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10 cm PowerPoint Presentation

10 cm

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10 cm

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  1. 10 cm

  2. “Next to man with this traps, the codfish is probably the most destructive enemy of the lobster …” Francis Hobart Herrick 1909 Natural history of the American Lobster

  3. “Cancer irroratus “Found in abundance in the stomachs of cod taken in Casco Bay” (Maine) Cancer borealis: “ ….found in stomachs of the cod taken on the Cod Ledges” (Portland Maine). S. I Smith. 1879 The stalkeyed crustaceans of the Atlantic coast of North America

  4. Prehistoric fishing village 3000 BC Rosier 1606 reported myriad large cod and haddock Fishing village 500 BC Trelawny Fishing Station 1633 Cashes Ledge Plymouth Colony 1620 AD Gulf of Maine Cape Cod Georges Bank

  5. Relict Populations of Large Predatory Fishes

  6. 80 60 COD SZ POL SZ 40 20 0 TOL PEM MAT MDI ARP NARP 100 COD SZ 90 Pollock POL SZ 80 70 60 50 40 30 20 10 0 TOL PEM MAT MDI ARP NARP Predatory Fish Abundance RARE ABUNDANT Fish Visitation Rate (#/m2/h) Cod Pollock Studies to determine Ecological Function Cod Body Size Body Size (cm) Coastal Offshore Steneck 1997.

  7. Algal and Invertebrate Abundances Relative to Fish Predators Predatory Fish Abundance Abundance RARE ABUNDANT 80 70 60 50 Fish Visitation Rate (#/m2/h) 60 Urchin #/m2 Cod 40 COD SZ Urchin Pollock POL SZ 30 20 40 10 0 20 100 80 Kelp 0 TOL PEM MAT MDI ARP NARP 60 % Algal Cover 100 40 Cod Body Size COD SZ 90 Pollock POL SZ 20 80 0 Body Size (cm) 70 60 0.3 50 Lobster 40 0.2 30 # Lobster / m2 20 0.1 10 0 0.0 TOL PEM MAT MDI ARP NARP Rare Abundant Coastal Offshore Study Regions Large Predatory Fish Steneck 1997.

  8. Algal and Invertebrate Abundances 80 60 Urchin #/m2 COD SZ POL SZ 40 20 0 TOL PEM MAT MDI ARP NARP % Algal Cover 100 COD SZ 90 Pollock POL SZ 80 70 60 50 40 30 # Lobster / m2 20 10 0 TOL PEM MAT MDI ARP NARP Study Regions Large Predatory Fish Relative to Fish Predators Predatory Fish Abundance Abundance RARE ABUNDANT 70 60 50 Fish Visitation Rate (#/m2/h) Cod 40 Urchin Pollock 30 20 10 0 100 80 Kelp 60 40 Cod Body Size 20 0 Body Size (cm) 0.3 Lobster 0.2 0.1 0.0 Rare Abundant Coastal Offshore Steneck 1997

  9. Fish Predation on Tethered Lobsters Predatory Fish Abundance Large Lobsters RARE ABUNDANT 80 0.5 70 - 78 mm CL 0.4 Fish Visitation Rate (#/m2/h) 60 0.3 Cod COD SZ Pollock POL SZ 0.2 40 0.1 0.0 Medium Lobsters 0.25 20 50 - 60 mm CL 0.20 0.15 0 TOL PEM MAT MDI ARP NARP Attack Rate (# eaten/day) 100 0.10 Cod Body Size COD SZ 90 Pollock POL SZ 0.05 80 Body Size (cm) 0.00 70 Small Lobsters 3.0 60 30 - 38 mm CL 2.5 50 40 2.0 30 1.5 20 1.0 10 0.5 0 0.0 TOL PEM MAT MDI ARP NARP Rare Abundant Coastal Offshore Study Regions Large Predatory Fish Predation Experiments 30 - 45 cm Steneck 1997.

  10. Cod Size Baselines 120 100 80 Atlantic cod body length (cm) 60 40 20 0 4500 4000 3500 3000 2500 2000 1500 1000 500 0 Years Before Present Trawled cod (55 cm Langton & Bowman 1980, Link & Garrison 2002) Offshore tethering study (Steneck 1997) Coastal cod (Ojeda & Dearborn 1989) 5000

  11. Predation Rates on Tethered Lobsters 70 60 Immune to predators after ~2 years 50 40 Predation rate (attacks/h) 30 20 10 0 0 20 40 60 80 100 Size (mm CL) Wahle and Steneck 1992

  12. Predator vulnerability in the past Vulnerable to predators 10 years 70 60 50 40 30 Attacks Per Hour 20 10 0 0 20 40 60 80 100 Size (mm CL)

  13. History of Lobster Landings in Maine 20000 18000 16000 14000 12000 10000 + 1 SD 8000 Average - 1 SD 6000 4000 2000 0 1880 1880 1890 1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 Year Boom! Bust Lobster Landings (metric tons) Steneck 1997.