Kamchatka: Land of Abundant Salmon ... Filets
Grade Level: 7-11
Estimated Time: Two class periods. One period to view selected Kamchatka video clips, introduce salmon and talk about fish in general. One class period to dissect and identify external and internal fish anatomy.
- Students will learn about the Kamchatka ecosystem.
- Students will learn about how salmon are vital to the food web.
- Students will learn how other animals are dependent upon salmon.
- Students will learn about the natural and manmade obstacles that salmon encounter while returning to spawn.
- Students will learn the definition of anadromous.
- Students will learn about the salmon spawning cycle.
- Students will learn what a fish is.
- Students will learn about the three main groups of fishes.
- Students will learn to identify external and internal bony fish anatomy and physiology.
- Students will work in pairs to dissect and identify external and internal bony fish parts.
- Students will write in their journals about their dissection experience as well as sketch and identify external and internal bony fish parts.
- Students will have fun!
With the return of the sockeye salmon in the early summer to the Kamchatka peninsula, a vital component in the region's life-sustaining food web is restored. The annual salmon spawning cycle ensures the continued survival of grizzly bears, sea eagles, arctic foxes, and other species (Bountiful Breed link could go here). For the salmon--an anadromous species of fish that migrates from salt water to fresh water--it has indeed been a long and perilous journey from the open ocean to the fresh water lakes, rivers, and streams in which they were originally hatched.
While on their journey, often encompassing thousands of miles, salmon have had to contend with sharks, killer whales, fur seals and other ocean predators intent on making a meal out of the salmon. Then, as the salmon leave the saline waters of the ocean for the fresh waterways of Kamchatka, a gauntlet of voraciously hungry bears awaits their arrival to begin an annual gorging cycle that will allow the bears to grow fat enough to sustain themselves during the long winter hibernation (Kamchatka Creatures link could go here). Even after reaching their home spawning grounds, the salmon face one more challenge--
tired and battered males often fight one another to the death in order to obtain the "honor" of spawning with a female salmon.
In addition to the natural predators that salmon must contend with, human activities impact the salmon's environment. The construction of dams and fish ladders can impede migration and often destroy immature salmon. Silt build up caused by logging and road building, and the discharge of nutrient wastes from agricultural operations and domestic sewage from urban centers also pose a real threat to the continued survival of the sockeye and other species of salmon through out the world.
Yet enough of the sockeye salmon survive both natural and manmade obstacles to make their perilous journey and return to the stream in which they were hatched. And all without having to ask for directions! An extraordinary memory and a keen sense of smell enable salmon to return to their birth stream after a nearly five year absence.
The males usually arrive back first, but the females normally select the spawning site, where they are aggressively courted by the males. Prior to this period the male salmon's colors take on a bolder shade and the lower jaw bends upwards to form a hook called the kype. The spawning site, or redd, is dug in the stream's gravel by energetic movements of the female's tail until it is approximately 10 ft. long and 12 in. deep. The salmon lay pair lay along side each other for about five minutes for each act of spawning. After each spawning session the redd is filled in and another is dug. In between, the adults rest in deep holes in the riverbed in order to maintain the necessary stamina for what may be a two-week marathon of spawning. Once the female has shed all of her eggs, 5,000 in some cases, both she and her male companion drift exhausted and with a loss of up to 40% of body weight back to sea where the vast majority of them die. However, the multitude of fertilized eggs ensures that this species of fish will survive for another generation.
So, what exactly is a fish? A fish is a vertebrate, an animal with a backbone, which has adapted to life in the water. Most fish have lateral lines which are small holes along each side of the fish used to detect low frequencies; breathe at least part time through gills; are protected by scales; and have a simplistic heart that operates one-way, allowing blood to flow through the heart to the gills and then to the entire body. There are three main groups of fishes: jawless fishes like lampreys and hagfishes; cartilaginous fishes, like sharks, skates and rays; and bony fishes, like rockfishes, tunas, and eels.
Salmon belong to the bony fishes group. The bony fishes group is the largest of the three main fish groups and contains slightly over 95 percent of all known species of fish. Bony fishes like salmon share similar external and internal anatomy traits (For anatomy illustrations see The Encyclopedia of Aquatic Life, p. 5, or go online to http://www.getaway.net/j3tropical/anatomy.htm).
Externally salmon have a mouth, eyes, dorsal and anal fins, tail or caudal fin, vent or anus, pectoral and pelvic fins, gill covers, and lateral lines. The mouth is used to catch and hold food as well as continually take in water to breathe. Eyes are used for a variety of sight-related activities, like hunting, avoiding predators and other dangers. Dorsal and anal fins work together much like a boat's keel to keep a fish from rolling over. The caudal fin works like a boat's rudder and propels the fish. The vent or anus allows urine, feces, eggs, and milt, male fish secretions, to exit a fish's body. Pectoral fins on some bony fishes are used to stabilize and steer, while on other species these fins are used for locomotion. Pelvic fins are used for balance and locomotion. Gill covers protect delicate filaments and work together with the mouth to force water containing oxygen over the gills. Lateral lines possibly function as sense cells to detect low to medium frequency sounds.
Internally salmon, like other fishes, have a swim bladder, gall bladder, heart, intestine, kidneys, liver, stomach, and gonads. The swim or air bladder is a membranous sac filled with gas that helps a fish control its buoyancy. The gall bladder is a sac that stores bile. The heart is a hollow muscular organ that circulates blood throughout the body. The intestine carries digested food from the stomach to the anus. The kidneys remove waste from the blood and produce urine. The stomach is a sac-like organ that digests food. Gonads, ovaries in the female and testis in the male, are reproductive organs.
- Overheads of fish external/internal anatomy or handouts
- Preserved fish (Salmon are too expensive; purchase perch, trout, etc. at a biological supply house)
- Dissecting pans
- Exacto knives or single-edge razorblades
- Surgical gloves (Students will be operating, after all.)
- Protective eyewear (optional)
- Smocks (optional; however, it could get messy.)
- Small post-its
- Fine point markers
- Old newspapers
- Trash bags (for fish waste)
- Composition journals
- Goldfish crackers, fish shaped cookies, and drinks (optional)
Procedure (Day One):
Procedure (Day Two):
- Group your students into teams of 4 to 6 people.
- Tell all teams to brainstorm what they know about salmon and fish in general, and to record their responses.
- Have a spokesperson from each team tell the class the results of their team's salmon/fish brainstorming session.
- Write their responses on the chalkboard. You may want to organize their responses into categories depending upon the variety and number of responses you receive.
- Show Kamchatka video clips on salmon (00:00-12:00). This segment highlights the salmon spawning cycle, the perils salmon face in returning to where they were hatched, external anatomy changes that occur in male salmon prior to spawning, and how other wildlife in Kamchatka are dependent upon the annual salmon cycle.
- Using their brainstorming responses and the video clips as springboards tell your students to take notes in their journals as you fill in the knowledge gaps by presenting more background on salmon and fish in general.
- End presentation with an announcement about tomorrow's fish dissection and identification activity.
- Group students into pairs.
- Distribute and spread newspapers onto tabletop surfaces.
- Distribute trash bags.
- Distribute dissection materials.
- Put on gloves, smocks, and protective eyewear.
- Place the fish in your dissecting pan.
- Using toothpicks, post-its, and markers have you students make flags and identify external fish anatomy parts.
- While assessing students' progress, have students write in their journals as well as sketch and label external fish anatomy parts.
- Remove external anatomy flags and dispose of in trash bags.
- Turn the dissecting pan so that the belly of the fish is away from you.
- Insert the tip of your knife into the fish's vent and cut forward along the belly, passing between the pelvic fins, until reaching the pectoral fins.
- Rotate knife and cut upward until reaching the lateral line.
- Cut along the lateral line until reaching above the vent.
- Rotate knife and cut downward until reaching the vent.
- Remove rectangular skin flap or tissue.
- Using toothpicks, post-its, and markers have you students make flags and identify internal fish anatomy parts.
- While assessing students' progress, have students write in their journals as well as sketch and label internal fish anatomy parts.
- Dispose of fish, newspapers, gloves, and other wastes in trash bags.
- Remove smocks and protective eyewear.
- Wash hands thoroughly.
- Collect journals.
- Distribute goldfish crackers, fish-shaped cookies and drinks for a post-dissection party!
For Younger Students
Salmon have an incredible sense of smell and memory that enables them, after a five-year absence, to return to the very same waters in which they were hatched. How does each of your student's sense of smell compare? Place a variety of aromatic scents (scent stations) around your classroom. With their journals in hand ask your students to identify each of the scents and what it makes them think about.
For Older Students
Compare and contrast between a fish and a human being the following internal body systems: respiratory, circulatory, reproductive, nervous, and digestive. Would you want to swap one of these systems with a fish? Which one and why?
Salmon face incredible natural and manmade obstacles in order to return to their home spawning waters. Natural obstacles such as sharks, grizzlies and other predators are all part of nature's web of life. Manmade obstacles such as logging, road construction, and the damming of once wild waters greatly reduce the success salmon spawning. Research the nearest salmon spawning site to your school and identify the route and obstacles that typical salmon would have to face in order to get there.
- Evaluate your students on their ability to correctly identify and label external bony fish anatomy parts.
- Evaluate your students on their ability to correctly dissect, identify and label internal bony fish anatomy parts.
- Evaluate the writing and content of your students' journal entries for this lesson and activity.
Banister, Keith, "The Encyclopedia of Aquatic Life," Facts on File, Inc.,1993.
Deans, Nora, et al, "Sea Searcher's Handbook," Monterey Bay Aquarium and Roberts Rinehart Publishers, 1996.
Love, Milton, "Probably More Than You Want To Know About The Fishes Of The Pacific Coast," 2nd Edition, Really Big Press, 1996.
Williams, Brian, "World Books Looks At The Sea And Its Marvels," World Books, Inc., 1997.
PBS Online Sites:
Nature: Showdown at Grizzly River Home
Other Online Sites:
Alaska Department of Fish and Game: Wildlife Notebook
J's Tropical Hatchery
Salmon from A to Z
Parker, Sybil, "Earthscape: Exploring Endangered Ecosystems," McGraw-Hill Companies, Inc., 1997.
Microsoft, et al., "Oceans: Explore the Mysterious World of the Deep," Microsoft Corporation, 1995.
Related National Standards
This lesson addresses the following national content standards found at http://www.mcrel.org:
and the following national science content standards found at http://www.nap.edu/readingroom/books/nses/html/:
- Develop an understanding of the diversity and unity that characterize life.
- Develop an understanding of how species depend on one another and on the environment for survival.
- Develop an understanding of characteristics of an organism.
- Develop an understanding of the life cycle of an organism.
- Develop an understanding of structure and function in living systems.
- Develop an understanding of the interdependence of organisms.