Steller Sea Lion Survey on Kuril and Iony Islands, Russia  (cont.)

(Feature: part 2)
Methods

During the survey two methods were used to count animals.  On smaller sites with suitable exposure to the sea (sloping towards the water without large rocks or boulders) surveyors counted animals from an inflatable boat with an outboard motor as close to shore as possible.  On large sites or those with poor exposure due to flat beaches or large rocks, surveyors landed on shore and made the counts from suitably high locations that allowed a good view of the entire site.  Counts were conducted using 7 X 50 or 12 X 50 power binoculars.  Pup counts were conducted only from shore. At least two observers counted pups while walking through the rookery, which caused adult animals to retreat into the water.  At some rookeries (the islands of Lovushki and Srednego) the pup counts were hampered by the presence of northern fur seals.

• Pup measuring, tagging, branding, and blood sampling

All pups that were handled during our work on the rookeries were measured.  Standard length was measured with a measure board and an axillary girth was taken with plastic measuring tape both with accuracy (± 1 cm).  All pups were weighed with an electronic scale (± 0.5 kg).  Brands were applied to the left front shoulder using techniques described by Merrick et al. (1986). Most of the branded pups were simultaneously tagged with paired plastic tags of different colors but with the same number as the brand.  Blood was collected from the caudal gluteal vein of the manually restrained pups using a 20#G 1.5” Vaccutainer® needle (Beckton-Dixon).  We attempted to collect 9 ml of blood in serum separator tubes (SST) and 5 ml of blood in tubes coated with the anticoagulant sodium heparin (GTT).  All blood samples were stored on ice until they were returned to shipboard laboratory facilities (<6 hrs).  Serum tubes were warmed to room temperature for at least 40 minutes prior to centrifugation to allow proper clot constriction.  Heparin tubes were placed on an agitator to remix samples and complete blood counts (CBC) were determined using a portable automated cell counter (HMT Vetscan, Abaxis, Inc.).  In addition, blood smears were made from heparinized whole blood to validate cell counts.  All blood collection tubes (serum and heparin post CBC determination) were centrifuged at 3,200 rpm for 6 minutes to separate blood products.  Serum was aspirated and aliquoted in 1 ml volumes and frozen for later determination of serum chemistries and other analyses.  Plasma was similarly aspirated and aliquoted and frozen for archival purposes.  Samples were frozen on board the ship for the duration of the cruise (<27 days) at approximately 0ºC.  Upon return from the field, samples were transferred to -40ºC. Clinical chemistries and cell counts were determined by the commercial veterinary laboratory, Phoenix Veterinary Laboratory, Everett, Washington.
 

Preliminary Results

The cruise lasted 30 days (23 June- 22 July 2001) during which we surveyed all five Steller sea lion haul-out sites along the southern part of Kamchatka Peninsula, 40 of 53 known sea lion sites on Kuril Islands, and all sites on Iony Island (Figure 8 below). Counts of Steller sea lions by age and sex classes were conducted on all rookeries and haul-out sites.  Due to lack of time and bad weather, 13 sites were not surveyed on the Kuril Islands.  Most of the sites not surveyed are typically winter haul-out sites, and relatively few animals (< 10 animals) were expected there during the summer.  As a result, few sea lions were missed during our haul-out survey, and our count data represent the status of the Steller sea lion population on the Kuril Islands and are usable for comparison trend analysis.

Pup data collections were successfully accomplished on five major rookeries in the Kuril Islands, as well as on one rookery on Iony Island.  A total of 619 pups were marked by hot brand, and of these, 572 were simultaneously tagged with paired plastic tags.  Photographs of each brand were taken to be entered into a database and will be used for future identification and to improve the brand quality.  Tissues collected from pups included 10-15 ml of blood from 335 pups (50-60 samples per rookery) and 129 skin punches from the rear flippers for nuclear DNA analysis.  Blood samples were collected for the purpose of assessing physiological condition and, prior to 2001, had not been collected from Russian-born Steller sea lion pups.  The period of collection overlaps with similar sampling efforts on Steller sea lion pups born on Aleutian Islands rookeries.  Collectively, these data will provide a comparison of the depleted but stable Kuril Islands population with the declining western stock of the Alaskan population.  More than 250 samples of plasma and erythrocytes were collected for the Institute of Biological Problems of North, Russian Academy of Sciences (Magadan).  They will be processed using electrophoresis methods to examine enzymes and nonenzyme proteins in blood for an estimation of allozyme variability at different rookeries in the Kuril Islands and at Iony Island and as a measure of their degree of isolation.

A total of 480 scat samples were taken from 17 rookeries and haul-out sites.  We also searched for animals branded in past years and obtained photographs or video footage of the brands seen.  A total of 257 marked animals were seen 798 times during the cruise.  One hundred eighty of them were new animals resighted for the first time after branding.  Two hundred thirty eight sea lions were fully identified (letter and all digits were read), but the place of birth could only be determined for 16 animals (by letter code or color of plastic tag); 3 animals had brands that were not readable.
 

Discussion

All data collected during our expedition are currently being analyzed.  All scat samples have been washed and the food remains have been preserved (fish bones, otoliths, beaks of cephalopods, etc.).

Preliminary data indicate that Kuril Islands pup masses were greater than predicted by linear relationships between standard length and axial girth of Steller sea lions born on Aleutian Islands rookeries.  This discrepancy was probably not a result of differences in mean pupping date, given the high incidence of neonatal pups observed on all Russian rookeries.  Though preliminary, results suggest a potentially interesting difference between the two regions that might be due to differences in condition, genetics, or a combination of factors.  In addition, Russian pups were observed with a high incidence of ectoparasites (Anthropleura spp., common name, sucking lice).  Lice are commonly observed on Steller sea lion pups, however, the degree of the infestation appeared to be usually severe among Russian animals (Browne, personal observation.)

A total of 4,897 Steller sea lions age 1+ years old and 1,896 pups were counted on all rookeries in the Kuril Islands, 1,509 non-pup and 952 pups were counted on Iony Island, and 119 non-pup animals were counted along the southeastern coast of Kamchatka Peninsula.  Our preliminary analysis of the count data shows that 57 percent more animals greater than 1 year of age were counted on the Kuril Islands in 2001  than in 2000 ( Figure 2 ).  Also, many more sea lions were counted during 2001 on rookeries ( Figure 3 ).  By comparing adult pups counts in 2001 with 2000, it is apparent that the number of animals age greater than 1 year old on all five rookeries was unusually low in 2000.  The number of non-pups was close or even lower than the number of pups.  Usually, the average number of non-pups on rookeries is about 30 percent higher than the number of pups.  It is likely that the count of animals of age 1+ on rookeries in 2000 was an undercount, most likely because the counts in 2000 were in the second half of July, which is late to accurately count sea lions.  The total number of newborn pups on the Kuril Islands during 2001 was similar to the count in 2000 and about 10 percent higher than the average number counted during the last 25 years.  The number of non-pups on Iony Island was 6 percent higher than the previous count in 1997, but the number of pups was 12 percent lower ( Figure 6 ).  Unfortunately, it is difficult to compare the data for the earlier counts because in 1997 the counts were obtained 2 weeks earlier than in 2001.

Additionally, during the pup count on the main breeding beach (where up to 50% of pups are born), many pups went into the water with the mature animals.  However the data suggest that there has not been a dramatic change in the abundance of Steller sea lions on Iony Island over the last 4 years.  We also searched the island for 2 days to locate branded animals but could find only 2 of 250 branded in 1997-98.  Both were females 4 years old without pups, and they both looked relatively smaller and skinnier than other females the same age seen on the Kuril Islands.

All the Steller sea lion haul-out sites were surveyed along the southern part of the Kamchatka Peninsula.  Sea lions were present on one site near Kekurny Cape only.  Similar to recent surveys there were no sea lions on Gavrushkin Rock and Sivuchiy Kamen’ Island, but they were present there year-round 15-20 years ago. There were no sea lions on Sivuchiy Cape in 2001.  Our data confirm a large decline in the number of Steller sea lions along the Kamchatka coast.

A full report with results of the Kuril and Iony Islands 2001 expedition will be prepared after processing all samples and analysis of the obtained data.  We plan to create a catalogue of all branded animals to distribute among scientists in Russia, Japan, and the United States that can be used as a field guide for observers in order to obtain more information on the identification and movement of branded Steller sea lions.

Dr. Vladimir N. Burkanov is a Russian marine biologist with Natural Resources Consultant, Inc., of Seattle, Washington, working under contract with the National Marine Mammal Laboratory.

• Introduction
• Methods
• Preliminary Results
• Discussion

AFSC Quarterly
Research Reports
Oct-Dec 2001