*Activity adapted from Nooksack Salmon Enhancement Association. For more of their salmon related curriculum visit http://www.n-sea.org/sfs-curriculum/

Subject

Life Science

Objectives

Learn the stages of the salmon life cycle

Be able to fill in the cycle diagram correctly

Understand how the life cycle of a steelhead is different from salmon but they are both salmonids.

Materials

Art supplies: crayons, colored pencils, etc.

Pages 7-12 of this document – can be displayed for students (optional)

Size/setting/duration

Entire class/classroom/~45 minutes

Background

In the Pacific Northwest, there are five Pacific salmon. They are part of a larger Salmonidae family (generally referred to as salmonids) that include other salmon and trout species. One of these salmonids is steelhead, which can spawn multiple times, rather than dying after spawning like salmon. For this lesson, we will focus on the five Pacific salmon species (Chinook, chum, coho, pink, and sockeye), but highlight how steelhead differ in their lifecycle. The salmonid life cycle is similar for all salmonids. However, the length of time spent in freshwater and saltwater varies to some extent for each species.

Salmonids are anadromous; this means that salmon are born in freshwater, spend most of their life in the ocean, and return to freshwater to spawn. Salmonids return from the ocean and enter the stream in the summer or fall to spawn.

When spawning, the female lays her eggs in the streambed and the male fertilizes her eggs with milt (sperm). The eggs are laid in the gravel nest, called a redd, and hidden from predators and direct sunlight. Each female deposits approximately 3,000 eggs in the gravel. The eggs remain hidden in the streambed for two to four months before they “hatch” into alevins. The alevins acquire nutrients from the yolk sacs that are attached to their bodies, growing rapidly in the gravel for one to three months. It is very important during the egg and alevin stages of the salmonids’ life cycle to have clean, clear, cold, flowing water and a clean gravel substrate.

Clean gravel is imperative; the eggs and alevins will suffocate if there is too much suspended sediment in the stream. Once the alevins have absorbed their yolk sacs, they surface from the

The Salmon Lifecycle

gravel in spring and early summer as fry. Fry nourish themselves by feeding on plankton and small insects (macroinvertebrates) in the stream. At this stage of life it is important for the fry to have good streamside cover for protection from predators and to keep water temperatures cool.

Different species spend differing time in the freshwater streams. Chum and pink salmon migrate to the ocean very soon after emerging from the gravel. Coho and sockeye remain in the stream for at least one year. Chinook are in the stream for three to eighteen months before migrating towards the ocean. Steelhead generally spend 2 years in their natal stream, which gives them time to grow large enough to carry the special tracking devices that are used to collect data for Survive the Sound. After spending time in fresh water, the juvenile salmonids head downstream and undergo changes that allow them to live in saltwater. This process is called smoltification. The young salmonids, called smolts at this stage, acclimate to the saltwater by staying in the estuary for one to three months. Here, the smolts feed on zooplankton, insects, shrimp, and small fish in the estuary. Once the adjustment from fresh water to saltwater is complete the smolts move into the ocean.

Ocean life for salmonids lasts one to seven years, depending on the species. During this stage of life, the sea-run adults grow large and feed on zooplankton (tiny animals), insects, and small fish such as herring. When they’re fully mature and strong (2-5 years depending on species), the Pacific salmon migrate from the ocean back to their natal stream (the stream where they were born) using their sense of smell and other senses. Once they’ve returned to the freshwater streams, we call them spawning adults, they swim upstream to reproduce, and the cycle begins again. Salmon usually spawn within 100 yards of the redd that they hatched from. After the salmon have spawned, they die, with the exception of steelhead which can return to the ocean and spawn up to 5 times. Their bodies decompose and give nutrients to the animals and plants along the stream. These nutrients are very important to the health of the riparian zone, as well as the animals that eat dead salmon (macroinvertebrates, bears, eagles, bacteria, etc.).

Procedure

1. Give a presentation/lecture to your students that demonstrates the salmon lifecycle, use the information in the ‘background’ section as your material. Include the above graphic on the board or on a slide so that students have a visual. Explain the cycle and what comes next and make sure they know it is a cycle, (that a sea run adult salmon will swim back to river to become a spawning adult). Instruct your students to take notes and be sure to clarify any unknown vocabulary words.

2. Once you explain the salmon life cycle, and the students have completed their notes on the salmon life cycle, have the students fill out the Salmon Life Cycle Chart (see last two pages). Instruct them to include the correct vocabulary word when labeling the lifestyle stage, encourage them to include a sketch or drawing of the lifestyle stage (including some of the habitat requirements related to that stage, i.e. gravel, hiding places, shade, etc.), and, have them specify where the stage takes place (ocean, river, estuary). If preferred, pick one stage to complete as a class on the board to be used as a reference.

Discussion Questions

1. At one stage of the life cycle do you think salmon are most vulnerable? Why? (after listening to some response, emphasis that every stage is critical and dangerous).

2. What lifecycle stage are the steelhead in Survive the Sound? (Answer: smolt)

3. What human activities do you think is impacts the salmon’s life cycle?

4. Why do you think salmon in the Puget Sound are having a hard time surviving? What stage do you feel they need the most assistance with?

5. Where in Puget Sound do you think salmon live? (emphasis being on all parts).

NGSS

https://www.nextgenscience.org/dci-arrangement/3-ls1-molecules-organisms-structures-and-processes

Salmon Life Cycle Chart (student copy):

Salmon Life Cycle Chart (teacher copy with answers):

Coho Eggs:

“Coho Salmon Eggs at Fish Hatchery,” Photo Courtesy of Bing Gallery: https://www.flickr.com/photos/138488921@N07/23400658570/in/photolist-BDQuww-9EBETT-9EFU6j-8rs9vr-

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Coho Alevin:

Photo courtesy of Jeffrey Rich, https://www.critfc.org/fish-and-watersheds/columbia-river-fish-species/columbia-river-salmon/#gallery

Coho Fry:

Photo Courtesy of Paul Kaiser and USFWS, https://www.flickr.com/photos/usfwspacific/5662309161

Coho Smolt:

Photo courtesy of Julianne Lorenzen, https://www.flickr.com/photos/99626801@N04/9475073472/in/photolist-WxrN8g-9dngqZ-fPtqjd-c9BreE-63ihrW-frheeJ-nubWad-9QpPSJ-yPsEHQ-5xmcsc-nvWHPT-dYF5sW-

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Coho Sea-Run Adult:

Photo courtesy of Washington Department of Fish and Wildlife, https://wdfw.wa.gov/fishing/salmon/coho.html\

Coho Spawning Adult

Courtesy of Washington Department of Fish and Wildlife, https://wdfw.wa.gov/fishing/salmon/coho.html