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Strong Seasonal Dynamics of Harbor Seals, Strong Seasonal Dynamics of Harbor Seals, an Upper-Trophic Predator in Cook Inletan Upper-Trophic Predator in Cook Inlet
Peter Boveng, Josh London and Robert MontgomeryPolar Ecosystems ProgramNational Marine Mammal Laboratory NOAA Alaska Fisheries Science CenterSeattle, [email protected]
Alaska Marine Science Symposium 2007
Photo: Michael Cameron
Major funding provided by Minerals Management Service, Alaska OCS Region
Scott PegauJulie Richmond
Cy St. AmandMike SimpkinsSteve Trumble
Jay Ver HoefDave Withrow
Peregrine Falcon MarineWayward Wind Seafood
Northwind AviationCommander NorthwestSuburban Air Express
People & merchants of Homer, Alaska
Ori BadajosSteve BairdJohn BengtsonMichael CameronBob CarusoShawn DahleJennifer De GrootKim DonahueMillie GrayL.A. HolmesJohn JansenSteve JeffriesBeth JenkinsonShawn JohnsonChuck MonnettBrian MurphyRay Outlaw
Strong Seasonal Dynamics of Harbor Seals, Strong Seasonal Dynamics of Harbor Seals, an Upper-Trophic Predator in Cook Inletan Upper-Trophic Predator in Cook Inlet
Peter Boveng, Josh London and Robert MontgomeryPolar Ecosystems ProgramNational Marine Mammal Laboratory NOAA Alaska Fisheries Science CenterSeattle, [email protected]
Alaska Marine Science Symposium 2007
Photo: Michael Cameron
Distribution of Harbor SealsDistribution of Harbor Seals
Bering Sea
Alaska
Distribution and abundance ashore in August is well known
Shelik
of S
trait
Afognak Island
What is the abundance and distribution of seals ashore at other times of year?
What is the distribution of seals at sea, and what areas are most important for foraging?
What physical and biologicalcharacteristics of terrestrial andmarine habitats are related to the seasonal abundance and distribution of harbor seals ashore and at sea?
Questions:
Coo
k In
let
Study Area
Gulf of Alaska
Kachemak Bay
Kamishak Bay
Aerial Surveys•June, August, October & April•June 2003 – October 2005•~1 week during diurnal low tides•Daily replication•GPS-linked digital photos
0
1000
2000
3000
4000
5000
6000
7000
8000
Jun
-03
Jul-
03
Au
g-0
3
Se
p-0
3
Oct
-03
No
v-0
3
De
c-0
3
Jan
-04
Fe
b-0
4
Ma
r-0
4
Ap
r-0
4
Ma
y-0
4
Jun
-04
Jul-
04
Au
g-0
4
Se
p-0
4
Oct
-04
No
v-0
4
De
c-0
4
Jan
-05
Fe
b-0
5
Ma
r-0
5
Ap
r-0
5
Ma
y-0
5
Jun
-05
Jul-
05
Au
g-0
5
Se
p-0
5
Oct
-05
Month-Year
Ave
rag
e T
ota
l Co
un
tSeasonal Abundance Ashore
Pupping & molting periods
JuneModerate to high numbers along west shore, with very high numbers concentrated in Kachemak and Kamishak Bays
AugustSeals more aggregated along west shore, with very high numbers concentrated in Kachemak, Kamishak, and Iniskin Bays, Big River, and southern Augustine Island
OctoberNumbers much lower and less aggregated throughout the study area
AprilSimilar to October, with concentrations beginning to rebuild in Kachemak Bay
Montgomery, RA et al. In press. Spatial modeling of harbor seal use of haul-out sites in Cook Inlet, Alaska. MEPS
Cook Inlet
Satellite-linked dive recorders (SDRs)
•Argos geolocation•Dive depth & duration•Hourly haul-out timelines
Sep 2004May 2005Sep 2005May 2006
SDRs deployed on:40 Males37 Females77 Total
Winter Movements
Spring Movements
Foraging Areas• State-space Kalman filtered tracks are analyzed to provide kernal density estimates for time spent in each pixel.
• Densities aggregated from multiple seals will be compared with relevant physical and biological data to identify important determinants of foraging habitat.
Conclusions•A strong seasonal pattern in numbers of harbor seals ashore reflects constraints imposed by the annual life history events of reproduction and molting
•When not constrained by these life history events, harbor seals spend much more time in the water and range more widely
•Although foraging patterns vary widely among individuals, we suppose that the aggregate spatial patterns of time spent at sea will reflect variations in characteristics of the marine habitat (workshop to be hosted at KBRR in Homer)
