Fish of the Great Lakes

1. Fish of the Great Lakes

2. Habitat • Depends on age and type of fish • Most prefer rocky, clear water stream beds as babies and cold, deep water as adults • pollution free

3. Dominant Fish Species • Lake Huron • 129 fish species, 15 are non-native • Walleye, Burbot, Yellow Perch, Rainbow Smelt • Sea lamprey is still a nusiance

4. Dominant Fish Species • Lake Michigan • 116 fish species, 20 are non-native • Whitefish, Steelhead, Coho Salmon, Alewife

5. Dominant Fish Species • Lake Erie • 86 fish species, 15 are non-native • Smallmouth Bass, Walleye, Yellow Perch • “The Walleye Capital of the World”

6. Dominant Fish Species • Lake Superior • 89 fish species, 21 are non-native • Lake Sturgeon, Whitefish, Sculpin, Brook Trout

7. Dominant Fish Species • Lake Ontario • 85 fish species, 17 are non-native • Bullhead, Yellow Perch, Smallmouth and Largemouth Bass

8. External Anatomy of a Fish • Fins = movement and stabilizers • Lateral Line = sense organ to detect movement and vibrations

9. Internal Anatomy

10. Internal: Digestion • Very similar to us • Esophagus, Intestine, and Stomach = passing, absorbing and breaking down food • Liver and Pancreas = produce enzymes

11. Internal: Respiration • Gills = made of feathery threads with capillaries for gas exchange Breathing Process • Water w/oxygen goes in through mouth • Water is push through gills • Oxygen molecules are trapped in gills • Oxygen gets into the blood stream by the capillaries in the gills

12. Internal: Circulation • Heart pumps blood in a loop (heart to gills, gills to rest of the body, back to heart)

13. Internal: Response • Brain = control center of the body • Olfactory bulbs = smell • Well developed eyes = color vision • Internal Ears = detect vibrations and movement of water

14. Internal: Movement • Contract and relax muscles on either side of backbone • Swim Bladder = gas filled bladder so that they float instead of sink

15. Reproduction • mostly externally • Mother digs a hole and deposits thousands of eggs and then father fertilizes them

16. The Fish Life Cycle

17. The Fish Life Cycle • To survive as a species, the species must REPRODUCE! • Most fish live their lives in preparation of reproducing

19. Fish Life Cycle (Salmon) • Eggs • Very fragile the first couple of weeks and several break • Eyes develop and are very light sensitive • Cool water flowing over eggs supplies oxygen and gets rid of waste

20. Fish Life Cycle (Salmon) • Alevin • Tiny fish that break out of the egg • Have a yolk sac attached to belly that supplies food and oxygen • Stay in gravel until are big enough to swim out • Several get trapped and die (only 10% survive)

21. Fish Life Cycle (Salmon) • Fry • Small fish the size of a finger or less • Start to swim to surface • Get their own food (small insects) and oxygen • Several organisms eat fry

22. Fish Life Cycle (Salmon) • Smolt • Teenager fish • Coloring changes to adult colors • Grow a lot • If saltwater fish…gills change to regulate salt

23. Fish Life Cycle (Salmon) • Adult • Full size • Adult colors • Travel far distances • Adult diet

24. Fish Life Cycle (Salmon) • Spawners • Reproductively mature fish (usually reddish) • Males and females swim upstream to the place where they were born and lay eggs or deposit sperm • Usually die afterwards

25. Great Lake Fish Concerns

26. Types of Pollution • Thermal Pollution = factories release warm water into the lakes and it has less oxygen • Sediment Pollution = soil gets washed into the lakes and makes the water cloudy • Chemicals = chemicals placed into the water hurt the health of the fish

27. Zebra Mussels • Cause a Total Change in the Ecosystem • Eat all the phytoplankton in the lake • no food for the little fish = little fish die • no little fish = no big fish

28. Mercury, Dioxin, and PCB’s • The 3 major chemicals measured for fish consumption advisories • Fat Soluble (accumulate in body tissue) • Carcinogens • Teratogens (cause birth defects)

29. Bioaccumulation • When chemicals move up the food chain • Organisms at the top of the food chain eat the most, so they get the most amount of chemicals

30. Fish Diseases • VHS (Viral Hemorrhagic Septicemia) = fish bleed to death • Type E Botulism = bacteria acts as a neurotoxin and paralyzes the fish

31. Estrogen Disruptors • Medicines get into the water and mimic hormones in fish • Causes infertility and changes to sexual organs in fish and amphibians • DON’T FLUSH MEDICINES!!!

32. Overfishing • Taking too many fish out of the lake at once • Very common before the 1950’s • Now controlled by fishing licenses and catch limits on commercial fishing

33. Climate Change • Warmer Water = • Less habitat for cold-water fish • Less dissolved oxygen in the water • More severe storms • More Evaporation = Less Water

34. Habitat Destruction • Causes of Fish Habitat Destruction • Dredging • Development • Filling in wetlands to make farmland • Pollution • Changing water levels

35. Aquaculture • Growing fish like crops to sell as food • Some are released into the wild and harvested during spawning • Others are raised through adulthood

36. GLFC • Great Lakes Fisheries Commission • Joint Gov’t agency between the USA and Canada • Makes all Fishing Regulations • Invasive Species Control