Ecosystems Fisheries-Oceanography Coordinated Investigations EcoFOCI Bering Sea Ice

Bering Sea-Ice Edge Expedition
Data - Seabird and Cetacean Observations

Seabird and Cetacean Observations During the Sea Ice 2006 Cruise, onboard the NOAA RV Miller Freeman (22 – 27 April, 2006)

George L. Hunt, Jr. & K. David Hyrenbach


School of Aquatic and Fishery Sciences,
University of Washington,
Box 355020,
Seattle, WA 98195, U.S.A.

 

As part of coordinated FOCI - RACE sea-ice operations, we censused marine bird and cetacean distributions in conjunction with acoustic surveys of the marginal ice zone.  One of us (KDH) surveyed marine birds and cetaceans from the bridge of the RV Miller Freeman, eye height of 10 m above the sea surface, during daylight hours while the vessel was underway.  The observer scanned the water ahead of the ship using hand-held 8X binoculars, and recorded all birds sighted within a 300-m arc, extending from the bow to the beam (90 degrees) on the side of the track with better visibility (e.g., lower glare).  We assigned each bird a behavioral code (flying with a specific direction, sitting on the water, feeding, following the ship, sitting on ice), and only recorded ship-following individuals when first encountered.  We also noted the number, behavior, and radial distance to any cetacean we encountered, as well as the weather conditions ( Beaufort Sea State, visibility, swell height) at hourly intervals.  We recorded these observations continuously into a field computer with a temporal resolution of 0.1 minutes. 

 

We surveyed a total of 453 km of track-line during four survey days (April 22, 23, 24, 27).  We recorded a total of 2,277 seabirds, and identified 2,093 (91.9 %) belonging to 13 different species (Table 1).  Six “common” species together accounted for over 98 % of all the identified birds: the Black-legged Kittiwake (33.2 %), the Thick-billed Murre (20.6 %), the Glaucous-winged Gull (19.3 %), the Northern Fulmar (17.3 %), the Glaucous Gull (5.6 %), and the Common Murre (2.1 %).  These locally-breeding species largely forage on fish, even though they also consume euphausiids and medusae.  Zooplankton-feeding seabirds were largely absent; with very low numbers of Parakeet Auklets (0.4 %), a generalist feeder known to consume euphausiids and larval fish.  We also encountered several rare species during our survey.  Most notably, we documented the occurrence of a Siberian (Vega Gull) and an Arctic (Ivory Gull) species in the Bering Sea marginal ice zone.  The remaining 184 (8.1 %) birds, including two pairs of closely-related species which are difficult to identify at-sea, were identified to genus.  Unidentified murres (Common or Thick-billed) and unidentified gulls (Glaucous or Glaucous-winged) accounted for 42.4 % and 57.6 % of these sightings, respectively.

We also recorded 10 cetaceans during this cruise, and identified 6 (60 %) to species level

(Table 2).  We documented three baleen (Humpback Whale, Minke Whale, Grey Whale) and one toothed (Killer Whale) cetacean species in the marginal ice zone.  In spite of their widespread occurrence in the Bering Sea in spring / summer, we did not encounter any Dall’s Porpoise during this survey.


Table 1.  Seabird observations during acoustic surveys along the marginal

sea ice zone by the RV Miller Freeman (April 22 - 27, 2006).

 

Total                Count

Proportion of Total

Overall Abundance

Species

(n)

(%)

(# / 100 km)

Black-legged Kittiwake

695

30.52

153.49

Thick-billed Murre

431

18.93

95.19

Glaucous-winged Gull

405

17.79

89.44

Northern Fulmar

362

15.90

79.95

Glaucous Gull

118

5.18

26.06

Unidentified Gull

106

4.66

23.41

Unidentified Murre

78

3.43

17.23

Common Murre

43

1.89

9.50

Ivory Gull

12

0.53

2.65

Parakeet Auklet

9

0.40

1.99

Red-faced Cormorant

9

0.40

1.99

Vega Gull

5

0.22

1.10

Arctic Tern

2

0.09

0.44

Herring Gull

1

0.04

0.22

Pigeon Guillemot

1

0.04

0.22

 

 

 

 

Total Birds

2277

100

502.87

 

Table 2.  Cetacean observations during acoustic surveys along the marginal

sea ice zone by the RV Miller Freeman (April 22 - 27, 2006).

 

Total                Count

Proportion of Total

Overall Abundance

Species

(n)

(%)

(# / 100 km)

Killer Whale

4

40.00

0.88

Unidentified Whale

4

40.00

0.88

Humpback Whale

1

10.00

0.22

Minke Whale

1

10.00

0.22

 

 

 

 

Total Cetaceans

10

100

2.21

 

 

NOAA - National Oceanic and Atmospheric Administration