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Life of a Salmon

In this unit, students will identify each stage of the salmon lifecycle as well as factors that affect salmon survival.

A watershed is a section of land where all of the area’s water is collected and funnelled into the same waterway. A watershed is made up of a unique mixture of habitats that influence each other. These habitats include forests, wildlife, creeks, rivers, lakes, farms and cities or towns. Watersheds come in all shapes and sizes.

Many human activities can negatively affect animals, particularly wild salmon, in their natural watershed habitat. Urban development can cause unhealthy runoff. Runoff is water that runs off land surfaces, quickly, into storm drains, ditches and sewer systems. This water eventually ends up in rivers and lakes, and polluted water can kill fish and their food sources. The more flash runoff, the higher the risk of flooding, which can erode stream banks and destroy spawning beds. The health of the watershed animal populations, including that of salmon, depends on the health of their natural habitat.

LIST OF ACTIVITIES

Salmon Life Cycle Mix & Match
Salmon Egg Protection
Salmon Life Lottery (group activity)
Salmon in the Food Web
Salmonopoly: Design Your Own Board Game
Impossible Salmon Tag (group activity)
Salmon Migration Obstacle Course (group activity)
The Adventures of Salmon: A Colouring Book
Salmon Connections: Estuary
Salmon Hexaflexagon

Objectives

  • Identify each stage of the salmon life cycle.

  • Identify factors (natural and man-made) that affect salmon survival.

Materials

  • See individual activities for materials

Background

Salmon Overview

Wild salmon have lived in the cold, pristine Pacific waters for thousands of years and have been an integral part of the Pacific Northwest’s history, culture and economy for as long as humans have lived here. Historically, B.C.’s First Nations have relied on salmon as a major food source.

Five species of salmon, and two closely related trout, are native to the North Pacific and each species has a life cycle ranging from two to seven years. These fish, collectively known as salmonids, are anadromous, meaning they are born in fresh water and migrate downriver to the cold open waters of the Pacific Ocean. They often travel for thousands of kilometres then miraculously return to the river of their birth. Exactly how salmon find their way home is under investigation, but they seem to rely on a combination of genetic coding, celestial navigation, electromagnetic currents and a strong sense of smell.

All salmonids start out as fertilized eggs, found in gravel regions of streams and lakes. They remain there while they are alevin, absorbing their egg sac. While they are fry they eat aquatic invertebrates. They undergo large physiological changes when swimming to the ocean as smolts, and live in the ocean for many years, growing into a large oceangoing adult. Once fully developed, the adults physiologically change again allowing them to move from salt water to freshwater as spawners to reach their home stream or lake. There they will spawn and lay eggs for the next generation.

Salmon must protect themselves from predators. They are particularly susceptible to predators when migrating so they seek deep pools for protection. In the ocean, some salmon stay together in a school, confusing predators with their flashy sides and causing them to be mistaken for a single large predator. A salmon’s predators change at different stages of its lifecycle, because of the salmon’s change in size and environment. Salmon fry are eaten by other fishes, members of their own species, snakes and birds. Once in the ocean, salmon are prey to killer whales, dolphins, seals, sea lions, other fish and, of course, humans. On return to their stream of birth, spawning salmon are at risk of being scooped up by bears and birds.

A salmon’s diet depends on its species and region. Typically, juvenile salmon eat zooplankton and aquatic invertebrates, mayflies, caddisflies, stoneflies and worms. In the ocean, salmon eat smaller fish such as herring, and crustaceans like krill.

Humans have strong and often negative impacts on salmon. Overfishing has led to a decline in some salmon stocks. Land development and dam building have damaged habitats and impacted salmon runs. This development has led to a decline in salmon populations in some areas.

In 1985, the Canadian and U.S. governments established the Pacific Salmon Treaty. The treaty outlines the conduct of fisheries, salmon management and research and enhancement programs.

Salmon Habitats

Streams and lakes provide living, feeding and spawning areas for salmon and related trout. A good water body for salmon has many different characteristics. Although young fish may not have the same needs as spawning fish, all salmon require an adequate flow of clean, cool water.

Both young and older salmon rely on streams and river features: pools and riffles.

Pools are areas of a stream or river where the water is deep, slow moving, and silt or clay lay on the bottom. These are important for salmon to hide from predators or relax in cooler water. Riffles are areas of a stream or river where the water is shallow, fast moving, and gravel or rocks lay on the bottom. Salmon rely on these for laying their eggs, and for adding oxygen to the water.

Unfortunately, waterways can be easily and seriously damaged. Damage can be caused by carelessness in logging and mining practices, or by poorly-planned city and community growth and the pollution that accompanies it. Healthy streams and rivers are important to fish and other aquatic animals and plants and should be treated with care and respect.

Salmon Struggles and How We Can Help

Salmon have struggles throughout their entire life. Most will die before they come back to spawn. Many of these factors that make their lives challenging are beyond our control, but there are also some ways in which we can help.

For instance, while many factors that damage watershed ecology and water quality are beyond our control, there are ways we can help save and preserve our streams:

  • Plant vegetation on the sides of lakes and streams to stabilize the banks.
  • Leave natural plants and debris such as stumps, fallen trees or boulders where they are.
  • Leave all animal life where it is.
  • Keep pets and livestock away from the water.
  • Use garden and lawn chemicals sparingly and with care.
  • Remove garbage from the stream area.
  • Direct soap suds, detergents, and waste water onto absorbent ground away from streams, not down storm drains or into roadside ditches.
  • Dispose of waste oil, gasoline or other household chemicals properly, and not down storm drains or domestic sinks.

Vocabulary

Anadromous: Fish that live mostly in the ocean but return to freshwater to breed.

Eggs, alevins, fry, smolts, ocean phase, spawners: Stages of the Pacific salmon life cycle.

Keystone Species: A species within an ecosystem that many others rely on. Without them, many other species would be negatively affected.

Milt: Milky substance produced by the male spawner. It contains the sperm and seminal fluid.

Parr marks: Vertical stripes along the side of salmon in the fry life stage. Found on all except Pink salmon.

Pool: An area of a stream or river where the water is deep, slow moving, and silt or clay lay on the bottom.

Redd: A shallow nest in gravel for depositing eggs created by a female salmon.

Riffle: An area of a stream or river where the water is shallow, fast moving, and gravel or rocks lay on the bottom.

Sediment: Particles of sand and soil that can clog a stream.

Sedimentation: The process by which sediments are deposited in a variety of environments. Sedimentation can cause water to be blocked and shifted to other areas. Sedimentation can choke reservoirs and raise the riverbed by depositing silt.

Silt: Very fine particles floating in the water.

Sockeye, Chinook, Chum, Pink, Coho: The five species of Pacific salmon.

Steelhead, Cutthroat: The two trout species grouped with salmon in the grouping salmonids. They also are anadromous.

Other Resources

First Nations Education Steering Committee | Science First Peoples Secondary |  Salmon and Interconnectedness PDF

Great Bear Sea | Elementary Resources | Secondary Resources

Native Languages of the Americas | Haida Legends

Fisheries and Oceans Canada | Stream to Sea K-12 Education

Pacific Salmon Foundation | Salish Sea Salmon Education Booklet

Government of Canada | Fisheries and Oceans | Salmon

Raincoast Conservation Foundation| Wild Salmon Program

Gulf of Georgia Cannery | Resources

Hatchery | Seymour Salmonid Society | Weaver Creek Spawning Channel

Metro Vancouver | K-12 Field Trips

North Shore Tourism | Capilano Salmon Hatchery

Phylo Card Game | Education

Salmonids in the Classroom

Seymour Salmonid Society | Education

Steveston Community Society | Steveston Salmon Festival

Stream of Dreams | Programs

The Coho Society of the North Shore | Education | Coho Festival

NOAA’s National Ocean Service Education |  Estuaries

U.S. Fish and Wildlife Service | Salmon Webcam

Vancouver Aquarium | Ocean Wise

Vancouver Aquarium | Salmon

Watershed Watch Salmon Society | Issues