The School House

Choosing salmon streams

Objective
To investigate elements of habitat quality in salmon streams.

Activity
Survey two stream sites to determine which offers better habitat for salmon. With your hand wrapped in a plastic six-pack ring, try to free it without using your other hand.

Background
If you were a salmon what sort of stream would you like to live in? Salmon generally like streams that:

• have clean gravel
  • they will not lay eggs on a muddy bottom
• have clean water
  • they do not like polluted sites
• have clear water
  • sediment would cover and damage eggs
• have flowing water
  • flowing water provides lots of oxygen
• have vegetation on the banks
  • vegetation stabilizes the banks and shades the water
• are not blocked by waterfalls
  • they are too difficult to get past
• are not altered or damaged by humans
  • channelized streams offer no places to rest

Streams that have these characteristics are more likely to offer good habitat for salmon.

Procedures

1. Select two local streams that may offer possible spawning sites for salmon.
   Teacher tip: select sites that are reasonably different with respect to habitat characteristics. Be sure to be very familiar with both sites.
2. Visit each site and characterize a 30 m representative stretch of the streams. Site characterization will likely take about 2 hours depending on the level of the students and the nature of the sites. To characterize the site, do the following:
   • Sketch a map of the site. Indicate point sources of pollution, vegetation, altered banks, riffles or rapids, large rocks, and any logs or branches in the water. Are there any waterfalls nearby?
   • Write a brief description of the stream bottom. Is it made of clay, sand, gravel, or bedrock? Is there a lot of detritus or mud?
   • Check the stream flow rate. Choose a straight stretch of them stream and stake out a 10 m stretch. Drop a float in the water and time how long it takes to flow down the 10 m stretch with a stopwatch. Repeat this 3 times and record the average speed in m/s.
   • Measure the turbidity of the stream. Place a white paper disk in the bottom of each jar. Collect water samples in clear jars, being careful not to collect water from where you just stirred up the bottom. Let the jars sit untouched for several hours. Describe how much sediment settles on the paper.
   • Count how many trees are along each bank.
3. Back in the classroom, discuss what each habitat characteristic means for salmon. Have the students conclude which stream would provide better

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