NOAA Technical Memorandum NMFS-AFSC-38

Movements and Behavior of Satellitetagged Spotted Seals (Phoca largha)

in the Bering and Chukchi Seas

L. F. Lowry, K. J. Frost, R. Davis, R. S. Suydam, and D. P. DeMaster

U.S. DEPARTMENTOF COMMERCE

National Oceanic and Atmospheric Administration

National Marine Fisheries Service

Alaska Fisheries Science Center

May 1994
NOAA Technical Memorandum NMFS

The National Marine Fisheries Service’s Alaska Fisheries Science Center

uses the NOAA Technical Memorandum series to issue informal scientific and

technical publications when complete formal review and editorial processing

are not appropriate or feasible. Documents within this series reflect sound

professional work and may be referenced in the formal scientific and technical

literature.

The NMFS-AFSC Technical Memorandum series of the Alaska Fisheries

Science Center continues the NMFS-F/NWC series established in 1970 by

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by the Northwest Fisheries Science Center.

This document should be cited as follows:

Lowry, L. F., K. J. Frost, R. Davis, R. S. Suydam, and D. P. DeMaster.

1994. Movements and behavior of satellite-tagged spotted seals

(Phoca largha) in the Bering and Chukchi Seas. U.S. Dep. Commerce

NOAA Tech. Memo. NMFS-AFSC-38,71 p.

Reference in this document to trade names does not imply endorsement by

the National Marine Fisheries Service, NOAA.
Movements and Behavior of Satellitetagged Spotted Seals (Phoca largha)

in the Bering and Chukchi Seas

L. F. Lowry1 K. J. Frost: R.

by

Davis2, R. S. Suydam3, and D. P. DeMaster4

1Alaska Department of Fish and Game

1300 College Road

Fairbanks, AK 99701

2

Texas A&M University

Department of Marine Biology

Galveston, TX 77553

3North Slope Borough Departmentof Wildlife

P.O. Box 69

Barrow, AK 99723

4Alaska Fisheries Science Center

7600 Sand Point Way N.E., BIN C-15700

Seattle, WA 98115-0070

U.S. DEPARTMENT OF COMMERCE

Ronald H. Brown, Secretary

National Oceanicand Atmospheric Administration

D. James Baker, Under Secretary and Administrator

National Marine Fisheries Service

Rolland A. Schmitten, Assistant Administrator for Fisheries

May 1994
This document Is available to the public through:

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iii

ABSTRACT

In August 1991, satellite-linked platform transmitter

terminals (PTTs) were attached to four spotted seals (Phoca

largha) captured near a coastal haul out at Utukok Pass in the

northeastern Chukchi Sea. The locations and diving behavior of

the seals were monitored for periods of 64-259 days. Usable

position information was obtained for about 50% of the days that

the PTTs were operational.] During August-October, seals made

long feeding trips southwestward into the southern Chukchi Sea

and returned to haul outs at Kasegaluk Lagoon. Durations of atsea periods ranged from 8 to 902 hours, and the four seals on

average spent 7% of their time hauled out. Three seals with

still functional PTTs began their southward migration in October;

two of them used haul outs in the Kotzebue Sound region and the

northern Seward Peninsula. Seals migrated southward through

Bering Strait in November and were near St. Lawrence Island in

mid-December. The two seals whose PTTs worked into March-April

spent the late winter and early spring in the sea ice south and

southeast of St. Matthew Island. Haul outs on ice were

infrequent, with seals hauled out only 6% of the time, on

average. The number of dives to greater than 10 m depth averaged

160 and 284 per day for two of the seals. All dives were to

depths less than 100 m, and most lasted for less than 10 minutes.,

This study demonstrated the utility of satellite-linked

telemetry for studying the biology of spotted seals.

Modifications to PTT programming should allow future efforts to

gather more detailed information on movements and diving

behavior. 

CONTENTS

Page

Introduction ................................................ 1

Methods and Materials ....................................... 1

Field Work ............................................. 1

Equipment .. .. . .. .. .. ............ .. . ... .................. 2

Data Analysis .......................................... 3

Results ..................................................... 5

Capture and Tagging of Seals ........................... 5

PTT Performance ........................................ 6

Haulout Behavior ....................................... 7

Movements of Seals ..................................... 8

Diving Behavior ........................................ 10

Discussion .................................................. 11

Utility of PTTs for Spotted Seal Studies ............... 11

Description of Spotted Seal Biology .................... 12

Implications for Population Assessment ................. 15

Acknowledgments ............................................. 16

Citations ................................................... 17

Tables ...................................................... 19

Figures ..................................................... 31

Appendices .................................................. 47
INTRODUCTION

Spotted seals (Phoca largha) are medium-sized pinnipeds of

the family Phocidae that occur principally in the Okhotsk,

Bering, and Chukchi Seas. Because of morphological similarities

with the North Pacific harbor seal (Phoca vitulina richardsi) and

their adjacent and somewhat overlapping ranges, they have at

times been considered a subspecies (Phoca vitulina largha) (Burns

and Fay 1970, Bigg 1981). However, ecological differences in

habitat use and reproductive activities (Burns 1970) and detailed

morphological and craniometric analyses (Shaughnessy and Fay

1977, Burns et al. 1984) have confirmed that substantial

differences exist between harbor and spotted seals.

Unlike the relatively well studied harbor seal, the biology

of spotted seals is not well described (Quakenbush 1988). Most

of the information available has come from studies conducted in

the Bering Sea ice front in spring (e.g., Burns 1970, Fedoseev

1976, Braham et al. 1984). Pupping, breeding, and molting all

occur in association with sea ice from March through May. As the

sea ice cover diminishes and coastal areas become ice-free,

spotted seals move to nearshore areas of Alaska and Siberia, some

of them migrating northward into the Chukchi Sea. During the

open water season, they are commonly seen hauled out on coastal

barrier islands, sandbars, rocks, and reefs.

Frost et al. (1983) compiled information on the major summer

haulout areas used by spotted seals along the coast of the

eastern Chukchi Sea. The most important area identified was

Kasegaluk Lagoon (named after the Inupiat word for spotted seal),

where 1,000 or more seals were commonly seen hauled out inside

the barrier islands. This led to a detailed study conducted

during 1989-1991 to document spotted seal distribution,

abundance, and habitat use in this region (Frost et al. 1993).

There have been no studies to describe the activities and

behavior of spotted seals in Alaska at different times of the

year other than during the spring. In August 1991 we conducted a

study at Kasegaluk Lagoon to assess the feasibility of capturing

and attaching satellite tags to spotted seals. The principal

objective of this study was to evaluate the utility of satellite

telemetry for identifying movements, habitat use, and diving

behavior.

METHODS AND MATERIALS

Field Work

Field studies were conducted at Utukok Pass, a break in the

barrier island system in the central portion of Kasegaluk Lagoon

(Fig. 1). Personnel and equipment were transported by boat from

Point Lay to Utukok Pass, where a field camp was set up during

4-7 August 1991.
2

Seals were caught using a net drifted in the lagoon near the

pass. The net was constructed with large-diameter multifilament

nylon twine with a stretched mesh size of 20 cm, and it was 3.7 m

deep and 88 m long. The top of the net was supported by foam

floats and the bottom weighted with a lead line. Seals that

became entangled were immediately taken into a boat, removed from

the net, and put into hoop nets constructed of soft nylon netting

with a mesh size of about 2 cm. They were then taken to shore.

Once on shore, seals were either physically restrained or

sedated with a mixture of ketamine and diazepam administered

intramuscularly at standard doses of approximately 2-4 mg/kg

ketamine and 0.05-0.10 mg/kg diazepam (Geraci et al. 1981). Each

seal was weighed, measured (curvilinear length), and tagged on

the hindflippers with individually numbered plastic tags.

Approximately 50 cc of blood was drawn from the extradural

intervertebral vein (Geraci and Smith 1975).

A satellite-linked platform transmitter terminal (PTT) was

glued to the fur of the mid-dorsal surface of each seal using a

fast-setting epoxy (Fedak et al. 1984; Stewart et al. 1989).

With this type of attachment, it was assumed that the PTT would

stay attached until the seal molted in May-June. After tagging

was complete, animals were placed above the tide line near the

capture site and left undisturbed until they chose to return to

the sea.

Prior to being attached to the seals, PTTs were tested over

a period of 1-4 days. They were placed in two locations on

barrier islands off Kasegaluk Lagoon at a height of 2-3 m above

sea level. Location data based on transmissions from the PTTs

were compared to test site coordinates determined from National

Oceanic and Atmospheric Administration (NOM) nautical charts.

Equipment

Two types of PTTs were used. Units manufactured by Wildlife

Computers (SLTDR 1.0W; Woodinville, Washington) measured 13.5 cm

x 12.5 cm x 3.8 cm and weighed about 1,050 g. Units from

Telonics (ST-3; Mesa, Arizona) measured 17.5 cm x 10.0 cm x 3.5

cm and weighed about 800 g. Both types were powered by four

lithium C cells and had 1 watt of signal output through whip

antennas. The PTTs transmitted on 401.65 MHz to receivers

onboard NOAA polar orbiting satellites. PTTs were equipped with

conductivity switches so that they transmitted only when they

were out of the water. Telonics tags transmitted once every 60

seconds; Wildlife Computers tags transmitted once every 45

seconds when the animals were at sea, and switched to a rate of

once every 90 seconds when animals were hauled out. Wildlife

Computers tags operated continuously from the time they were

attached, while Telonics tags were duty cycled and sent data for

7 day periods followed by 7 days of no transmissions. Data
3

transmitted included PTT identification code, temperature, and

information on the number and duration of dives. Wildlife

Computers tags also gave data on dive depths and battery status.

Wildlife Computers tags collected and reported dive data in

bins. The minimum depth registered as a dive was 10 m. During a

dive, the SLTDR sampled depth every 10 seconds to-determine dive

duration and maximum depth. At the end of each dive, it was

incremented to one of six user-defined bins for maximum depth and

for duration. A set of bins was referred to as either a depth or

duration histogram. Depth bins were 10-50 m; 51-100 m; 101-150

m; 151-200 m; 201-250 m; and more than 250 m. Duration bins

were : 0-120 seconds; 121-240 seconds; 241-360 seconds; 361-480

seconds; 481-600 seconds; and more than 600 seconds. Data for

each bin were accumulated over 24-hour periods. Data were stored

for the previous 4 days and were transmitted whenever contact was

made with the satellite.

Telonics tags reported the duration of the previous dive

(i.e., the length of time since the conductivity switch had last

been dry), the number of dives in the previous 12-hour period

(i.e., the number of separate times the conductivity switch had

been dry), and the total amount of time spent diving in the

previous 12 hours (i.e., the total length of time that the

conductivity switch had been underwater).

Data Analysis

Data were obtained through the Argos system. Argos is a

joint program of the French Space Agency, the U. S. National

Aeronautics and Space Administration, and NOAA. Argos packages

are flown on NOAA Tiros spacecraft, and data processing is done

by Service Argos Inc., a subsidiary of the French Space Agency.

The Argos system recorded date and time of each signal

received by the satellite (termed an "uplink") and calculated a

location for the PTT based on Doppler shift whenever sufficient

signals were received during a satellite pass. The accuracy of

location calculations varies based in part on the number of

uplinks that occur during a satellite pass. Service Argos

assigns a quality ranking to location information. This rank is

based on predicted accuracy which suggests that for the best data

(assigned quality number 3), predicted locations are expected to

be within 150 m of actual locations 68% of the time. Locations

that are based on few uplinks or have other potential problems

are assigned quality 0. Processing of data to calculate quality

0 locations is an extra cost option, and we requested the

additional processing only for Wildlife Computers PTTs. Quality

0 locations were used principally to provide approximate

positions of seals on days when no quality 1-3 fixes were

obtained. When only one uplink occurred during a satellite pass,

sensor data were recorded but no location was calculated.
4

Stewart et al. (1989) and Mate et al. (1992) provide additional

description and analysis of the Argos system and its application

to marine mammal tracking.

For analysis and presentation of data, dates and times

reported by Service Argos were converted to true local time from

Greenwich mean time by subtracting 11-hours.

The distance and speed between each sequential pair of fixes

were calculated for all location records, and the results were

used to screen out inaccurate locations. Apparent movement

speeds of greater than 20 km/hr for periods greater than 5

minutes were considered suspect. Upon inspection of the data it

was evident that these high speeds were due to one or more

location fixes that clearly did not fit with the rest of the

data. These records were deleted from the database and distances

and speeds were recalculated.

A combination of location and sensor data was used to assess

when seals were hauled out. Wildlife Computers PTTs reported the

seals as hauled out or at sea based on the status of conductivity

sensors. After the tenth transmission with no interruption of

the conductivity switch, subsequent transmissions indicated that

the seal was hauled out of the water. When the conductivity

switch was interrupted, the status changed immediately back to

at-sea. As a result this indicator underrepresented the actual

duration of haul outs in two ways. First of all, since there was

a delay of 10 transmissions before the beginning of a haul out

was indicated, the haul out probably began about 450 seconds

previously. To correct for this in data analysis, each haul out

was assumed to have begun 7 minutes prior to the time indicated.

Also, when seals are at coastal haul outs in the Chukchi Sea,

they often lie in very shallow water where splashing or brief

immersions of the conductivity switch could result in at-sea

readings. Therefore, location records from around the times when

sensors indicated haul outs were inspected, and the duration of

the haul out bout was considered to include the entire period

that the seal was in the vicinity of the haul out.

Telonics PTTs did not have a specific indicator of haul

outs, but with every transmission they indicated the duration of

the previous dive. Instances where the indicated duration of the

previous dive remained constant for four or more transmissions

were considered to represent seals hauled out. The time of the

first identical transmission in the series was considered the

start of the haul out bout, and the end was recorded as the time

when the duration of the previous dive changed. When seals were

in the Chukchi Sea there were some periods adjacent to the

apparent haul out bouts in which there were a few dives indicated

that were consistently short (less than 60 seconds), and for

which locations plotted at or adjacent to the haulout site.

Those periods were included in the determination of the total
5

duration of haul outs. Similar decision criteria were used by

Born and Knutsen (1992) to determine haul outs of walrus

(Odobenus rosmarus) from satellite telemetry data.

In most cases, it was possible to distinguish haul outs on

land from those on ice simply by location. On some occasions in

November, haul out locations plotted near shore and could have

been either on land or on newly formed ice. In these instances,

the series of location fixes received during the haul out bout

was examined, and the substrate was considered to be ice if there

was substantial variation among them (i.e., indicating that the

seal was on ice that was drifting).

Dive data from Wildlife Computers tags were processed using

software provided by the manufacturer. An error-checking

algorithm was used to validate messages. Histogram messages were

sorted by date, period, and type, and duplicate messages that

provided data for the same day were removed.

A Kolmogorov-Smirnov test for goodness of fit (KS) was used

to test for uniformity in the hauling patterns of spotted seals

by time of day. Because hauling behavior is thought to change

seasonally, diel patterns of haul outs were tested separately for

the following periods: 4 August through 31 October 1991; 1

November through 31 December 1991; 1 January through 29 February

1992; and 1 March through 19 April 1992. In all tests the alpha

was set at 0.05.

RESULTS

Capture and Tagging of Seals

Four spotted seals were captured during the period 4-7

August (Table 1). No capture attempts were made on 5 August due

to stormy weather. Seals swimming toward the net at the surface

appeared to see and avoid the floats. However, when underwater

they did not seem to detect the webbing and readily became

entangled. The water was quite muddy. None of the seals

appeared injured or unduly stressed by the capture operations.

Three males and one female seal were captured. All animals

appeared to be in excellent physical condition, ranging in weight

from 45.5 to 106.8 kg. The three largest seals were sedated

prior to tagging; the other was restrained physically. The total

time required to measure an individual seal, collect blood, and

attach the PTT and flipper tags was approximately 60 minutes.

The seal that was not sedated went immediately into the water and

swam away from the tagging site. Sedated seals remained on the

beach an additional 20 to 40 minutes until they had recovered

from the effects of the drugs. Individual seals will be referred
6

to in this paper by their PTT identification number- (see Table

1).

PTT Performance

Satellite fixes were obtained from PTTs at two locations on

land: one approximately 10-km north of Point Lay (69°49.8'N,

162°59.0'W), and the other at the tagging site at Utukok Pass

(70°05.0'N, 162°31.0'W). The mean values of quality 3 locations

derived from PTTs were virtually identical to the chart

coordinates (69°49.6'N, 162°59.0'W and 70°05.0'N, 162°30.7'W).

Since the positions derived from the satellite data are probably

more accurate than those obtained from charts, variation among

quality 3 locations and errors in quality 1 and 2 locations were

determined by comparing each individual fix with the mean of the

quality 3 locations (Table 2). On average, quality 3 fixes at

the test location north of Point Lay varied by only 120 m; the

errors in quality 2 and 1 locations were about twice as large.

For all quality categories the mean error was about three times

greater for fixes at Utukok Pass. No quality 0 locations were

received from the transmitters on land.

After they were attached to seals, PTTs sent signals for

64-259 days. The first PTT to stop sending signals was last

heard on 10 October 1991; one unit continued to transmit until 12

April 1992 (Table I). The periods over which signals were

received were as follows: PTT 14098-149 days; PTT 14099-64 days;

PTT 10919-215 days; and PTT 10920-259 days. Because the Telonics

tags were duty cycled, the actual number of days that the

transmitters operated was about one-half of the total time (111

days for PTT 10919 and 133 days for PTT 10920). However, the

Telonics tags were activated at mid-day so that during each on

cycle there were two half days and six full days of transmission.

Therefore, the total number of calendar days on which data could

have been received was 126 for PTT 10919 and 152 for PTT 10920.

In total, 1,571 location records for all PTTs combined were

received from Service Argos. When those records were screened

based on the assumption that seals were unlikely to swim at

speeds greater than 20 km/hour for more than 5 minutes, 126

records were deleted. Of those, 119 were location quality 0, 5

were quality 1, and 2 were quality 2. The remaining data set

included 631 class 0 locations and 814 locations of classes 1, 2,

or 3.

When only quality 1-3 locations are considered, the total

number of fixes obtained for a single seal ranged from 51 to 289

(Table 3). Most were of location quality 1 (49%-60%) or quality

2 (35%-47%); relatively few were quality 3 (4%-6%). On average,

each PTT gave 0.8 to 2.6 fixes of quality 1-3 per operational

day. One or more fixes of quality 1-3 were obtained on 23%-59%

of the days that each PTT was operational. Quality 0 locations
7

provided positions for seal 14098 on 52 additional days and for

seal 14099 on 12 additional days.

Haulout Behavior

Interpretations of the daily behavior of each seal based on

PTT data are given in Appendices A-D. In August and September

all recorded haul outs were at either the tagging site, Utukok

Pass (8 records), or to the north at Akoliakatat Pass (5 records)

(Fig. 2). Three of the four seals hauled out at the southern end

of Kasegaluk Lagoon in early to mid-October, and two later hauled

out on land in Kotzebue Sound and on the north side of the Seward

Peninsula. Undoubtedly some haulout bouts were not recorded

since two of the transmitters were operational only 50% of the

time. After mid-November all haul outs were on ice.

There was great variability in the lengths of haulout bouts

and at-sea periods for seals in the Chukchi Sea during

August-October (Table 4). Recorded haulout bouts ranged from 0.5

to 114.0 hours, with considerable variability within and among

individual seals. Lengths of at-sea periods could be determined

only for transmitters that were not duty cycled: they ranged from

8.1 to 902.2 hours. 'Based on the total time hauled out and the

total time at sea, individual seals spent 1.2%-13.9% of their

time on land and 86.1%-98.8% of their time at sea (Table 5).

Combining data from all individuals, the four seals on average

spent 6.8% of their time hauled out on land.

Data on the amount of time spent hauled out on ice were

compiled for semi-monthly periods from November through mid-April

(Table 6). Two of the three PTTs that functioned during this

time were duty cycled, so the number of haulout bouts is

underestimated. Nonetheless, the results show that seals hauled

out infrequently with no obvious seasonal trend. Mean durations

of individual haulout bouts (only complete haul outs included)

for each seal were: PTT 10919-6.5 hours (s.d.=5.11, range

1.5-20.5 hours, n=20); PTT 10920-4.3 hours (s.d.=3.58, range

1.2-15.6 hours, n=22); and PTT 14098-7.9 hours (s.d.=4.0, range

0.2-14.2 hours, n=9). The overall mean duration of an on-ice

haul out was 5.8 hours (s.d.=4.46). The proportion of the

monitored time that individual seals spent hauled out within a

semi-monthly period varied from 0% to 51.2%, with a combined

average for the three seals of 6.2% (Table 7).

Because signals from the PTTs were not monitored constantly,

it is not possible to determine the precise time of day that

haulout bouts began and ended. In order to look for diurnal

haulout patterns, we calculated the number of times that PTT data

indicated a seal was hauled out at any time within each hour of

the day. These data on frequency of haul out by hour were

grouped by individual seal for four seasonal periods (Appendices

E-H).
8

When data for all seals were combined, there were obvious

seasonal changes in the time of day during which seals were

recorded as hauled out (Table 8, Fig. 3). During August-October,

seals hauled out with equal frequency during all hours of the day

(KS score=0.016, n=312, P<0.59). In November-December, haul outs

varied by hour (KS score=0.108, n=178, 0.01<P<0.05); the peak

haul out occurred during 0200-0700 hours and l700-2100 hours.

The pattern was similar in January-February with a distinct

minimum in haulout activity during 0800-1600 hours (KS

score=0.155, n=129, P<0.01). In March-April, haulout behavior

was not constant over time (KS score=0.206, n=57, 0.01<P<0.05).

During this period, haulout frequency was highest between 1100

and 1600 hours.

Movements of Seals

During the time that the PTTs were functional, spotted seals

moved over great distances. Based on the sum of distances

between sequential locations, the total distances over which

seals were tracked were: PTT 10919--6,036 km in 212 days; PTT

10920--4,426 km in 259 days; PTT 14098--9,642 km in 149 days; and

PTT 14099--2,355 km in 64 days. Overall movements are shown in

Figures 4-7, in which alllocation records that fit the

time/speed criteria are plotted.

During August, September, and October, seals made trips to

sea from coastal haul outs in the eastern Chukchi Sea (Fig. 8).

Seals 14098 and 14099 spent most of their time between Kasegaluk

Lagoon and Point Hope in a roughly triangular area extending

offshore from Point Hope to a distance of about 200 km.

Information on at-sea movements is much less detailed for seals

10919 and 10920 because their PTTs were duty cycled, and quality

0 location data were not obtained. It appears that their

movements to sea were also mostly to the southwest from Kasegaluk

Lagoon. Seal 10919 made two trips from Kasegaluk Lagoon to just

north of Bering Strait and back.

The characteristics of trips to sea are listed in Table 9

for those instances where the complete trip is recorded in the

data. Data from duty cycled PTTs were not included unless two

haulout bouts occurred during a continuous 'I-day period when the

transmitter was on. Estimates of distances covered and speeds

are minimums because they are based on straight-line distances

between sequential locations.

The longest recorded trip was for seal 14099; it was at sea

for 902 hours (37.6 days) and traveled a minimum distance of

1,685 km. It is quite possible that longer trips were made by

seals with duty cycled PTTs. For example, seal 10919 was located

at Utukok Pass on 15 September and on 30 September, it was off

Inchoun on the Chukchi Peninsula, a straight-line distance of
9

530 km. On 14 October, it was again hauled out at Kasegaluk

Lagoon near Naokok Pass.

Three PTTs were still operational when seals began their

southward migration from Kasegaluk Lagoon (Fig. 9). Seal 10919

left Naokok Pass on 16 October and travelled to Kotzebue Sound,

where it-hauled. out at Cape Espenberg on 10 November. Seal 10920

went to sea from Akunik Pass on 17 October and also moved to

Kotzebue Sound, hauling out off Kotzebue on 30 October and in

Shishmaref Inlet on 3 November. Because these two PTTs were duty

cycled, it is possible that other haul outs were used, as well.

Seal 14098 left Utukok Pass on 3 October, and its next recorded

haul out was on ice north of the Seward Peninsula on 14 November.

Since that PTT was not duty cycled, it appears that seal 14098

was at sea for approximately 990 hours (41.2 days) while on its

southward migration.

Seal 10919 passed southward through Bering Strait between 17

and 23 November (while the duty cycle was off). It was

subsequently located several times along the Chukchi Peninsula in

Seniavin Strait and off Cape Chukotskiy (Fig. 9). On 14

December, it was located near the northwest tip of St. Lawrence

Island.

After passing through Bering Strait sometime between 4 and

10 November (while the duty cycle was off), seal 10920 was

located in Port Clarence, along the south side of the Seward

Peninsula, and in Norton Sound (Fig. 9). During 9-13 December,

it was in the vicinity of St. Lawrence Island.

Seal 14098 passed southward through Bering Strait during

16-17 November. It then spent time along the Chukchi Peninsula

in the vicinity of St. Lawrence Bay, Mechigmen Bay, and Cape

Chaplino (Fig. 9). From 19 to 22 December, seal 14098 was in the

vicinity of St. Lawrence Island.

From St. Lawrence Island, all three seals moved generally

southward, presumably with the advancing sea ice front (Fig. 10).

Seal 14098 moved south in a virtually straight line. With the

exception of one haul out on 29 December, it spent almost all of

its time in the water until 1 January when it began a series of

haulout bouts that lasted until the PTT stopped transmitting on 2

January. Seals 10919 and 10920 moved southward more slowly.

Their positions on 6 January were 130 km and 205 km farther to

the north than 14098 on 2 January. During January-March, seals

10919 and 10920 made considerable north-south and east-west

movements, but they stayed in the general area south to southeast

of St. Matthew Island.

Minimum distance moved and rate of movement of seals during

their southward migration and while in the Bering Sea are

summarized in Table 10. Because their PTTs provided fewer
10

locations, data for seals 10919 and 10920 are biased low. The

rates of movement for seal 14098, which were at least twice as

great, may be more realistic. The most rapid period of movement,

with an average speed of 90 km/day, was for 14098 when the seal

was moving southward from St. Lawrence Island in late December.

Diving Behavior

The Telonics PTTs did not have a pressure sensor, and they

reported dive information based only on when conductivity sensors

were wet or dry. The data that were reported included some dives

that were of reasonable length, but in many instances the data

suggested that dives lasted several hours or days. Since there

was no way to determine which dive records were valid and which

were not, no analysis was done on the dive data from the Telonics

PTTs.

The Wildlife Computers PTTs used pressure sensors to measure

the duration and maximum depth of dives, which was summarized in

24-hour histogram bins. Information on depth and duration of

dive was collected for over 21,000 dives made by seal 14098 and

over 12,000 dives by seal 14099. The minimum depth for which the

pressure sensor recorded a dive was 10 m. Because all of

Kasegaluk Lagoon and the nearshore waters along the Chukchi Sea

coast are less than 10 m, dives in these shallow areas were not

recorded and are not represented in the data. For both seals,

the majority of dives were in the 10-50 m range and none were

deeper than 100 m (Table 11, Fig. 11). Seventy-seven percent of

all recorded dives for seal 14098 and 69% for seal 14099 were

10-50 m. For both seals, there was considerable monthly

variability in depth of dive (Fig. 12). In August, 84% of the

dives of each seal were 10-50 m. The proportion of shallow dives

decreased to 62%-67% in September and 48%-56% in October. PTT

14099 stopped transmitting in October. During the southward

migration in November-December, the dives of seal 14098 were

again shallower, with 84%-95% of all recorded dives in the 10-50

m depth bin.

The number of dives recorded per day was substantially less

for the large adult female than for the smaller male (Fig. 13).

The adult female (14098) made an average of 160 dives per day

while the smaller male (14099) made 284 dives per day. There was

considerable variation in the average daily number of dives by

each seal, but seal 14099 always made approximately 50% more

dives. During August-October both seals had periods of intense

diving followed by one or more days of few or no dives greater

than 10 m. There was less variation in the number of dives per

day for the adult female, but after 1 November her diving

behavior became less regular.

The duration of dives differed considerably between the

adult female (14098) and the young male (14099) (Table 12, Fig.
11

14). Only 14% of the total dives by the young male were longer

than 4 minutes, and less than 1% were longer than 8 minutes. In

contrast, 69% of dives made by the female were longer than 4

minutes and 12% were longer than 8 minutes. After migration

began in November, the female made more short dives and fewer

dives of intermediate length (Fig. 15). The percentage of long

dives remained about the same. Forty-three percent of her dives

in November and December were from 0-4 minutes, 44% were from 4-8

minutes, and 13% were longer than 8 minutes.

DISCUSSION

Utility of PTTs for Spotted Seal Studies

During our 1991 field work, spotted seals were relatively

easy to catch. Weather was generally windy and water in the

lagoon was relatively murky. Seals did not appear to detect the

net, and four animals were caught in the 3 days that we were able

to work. In contrast, when we attempted to catch seals in August

1992 the weather was good and the lagoon water was clear. Seals

detected the net more readily and were much more difficult to

catch. It appears that muddy conditions in the lagoon are

necessary for effective netting of seals using the equipment and

techniques that were available to us.

In general the PTTs that we attached to spotted seals worked

well and provided a wealth of data. One unit (14099) failed

prematurely, apparently due to faulty batteries. Prior to the

failure of this PTT on 10 October 1991, there were several

periods of 4-9 days when no signals were received (Appendix D).

This was probably due to the automatic low battery power shutoff

in the PTT being triggered when the unit was in cold water. The

last signals were received about 1 hour after the seal had hauled

out.

We obtained quality 0 location data for only two of the

PTTs. While it was not possible to verify the accuracy of those

locations, most of them (631/750) passed the criteria that we

used to screen out unrealistic positions (apparent speeds greater

than 20 km/hour for more than 5 minutes). Since no quality 3

locations and few quality 1 or 2 locations were deleted, we think

the screening criteria that we used were appropriate. Using the

quality 0 locations resulted in a near doubling of the number of

days on which the seals' locations were known (from 57 to 109

days for 14098 and 15 to 27 days for 14099). We recommend that

quality 0 location data be obtained for all PTTS put on spotted

seals in the future.

Duty cycling two of the PTTs resulted in an approximate

doubling of the period sampled, and extended the data series into

March-April. However, there was a considerable loss of ability
12

to interpret the data, particularly with regard to the

characteristics of feeding trips in the Chukchi Sea.

The Telonics PTTs did not provide useful information on

diving behavior. Since they were mounted in the middle of the

seals' backs, the conductivity switches did not break the surface

after every dive. While the indicated duration of some dives

appeared reasonable, many were unrealistically long. Telonics

PTTs are available with an alternate programming mode in which

they record the amount of time the conductivity switch is dry

during a preset period of the day. This could provide useful

information on haulout behavior, and we recommend collection of

this type of data if additional Telonics PTTs are used on spotted

seals.

The Wildlife Computers PTTs provided data on the maximum

depths of dives and duration of dives. We had hoped to use these

data, in combination with information on water depth and the

seal's location, to indicate whether seals were feeding in the

water column or near the bottom. However, the PTTs that we used

had been designed for use on harbor seals that may feed in deep

water, and the minimum depth to be considered a dive (10 m) and

the depth bins were not ideal for spotted seals. The nearshore

Chukchi Sea, particularly Kasegaluk Lagoon, is so shallow that

the seals could have been diving regularly in this region and the

PTTs would not have registered these dives. The shallowest depth

bin (10-50 m) was too broad since much of the Chukchi Sea is less

than 50 m deep and all of it is less than 75 m deep. Over twothirds of the total dives by both seals were in the first bin,

which provided little insight into the seals' behavior. In the

future, we recommend that PTTs for spotted seals that are

equipped with pressure sensors be programmed to record dives with

minimum depths of 4 m, and that the dive depth bins be set to

provide additional resolution in depths of less than 100 m.

Description of Spotted Seal Biology

Observations of locations and numbers of spotted seals

hauled out in Kasegaluk Lagoon have been recorded for many years

(Frost et al. 1983). Aerial surveys were conducted in 1989-1991

to document use of particular haul outs, and the seasonal

variation in seal numbers (Frost et al. 1993). However, none of

that information provided any insight into the movements, site

fidelity, or diving behavior of seals. It was unknown how often

they hauled out; whether individual seals used more than one haul

out location; whether they fed in and near the lagoon, or

travelled to other areas; and when the southward migration began.

Data from this study indicate that during the period from

August through mid-April, spotted seals haul out infrequently.

During August-October, the four seals that we tagged spent an

average of only 7% of their time on land. During November to
13

early April, they spent 6% of their time hauled out on ice.

There was no synchrony apparent in the days on which the four

seals hauled out. Tagged seals were recorded as hauled out on

land on 22 days during August-October: 11 August was the only day

on which more than one seal hauled out. During November to early

March, seals hauled out on 33 different days, but there were only

eight instances when two seals were hauled out on the same day

and none when three were hauled out.

The tagged seals showed significant seasonal changes in the

diurnal pattern of hauling out. During August-October, seals

hauled out with equal frequency during all hours, which confirms

the results previously obtained from analysis of aerial survey

counts (Frost et al. 1993). During November-February, seals

showed a strong tendency to haul out less often during mid-day.

Possible reasons for such a pattern are presently unknown. In

March and April, seal behavior was different, and haul outs

occurred predominantly during mid-afternoon. This may have been

due to increasing daylight and temperatures and the onset of

seasonal activities such as pupping and breeding.

Data from the tagged seals demonstrated that spotted seals

using Kasegaluk Lagoon haul out at more than one location. Three

of the four tagged seals used both Utukok and Akoliakatat Passes

for hauling out in August and September. The fourth, seal 14099,

hauled out only once after being tagged at Utukok and that was at

the same location. No other haul outs were recorded as being

used in August and September, although two of the seals were

monitored only half of the time and they could have used other

haul outs when the PTTs were not transmitting. During

mid-October, when Kasegaluk Lagoon began to freeze, three of the

seals hauled out near the southern end of the lagoon before

beginning their southward migration. The large female (14098)

did not, and her last haul out on land was at Utukok Pass on

October 3. She did not haul out again until November 14, on ice.

The use of the southern passes during October is in agreement

with reports of Point Lay residents that spotted seals use the

southernmost passes in Kasegaluk Lagoon after the lagoon to the

north begins to freeze (Warren and Dorcas Neakok, Point Lay,

Alaska, personal communication, 7 August 1991). In fact, the

Inupiat name for the most southern part of Kasegaluk Lagoon

(Kasigialik) means "place where spotted seals remain."

No new land haul outs were identified as a result of this

study. The haul outs used by the four spotted seals tagged in

1991 had all been previously identified by coastal residents or

in the course of biological studies (Frost et al. 1983, Frost

et al. 1993). One or more of the tagged seals spentsome time in

most of the previously known haulout areas in northern Alaska,

although according to the telemetry data, they did not always

haul out. After leaving the Kasegaluk Lagoon region in

mid-October, seals spent time near haul outs in Kotzebue Sound,
14

Port Clarence, northern Norton Sound, and the south side of St.

Lawrence Island.

Perhaps the most surprising finding of this study was the

great distances that spotted seals travelled during their summer

foraging trips. The smallest male (10919) made two round-trips

from Kasegaluk Lagoon to the area just north of Bering Strait, a

one-way distance of over 500 km. On one of these trips the seal

went to the coast of the Chukchi Peninsula just west of Inchoun,

a major spotted seal haul out. Although the locations plotted at

the coast, the PTT sensors did not record the seal as being

hauled out. However, the PTT was duty cycled and was not

transmitting during part of the time the seal was in this area.

Two of the seals made trips of more than 300 km along the Alaskan

coast to Cape Lisburne, Point Hope, and/or Kivalina. Only the

adult female remained, relatively close to Kasegaluk Lagoon.

Until the middle of October, the farthest she travelled was about

100 km to the southern end of the lagoon.

The pattern of the fall migration was quite consistent among

the three seals that still had functional transmitters. Movement

southward began in mid-October. None of the tagged seals were

located north of Point Hope after 6 November. All three passed

through Bering Strait during the first 3 weeks of November, and

all were near Saint Lawrence Island sometime during 13-22

December. After December, rates of movement differed, but the

three seals all were generally south of Saint Matthew Island from

January to April.

Although there were problems with the settings that we used

to collect depth of dive data, some interesting information was

obtained. Diving behavior appeared to change with time. In

August, over 80% of the dives of both seals were less than 50 m

deep. This correlates well with information on water depth at

the locations where they were diving: both seals spent most of

the month near shore in shallow water along Kasegaluk Lagoon or

in Ledyard Bay. On some days when the seals were in Ledyard Bay

the PTTs registered no dives, which is consistent with the fact

that most of Ledyard Bay is shallower than 10 m. During late

August, seal 14098 was located west of Cape Lisburne in water

deeper than 50 m, yet most of her dives remained less than 50 m.

In September, both seals made more dives (33%-38%) in the

50-100 m range, and both began to feed in the area west and

southwest of Cape Lisburne and Point Hope. Neither spent time in

Ledyard Bay. As the number of shallow dives decreased, the

number of dives shorter than 2 minutes in duration also

decreased. In October, more of the dives of both seals were

greater than 50 m, and there were fewer dives of short duration.

Seal 14099 was located over 150 km west of Cape Lisburne where

the water is deeper than 50 m. Seal 14098 spent a few days in
15

shallow water north of Cape Lisburne, but most of the time it was

in deeper water west and southwest of Point Hope.

In early November, seal 14098 returned to Ledyard Bay and

registered no dives while in this shallow area. This was

followed by a few days spent diving in deeper water southwest of

Point Hope. Most of her dives during late November and December

were less than 50 m, and many were of short duration (less than 4

minutes).

These data suggest that feeding and diving behavior changed

through summer and fall, and that the seals may have been moving

to take advantage of variations in the availability of prey.

Future tagging efforts using PTTs with different depth bin

settings should provide more useful information about diving and

feeding behavior.

Implications for Population Assessment

Spotted seal surveys are usually conducted when seals are

hauled out on sea ice during the spring (e.g., Braham et al.

1984), or on land haul outs in the summer (e.g., Frost et al.

1993). Because only one PTT continued to function into April, we

did not gather much information that could be used to interpret

the results of spring surveys. Different types of PTTs or

different programming could be used to extend battery life and

gather information on haulout behavior during spring. We

attached a 0.5 watt Wildlife Computers PTT to one spotted seal at

Utukok Pass in late August 1992, and that tag provided continuous

data through mid-April 1993.

The information that we obtained has major implications for

surveying and estimating the abundance of spotted seals based on

summer counts. Prior to this study, we knew that not all the

spotted seals using an area hauled out at the same time on the

same day. However, the alternation between very high counts and

very low counts suggested some synchrony in haulout behavior,

perhaps dependent on weather (Frost et al. 1993). We had assumed

that maximum counts probably represented a substantial proportion

of the seals using the area, and therefore could be used as a

reasonable estimate of minimum abundance. Clearly, this is not

the case. Seals are present at Kasegaluk Lagoon haul outs on

almost every day of the summer and early autumn, yet tagged seals

hauled out on only a few days each month.

Frost et al. (1993) flew aerial surveys of seal haul outs in

Kasegaluk Lagoon during 18-22 August and 25-29 September 1991.

Seal 14098 was hauled out on 18-19 August, but not during 20-22

August. None of the other three seals hauled out during this

period. Relatively few seals were counted on 18, 21, and 22

August (157-425), but counts were quite high on 19 and 20 August

(853-1235). Counts were relatively high on all three survey days
16

in late September, with the highest count of the season on the

29th (2,137-2,237). Seal 14098 was at haul outs on all the

September survey days, seal 14099 did not haul out, and the other

two PTTs were duty cycled off. Thus, although aerial survey

counts were high on some days and low on others, telemetry data

showed that not all seals were hauled out even on the days when

the highest counts were made.

Use of satellite telemetry in conjunction with aerial

surveys could provide better estimates of spotted seal abundance.

However, a larger sample of tagged seals is needed to estimate

the fraction of seals that are hauled out and counted during

surveys. A preliminary analysis using data collected during this

study suggests that a population estimate with a coefficient of

variation of 30% could be obtained if data on haulout behavior

were obtained from 10 to 20 tagged seals (J. Laake, NMML,

Seattle, WA, pers. commun., 21 September 1993).

ACKNOWLEDGMENTS

Funding for preparation of this report was provided by the

National Marine Fisheries Service, National Marine Mammal

Laboratory (NMML). The NMML also assisted in this project by

covering the cost of acquiring some Argos data, and by allowing

us to operate under their Scientific Research Permit to Take

Marine Mammals. We particularly thank Howard Braham for his

continued interest in spotted seals and his support of our work.

Additional support for this project was provided by the Alaska

Department of Fish and Game, the North Slope Borough Department

of Wildlife Management, the Texas A & M University Department of

Marine Biology, the U. S. Department of the Interior Minerals

Management Service, and the U. S. Marine Mammal Commission. For

assistance with field work, we thank Marie Adams, Geoff Carroll,

and in particular Warren and Dorcas Neakok. Assistance with the

analysis and presentation of data was provided by Rob DeLong,

Brent Schefter, and Gregory Emmanuel. We thank Jeff Laake for

his helpful review of the draft report.
17

CITATIONS

Bigg, M. A. 1981. Harbor seal. P. 1-27. In: S. H. Ridgway and

R. J. Harrison (eds.), Handbook of marine mammals. Academic

Press, London.

Born, E.-W., and L.O. Knutsen. 1992. Satellite-linked radio

tracking of Atlantic walruses (Odobenus rosmarus )

in northeastern Greenland, 1988-1991. z. Saugetierkunde

57:275-287.

Braham, H. W., J. J. Burns, G. A. Fedoseev, and B. D. Krogman.

1984. Habitat partitioning by ice-associated pinnipeds:

Distribution and density of seals and walruses in the Bering

Sea, April 1976. P. 25-47. In: F. H. Fay and G. A.

Fedoseev (eds.), Soviet-American cooperative research on

marine mammals. Vol. 1. Pinnipeds. U.S. Dep. Commer., NOAA

Tech. Rep. NMFS 12.

Burns, J. J. 1970. Remarks on the distribution and natural

history of pagophilic pinnipeds in the Bering and Chukchi

Seas. J. Mammal. 51:445-454.

Burns, J. J., and Fay, F. H. 1970. Comparative morphology of

the skull of the ribbon seal, Histriophoca fasciata, with

remarks on systematics of Phocidae. J. Zool. (Lond.)

161:363-394.

Burns, J. J., Fay, F. H., and Fedoseev, G. A. 1984.

Craniological analysis of harbor and spotted seals of the

North Pacific region. P. 5-16. In: F. H. Fay and G. A.

Fedoseev (eds.), Soviet-American cooperative research on

marine mammals. Vol. 1. Pinnipeds. U.S. Dep. Commer., NOAA

Tech. Rep. NMFS 12.

Fedak, M. A., S. S. Anderson, and M. G. Curry. 1984. Attachment

of a radio tag to the fur of seals. Notes from the Mammal

Society 46:298-300.

Fedoseev, G. A. 1976. Principal populational indicators of

dynamics of numbers of seals of the family Phocidae.

Ecologiya 5:62-70.

Frost, K. J., L. F. Lowry, and J. J. Burns. 1983. Distribution

of marine mammals in the coastal zone of the eastern Chukchi

Sea during summer and autumn. U.S. Dep. Commer., NOAA,

OCSEAP Final Rep. 20:563-650. Available from U.S. Dep.

Interior, Minerals Managements Service, Anchorage, AK.

Frost, K. J., L. F. Lowry, and G. Carroll. 1993. Beluga whale

and spotted seal use of a coastal lagoon system in the

northeastern Chukchi Sea. Arctic 46:8-16.
18

Geraci,. J. R., and T. G. Smith. 1975. Functional hematology of

ringed seals (Phoca hispida) in the Canadian Arctic. J.

Fish. Res. Board Can. 32:2559-2569.

Geraci, J. R., K. Skirnisson, and D. J. St. Aubin. 1981. A safe

method for repeatedly immobilizing seals. J. Amer. Vet.

Med. Assn. 179:1192-1193.

Mate, B. R., S. Nieukirk, R. Mesecar, and T. Martin. 1992.

Application of remote sensing methods for tracking large

cetaceans: North Atlantic right whales (Eubalaena

glacialis). Final Rep. to U.S. Dep. Inter., Minerals

Management Service, Reston. VA. OCS Study MMS 91-0069.

Quakenbush, L. T. 1988. Spotted seal. P. 107-124. In: J. W.

Lentfer (ed.), Selected marine mammals of Alaska: Species

accounts with research and management recommendations.

Marine Mammal Commission, Washington, D. C.

Shaughnessy, P. D., and Fay, F. H. 1977. A review of the

taxonomy and nomenclature of North Pacific harbour seals.

J. Zool. (Lond.) 182:385-419.

Stewart, B. S., S. Leather-wood, P. K. Yochem, and M.-P.

Heide-Jorgensen. 1989. Harbor seal tracking and telemetry

by satellite. Mar. Mamm. Sci. 5:361-375.
19

Table l.--Spotted seals captured and equipped with satellitelinked platform transmitter terminals (PTT) at Utukok

Pass, Alaska, August 1991.
20

Table 2. --Results of accuracy tests of satellite-linked platform

transmitter terminals (PTT) at Kasegaluk Lagoon,

Alaska, August 1991.
21

Table 3. --Number and quality of location fixes obtained for

satellite-tagged spotted seals.
Table 4. --Durations of haulout bouts and trips to sea of spotted seals in the

Chukchi Sea during August-October 1991. Times are given in hours.
Table 5.--Characteristics of haulout bouts and trips to sea of spotted seals in the

Chukchi Sea during August-October 1991. Times given are in hours. Ranges

are shown in parentheses.
24

Table 6. --Amount of time (hours) hauled out on ice for

spotted seals in the Chukchi and Bering Seas,

November 1991-April 1992. Numbers in

parentheses are the number of haulout bouts

within the period.
25

Table 7. --Percent of time hauled out on ice in the Chukchi and

Bering Seas for individual spotted seals and all seals

combined.
26

Table 8. --Frequency of hauling out of spotted seals in relation

to time of day. Data from all individual platform

transmitter terminals are combined.
Table 9. --Characteristics of trips to sea by spotted seals during August-October 1991.
Table 10. --Movements of satellite-tagged spotted seals during the southward migration in

the Chukchi and Bering Seas, October 1991-April 1992.
29

Table 11. --Depths of dives of satellite-tagged spotted seals in

the Chukchi and Bering Seas, August-December 1991.
Table 12.--Durations of dives (minutes) of two satellite-tagged spotted seals in the

Chukchi and Bering Seas, August-December 1991. Percentages are given in

parentheses.
31

Figure 1. Map of the northeastern Chukchi Sea showing Kasegaluk

Lagoon and Utukok Pass.
Figure 2. Map of the eastern Chukchi Sea and Bering Strait

showing locations on land used for hauling out by

satellite-tagged spotted seals, August-November 1991.
Figure 3. Seasonal changes in diurnal haulout patterns of

satellite-tagged spotted seals in the Chukchi and

Bering Seas, August 1991-April 1992.
Figure 4. Map of the Chukchi and Bering Seas showing movements of

seal 14098 during August 1991 to January 1992.
Figure 5. Map of the Chukchi and Bering Seas showing movements of

seal 14099 during August 1991 to October 1991.
Figure 6. Map of the Chukchi and Bering Seas showing movements of

seal 10919 during August 1991 to March 1992.
Figure 7. Map of the Chukchi and Bering Seas showing movements of

seal 10920 during August 1991 to April 1992.
Figure 8. Map showing summer feeding trips of satellite-tagged spotted seals in the

Chukchi Sea, August-October 1991.
Figure 9. Map showing the fall migration of satellite-tagged spotted seals in the Chukchi

and Bering Seas, October-December 1991.
Figure 10. Map showing the winter movements of satellite-tagged spotted seals in the

Bering Sea; December 1991-April 1992.
41

Figure 11. Depths of all dives recorded for two satellite-tagged

spotted seals in the Chukchi and Bering Seas, 1991.
Figure 12. Monthly distribution of depths of dives recorded for

two satellite-tagged spotted seals in the Chukchi and

Bering Seas, 1991.
4 3

Figure 13. Number of dives recorded per day for two satellitetagged spotted seals in the Chukchi and Bering Seas,

1991.
Figure 14. Duration of all dives by month for two satellitetagged spotted seals in the Chukchi and Bering Seas,

1991.
Figure 15. Monthly distribution of duration of dives recorded for

two satellite-tagged spotted seals in the Chukchi and

Bering Seas, 1991.
APPENDICES
THIS PAGE INTENTIONALLY LEFT BLANK
49

Appendix A.-- Daily activities of seal with PTT 10919.

Positions of animals on land or ice are the

average for all fixes obtained during that haulout

bout. Positions at sea are the average of all

fixes obtained during that day.
50

Appendix A. --Continued.
51

Appendix A. --Continued.
52

Appendix A. --Continued.
53

Appendix A. --Continued.
54

Appendix A. --Continued.
55

Appendix B.-- Daily activities of seal with PTT 10920.

Positions of animals on land or ice are the

average for all fixes obtained during that haulout

bout. Positions at sea are the average of all

fixes obtained during that day.
56

Appendix B. --Continued.
57

Appendix B. --Continued.
58

Appendix B. --Continued.
59

Appendix B. --Continued.
60

Appendix B. --Continued.
61

Appendix B. --Continued.
62

Appendix C.-- Daily activities of seal with PTT 14098.

Positions of animals on land or ice are the

average for all fixes obtained during that haulout

bout. Positions at sea are the average of all

fixes obtained during that day.
63

Appendix C. --Continued.
64

Appendix C. --Continued.
65

Appendix C. --Continued.
66

Appendix D.-- Daily activities of seal with PTT 14099.

Positions of animals on land or ice are the

average for all fixes obtained during that haulout

bout. Positions at sea are the average of all

fixes 'obtained during that day.
67

Appendix D. --Continued.
68

Appendix E.-- Frequency of hauling

seals in relation to

October 1991.

out of individual spotted

time of day, 4 August-31
Appendix

69

F.-- Frequency of hauling out of individual spotted

seals in relation to time of day, 1 November-31

December 1991.
70

Appendix G.-- Frequency of hauling

seals in relation to

February 1992.

out of individual spotted

time of day, 1 January-29
71

Appendix H.-- Frequency of hauling out of individual spotted

seals in relation to time of day, 1 March-19 April

1992.
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AFSC37 BUCKLEY, T. W., and P. A. LIVINGSTON. 1994. A bioenergetics model of walleye pollock (Theragra

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32 PEREZ, M. A. 1994. Calorimetry measurements of energy value of some Alaskan fishes and

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27 LOW, L-L. (coordinator). 1994. Status of living marine resources off Alaska, 1993, 110 p. NTIS No.

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groundfish fisheries off Alaska, 1992, 102 p. PB94-142759.

24 SINCLAIR, E. H. (editor) 1993. Fur seal investigations, 1991, 142 p. NTIS No. PB94-118171. 

23 PARKS, N. B., F. R. SHAW, and R. L HENRY. 1993. Results of a 1988 trawl survey of groundfish

resources of the upper continental slope off Oregon, 164 p. NTIS No. PB94-118163.

22 YANG, M-S. 1993. Food habits of the commercially important groundfishes in the Gulf of Alaska

in 1990, 150 p. NTIS No. PB94-112463.