SEA OTTER STUDIES - 1969

by Karl Schneider SEA OTT ER STU DIES - 1969

This report is a comp il ation of a numbe r o short reports _written for the marine mammals staff files. While it serves some of the purposes of a segment report, ft was compiled for the use of the staff only. Many of the conclusions and ideas expressed are tentative and based on incomplete analysis or the dat.a .

The contents of the report are as follows:

Proje"ct Statement Aerial Count (Aleutians, Alaska Peninsula, Shumagins) Survey -Sitka to Cape Spencer Survey - Klag Bay Area Sightings - Yakutat Bay History of Harvests and Transplants Age Determination Age Structure Growth Reproduction Tagged Otter

In addition to the work presented here, much time was spent on a sea otter transplant, observing the effects of nuclear testing at Amchitka and collecting information on pelt sales. Analysis of much information and specimens collected since 1967 is still incomplete and will be written up at a later date . ·­ .. ­

STATE: Alaska JOB T ITL.E: . Sea Otte.r · JOB NO.: . G-2

. NAME AND TITLE OF PRINCIPAL INVESTIGATOR: Karl Schneider, Study Leader

NAME AND ADDRESS OF FISH AND GAME AGENCY: Alaska Department of Fish and Game, Subpart Building, Juneau,-. Alaska­

~ :. ·-­ · --- -~ · JOB DESCRIPTION:

OBJECTIVES: 1. To determine trends in distribution changes of sea otter populations in areas where repopulation of former habitat is incomplete.

2. To determine the effectiveness of aerial, surface and photographic· counts as census tools.

)-. To obtain information relating to molt, breeding biology, population sex and age composition, growth and food habits of the sea otter in selected. parts of its range.

4. To evaluate the use of reproductive rates, pup survival rates, sex and age composition and food habits as tools for measuring the effects of harvesting sea otter populations.

PROCEDURES: J. Aerial counts will be made in areas where low density populations are believed to exist and in areas where unoccupied habitat adjoins areas with relatively high popul­ ations. In Apr i 1, a count wi 11 be made of the entire so_uth side of the Alaska Peninsula and Unimak Island using a twin engine aircraft. Similar counts will be made in the Kodiak, Prince William Sound and .Kenai Peninsula areas· with available aircraft in conjunctfon with other work. Aerial counts will be made in Southeast Alaska in J~ne and boat counts ~ill be made in areas where concentrations appear to be established.

2. Duplicate counts from fixed-wing aircraft, helicopter, boats and shore will be made when possible, to determine the degree of variability to be expected with each method and to compare methods. Experiments with fixed-wing aircraft will be conducted in conjunction with the April count. Hel i­ copter counts will be used only when helicopters are made ~vailable by other agencies such as the U. S. Navy at Adak. Boat, shore and aer i a 1 counts wi 1-1 be made and compared in Southeast Alaska. Boat and shore counts wi 11 be made on Amchitka in July and probably sometime during the winter depending on AEC activities. A boat count of the Delarof · Island will be made in August.

Experiments to test the feasibility of photography for counting sea otters wi 11 be conducted on all of the counts.• Different types of film including infrared will be used under different conditions of visibility and on different concentrations of animals. , _ :

3. Pelt samples, female reproductive tracts, testes, skulls, teeth, stomach contents and body measurements will be collected · from animals harvested in August and from any other _animals . that become available throughout the year. Specimen material will be analysed as time permits between October and May. Reproductive tracts will provide information on br~eding biology. Skull and body measurements will provide information ·on growth. Age determination by cementum layers in teeth will provide information on populations age structure and be correlated with reproductive and growth information. Pelt samples will provide a better understanding of the time and nature of the molt. Stomach contents will be analysed for food habits information. ·

4. Surface counts will be conducted in proposed harvest areas prior to the harvest. These counts will include numbers of adults, numbers of pups and a. rough ~etermination ~f the geographical distribution of sexes. These counts will be conducted in islands accessible by air in July and on less accessible islands in August immediately prior to harvesting. Information gained from the a·nalysis of specimefl' material from harvests and from the composition counts will be correlated with that collected from other years and from other .islands. Complete analysis of this information will not be possible until information is available for several years frbrn the same islands.

\.JORK SCHEDULE: 1. Apri 1 15 to June 30 2. July 1 to August 31 . 3. August 1 to May 31 4. July 1 to August 31

EST IMATED MAN DAYS REQUIRED: 1. Leader and Game Biologist - 60 man days 2. Leader and Technician- 40 _ ma~ days 3· Leader and Game Biologist II - 330 man days 4. Leader and Technician - 35 man days

LOCATION OF \o/ORK: 1. Coastal waters of Southeast Alaska and from Prince William Sound to Unimak Pass . 2. Coastal waters of Prince Will lam Sound . to the Rat Islands. 3. Western Andreanof, Delarof and Rat Islands and Anchorage. 4. Western Andreanof, Delarof and Rat lsla~ds.

WORK ASSIGNED TO: : Karl Schneider, Study Leader

PROGRESS REPORT DUE: January 31, 1970

JOB DURATION: July l, 1969 to June 30, 1970 Cost: Federal Share$ 22,250 State Share 8,750

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AERIAL COUNT OF SEA OTTERS ALEUTIAN ISLANDS, ALASKA PENINSULA AND SHUMAGIN ISLANDS

Apri 1, 1969

. Between April 8 and April 22, 1969 an aerial count of sea otters was made .in the Delarof ls~lands, central and eastern Andreanof Islands, Islands of Four Mountains, Fox Islands, the north side of the Alaska Peninsula from Bechevin Bay to Moffet Point and the Shumagin Islands.

An Aero Commander 500B aircraft (N6392U) chartered from the Bureau of Land · · · ······· ··· ···Ma· ii~9eO,e .rit... wa·s i=iown around ·each· islan·d-·slightlYoff shore at altitudes ranging from 150 to 250 feet and an airspeed of 100 to 120 mph. The aircraft was piloted by Cal Ward of BLM. Karl Schneider and James Faro of the Alaska Depart­ ment of Fish and Game served as observers. Schneider sat next to the pilot on the inshore side of the aircraft and counted animals directly ahead and to the right of the aircraft. ·Faro sat behind the pilot and counted to the left (offshore). An attempt was· made to follow the shore as closely as possible. Previous counts made by the U.S. Fish and Wildlife Service used a DC-3 aircraft which is consider­ ' ably larger and less maneuverable than the Aero Commander. For this reason, the r' present count probably provided better coverage of animals close to shore and in bays. However, the DC-3 makes it possible to position more observers to cover off shore areas. Counts made with both types of aircraft appear to be of a similar order of magnitude indicating that the segment of the population counted may be different but of a similar size with each count.

A number of factors affect the size of counts. Recent experiments indicate that fixed-wing aircraft counts tend to be lower than helicopter counts and all aerial counts tend to be lower than those made from a skiff. Experience from harvests and transplants indicate that many animals are missed by all of the techniques used so far.

The shape of a shore line will affect the advantages of one method over another and the percentage of animals seen probably varies on different islands even when all other conditions are equal. · ~

Experience and ability of the pilot and observers is always a factor. Turbu­ lence affecting the aircraft particularly on the downwind side of islands can affect the altitude, airspeed and distance from shore at which the aircraft must be flown. Extreme turbulence can distract the observers.

While sea otters are relatively easy to "identify from the air, large numbers of seals and sea lions in the water can be corifusing and cause sea otters to be missed. This was most noticeable at Seguam and Akutan on the present count.

.I In some areas, such as the Shumagin Islands, sea otters tend to be wary and dive well ahead of the aircraft. Animals seen ahead of the aircraft often disappear before positive identification can be made. This factor did not appear to be a problem in the Aleutian Islands where otters are relatively tame.

Visibility can be affected by a number of factors; however, waves and light reflection are the most critical. Only five days out of 14 had conditions of visibility that were acceptable for any type of counting. None were ideal. ·..

I Choppy waves, surf and glare from sunlight on the water· restrict visibi 1ity. Glare and chop, individually and in combination, create a variability in c-onditions which seriously 1imits the. effectiveness of aerial counts."

Another important factor is the distribution of animals. When most of the animals are resting in pods ranging up to several hundred animals, the ctiunts tend to be much higher than when the same number of animals is scattered and feeding. This is particularly true under less than ideal conditions of visibility. The distribution of sea otters can be influenced by time of day, tide conditions, present weather conditions, weather for the past' few days, etc. Counts made in the Shumagin Islands were made under un­ favorably conditions of visibility; however, many of the animals remained in pods of 20 to 40 all morning making the counts higher than would normally be expected. · By afternoon the animals had scattered and _t~e counts were lower. Another example is the area nofth.of Unimak Island and lzembek Bay where_a very high count was made in 1965 by the USFWS when the animals were in large pods near sho~e after several days of strong winds. The present count was made after several days of calm weather and the animals were scattered over a 1000 square mile area. The number counted was considerably lower than the 1965 count.

Many other factors such as distribution of kelp have lesser effects on the counts.

In general, the variability in factors influencing this type of count is so great that the results are not rei iable for population estimates or for determining short-term fluctuations in dense populations. However, aerial counts should be useful to determine general distribution and abundance and to follow large changes in population size. Such changes are occurring where relatively dense populations are expanding into habitat that is either un­ ' occupied or sparsely occupied. Aerial counts are also the quickest way to familiarize new personnel with large areas of habitat.

The following is a list of definitions of terms used to describe counting conditions. Application of these terms is 'completely subjective and based on the writer 1 s experience.

Excellent- Surface of water relatively calm. Usual ly overcast with little surface glare. Single animals easy to spot at a distance.

Very good - Su~face may be s11~htly choppy~ but not enough confusing reflection to prevent spottihg of animals off shore.

Good - Off shore animals may be difficult to spot but single ~ni mals near shore and in kelp beds and small pods every~here · ar• ~ re~dily spotte~ • . ~ . . : . . - . . . Fair- Usually choppy or surface glare. Single animals in kelp beds or in the lee of rocks or shore and most groups of animals relatively easy to see. Other single animals and some pods in deep bays, in the shadow of cliffs or off shore may be missed.

Poor·- Single animals difficult to spot and many pods may be missed, but conditions still good enough to get a rough idea of the distribution of -.. animals.

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Description of Conditions During April, 1969 Aerial Count of Sea Otters

4/10 Kanaga - 15 to 25 knot wind, water choppy_, _broken ov~rcast, surface glare, conditions poor. Started count at Round Head at 9:13a.m. Stopped count because of poor conditions on Pacific side.

Little Tanaga, Umak, Asuksak, Tanaklak, Aziak - (10:00 to 10:55 a.m.) Cond.itions better than at Kanaga but deteriorating. Water choppy on the''south sides creating poor visibility. Surface glare on north side with fair visibility.

4/11 Kanu Island- (9:15a.m.) ~ater choppy, broken overcast with surface glare, frequent rain and snow squalls. Conditions pqcir, -~. ttempts · to count nearby islands abandoned.

4/12 Delarof lslanm- (9:45- 11:45 a.m.) Wind about 5 knots at Adak but probably 20 to 30 knots over water. · Heavy surf and squalls prevented count of most of Gareloi. Bad chop on the south sides and surface glare on the 1101 tlr--s-i-des made concHt ions a-round -Unal-ga ,--K-ava 1ga, -Ogli uga, Skagul and llak Islands fa_i r to poor. Heavy surf on the wes't sides of Amatignak and Ulak created very poor conditions. The east sides had ------tat-r-vts+bi·t i ty. ­

4/13 Great Sitkin - (8:40 a.m.) Conditions poor on west and north side and good on east and south sides, but with some surface gl a. r~~ _

·, Kanu, Tagadak, lgitkin, Ulak, Chugul, Umak,.Anagaksik, Little Tanaga, Tagalak, lkiginak and Oglodak- (1 :IJO - 11:00 a.m.) Surf on exposed southeast sides, some glare on northeast sides. Conditions poor in spots but generally good.

Atka and Amlia ~ (1 :15- 4:30 p.~. · Conditions good to very good on north ··sides with light ripples and little glare except large squalls prevented count east of Pinacle Rock on Amlia Surf, surface glare and squalls created conditions that were generally fair on the south side, but some areas were poor.

4/14 East tip of Amlia- (10:10 a.m.') Bad surface glare. _, Seguam- ~10:15 a.m.) Light ripples on surface. Glare bad. Many sea lions ·in water ma-king identification of heads difficult and many sea otters may not have been counted. Conditions generally fair.

lslan~of Four Mountains- (11 :00- 12:20 p.m.) Conditions similar to - Sequam but worse in spots. __Large numbers of birds prevented count of Chagulak . . / Akutan and Akun- (4:00- 6:00p.m. Conditions similar to Sequam, but worse on south sides. Many seals and sea lions in water.

4/15 Rootok, Avatanak, Tigalda, Ugamak, Baby Islands and Unalga - (7:25 - 9:00 a.m.) Conditions good on north sides. Heavier chop on south sides creating fair conditions. -3­ Umnak and Samalga (10:40 12:.15 ~oon) Conditions fair near shore but . choppy and poor off shore. Heavy surf on Pacific side of Samalga. Counts were con'centrated on points and rocks. Sandy beaches were counted at high speed.

Unalaska ~ (12:30 - 1:30 p.m.) Did not count into deep bays concentrated . on points and groups of rocks. Visibility ranged fromfair to _good,

Unimak to lzembek Bay and Amak Island - (2:40 - 5:45 p.m.) Conditions ranged from fair to very good west of Amak. Calmer 8 to 10 miles off shore than ~ ...... _...... :.... n~ar .. _ shore~ ... Li _ gh~ _ chop c:tnd . su~fa. c~~larehindered visibility in certain directions. Most of animals scattered. Visibility very good and animals in groups of 5 to 10 on return half of transect just west of Amak. Conditions from Amak east deteriorated to poor• • • 1'!; 4/16 Bi Koniu'i little Koniu'i Simeonof Southeast side Turner Bendel, Spectacle and Near Island - 10:00 - 12:50 p.m. Sky clear. Very bad surface glare, _light chop or ripples, depending on location. Single animals difficult to see although many remained in small pods all morning. Animals very often dove well ahead of airplane. Many heads dove before identified and were not counted, but most were probably otter. Much of count would have been very poor if animals were scattered.

Northwest side of Na ai Chernab ura and Andronica Islands and t he Haystacks- (3:00 ~4:40p.m. Wind picked up, water rougher than a.m. Glare still bad and animals more scattered. Conditions generally poor. Even large groups of otter may have been missed.

No attempt was made to count shallow areas off shore.

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~4-

j I T I AERIAL COUNT OF SEA OTTERS APRIL, 1969­

PARTIAL OR ISLAND COUNT DATE COMPLETE COUNT VISIBILITY

Delarof Island

Gareloi 5 4/12 Partial Poor Unalga 9 4/12 Complete Fair . Kavalga 118 4/12 Complete Fair to Poor Sea Otter Pass 36 4/12 Complete Fair Ogliuga & Skagul 105 4/12 Complete Fair Ulak 55 4/12 Complete Poor Amatignak 68 4/12 Complete Very Poor 6 4/12 Complete Poor .:1'! llak Andreanof Islands

Kanaga 153 4/10 Partial Poor Great Sitkin 343 4/13 Complete Poor to Good Aziak 4 4/10 Complete Poor to Fair Tanaklak 4 4/10 Complete Poor to Fair Asuksak 7 4/10 Complete Poor to Fair Kanu 20 4/11 Complete Poor Kanu 35 4/13 Complete Fair Tagadak 21 4/13 Complete Fair lgitkin 190 4/13 Complete Fair Ulak 15 . 4/13 Complete Fair Chugul 119 4/13 Com plete Fair Umak 116 4/10 Complete Poor Umak 164 4/13 Complete Fair to Good Anagaksik 0 4/13 Complete Fair to Good Li tt1e Tanaga 139 4/10 Partial Poor Li tt 1e Tanaga 203 4/13 Complete Poor to Good Tagalak 68 4/13 Complete Fair Fenimore Pass & Rocks 42 4/13 Complete Fair lkiginak 33 4/13 Complete Fair · oglodak 9 4/13 Complete Fair Atka Pass 7 4/13 Complete Fair Atka 464 4/13 Partial Fair to Good Aml ia 140 4/13 Partial Fair Seguam 97 4/14 Complete Poor Islands of Four Mountains

Amukta 0 4/14 - Partial Fa r Chagulak 0 4/14 Partial Fa r Yunaska 0 4/14 Partial Fa r Herbert 0 4/14 Partial Fa r Carl isle 0 4/14 Complete Fa r Chuginadak 0 4/14 Partial Fa r Kagami 1 _ 0 4/14 Complete Fa r U1i aga 0 4/14 Complete Fa r

' .., ~... .. ·• •·· Aer .ial Count of Sea Otters, Apri 1 1969 (Cont.)

PARTIAL OR ISLAND COUNT DATE COMPLETE COUNT VISIBILITY

Fox Islands Samalga & Cape Sagak 27 4/15 Complete Fair to Poor Umnak 9 4/15 Partial Fair to Poor Unalaska 6 4/15" Partial Fair to Good Baby Islands · 0 4/15 Complete Fair to Good ·Unal ga 0 4/15 Complete Fair to Good Akutan 1 4/15 Complete Fair Akun 3 4/15 Complete Fair Rootok 2 4/15 Complete Fair Avatanak 0 4/15 Complete Fair P' Tigalda 49 4/15 Complete Fair to Good Ugamak 0 4/15 Complete Fair to Good Aiktak {) 4/15 Complete Fair to Good N. Side Unimak to lzembek Bay 482 4/15 Part i a 1 Poor to Very Good

Shumagin Islands

Castle Rk. 0 4/16 Complete Poor to Fair Big Kon i uj i 296 4/16 Complete Poor to Fair Peninsula 15 4/16 Complete Poor to Fair Little_ Koniuj i 232 4/16 Complete Poor to Fair Atkins 58 4/16 Complete Poor to Fair Simeonof 329 4/16 Complete Poor to Fair Nagai 232 4/16 Complete Poor to Good Near 150 4/16 Complete Fair Turner 6 4/16 Complete Fair Bendel 27 4/16 Complete Fair SpectacJe 8 4/1.6 Complete Fair Bird 76 4/16 Complete Poor Chernabura 6 4/16 Complete Poor Andronica & The Haystacks 75 4/16 Complete Poor to Fair ...... : ..

. Discussion of Results .

Delarof Islands

The 1969 count was somewhat lower than the 1965 count. It Is probable that the population has been declining as the Amchitka population did, however, the difference in these two counts may be entirely due to poor counting · conditions. The count was continued under these conditions to familiarize personnel with the area and should not be interpreted further. - - ---

Andreanof 1~1~hds · ·

The Kanaga count was stopped because of poor conditions. In the area :f! covered, 153 were counted. In 1968, one hundred and three were counted in the same area under better conditions of visibility, but with different observers and possibly a different distribution of animals. Approximately 200 animals had been removed from this area during a harvest conducted between the two counts. The fact that the 1969 count was higher when one might expect it to be lower illustrates how the many variables can reduce confidence in such counts as census tools.

Great Sitkin, Umak, Little Tanaga and the nearby islands appear to have had a reduction in sea otter numbers since 1965. Some of the reduction in the counts was probably due to the fact that a number of large groups were counted in 1965 while in 1969 the animals were more scattered. However, there was a very substantial increase in sea otter numbers from lgitkin Island to the west end of Atka indicating that many of the animals have moved eastward following the same pattern of expansion into sparsely populated habitat that has been demonstrated by USFWS counts in the past. Populations in the Little Tanaga­ Great Sitkin area remain dense.

Sea otters were found on the north side of Atka for the first time. This area was last surveyed in 1962. There was also an increase on the western half of. the south side. These animals on both sides almost certainly have moved in from the islands to the west. The population from Cape Tadluk to Amlia Pass may have expanded somewhat since 1965, however, there is no indication of significant movements of large numbers of animals. No animals were seen in Nazan Bay, however, residents of Atka report occasional animals near the village.

No significant change is indicated in the Amlia population by the counts. Some animals have moved around the east end to the north side of the island, however, there does not appear to be any signi~icant populations on the north side at this time. There was a substantial increase in the count on Seguam Island even with poor visibility. It is possible that a number of animals have moved from Amlia, but it is more 1ikely that the differences are due to reproduction and . variability inherent in the cou~nting techniques.

Islands of Four Mountains

No sea otters were seen in this island group on this or any previous survey. However, Johh Kl ingbei 1, an ADF&G pi lot, reports seeing about a doze!'\ sea otters

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Is1ands of Four Mountains (Continued)

· near Chuginadak,. Carlisle and Kagamil Islands in March, 1969. This is probably a reliable report and indicates that a small _n~mber have crossed over from the · small Samalga Island population. This doei not appear consistent with the patterns of expansion that are being observed in the Andreanof Islands. However, it is consistent with what appears to be a different pattern emerging in the l Fox Islands.···. 1 Fox Islands

I Samalga Island and the western tip of Umnak Island have supported a small ! population for a number of years . . Sightings have usually involved 10 to 14 animals and there has been no indication of an increase. The 1969 count of 27, I the discovery of small concentrations near Kigul Island and the western tip of I Unalaska plus reported sightings in Makushin Bay on Unalaska and in the Islands of Four Mountains indicate that the population of these islands may be expanding with small numbers scattering considerabl~ distances to become established in small areas .which appear to be the best pieces of sea otter habitat in the area. It is possible that the Samalga population has served as a nucleus for this expansion. The information is too sparse to determine conclusively whether this is the pattern. · The total numbers of animals ·are undoubtedly small, and it is questionable whether repopulation in large numbers· will occur in this manner before the large populations to the east expand into these areas.

What appears to be a similar situation exists in the Krenitzin Islands. A small population exists near Tigalda Island. · The 1969 count is the highest yet, however, none of the surveys are comparable so it is a matter of speculation as to whether this population is increasing or not.

Scattered individuals were seen around the other islands in the area. Ed Cal lese of Unalaska, who has hunted seals in the area, reports that the only sea otter he has seen recently in the area was in Beaver Inlet on Unalaska. The 1969 count and reports from individuals ind.ic~te that the Tigalda population is the only concentration in the area and the other animals probably have wandered from this population. ·

Unimak Island to Moffet Point

A large and somewhat unique population exists in the large shallow area north of Unimak Island and the Alaska Peninsula to Port Moller. This population apparently remains off shore and the animals seldom haul out on land. . Because of the vast area occupied by the animals, no attempt was made to get a total count. Efforts were directed toward delineating the area being used. In 1965, approximately 2,500 sea otters were seen in the area covered by the 1969 survey. In 1969, four hundred and eighty-two were counted. The difference in numbers is probably due to a more complete coverage in 1965 and the fact that the animals were in large groups in 1965, whereas they were widely scattered in 1969. In 1965, the count followed several days of strong northerly winds. The 1969 count followed several days of very calm weather. This indicates a strong influence on otter dis~ribution by weather preceding the count with a corresponding influence on th~ number counted.

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. . - 1~ • • ...... ~......

Unima·k Island to Moffet Point (Continued)

In 1965, many sea otters were seen beyond the three mile 1imit. alt~_ough most were within the limit. In 1969,almost no sea otters were within the three mile limit and in one area none were seen within 10 miles of shore. . Flight 11nes were extended off shor~ until no m6re animals were seen. In · general, the outer 1imit of the animals was around the 40 fathom curv~. One · flight 1ine was extended 30 miles from shore. The last sea. otters were seen 26 miles from shore. The otter appeared to be feeding on invertebrates and presumably were regularly diving in at least_40 fathoms of water. The bulk of the animals were within a 1,000 square mile area.

Shumagin Islands. .• There was no definite change in the populations of the islands counted from the 1962 USFWS survey. The animals evidently move back and forth between the islands. The southern islands still support a substantial population. Reports from residents of Sand Point indicate that the populations are increasing in the northern Shumagins, however, weather conditions prevented counts on these islands.

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264 217 . 242 418 \367 . 179 230 318 353 234 387 75 154 2 15 225 283 272 221 198 247 199 262 181 250 174 193 170 217 165 108 113 86 107 229 167 92 191 75 78 70 81' 83 72 218 207 191 172 71 71 73 ~.85 110 89 91 119 102 97 124 t? 212 59 67 174 98 75 159 64 o9 59 90 128 191 61 89 103 . 109 s e1"~ 92 81 79 178 67 64 90 107 11 6 126 13 8 174 163 . 153 ~ -- · - - - .. 58 M· C 89 99 14i r' 83 84 68 89 42 t_. 51 73 s 53 66 34 106 155 , . 48 144 146 148 44 i 4 1 107 146 93 119 86 145 99 93 92 ' 154 83 .. 123 87 s 97 144 91 79 ., 132 r 89 98 96 83 72 61

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SEA OTTER SURVEY SITKA TO CAPE SPENCER

June 13 - 19, 1969

On June 13, 1969 an aerial search for sea otters was conducted from Sitka to Torch

Bay near Cape Spencer. A Cessna 206 was flown at an altitude of 150 to 200 feet

around the outside of Kruzof Island, the Khaz Peninsula, and Yakobi Island. Most

~ small islands and rocks on the outside coast were covered. Observers were Karl

Schneider and Jerry Deppa. Visibility was fair with a few good spots. The sky was

clear and there was a light chop on the surface of the water. Surface glare ·was

moderate to bad.

Three sea otters were seen on the east side of the Granite Islands nearKhaz Bay and

two were seen south of Cape Bingham on Yakobi Island.

Weather prevented a search of the Biorka Island, Heceta Island and Barrier Island

- release sites.

Between June 15 and June 19, Schneider and Deppa made a trip by skiff from Sitka to

Klag Bay and back. Originally it was intended that the entire coast from Sitka to

the north end of Yakobi Island would be searched from the skiff. However, fog and

rough water limited the effective search to the area between Khaz Point on the west

side of the Khaz Peninsula to Cape Edward on Herbert Graves Island.

The following sightings of sea otters were made:

6/16 13 (approximately) adults + at least 1 pup in the rocks immediately south of Black Island

6/18 6 adults + 1 small pup scattered around the Granite lsland~od 25 adults and sub-adults, 5 small pups and 1 large pup in a peel south of Black Island 1 adult near Ramp Island on the south side of Kh~z Bay

T .. ·-. . ,.. -2­ ...... ~. .-

.The location of theanimals sighted on 6/18/69 are shown on the map. The aerial

and surface. sightings represent a minimum of 41 animals. These are Cape Bingham 2 adults ·· Black 1.- Granite 1. 31 adults, 7 pups Ramp 1. - 1 adult

1

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. ,~ ~ ....•. -.; • !; p . . ' - .., ·._.:..:-. _ ..._ ...... ~.. ;.-· ... _ -·. Sea Otter Survey - Klag Bay Area

... October 8-9, 1969 ·~~ - ... ____:. :-_:__ --...... ,.:..... :_-::_ _:,_ . . ~·· ····· ·····: ...... on·..october .8 .and 9 a search . for . sea . otter.: w~s . made ...in .the Klag Bay area · utilizing a 16 foot skiff. Observers were John Vania and Don Strode. Weather and water conditions were extremely poor. The sky was overcast with low-hanging clouds. There were intermittent rain showers. The sea had very large swells with a bad chop. I I .I I Two otter were sighted off Black Island. No other otter were seen. The I otter were adults. I The area covered is circled on the attached map. ,. ! The survey was very p6or because of weather conditions. The results in no way indicate what the true status of the transplanted population is. More surveys under much better conditions will have to be conducted.

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Sea Otters in Yakutat Bay

. In 1966, 10 sea otters were released in Yakutat Bay. Since that time, there have been one or two uncomfirmed reports of sea otters th~re, however, no surveys have been made in the area.

' Walter Puckett, a guide, reported seeing the following between October 1 - 8, 1969:

South of Knight I 6 or 7 in· ·a-- group East of Dolgoi I 4 or 5 ··Iiaenke· I "several" Total about 15

. ~ He had more sightings, but believes he , saw the ·same individuals. There were about 15 different individuals. He has seen about 4 or 5 a year for the last 3 years, but never saw any before that. These reports were not confirmed, but his descriptions were accurate and he has seen sea otters before near Montague Island in Prince William Sound.

-· FORM FG • 7.4

' ' L. :;~ORANDUM State of Alaska DEPARTMENT OF FISH AND GAME TO:' ' : r Karl Schneider FILE NO: Game Biologist ·__Anc;:_horage DATE May 23, 1969 I . '; -1\4: . FROM: James Faro --~ SUBJECT: Survey of Augustine 1s land ­ 1 Game Biologist - Kamishak Bay I . ...,._ ...... Anchorag~ ----· · ......

No sign of oil pollution was observed _d.uring a reconniassance flight made to Augustine Island - Kamishak Bay on May 22. Sea birds, ducks, and seals w~re common and no sign of recent mortality or oil stains were observed on the beaches. Unfortunatly because of the low tidal conditions we were unable to land for closer inspection.

-----Although conditions for a count were not ideal, I personally tallied 130 sea otters off the western half of Augustine Island. A probable two additional otters were observed_off -- tFieeasterri half. The above figure is minimal as additional otters wer~ · reported by the pilot ~hat I did not observe. Conditions of the count were: - ---wDa•te: -Ma.y 22, 1969 . Type of Aircraft: C~s~na 180 on floats Pilot: Jack Lee Wind: Southeast, 1ight · ·;. Sky: High broken overcast Sea: Light chop and ~well, occasional white cap Glare: Moderate Time: Approximately 2:30-3:00 PM Observers: Faro and Divinyi JF:dxg

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Harvests And Transplants

No sea otter harvest was conducted in 1969. However, a total of · 251 animals was removed from ~rnchitka. Fifty-eight of these were transplanted to Khaz Bay on Chichigof Island, 29 to British Col:.. . umbia, 29 to Washington and 4 to the Tacoma Zoo. One hundred and seventeen died during the transplant and 14 died during Bat­ telle Merrtorial Institute's studies associated with the nuclear test "Milrow".

~_:_TaJ)J.e ·1 ·· summa'rl.ze·s .the number · 6:E 'se·a. Otters·· removed from various populations from 1951 to 1969. This includes all animals legally removed dead or alive by the USFWS, ADF&G and·valid permit holders. It does not include illegal kills which are not known to exceed more than a few animals at any· tirne or place nor does it include beach dead animals.

~e numbers on Table 1 do not always agree with harvest numbers listed in previous reports. These other numbers are numbers of pelts obtained. Some are beach dead animals and some small pup -pelts were worthless and were not saved.

Table 2 summarizes the numbers of sea otters transplanted to various areas. This includes all transplant attempts up to 1969 regardless of their success.

A total of 961 sea otters were removed from Arnchitka between 1967 and 1969. This is an average of 320 per year which may represent a 10 percent annual removal. However, it should be noted that virtually all sea otters· removed from Arnchitka since 1951 have come from the southeastern half pf the island. A very high percentage of these carne from the area between Ivakin Point and Crown Reefer Point. In 1969, there were noticeably fewer sea otters in this area, however, they continued to be abundant elsewhere. ..

Table .l. Numbers of Sea Otters Removed from Alaskan Populations 1951-19691•

1951 54 55 56 57 59 60 62 63 65 66 67 68 69

,. USFWS Studies 35 22 37 26 21 39 2 Amch itka Is. ADF&G Transplant 476 237 ADF&G Harvest 180 311 205 Other 52 243 143 Total 35 22 37 26 21 39 180 311 210 500 251 Kanaga Is. ADF&G Harvest 318 Adak Is. · ADF&G Harvest 300 194 Shumagin Is. , Sanak & Unimak Is. USFWS Studies 14 2 ADF&G Transp1ant 41 Hinchinbrook Is. ADF&G Studies 1

Montague & ADF&G Transplant 39 Green Is. ADF&G Studies l

1. Includes all animals that were harvested, died during studies and transplant attempts or were transp lanted to other areas or zoos. Does not include natural mortality or illegal kills.

2. Woodlanp . ~ark Zoo. ., 3. · Battelle Memoriat lnstutute.

·.•·· .~·· . . .. Table 2. Numbers of Sea Otters Transplanted 1955-1969.

l955 195b 1959 19b5 19bb 19bS 19b9

Aleutians Attu I • 5

Otter I. 191 Pribilofs St. Paul I • 7 St. George 1. 57 Yakutat.· Bay 10 Khaz Bay 23 20 93 58 (Chichigof 1.)

Southeast Yakobi I • 30 AIaska Biorka I • 48 Barrier Is. 55 H4'ceta I • 51 Cape Spencer 25

Brit.ish Columbia 29 ­ Washington 292

. 1. None believed to have survived.

2. At least 13 died shortly after release. '\ Note: 1955 to 1959 by USFWS, 1965 to 1969 by ADF&G. In some cases one or two of the above · an imals died near the time of release. SEA OTTER AGE DETERMINATION

(Methods and Interpretation used on 1967 and 1968 Teeth)

Decembe~ 29, 1969

.·

•" . ~.0:: - .. ' METHODS

...... ~ ...... Some layering can be found in the cementum of all sea otter teeth. The upper 13 and upper and Tower PMl have the most distinct and regular layers. The lower PMl is usually the best, particularly for locating the first two or three layers' near the root tip. Longitudinal sections from the center of the tooth are best as it is often necessary to look at the entire rooth from gum to root tip. Sections cut at an angle or away from the center of the tooth have less distinct layers. · .. Geismsa•s stain is usually better than hematoxylin or Paragon Multiple Stain for Frozen Sections. It produces a lighter background with sharper lines. It is often advantageous to have several sections stained to different degrees. ·

Formic and nitric acids were tried for decalcification of the teeth but 3% HCI proved to be the most satisfactory. · Sections stored in 1% formalin produced poorer slides than those stored in Loess• solution;

Whole, undecalcified teeth should be stored in Loess• solution to prevent drying of the cementum which produces dark edges when stained.

· Teeth pulled from raw skulls seemed to produce sharper lines and the edges were definitely easier to read than those pulled after the skull was cooked. It may be difficult to pull teeth from adult jaws without breaking the root. If they are allowed to rot for several days, most teeth will come out easily. On older animals, it is necessary to chip bone away from the tooth to prevent breaking the bulb-like tip of the root which is important for reading the tooth.

Sections are readwith a variable-power, stereo scope. The sections are scanned at 40 to 60 X, then more readable areas are selected and examined und~r 100 to 120 X. Varying the magnification and light intensity help . Often it is easier to separate major lines from intermediate lines at a lower power ans subdued light. A fluorescent illuminator produces a soft uniform light that _makes sections easier to read.

It is important to count layers at different places on the tooth (Fig. 8, 9 , 10). Near the gum line (Section A, Fi~. 7-8) the cementum appears dense and layers tend to be very even and regular. However, on some teeth, there are many intermediate lines which may be impossible to separate from major lines. The first one or two lines may blend with the interphase. On older animals (eg. 8+), the outer layers may not be laid down this high on the · tooth (Fig. 13) . However, this a rea often provides a good check to CO,!llpa re with other areas and on some teeth it is the only place where distinct layers can be seen.

1 .. ~. ...;jor

:......

The sides of the root (Section B, Fig. 7, 8, 9, 11, etc.) vary considerably, some lines may not be distinct. Occasionally, very sharp, regular 1ines can be seen and it appears that the precise age can be determined. However careful examination of other areas may turri up more outei layers. Some inner lin~s may disappear in this area (Fig. 6).

The b~;st area to count is usually the area near the tip of the dentine where the tooth curves in before forming the bulb of cementum at the tip · (Section C, Fig. 7, 10, & 12). This is most pronounced on the anterior side of the section (directly below- the cusp of the tooth). At this point the --- -"'"···layers fan-out-and are easier to disti.ngulsh.-_ . lt .Js. __ the _best and often only point at which the first two or three layers can be sorted out. It is also often the only area where outer layers on animals over 10 can be found.

The layers in the bulb at the root tip (Section Dr Fig. 7) are not sharp. However, broad bands are laid down and it is often possible to check the count from another area against the alternating lighter and darker bands found here.

INTERPRETATION

With light transmitted through the section from below there are fine dark lines separated by broad 1ight bands. For the purpose of counting, each dark line is considered to be one year. There is an area of doubt here because the first line is not necessarily laid down when the animal is one year old. The width of the band before line one varies (Figs. 1 and 2). Because the animal may have been born at any time 6f year, a possible error of several months may occur here.

On younger animals (less than 5 or 6) a band at the outer edge beyond the last line was often written as a+ indicating that the final year was not yet complete (Figs. 8-10). On _older animals where layers are narrow the outer edge was counted as the last year.

Some lines may not be sharp enough to be counted. Cementum may not be deposited in thick enough layers after 10 years or so to be counted. Intermediate lines may be counted inadvertantly.

The exact age can seldom be set with certainty. For many purposes it will be necessary to lump animals into age groups. For example, the uncertainty of counting outer layers may require lumping all animals 10 or over even tho.ugh many can be set at older ages with cert.ainty.

The following is a description and interpretation of each line.

Line 1: This line may blend in with the interphase on the sides of the tooth (Ffg. 4). It is easiest to see around the tip of the root (Figs. 1-2). A considerable amount of cementum is laid down in the "bulb'' and the first line is sharpest just above the bulb. This is usually easy to see on lower PM] but difficult on other teeth. -In some cases, there is no sharp line, only a slight change in coloration (density?) of the cementum.

-2­ ...... ~ . ~ ~...... , ... ~ .....

Line 2· The band between 1 and 2 is usually broader than between the interphase .and 1. Line~ is seldom sharp (Fig. 4) and is often visible in only one or two places. In some cases it may be · necessary to assume the existance of : line 2 on the basis of the pattern of other lines and the width of the light band after line 1 (Fig. 3). •; Line 3: The band between 2 and 3 is usually about the same width as ··~···- between 1 and 2 (Fig. 4), but may have many fine irregular 1ines.. in it. Line 3 may be faint and mixed in with irregular lines and the 4th line will be the first sharp. line (associated with sexual maturity?).

Line 4: Sometimes the first sharp line. The band between 3 and 4 is usually similar in width to subsequent bands and thinner than the previous two bands. The ceme~t~m often appears denser beyond line 3. The spacing from 4 to line 8 or 10 (occasionally farther) is fairly regular and the lines are fairly sharp. · However, some lines will be sharper than others, some will run together in places (Fig. 6) and some may be double lines (Fig. 14).

Lines 8 or 10+: Usually around 1ine 10 the 1ines may become irregular and only visible in a few points. Apparently less cementum is deposited after this. In some cases the lOth line may actually represent several years . There are exceptions when there is an actual increase in cementum deposition and broad irregular bands are formed. Most of the teeth which have been read to 15 or more are of this type. Normally, it is rare to be able to distinguish more than 12 to 14 lines. Ages of 10 and above should be considered minimal.

-3­ .. DECALCIFICATIOU, SECTIOUHJG AND STAINING OF SEA OTIER TEETH · Upper 1 or PR , or lower PM , decalcified In 3t HCI until soft. -Time required....._ 3 1 1 for sufficient decalcification wtll depend on ·volume of acid used, number of teeth

decalcified In this volume, temperature, and size and "age11 of tooth•. When 50 teeth

were pt~ced tn Individual capsules and decalcified In approximately l __ l_l_ter of acid

· solution Incisors softened after 13 to 24 hours and premolars after 8-24 hours. Teeth

were rinsed -for - ~(minimum of half day In constant excha_!1ge of tap water and then stored In water In refrigerator.

Attemp~ was made to section teeth directly after water rlnse. If teeth n1us t ,~ ·· be stored for longer periods before sectioning, Loess' solution was found -to be the m6st acceptable preservative. Teeth In Loess• solution must be soaked In water prror to sectioning to avoid t ncornplete freezing In cryostat. longitudinal sections 32 microns thick are cut on IEC cryostat at -14° C. These sections may be stained Immediately or placed In Loess' solution for future use. Incisor

crowns were trimmed before sectioning. Prer.~lars were sliced untrimmed.

Working solution of Glemsa stain Is m"de up Jn sr:~all amounts and discarded when signs of heavy precipitation occur (usually after 30 minutes). For 25cc of working stain: 23.5cc distil Jed HOU

J.Occ Gler.tsa buffer solution pH 6.5 (Paragon) (Po buffer ?) (Gie::nsa buffer 4 pH 6.8 also usab ler O.Scc' Glemsa stock stain (Paragon) Small amounts of stain (approximately Sec) poured In small Petrie dish. Tooth sections taken out of Loess• solution, rlnsod in HOH, and placed In covered staining dish for. 10-12 minutes. Sections taken out of stain, rinsed off quickly In water and placed on slide for viewing. Slide ts then air dried vertically for 16-1 8 hours. Slides are then placed In Copeland jar containing xylene for flnaJ dehydration and

clearing, after w·htch they are dried \-lfth Kim Wipes, Permounted and protec~ed with a covers Itp.

' •...... ,_ . ~,. - " ..

AGE STRUCTURE

· 1968 Harvest

The age structure of the 1968 harvest is presented by area and sex in -Figs. 1 and 2. Pups less than 1 year old were handled separately and are not presented here. In many cases, a pos­ sible error o.f a year or two exists in the estimation of age. ~e tendency is probably to underestimat~ the age o~ olde~ _ ani~a~s.

From Fig & •• l ...th~re appears to be a relatively even distribution of ages of females. The distribution probably is typical of an unhunted population with a low rate of natural mortality other than that associated with age. Natural mortality in the first year of life would not be visible on these graphs.

The age structure of males (Fig. 2) brings up some interesting points. All the males in the Adak samples are between 7 and 14 years old. There were also a number in their first year of life which are not s·hown here. ..This illustrates the geographical segregation of certain sex and age classes.

Geographical Segregation of Sex and Age Classes Both areas on Adak are so called "female areas". Once males are weaned they apparently leave these female areas and only return to breed. The information would imply that males are not sexually mature until seven years of age. The possibility that they are capable .of ·breeding before that age, but are unable to compete · with older animals should be investigated. Sea otters rarely fight in the wild, however, a large male in the Tacoma Zoo regu­ larly harassed a young male in the .presence of three females. Whether such competition is responsible for keeping younger males out of the female areas or whether other, less crowded areas are simply more attractive is not known. One would expect competi­ tion for food to be greater in the heavily populated female areas.

The Kanaga samples are from larger sections· of the island includ­ ing female areas and those that are male or "single animal" areas. These latter areas tend to be off-shore particularly off major points and in passes between islands. Females without pups as well as males are found in these areas. A particularly large percentage of young males was found in Kanaga Pass. These are included in the Eddy Rock to Hive Rock sample.

Male areas are often mentioned and large pods of sea otters with­ out any pups are often considered to be all mal es. After har­ vesting and netting sea otters on a number of islands, it appears that these groups are usually at least half females which do not happen to have pups. Only a few very restricted areas are almost all male areas. There are usually well off the tips of major points. They are very few in number and very restricted in extent.

Some small sections of beach appear to be male hauling areas, however, many animals in the water near these hauling areas are females. R 2470 · 20 20 Squares to the inch / VERNON 'b'f\ LINE ~~. ~. \ ). ,_ I •

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In sununary, ·"female areas" are usually more protected areas where females with pups tend to congregate. These are important breed­ ing areas and large males enter these areas for breeding. Young males and some females without pups tend to move out into more exposed ~reas presumably where food is more available . Adult males may have a seasonal fluctuation in sperm production and leave the female areas when sperm production is reduced, or sperm production may be relatively constant and certain indivi­ . :.... duals may rerttain in ·these·· areas all year · ~ ·- ·Presumably, some breed­ ing activity takes place in all areas, so it would not be necessary for males to enter "female areas" for opportunities to mate. · However, the opportunities to mate are probably greater in major female areas, particularly if females tend to wean their pup then mate again before moving out of these areas.

The marked segregation of males in the Adak samples suggests that some form of territoriality may exist among breeding males. If territoriality does exis·t it may be flexible and other breed­ ing age males. may be tolerated.

In order to determine these things, it will be necessary to examine the testes of males and note the location where all types of ani­ mals are collected more precisely than has been done in the past.

The segregation of sex and age classes is certainly not a total thing. It appears to be greatest where geographical boundaries such as bays, points and kelp beds are well defined. Females with pups are found off-shore particularly in good weather. Stret­ ches of relatively even shore line with no deep bays may have cer­ tain areas where a particular type of animal is found, but the segregation is not as pronounced as in areas such as the Bay of Islands.

1968 Transplant Fig. 3 presents the ages of the sea otters that died during trans­ plant activities. There is a fairly heavy mortality among animals ~ of both sexes less . than 2 years old. Dependent pups are not caught as often as might be expected and the numbers that died were a fairly large percentage of those caught. Yearling otter may be more susceptible to capture so the large number that dies may not be entirely due to an inability to withstand handling .

. Other than the younger animals there doesn't seem to be any indi­ cation of a greater susceptibility of any age group to injury and death due t6 handling of the females.

The age distribution of males is curious in that no animals over 9 years old died. There are several possible reasons . for this dis­ tribution of ages. First it may be a result of the small sample and tooth reading technique. Outer cementum layers are not always visible and several of the 9 year olds may actually be olde~. Second, relatively few large males are .caught in nets. The tech­ nique may be selective for younger animals. 1

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Longevity The age distribution in Figs. 1, 2 and 3 indicates that females regularly live to be 15 years old and individuals may approach 20 years. No males were believed to be _over 15 years old. Fe­ males may tend to live longer than males, but it is possib~e that a larger sample would turn up older males. Another possibility"is · that older males may cease to breed as a result of physiological changes or an inability to compete with younger animals. _ These older males...might then tend to move to areas which are less pop­ ulated and be less susceptible to hunting or netting. GROWTH

The growth information discussed here is presented in Figures 1-20. This informati-on has not been analysed completely and the discussion is based on general observations on the graphs.

Weight - Female The growth curves for Amchitka, Kanaga and the west side of Ad~k (Figures 1, 3, 4, and 5) are all quite similar. Theyincrease• rapidly · for the first two years then gradually until ·age five or six where it levels . ~--··· · · · ····· off· ·· at ··· a~ ·· a ·v~ · r -age . oi= abo~ · t 45 lbs: · · rhe.re . i"s..graCi~ai .. inci-ease to an average of 50 to 55 lbs. at age 12 or 13 then there appears to be a slight decline.

The weight curve of the females. on the east side of Adak (Figure 2) is quite different. The weight increase6rapidly to well over 50 lbs . at age three then levels around 55 lbs. by age five. There appears to be a gradual decline after that. The apparent decline is probably deceiving. This area was re 1at~vel y unpopu-l-ated unt i 1 1965 . Sea otters older than 8 or 9 probab 1y - moved into the area from heavily populated areas on the other side of the island. , These animals went through the main period of growth under greater .,.,.__--rcompetrt·ion·for-food -:- The-younger animals were probably born in the area and have h d abundant food since birth.

__Ib.e other samples (Figures 1, 3, 4, and 5) are from areas that have supported large populations for many years~

Jhe rate of growth appears to be much greater under better hab•tat conditions. The maximum size may be greater, but in females this difference is not as striking as the increased rate of growth.

Weight -Male The weight curves of males (Figures 6 - 10) are of a different shape than those of females. Males continue to gain weight at a comparatively rapid rate which is almost linear. There is 1 i~tle sign of leveling off until age 12. Because the curves are almost linear differences in the average max­ imum weight for each area reflect difference in growth rates. At the west end of Kanaga average males reach about 65 lbs. (Figure 9). The growth at Amchitka is similar but the sample lacks older animals (Figure· 10). Males on the east side of Kanaga and west side of Adak are larger, about 75 lbs. (Figure 6 and 8). *Those on the east side of Adak are the largest, averaging about 85 lbs. {Figure 7). These differences are consistent with the past history of the areas. Males in areas which have supported large popuiations longer are a full 20 lbs. 1ighter than those from recently populated areas.

Total Leng-th- Females The totai length curves for females (Figures 11-15) are similar to the weight curves except that the levefing off is more abrupt and only a slight increase in length occurs after this point. The differences between areas are similar to those reflected in weights. Females from Amchitka and western Kanaga {Figures 14 and 15) level off at 6 years of age at a length of approximately 128 em. Females from eastern Kanaga and western Adak (Figures 11 and 13) begin to level off around 6 years but the length continues to increase to an average of about 135 em. Those on the eastern side of Adak (Figure 12) grow.more rapidly and level off at about 135 em. at an age of 3 to 4 yea~s. Again the older animals probably came from other areas and the younger animals may eventually become larger. I •• ~. 0 • • Total Length -Males The differences ·in total lengths of males (Figures 16-20) again reflect the differences between areas although the differences are less than found in the weight curves. Males reach their full length at 6 to 8 . years, probably slightly sooner on the west side of Adak (Figure 17) however, the growth part of this curve is missing. Again Amchitka and western Kanaga . animals ~re smaller (140 em) while those in the other areas are progressively larger from west to east.

Use of Growth Curves Total length and weight curves appear to reflect differences _ in habitat quality. This is probably due to differences in food availability and quality. Because of these differences, length and weight may be useful as management tools to determine the status of a population.

Other measurements, such as long bone size, skull measurements, etc., should be investigated for this purpose.

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Reproduction

Table 1 summarizes the information from female reproductive tracts collected from 1967 to 1969. The criteria used for the various categoFies are:

Nulliparous - Horns of uterus small, thin and smooth. Usually no corpora lut.ea or corpora albicantia although there is occasionally evidence of a past ovulation, but no evidence ...... of .. implantation...... : ......

. _Multiparous - Uterus thicker, corpora lutea and/or corpora albicantia present. Includes primiparous animals {these are not readily separated from multiparous animals) •

Anestrus - Largest follicle under 3.5 mm, no corpus luteum.·

Proestrus -Follicles over 3.5 mm.

Estrus - Follicles approximately 10 mm.

Unimplanted Pregnant - Corpus luteum present {usually under 10 mm and with a central antrum), no gross sign of implantation.

Pos_t Partum - Uterine horn still noticeably enlarged; fresh, rough-looking placental scar, newly formed corpus albicans with some luteal tissue remaining.

The information from sexually mature females including 1962 and 1963 data from Kenyon is presented graphically in Fig. 1. This graph assumes that the samples were collected uniformly, which may not be the case. There is bias in all the samples because of collecting methods. ·

Females with pups are often avoided in harvests. Most of these animals would be considered anestrous. This would effectively reduce the percentages of females in the other categories. On a skiff survey, 7 percent of the animals counted had pups that were readily identified. Assuming this is the number of animals n9t shot because of the pups it can b~ calculated that 15 per­ cent of the sexually mature females are purposely avoided. The actual percentage probably varies with the hunter and conditions. However, this probably indicates the order of magnitude of this bias.

Fig. 1 indicates seasonal fluctuations in sexual activity. In most cases, the samples fit the pattern fairly well. The most glaring exception is in the 1968 and 1969 Amchitka samples. These samples are from the same area at the same time of year and were collected from transplant mortalities. The percentage in each category except unimplanted pregnant and implanted preg­ nant are very similar. However, in 1968 there was a larg~ per­ centage of implanted pregnancies with large fetuses and very · few unimplanted pregnancies. ~------~~~------~======~~======~

.... Table 1. Summary Qf Female Reproductive Information

M U L T I P A R 0 U S Null i- Proestrus Un imp 1. lmpl. Fetus Weight Class Post Dates Island parous Anestrus Estrus Preq. Preq. 1 2 3 ,.. g- Partum Unk. Total 2 20 2 __..-- 5 2 6/23/68 ' Amchi tka3 20 17 2 3 ' 1 3 9 3 67 . - 8/13/68 (38. 6 ) (4. 6) (6.8) (45.4) (2. 3) (4.6) (6.8) (11.3) (20.4) (4.6) 7/6 - Amchitka3 I 20 17 4 14 10 0 1 1 2 6 Tl 0 ·66 8/12/69 (36.9) (8. 6) (30.4) (21. 9) (0) (2.2) (2.2) (4.3) ( 13. 2) (2. 2) 9/25 - Amch itka ·I 54 55 18 19 23 4 0 0 10 3 6 3 172 10/6/67 (47.8) (15.7) (16.5) (14.8) (3. 5) (0) (0) (8.7) (2.6) (5. 2) 9/10 ­ 9/17/67 Adak 53 71 14 30 40 ' 6 6 8 9 11 5 4 217 (44.4) (8.8) (18.8) (25.0) (3.8) (3.8) (5. 0) '(5. 6) (6.8) (3. 0) 10/18 ­ .. 10/20/68 Adak 204 46 11 24 13 2 3 0 4 4 6 0 120 (46) (11 ) (24) (13) (2) (3) (0) (4) (4) (6) - . 10/12 ­ 10/15/68 Kanaga 394 58 13 31 .31 4 4 7 11 5 6 1 179 (41.3) (9.3) ~) (22.2} (2. 9) (2.9) (5.0) (7.8) (3. 6) (4.3) Resorp. I

' \ ·1. Fetus weight classes: : 1 = 0-lg, 2 = 1-lOg, 3 = 10-lOOg, 4 = 100-lOOOg, 5 = lOOO+g

I • 2. Percent of sexually ma~ure females . 3. Transplant mort a 1 it i es . · 4. Reproductive tracts not collected from many young (nulliparous)

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In 1969, the number of unimplanted pregnancies was much greater. However, the total number of pregnant animals was almost identi­ cal for the two years. This might indicate a change in the · timing of the peak of breeding without a change in the rate of pregnancy. · No explanation can be off~red at this time, but it does raise the possibility that when an animal tends to breed · once every two years it is possible thattwo separate two--year cycles may be established for a period of time similar to · salmon runs. If this situation _occurs there ·would be problems in trying to compare samples from · different years and different islands ...... -.. ·

Gestation Periods, Peaks of Breedinq and Pupping Fig. 2 presents the total percentages of pregnant females (unimplanted and implanted) throughout the year. These percent­ ages are probably slightly high because of hunting bias. . . If the total gestation period was 12 months, one would expect the percent of pregnant animals to remain fairly constant throughout the year. The information in Fig. 2 suggests that the gestation period is considerably greater or less than 12 months.

Kenyon's manuscript-presents an estimate of the gestation period calculated by Dr. D. G. Chapman of the University of Washington. Chapman used Hugget and Widdas' (1951, J. Phys., 144:306-317) procedure to estimate the implanted period. Data from Jan. - Feb., 1962, March 1963 and July 1963 were used. October 1962 data did not include any implanted pregnancies.

The specific growth velocity is estimated by plotting a regression of the cube roots of the mean weights in each weight class and the mean time in months (based on percentages to give equal re­ presentation to each time of year) • ­

~able 2 presents Chapman's estimates and. a new estimate adding data from the 1967 and 1968 harvests. Data from the transplants of 1968 and 1969 were omitted because of the possibility that females with large fetuses were more susceptable to injury from ~ handling. Chapman's estimate (Table 2B) was 154 days while the new estimate (Table 2C) was 109 days. This is the period of linear growth and does not include the initial period while the fetus becomes established. Chapman allowed 2 weeks for this period. The difference between the estimates is undoubtably due to sam­ pling. The July sample included only nine animals. Chapman's estimate relies very heavily on this small sample.

If sea otters bred uniformly throughout the year it would be im­ possible to estimate the gestation period from this method. The method assumes a peak of breeding activity. When a species breeds throughout the year a~d the peak is not pronounced, a large sample from all times of year becomes necessary. The data used by Chap­ man obviously is not adequate and it is very likely that the new - estimate is still not good enough .. ..,,. ~ I ·- I ~ . .. I - - ­ i - ~ . I .. , 1 ------·-. - ­ -: I­ - .. - ! ' - ' \ \ ~ , ­ \ .- ­ - - I - - - ~------.. I. ·- . I -- -1--r ------­ ~ ...... ! -·. I I \.- I ­ --.-----­ I I ~ I ~ ~ ------'1 ~ ' I ' ~ r- \l I I \. ~ ~ !I I I I --1-----:------­ I ~ I I 1------\., ~ i I I ~ I ~ (~- \! I I \.., ~ - ~ ~ I ~ I l. ~ ~ "­ I I ~ I l, - ~ - -\-... ! I ­ I . c I \l I \) ·~ I ~ \.. ~ ~ - ~ !I I I s:: ~ 1­ e ------~ ~ ·I -(\.. ~ I I ! t I c. I t ·' i~ I ::s I~ I ~ I \ t . , I I ~ I t ...... ' I~ I ------' ..... l.l. i I r----- I I I \ I I '\ . \-, i

~ ~ ~ ~ I ~ c;::, I ~ "· ~ I ~ ~ ('t) N .....

:1 ~ ;).J: 11-f. tp w J-t? •' · % i5 . I I Table 2. Estimated Length of Implanted Period.

A. Percent of Fetuses · in each ·weight Class. .. Time of Collection After January 2 3 4 5

month . ~ ... -.. . . 31 15 15 38 0

3 months 18 12 22 35 12

7 months 0 0 22 33 44

9 months 20 7 10 40 23 -l-0-months -14 18 -12 33 23

B. Chapman's Estimate Based on 1, 3 and 7 Month Samples.

Mean Time in Months after January 1.7 1.9 4.0 3.5 6. 1 Cube root of Unweighted Mean Weight 0.74 2.21 3.27 7. 18 11.45 Specific growth velocity = 0.076/day.

Estimated implanted period = 154 days.

C. Estimate Based on all Samples

Mean Time in Months after January 4.8 5.7 5.5 6.0 7.7 Cube root of Unweighted Mean Weight 0.68 1.7 3.5 7. 4 11.4 Specific grwoth velocity = 0. 113/day.

Estimated implanted period = 109 days. .. -3­

It should be recognized that using samples from different years and different populations may cause some error.

Chapman carried his estimates on to estimate the unimplanted period by comparing the frequency of unimplanted and implanted pregnancies for each season. He estimated that 60 percent of .the pregnancies were unimplanted, therefore the unimplan~ed period. was half again as long as the implanted period. However, be . · used the very small summer sample and ah even smaller fall sample giving them equal weight to the larger samples • .. ·. . . ·······..... ·using ' the·more' r 'eceiit lnf6rmati6ri ·arid throwing 'out the small samples the estimate is 52 percent of the pregnancies are unim­ pla,nted.

Therefore, the two estimates for the total gestation period are:

Chapman's Estimate Revised Estimate

Unimplanted Period 154 days 109 days

Establishment of Embryo 15 15

Implanted Period 230 118

Total Gestation Period m-days 242 days ~ or Approximately 13 months 8 months

Neither estimate should be considered precise. In addition to the inherent sampling problems, there is a good possibility that the unimplanted period is·variable. The estimates do illustrate the problems involved and the results of the larger sample indicate a gestation period of substantially less than a year. This is more consistent with other information (Fig. 2).

Peaks of Breeding and Pupping All the curves in Fig 1 and 2 are influenced by more than one variable so it is difficult to draw precise conclusions from them. Generally the curves indicate the greatest number of pups are born in the period from June or July through November and the greatest breeding activity occurs from September through January. The information suggests a gestation period closer to 9 months rather than the 12 months assumed by some studies.

Fieguency of Pupping The mean percentage of pregnant animals throughout the year appears to be about 50 percent of the sexually mature females. This sup­ ports the theory that most females pup once every two years.

That females seldom breed while accompanied by a pup is also sup­ ported by the fact that only one out· of 120 lactating females was definitely pregnant (excluding those with term £etuses) .•However, Table 3 indicates that an average of 14.2 percent of the lactating females have enlarged follicles or possible corpora lutea. This Table 3. Reproductive Condition of Lactating Females.

2 Location Date Active %Active

Bay of Is·., Adak Sept. 1967 9 1o. 0.

Amchitka · Sept ...Oct., 1967 17 ·-2­ -1o. 5

Mid Pt. -Blind Pt~, Adak Oct. 1968 19 3 13.6 Bay of Is., Adak Oct. 1.968 22 4 15.4 Kanaga Oct. 1968 32 53 13.5 Amch i tka Ju 1y-Aug., 1969 4 2 33.3

Total 103 17 14.2

1. Anestrous or pregnant with term fetus.

2. Large follicles or corpus luteum present.

3. Includes one implanted pregnancy with small fetus. - -4­

indicates that females continue to ovulate or at least go into proestrus while supporting a pup, but only occasionally become pregnant. This is also supported by the fact that one corpus albicans may be formed per year after sexual maturity (Tables . 4 - 7) • Some lutenization probably occurs and a corpus albicans is formed for each ovulation even though pregnancy does not' result. ' It would appear that a failure to breed every year may be be~avioral rather than physiological.

. Multiple Ovulation and Twins . · ...... The following is a summary of· suspected multiple ovulations and twin fetuses. In all cases, the corpora lutea were of similar size .and completely separate, often in differ~nt ovaries . . ' Total pregnant females 258

Implanted pregnancies 137 Unimplanted pregnancies with 2 CL(Corpora Lutea) 6

Implanted pregnancies with 2 CL and 1 Fetus 4

Implanted pregnancies with 3 CL and 1 Fetus 1 Implanted pregnancies with 2 CL and 2 Fetuses 4

Total multiple ovulations 15

Number of CL's per pregnancy 1.062

Percent multiple ovulations 5.~/o

·Percent twin pregnancies 2. 9%

In addition to these, one instance of triplets was recorded. All had implanted in the same horn and were being resorbed. Only skel­ etal .fragments remained.

All multiple fetuses appear to be the result of separate ovula­ tions and all had separate placentas, however, all implanted in a single horn.

Age of Sexual Maturity Tables 4 - 7 list the frequency of numbers corpora albicantia and corpora lutea found in females of different areas. It should be recognized that the ages may not always be exact. Animals from Arnchitka appear to become sexually mature when about 4 years old. It appears that more animals may become mature earlier on Adak. The information is too limited to make any definite conclusions from this, however, the food availability is probably bette~ at Adak and an earlier age of sexual maturity may be a response to better nutrition. I, ! . ' I T - < _,. --- /'" • t!, • l - . · · rable 4: Frequency of occurance of Numbers ofCorpora Albicantia

0 - - -· _, . · ·'~-~ .. Amch i tk~ - Jurie-Augus t 1968. _., ...... _,...... • ..•. : . ~~f- . '"f • -~- •• --...-. . _: ..:--~ ·_; .: ,:...... ::., ...~ .: ~- . . - ~ . - . ' ... . .~·· . :" . . . . . ; : ·. N U MB E R 0 F . C 0 R P 0 R A

' ~_; - AGE ...... 11 (Years) 1 .. 2 . 3 4 . 5 6 7 8 . 9 . 10 -­ .. - .. - --­ ···­ - ·­ -­ -­ -· -· . - . ­ -­ . .. .• - - ­ .. - . -

... -~ -· :. ···-= ~ :'"!······· ..... Q~L...... • . 1-2 -­ - -

2 . .. . ' .. - - 3

4 1 1 • . - 5 2 ( 1)

6 1 1 ( 1)

7 2 (1) 1

8 1 1 ( 1)

9 2 ( 1) 1 ( 1) 1 ( 1)

10 1 ( 1) 4 (3) 2 1 ( 1)

11 2 ( 1) 1

12 1 ( 1) 2 ( 1) l (1)

13 1 14­ 1 1 ( 1) .. 15 . 2 1 16 1

17

18 ... . 19 1

Numbers tnside parenth~ses = Number of individuals with corpus luteum.

. .

·.. ' •· ' ...... 0 ...... o •., ...... ,. .;.:··· ~· - ...... - ;. .o • ... /. ·-· ...... ·:- ::-'; .. w

•• ~. 0 ~ : . . . ,_ Jab1e 5. Frequency of occurance of Numbers of Corpora A1bicantia •.o ••

_ : · "·· ·• .. ;, . .. ·· ·.. · ' Kanaga ~ October 1968. ,7 .. ... ,.. -~·-~--~ ·i:~:..::!" ~ ·.• •·• . . . -. • '.:." -.:...... ·. ··~-. ·.,_- .. •· .... ·-· =·. ~ : . :~ ::.~· .. ~ . : . .. " ,: . } ·.· ...... ~ · .· --~---. ·, ... ··. . ... c ·oR. PORA · A. LBICA .NT -' IA .

, ~.: ' AGE - . 11 (Years) .-. 2 3 4 5 6 7 8 9 10 1 ...

·-­ ~ -. - -· -­ - - . 0-1 - . ·. . . . ' -~ ...... 1-2 ..

2 . .

3

4 2 ( 1) 4 ( 1) (Plus 2 with corpus 1uteum but no corpora a1bicantia) 5 3 . 6 6 (3) 10(5) 1

7 4 (4) 1 ( 1) 8 4 5 ( 1) 3 . 9 2 ( 1) 3 2 ( 1) 3 (3) 1 10 1 3 ( 2) 5 ( 1) 1 ( 1) 1 ( 1)

11 1 ( 1) 2 3 3 (1) 1 ( 1) 1

12 1 4 ( 1) 1 ( 1) 2 ( 1) 1 1

. -13 1 ( 1) 3 (3) 4 ( 1) 2 (2) 1 ( 1) 1 1 ( 1) 14 ' .. tf 15 1 ( 1) 2 1 1 ( 1) 16 . 1 1 ( 1) 1

17 1 ( 1)

18 .

Numbers i~side parenth~ses = Number of individuals with corpus 1ute~m.

' -~ .­ ~- , -~. .. •, . ~~ r. . .. I 1,. ·.. · _ : . , ·. · Tab 1 e 6 . Frequency of occurance of Numbers of Corpora A 1 b i cant i a .. .• ' ' ..,~ · I' · ·· ... .· ..·,. Mid Pt · :-B1indPt·., Adak ... October· 1968. ~ • • _ _f' . ·.·. • • •. ? • ... ::" --- ~ • -· -· • • • : ...... :"" .. · .·_ ; . _· .... -· ·: . . -~- : .. : ~ . . N U M B E R 0 F C 0 R P ·o R A A L' B I cANT I A'

r •_; - AGE - .. 4 5 6 7 8 · 9 10 11 (Years) 1 ... 2 .. 3 ' ' __, .. ,..;..,.__,­ -· -·­ " .. -­ ··· ·-· --. - --­ ­ - -· ­ - - .. . - . - 0-1 ~- ' ·., ...... ·.. ~ ~· .· ·.; .·. ..- ...... ····-· ...... :-•··­·-· ·· ...... - ······ ·:· ::: . '······ ·· ·· ····,. . ·-······-··· ·· 1-2 -· - -

2 1? (Plus one with corpus. luteum but no CC?rpus a 1b i cans) I I I I 1 3 (On} with corpus luteum but no corpus a 1bicans~

4 2 ( 1 )

5 1 1 ( 1)?

6 1 ( 1) 1

7 1 ( 1)

8 1 ( 1) 1

9 2 ( 1) 1

10 1 1 (1) 1

11 1 2 1 ( 1)

1 2 1 ( 1) 1 '1

13 l 1 1 1'

14 1 15 . 1 .( 1) 1 16 1 17 .. ... 18 1 .

Numbers inside parentheses = Number of individuals with corpus 1uteum.

. ' ' . . ~: • - .. ~ .- .. 004 .. :.. .. . - - ...... • • ......

. . .. ' · ~ .Table 7· Frequency of occurance of Numbers of Corpora ·A1bicantia· -· -·. -;;:• . _ ·, __ : ·.;_.'(h~ee f\rm Bay - Bay of Is 1ands, Adak - Qctober '1968. •...... ~ .. 0 I J ·.:: ' ..._ -~ 0 ... _: • " ; ·~ -~ 0 0 :_ F .....\.. - ~-~· o , • ' ! ~ ~ ..··...... -·- N u M B E R ,, 0 F .,c.0 .~- -\ . ~ .R A'·.:. A.c.B.·I .c~·A _._ NT·-, .A: ' "":·' .... AGE : '4.{'· . (Years) · 1.-. 2 3 4 -5 6 7 8· 9 10 . 11 .. ' I .._. : •. . . - - f--­. .-.. - - -­ - - --. ·o-t ·­ ...... - ... -· 1-2 -­ .... ' 2 One with corpus luteum but no corpora alb icant ia ·I I I I I I I 3 One with corpus luteum but no corpora albicantia

4 2 1?

5 1 ( 1) 3 (Plus one with corpus luteum but no corpora albicantia)

6 1 ( 1) 2 ( 1)

7 .1 2 (2). 1

8 1 ( 1) 2 ( 1) 4 ( 1)

9 2 ( 1) 2 ( 2) 1 ( 1) 1

10 2 ( 1) 2 2 3 ·1

11 1 ( 1) 2 2 3 ( 1)

12 1 1 ( 1) 2 ·( 1)

. -13 2 (1) l 1 ( 1~

· 14 1

15 1 1 16

17

18 ..

Numbers i~side parentheses = Numb~r of individua ls with corpus _luteum.

' -s- Frequency of Ovulation From Tables ·4 - 7 it can be seen that the maximum number of. corpo~a albicantia for each age roughly equals the number of. years after sexual maturity indicating that some animals ovulated once every year a~ter maturity. It can be assumed that many corpora albi- · cantia a.re invisible macroscopically after several years, parti­ ·cularly if they are not remnants of a corpus luteum· of pregnancy. Therefore, it is. possible that most females ovulate every year. This possibility is also supported by the high incidence of large follicles in lactating females. Table 3 . .. . ~- ...... ~ ...... ".. " ...... " ...... Maximum Breeding Age Tables 4 - 7 indicate that at least some females continue to breed at a very old age. The samples are to small to determine whether a significant number become unproductive at any point .

. .... -

Tagged Sea Otters

The following sea ·otters were released at Amchitka by Battelle Memorial 11 11 Institute after the nuclear test Milrow • Each otter wore a single monel metal cattle tag i_n a hind flipper• .,. ·•

Tag No. ·~ Sex Weight Date & Location

...... UOl...... -...... d ...... " 26 .. lb.. " " ...... ·• · ......

1102 (f 43

1103 ~ 30

1104. ~ 35

1106 (f 47

1107. ~ 44 w/pup Released at Constantin~ Harbor 10/6/69 or 10/12/69. 1108 (f 47

1109 ~ 50

1120 ~ 34

1122 (f 32

1124 ~ 38

1125 (f 36 ' . 1110 (f 57

1111 C.( 48 2 released west of Ri fle Range Pt. 10/2/69. 1112 ~ 44 2 released Constantine Hbr. 10/6/69. .; 1J13 (f 39

1116 (f 54

1117 ~ 29 2 escaped west 9f Rifle Range Pt. 10/2/69. 11 I 9 ~ 40 1 released Constantine Hbr. 10/6/69.

..