Post on 04-Feb-2016
description
USFWS Migratory Bird Program
James R. Kelley
Mississippi Flyway Representative
Canvasback Harvest Strategy:Canvasback Harvest Strategy:Update for the 2008-09 SeasonUpdate for the 2008-09 Season
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
Canvasback
Year
Millio
ns
1955 1965 1975 1985 1995 2005
Strategy componentsStrategy components
1)1) One continental populationOne continental population
2)2) Spring population objective Spring population objective ≥ ≥ 500,000500,000
3)3) Model of population dynamics…….. Model of population dynamics……..
Canvasback population model:
Number of canvasbacks next May =
(Number this May × Summer survival
+ Number of Juveniles in Fall
− Number killed in fall)
× Winter survival
Fall Age RatioFall Age Ratio
Year
Age ratio (immature/adult)
O = Estimated from harvest dataP = Predicted from pond model
1994 1996 1998 2000 2002 2004 2006 2008
0.0
0.2
0.4
0.6
0.8
P P
P P
P
P
PP
P
P
P
PP
P
P
O
O
OO
OO
O
O O O
O
O
O
*
Preliminary estimateU.S. harvest data
Spring AbundanceSpring Abundance
Year
Canvasbacks(1000s)
O = Estimated from survey dataP = Predicted from canvasback modelC,R,L,2 = 2009 model predictions for closed, restricted, liberal & 2-bird seasons
1996 1998 2000 2002 2004 2006 2008
0
200
400
600
800
1000
P
P
P
P
P
P
P P
P
P PP
P
P
O
OO
O O O O
OO
OO
O
O
O
OC
R
L2
2008-09 Harvest Season Recommendation2008-09 Harvest Season Recommendation
1)1) Canvasback strategy calculates an allowable harvest Canvasback strategy calculates an allowable harvest
of only 24,700 birds for the 2008-09 hunting season.of only 24,700 birds for the 2008-09 hunting season.
2)2) The predicted harvest under a restricted AHM The predicted harvest under a restricted AHM
season is 61,758 canvasbacks in the U.S.season is 61,758 canvasbacks in the U.S.
3)3) The harvest strategy indicates a closed season for The harvest strategy indicates a closed season for
canvasbacks this year.canvasbacks this year.
4)4) Under a closed season, the model predicts 537,519 Under a closed season, the model predicts 537,519
canvasbacks in spring 2009.canvasbacks in spring 2009.
• 2008 estimates of canvasback breeding population 2008 estimates of canvasback breeding population lowest since 2002; second lowest in last 15 years.lowest since 2002; second lowest in last 15 years.
• Canadian pond estimates are also low. Canadian pond estimates are also low.
• Preliminary harvest estimates for 2007 near model’s Preliminary harvest estimates for 2007 near model’s harvest prediction for a 2-bird bag.harvest prediction for a 2-bird bag.
• 2007 model prediction failed by substantially 2007 model prediction failed by substantially overestimating 2008 breeding population.overestimating 2008 breeding population.
• Overestimate likely due in part to overestimation of Overestimate likely due in part to overestimation of the age ratio.the age ratio.
• FWS is committed to model and harvest strategy FWS is committed to model and harvest strategy improvements, as competing priorities allow.improvements, as competing priorities allow.
G. Scott Boomer U.S. Fish and Wildlife Service
Progress towards an assessment and decision making framework to inform
scaup harvest management
34
56
78
9
Scaup
Year
Mill
ion
s
1955 1965 1975 1985 1995 2005
Scaup Estimates
1960 1970 1980 1990 2000
01
23
45
6
Year
Pop
ulat
ion
in M
illio
ns
Boreal ForestPrairie-ParklandTundra
Scaup Breeding Population Estimates (1955 - 2005)
Proposed Methodology to determine scaup regulatory alternatives
Derive policy
Predict future state
Harvest ~ f (Historical Regulations)
Harvest
Update
population
parameters
Monitor
BPOP & Harvest
.))/1((1111t
teHKNrNNNtttt
N = population size
r = intrinsic rate of increase
K = carrying capacity
H = harvest
e = process error
Assessing the Harvest Potential of Wood Ducks in Eastern North America
25
30
35
40
45
Total ducks
Year
Mill
ion
s
1955 1965 1975 1985 1995 2005
Year
Nu
mb
er
of P
on
ds
(in
Mill
ion
s)
1960 1965 1970 1975 1980 1985 1990 1995 2000 2005
02
46
81
0
Prairie CanadaNorthcentral USTotal