Points of concern in Sea Duck conservation

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REPRODUCTIVE STRATEGY OF MERGINI TRIBE (SEA DUCKS) IS OPPOSITE SPECTRUM OF ANATINI TRIBE (DABBLERS)

  1. Sea ducks are less able to compensate for an additional form of mortality such as hunting because these species have a "K-selected" reproductive strategy:
    • long lived, with low natural mortality
    • annual adult survival is high ( in a healthy population),
    • annual recruitment to breeding age is low,
    • annual breeding rates and success are variable
    • clutch sizes tend to be small
    • low annual production or recruitment rates to breeding age
    • variable annual rates of non breeding by adults
    • deferred sexual maturity. (2-3 years)

  2. r- dabbler and K-diver species are at the opposite ends of the threshold spectrum, R- DABBLERS (MALLARDS) ARE OPPOSITE THE ABOVE LIST.
    • The r-K concept indicates that mortality rates should be
      1.  highest in the r-dabblers
      2.  intermediate in the K-dabblers
      3.  lowest in the K-divers
    • Biologically, The Mergini tribe should have the most restrictive bag limit yet it continues to be grossly excessive

  3. The K-selected reproductive strategy minimizes the importance of annual investment in reproduction and maximizes the importance of annual survival.

  4. Management for recovery of declining sea duck populations is difficult because K- selected life history traits may limit rate of recovery

  5. Small population growth may result even in the absence of threats.

  6. sea ducks are much more sensitive to changes in adult survival than to annual variability in recruitment

  7. Population stability of sea ducks is dependent on high adult survival and a few successful years of production.

  8. Species which maintain population stability through high adult survival are sensitive to increased mortality. Long lived Sea ducks are much more sensitive to changes in adult survival than to annual variability in recruitment.

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Alaska Wild Animal Recovery Effort
Box 170, Homer, AK 99603
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E-mail: bear@alaska.net