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The Effect of Fishing on Species and Genetic Diversity

The Effect of Fishing on Species and Genetic Diversity. Genetic resources are an important element of conservation Species Within Species. I. The Loss of Species. Is this a problem in the sea? How do we know? . Latimeria chalumnae (coelacanth) c. 1938. Steller’s Sea Cow

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The Effect of Fishing on Species and Genetic Diversity

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  1. The Effect of Fishing on Species and Genetic Diversity

  2. Genetic resources are an important element of conservation • Species • Within Species

  3. I. The Loss of Species • Is this a problem in the sea? • How do we know?

  4. Latimeria chalumnae (coelacanth) c. 1938

  5. Steller’s Sea Cow Caribbean Monk Seal Eelgrass Limpet Rocky Shore Limpet Asian Periwinkle Horn Snail New Zealand Grayling Sea Mink Great Auk Vanvoorstia bennettiana (Australian red alga) Documented Extinction

  6. Sea Turtles, Sharks, Rays ...

  7. The Role of Fishing in Extinction Events

  8. II. Loss of Populations

  9. Pacific Salmonids • Population rich • 106 populations extirpated in US • 142 populations extirpated in Canada • In the last 30 yrs over 40% of range lost

  10. 46 43 63 57 4VsW September/October 1996 longline survey catches

  11. Marine fish have much more genetic structure than previously supposed

  12. Maintenance of Genetic Diversity • Organization of populations in time and space • Ratio of within and among population variation

  13. Events Prior to Extinction • Extirpation • Range contraction • Fragmentation

  14. Adriatic Sea stock of Beluga Sturgeon • Atlantic Ocean population of Gray Whale • Gulf of St. Lawrence walrus • populations of 82 species of marine fish in North America believed to be at risk

  15. Brosme brosme (cusk) Abundance 1970-2000

  16. Loss of Populations = Loss of Genetic Diversity

  17. A significant amount of genetic diversity could be attributed to spatial structure • No variance component could be attributed to temporal changes Ruzzante, Taggart et al. In Press. Stability in the historical pattern of genetic structure of Newfoundland cod (Gadus morhua) despite the catastrophic decline in population size from 1964 to 1994. Conservation Genetics

  18. III. Loss of within population genetic diversity

  19. Selective Fishing

  20. By removing the large fish selectively over time the remaining fish are slow-growing and early-maturing • Genetic or Ecological? • temperature • abundance of prey • degree of competition

  21. Traits affected by fishing? • Weight-at-age • Length-at-age • Age-at-maturity • Length-at-maturity • Spawning season • Number and size of eggs

  22. Selective fishing can cause heritable differences in life-history traits that control sustainable yield

  23. Species extinction Genetic complexity Selective fishing Address at the population level Manage spawning components Reduce fishing intensity Structure effort Reduce selectivity Reduce fishing intensity Problems and Solutions

  24. Numbers are not enough

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