USFWS Migratory Bird Program

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USFWS Migratory Bird Program. James R. Kelley Mississippi Flyway Representative. Canvasback Harvest Strategy:. Update for the 2008-09 Season. Strategy components. One continental population Spring population objective 500,000 Model of population dynamics. - PowerPoint PPT Presentation

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<ul><li><p>USFWS Migratory Bird ProgramJames R. Kelley</p><p>Mississippi Flyway Representative</p></li><li><p>Canvasback Harvest Strategy:Update for the 2008-09 Season</p></li><li><p>Strategy componentsOne continental population Spring population objective 500,000 Model of population dynamics.. </p></li><li><p>Canvasback population model:Number of canvasbacks next May =</p><p>(Number this May Summer survival + Number of Juveniles in Fall Number killed in fall) Winter survival</p></li><li><p>Fall Age RatioYearAge ratio (immature/adult) O = Estimated from harvest dataP = Predicted from pond modelPreliminary estimateU.S. harvest data</p></li><li><p>Spring AbundanceYearCanvasbacks(1000s) O = Estimated from survey dataP = Predicted from canvasback modelC,R,L,2 = 2009 model predictions for closed, restricted, liberal &amp; 2-bird seasons</p></li><li><p>2008-09 Harvest Season RecommendationCanvasback strategy calculates an allowable harvest of only 24,700 birds for the 2008-09 hunting season.The predicted harvest under a restricted AHM season is 61,758 canvasbacks in the U.S.The harvest strategy indicates a closed season for canvasbacks this year.Under a closed season, the model predicts 537,519 canvasbacks in spring 2009.</p></li><li><p>2008 estimates of canvasback breeding population lowest since 2002; second lowest in last 15 years.Canadian pond estimates are also low. Preliminary harvest estimates for 2007 near models harvest prediction for a 2-bird bag.2007 model prediction failed by substantially overestimating 2008 breeding population.Overestimate likely due in part to overestimation of the age ratio.FWS is committed to model and harvest strategy improvements, as competing priorities allow.</p></li><li><p>G. Scott Boomer U.S. Fish and Wildlife ServiceProgress towards an assessment and decision making framework to inform scaup harvest management</p></li><li><p>Scaup Estimates</p></li><li><p>Proposed Methodology to determine scaup regulatory alternativesDerive policyPredict future stateHarvest ~ f (Historical Regulations)</p><p>Harvest</p><p>Updatepopulation parametersMonitorBPOP &amp; Harvest</p></li><li><p>N = population size</p><p>r = intrinsic rate of increase</p><p>K = carrying capacity</p><p>H = harvest</p><p>e = process error</p></li><li><p>Assessing the Harvest Potential of Wood Ducks in Eastern North America</p></li><li><p>Abundance(t+1) = (Fall Adults(t) + Fall Juveniles(t) Harvest(t)) * winter survivalN(t+1) = spring breeding population estimate of canvasback in year t+1N(t) = spring breeding population estimate of canvasback in year tS(s) = Summer survival rate of adults, May-August, 0.936A(t) = estimated production rate in year t, imm/ad, A(t) = 0.75*[-0.063 + (1.48x10-7)*(Number of Canadian ponds in year t)]H(t) = harvest in year tCLR = crippling loss rate = 0.3S(w) = winter survival rate, February-May, 0.926</p><p>Abundance(t+1) = (Fall Adults(t) + Fall Juveniles(t) Harvest(t)) * winter survivalN(t+1) = spring breeding population estimate of canvasback in year t+1N(t) = spring breeding population estimate of canvasback in year tS(s) = Summer survival rate of adults, May-August, 0.936A(t) = estimated production rate in year t, imm/ad, A(t) = 0.75*[-0.063 + (1.48x10-7)*(Number of Canadian ponds in year t)]H(t) = harvest in year tCLR = crippling loss rate = 0.3S(w) = winter survival rate, February-May, 0.926</p><p>This chart shows the fall age ratio predicted from canvasback model (P) +/2*SE and estimated fall age ratio (from FWS and CWS harvest data; white O for observed, no error estimates). The yellow lines are 95% confidence intervals on the predicted harvest age ratio.The fall age ratio for 2008 is predicted to be 0.29. The predicted ratio for 2007 was 0.51, but the estimated value was substantially lower (0.32). The observed fall age ratios typically fall within the 95% confidence interval of the predicted fall age ratio (although CIs are wide; cv =(30-60%).)This graph shows the spring breeding population estimated from May survey data +/ 2*SE. The yellow P indicates the value predicted by the canvasback model, using the estimated harvest, spring population and spring ponds from the previous year. Orange letters are model predictions for 2009 based on 2008 estimates of canvasback population, Canadian ponds, and predicted harvests under the restricted (R), liberal (L), and liberal, 2-bird bag (2) scenarios + assuming a closed season (C). </p></li></ul>

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