Objectives
Students will be able to:
- argue convincingly on either side of the question, "is it worth spending money and/or effort to save threatened fish species?";
- identify at least one fish species that is threatened with extinction in Ontario today; and
- analyze data on species under threat, and suggest appropriate management solutions for at least one fish from one COSEWIC category.
Method
Students will be presented with profiles of selected fish species from one of the six categories that the Committee On the Status of Endangered Wildlife In Canada (COSEWIC) uses to indicate the relative degree of threat of extinction. Students will analyze the data using several criteria and determine possible management strategies. Where strategies have already been implemented, students can make comparisons.
Materials
Background
Many people think of animals other than fishes when they think of extinct or endangered species. But many fishes in Canada are being threatened with extinction. According to the Committee on the Status of Endangered Wildlife in Canada's list, many fishes have experienced a severe reduction in population and/or have disappeared from waters where they had been known to exist. The most serious problems affecting fishes are: changes in water quality and quantity; habitat changes affecting available food, shelter and space; and fishing stress from commercial and sport fishing. COSEWIC assigns fishes to one of the following categories:
EXTINCT: Any species of plant or animal that no longer exists anywhere, such as the blue pike (also called blue walleye and blue pickerel) of Lake Erie.
EXTIRPATED: Any native species no longer existing in the wild in one place but existing elsewhere. For example, the paddlefish is no longer found in Lake Huron or Lake Erie, but survives in the Mississippi River system of the United States.
ENDANGERED: Any native species whose existence in Canada is threatened with immediate extinction through all or a significant portion of its range owing to the action of humans. An example is the pugnose minnow, which is rapidly disappearing from Southern Ontario.
Procedure
- Ask students if they know of any living things that are threatened with extinction in the world or in Canada. Compile a list, and check to see if any fish are on it. Pose the question, "who cares? Is it really worth trying to save threatened species?" Play devil's advocate, or, if opinion seems reasonably split, hold a more formal debate on the question, allowing students time to research their position. Common arguments include:
|
Pros Inherent "right" of all living things to keep living. |
Cons Things have always gone extinct. |
Some strategies, e.g. eliminating pollutants, have broader benefits. Summarize the debate.
- Note that the rest of the lesson assumes an affirmative answer to the question raised in Step 1, and is the position of many individuals, organizations and government agencies. Explain that they will look at Ontario fish as a case study in species protection and rehabilitation.
- Assign one profile card to individuals and small groups, and have students develop a chart to summarize the information they extract. Categories should include the Committee on the Status on Endangered Wildlife in Canada designation, role/place in ecosystem, importance to people, range and locations found, stress on species, action taken to date and suggested solutions.
- Prompt students with questions leading to discussion of alternatives and selection of a solution or solutions. The following are some possible solutions.
- Prevent fishing.
- Design a fish regulation to protect fish stock.
- Catch some fishes and place them in a better sanctuary, lake or stream.
- Try to raise fishes in culture stations, then restock the lake or stream.
- Protect the nursery and spawning habitat by regulating land development.
- Prohibit anglers from using the designated fishes as bait.
- Prohibit all harvest of baitfish.
- Build streambank erosion structures to minimize sedimentation.
- Plant trees to stabilize banks and reduce sedimentation.
- Assess the size of fish populations frequently.
PROFILE 1
THE SILVER SHINER
The silver shiner is rare in Canada. It is one of Canada's most beautiful minnows and is found in the deeper pools of medium to large streams with moderate to high water velocity. The adult fishes are small, growing to no more than 13 cm in length.
In Ontario, silver shiners can be found in the streams that run into Lake Erie, Lake St. Clair and Lake Ontario. These populations vary a great deal in size and little precise population data is known for the few stream locations where they have been sampled.In the United States, silver shiners can be found throughout the east-central states, such as New York, Pennsylvania, Ohio, Indiana and Kentucky. Populations fluctuate greatly throughout these areas decreasing in some areas and increasing in others. Silver shiners show a preference for clear streams that are high in oxygen and have sandy, gravelly or rocky bottoms. Here they feed on insects such as mosquitoes, which they catch by jumping at the surface. They also feed on immature insects and other aquatic organisms below the surface and at times even on algae. Silver shiners are eaten by smallmouth bass and rock bass, and are often used as bait by anglers even though they survive only a short period of time in a minnow pail.
Little information is known about factors affecting silver shiners. Climatic conditions may be important; Canada is at the northern edge of the species' range. Weather in Ontario could be especially critical in determining winter survival and spawning success. Habitat loss, environmental contamination such as sedimentation and pollution, dams, and stream channelization may also be responsible for small populations, particularly in the United States. The Canadian population may be naturally limited due to climate and cannot be expected to expand significantly.
No specific protection for the silver shiner now exists in Canada, although the fish habitat section of the Fisheries Act does afford general protection if enforced. The species was assigned a rare status by COSEWIC in April 1983.
REFERENCE
Baldwin, M.E. "Updated status of the Silver Shiner, Notropis photogenis, in Canada". In Canadian Field-Naturalist 102(1), 1988. pp.147-157.
PROFILE 2
AURORA TROUT
The aurora trout is a distinct form of the brook trout that has been classified as endangered in Canada due to loss of its natural habitat by pollution and acid rain.
The aurora trout is similar to the brook trout but lacks the worm-like markings across the back which extend into the dorsal and caudal fins of the brook trout. Also, the red spots with blue halos, which characterize the brook trout, are replaced by a gleaming silver or purplish sheen, more or less uniformly distributed over the body of the aurora trout. The aurora trout feed on aquatic invertebrates, insect larvae, crayfish and smaller species of fishes.
The four Canadian lakes from which aurora trout were originally identified were in the region north of Sudbury, in northeastern Ontario. During the late 1950s and 1960s, the aurora trout populations in these lakes declined and by 1971 had almost disappeared.
Aurora trout were native to these cold, deep lakes with few nutrients and little plant or animal life (oligotrophic lakes). Since these lakes are found on pre-Cambrian bedrock, they have little capacity to buffer acidic precipitation and thus became acidified quickly.
The MNR developed a hatchery program to save this unique fish. Several lakes are stocked with aurora trout to provide a source of spawn for hatchery incubation. No significant natural spawning success in these stocked lakes has occurred so these populations will be dependent on hatchery stocking for some time.
With the reduction in smelter emissions in the Sudbury area, lake water quality has been gradually improving. Aurora trout introduced back into their native lakes in the early 1980s have survived for up to three years, but there has been no reproductive success. In the fall of 1989, the Ministry of Natural Resources attempted to assist the lake recovery process by adding lime to Whirligig Lake, in the hopes of neutralizing enough acidity to allow the survival of eggs and young. The lake was stocked with its native trout in the spring of 1990, and will be monitored over the next few years to assess survival and reproduction. Additional, legislated reductions in acid emissions may reduce acid rain enough in the future that further liming will be unnecessary, and the aurora trout can once again live naturally in its native habitat.
The lakes stocked with aurora trout have been made into fish sanctuaries. There is, however, limited fishing allowed on some of these lakes.
REFERENCE
Parker, B.J., and C. Brousseau. "Status of the Aurora Trout, Salvelinus fontinalis timagamiensis, a Distinct Stock Endemic to Canada". Canadian Field-Naturalist 102(1), 1988. pp. 87-91.
PROFILE 3
DEEPWATER SCULPIN
In North America, the deepwater sculpin is considered a glacial relic and is the largest of the freshwater sculpins. It has an unusual shape with a slender, elongated body and head and has smooth, mottled skin with tubercles or prickles that feel rough to the touch. The lateral line is conspicuously raised and appears chain-like along the length of the body. The deepwater scul-pin remains common in some lakes in Canada such as Lake Huron, but is believed to be extir-pated from Lake Ontario and possibly Lake Erie.
The deepwater sculpin is a bottom dwelling fish found in the Great Lakes at depths greater than 73 m. These lakes are cold and deep, with mud, clay, silt, sand or rocky bottoms. Deepwater scul-pins feed on organisms that live on or near the lake bottom. This species is a favoured prey of the lake trout and considered a vital link in the conversion and transport of energy in the deepwater food web.
The disappearance of deepwater sculpins from Lake Ontario may have been caused by several factors such as DDT pollution and predation or competition by alewives. This species is not a commercial or sport fish. There is no specific protection for this species in law. The fish habitat section of the Fisheries Act provides minimal, general protection if it is enforced.
REFERENCE
Parker, B.J. Status of The Deepwater Sculpin, Myoxocephalus thompsoni, in Canada. Canadian Field-Naturalist 102(1), 1988. pp. 126-131.
Extensions
- Encourage students to participate in a local fish or wildlife habitat improvement project.
- Have students identify a species that has been classified by COSEWIC and is of local interest. Have them investigate the problem (why the species has been classified) and write a letter to their MPP and/or MP asking for their position on the matter. This could introduce students to the concept of citizens' action groups.
- Where spawning beds are known to exist nearby, have students volunteer to monitor the beds during spawning season to help deter poachers. Please stress that students should not intervene or confront poachers in any way, but rather record as much information as possible and pass it on to the local MNR office. Information can be anonymous. Ask the Conservation Officers at your local MNR district office for further advice. This would not have to be restricted to fish species with COSEWIC status as continued poaching may add other species to this list.
- Have students find out about other endangered animal or plant species in Ontario.
- Through individual reflection and small group discussion, have students explore their own values system related to the debate in procedure 1. What beliefs do they hold that caused them to argue a particular position? Are their own actions or behaviours always consistent with those beliefs?
Evaluation
Have students create a profile of another rare/endangered fish or wildlife species that includes management solutions.
Reference
Committee on the Status of Endangered Wildlife in Canada
Place Vincent Massey,
16th floor, Rm. 1652
St-Joseph Blvd.,
Hull, Quebec
K1A 0E7
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