Harvesting Multiple Stocks of Ducks

This study was conducted to help assess whether recent harvest rates of ducks banded before the hunting season in the United States varied among stocks (i.e., species, age-sex cohort, location of banding) and whether regulatory actions have been successful at shifting harvest pressure among stocks in the desired manner. Direct recovery rates during 1976-91 were used to index harvest rates and were influenced to some degree by location of banding, age class, sex, species, and hunting regulations. However, differences in recovery probability among species were consistent (P = 0.787) over 3 periods with different hunting regulations (1976-84, 1985-87, 1988-91), despite regulatory changes designed to affect species differentially. Band-recovery models that excluded the interaction between hunting regulations and sex of ducks were inadequate (P ≤ 0.013), suggesting sex-specific changes in recovery probabilites with changes in regulations. There was little evidence (P ≤ 0.151) that regulatory changes affected recovery rates of ducks from 3 banding reference areas differentially. Harvesting duck stocks in an optimal manner requires an ability to harvest selectively, a good understanding of each stock's dynamics, and knowledge of any interdependence in stock sizes.