage (final count ÷ initial count x 100).
During subsequent sessions add human-created challenges to the
equation:
- One or two students can represent human-introduced brook trout.
Brook trout must stay in the river area.
- One student can represent a landslide zone caused by a nearby
clear-cut forest and gravel road. This student must stay in a
general area delineated by two of the cones.
- One or two students can represent climatic heaters. These students
may roam all the waters.
After all sessions have been completed, review the return rate
chart. How was return rate affected by adding challenges to the
ecology of the river system?
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