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Irruption

Irruption. Increasing. Numbers. Time. Key Points. What is the rate of increase when population is reduced What is the eventual number that is achieved How does the rate of increase and number achieved vary in response to the fishery, habitat changes, or changes in other aquatic populations?.

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Irruption

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  1. Irruption

  2. Increasing Numbers Time

  3. Key Points • What is the rate of increase when population is reduced • What is the eventual number that is achieved • How does the rate of increase and number achieved vary in response to the fishery, habitat changes, or changes in other aquatic populations?

  4. B = D B > D B < D Numbers Time

  5. Survival Curves

  6. Longevity: Age 20 Age 8 Age 4

  7. Yellow Perch

  8. Hermaphroditism • Protandry • Start life as a male, then become female • Sea basses and groupers • Protogyny • Start life as a female, then become male • Wrasses, parrot fish • Self-fertilizing • Simultaneously male and female • Sea basses and grouper • Parthenogenesis • Female only • Some mollies – in this case, male is needed to initiate egg development but no gene transfer • Very common in Cladocerans (Daphnia, or “water fleas”)

  9. Natural Mortality=20% Fishing Mortality=50% Natural Mortality=20%

  10. Yield Age 3 Age 2 Age 1 Effort

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