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Alaska Ecosystems Program

Russian Steller Sea Lion Research Update (cont.)

- Pup Branding and Sampling:

figure 1, click to enlarge
Figure 1.  Click image to enlarge.
 
 

In the Russian Far East, the first attempts at tagging newborn Steller sea lion pups to study their winter migrations occurred during the mid-1960s. However, the sample sizes were small (45 pups), and the work did not provide any useable results. Ultimately, several more attempts were made to tag pups with metal and plastic tags, and the results of this work provided the first data on migrations of young Steller sea lions between rookeries and haulouts. However, these tags were only retained for 3-4 years.

The first mass branding of pups in Russia was performed during the joint research cruise of TINRO and NMML scientists in summer 1989, and branding has been carried out regularly since 1996 (Table 2). In total, 8,486 Steller sea lions have been marked on 9 of the 10 major Steller sea lion rookeries in Russian waters, including 1,524 sea lions that were tagged with front flipper tags and 6,962 that were branded (Fig. 1, Table 2).

In parallel with pup branding, morphometric data (body length, axillary girth, and weight) were regularly collected and, beginning in 2002, a small tissue sample was taken from each branded pup for genetic research. In addition, blood samples were collected from 10-30 animals at each site to monitor health conditions and for archival purposes.

 Table 2.  Summary of Steller sea lion branding and tagging in Russia, 1985-2008.
 
YEAR R O O K E R Y TOTAL Grand
Total
Manati Medney Zozlov Zheleznaya Antsiferov Raykoke Lovushki Srednego Brat Chirpoev Iony Matykil' MPT* Brand
1985 2                                                2       2  
1987 20                                           20       20  
1988 8                                           8       8  
1989 3                   139   200   200   200           3   739   742  
1991     50               100   200       100           450       450  
1992     100   82   12                               194       194  
1993     100   74                                   174       174  
1994     100   47                                   147       147  
1995     100   50           101   100   100               451       451  
1996     100   50       100   100   100       100               550   550  
1997     25   50       100   100   100       100   100       25   550   575  
1998     87   50       100   100       100   100   150           687   687  
1999     100   50       50   100   100   80   100               580   580  
2000         50                               90   50   90   140  
2001     95           100   100   100   100   76   143   81       795   795  
2002     85   50                           100   150       385   385  
2003     54           100   100   77   100   100               531   531  
2004     100   50                           150   150       450   450  
2005                 100   100   105   100   100               505   505  
2006     100   50                           150   150       450   450  
2007                 100   100   100   100   100               500   500  
2008     100   50                                       150   150  
Total MPT 33   475   303   12       201   300   100   100           1,524          
Total brand     821   400       750   939   882   780   976   793   621       6,962      
Grand Total 33   1,296   703   12   750   1,140   1,182   880   1,076   793   621   1,524   6,962   8,486  
 *MPT = metal or plastic tags.
  Numbers in regular font are metal or plastic tags.
  Numbers in bold font are brands.


- Observations of Branded Sea Lions:

In Russia, observations of branded Steller sea lions are carried out mainly on the breeding rookeries (Table 3). Two or three observers spend up to 3 months camped near 8 of the 10 primary rookeries to collect daily resights of branded sea lions. As with similar work in Alaska, digital photos are collected for verification of the encounter and for positive identification of individual animals (photos of brands are compared with the brand resight database).

For juvenile animals (ages 1-3), all observations note the presence or absence of a tending adult female, and for mature females the presence of an older dependent or a newborn pup is also noted. All observations also note whether the adult female is nursing and if any copulations are observed. Data are entered into a database daily.

Table 3.  Steller sea lion brand resight effort (days) on Russian rookeries
during the breeding season, 2002-08.
 
Rookery 2002 2003 2004 2005 2006 2007 2008 Total
Medny/Yugo-Vostochny 78   83   73   86   80   87   71   558  
Kozlov Cape 52   47   43   64   81   60   3   350  
Antsiferov/rookery 33   53   57   49   60   47   45   344  
Lovushki/Dolgaya 35   51   55   54   59   51   38   343  
Raykoke 39   52   54   54   56   44   24   323  
Brat Chirpoev/rookery 37   50   51   54   55   43       290  
Sakhalin/Tuleny 59   43   40   28   30   33       233  
Yamsky Islands             34   38   43       115  
Total 333   379   373   423   459   408   181   2,556  

In addition to the ground-based observations on the rookeries, vessel surveys over large areas are conducted to record and photograph branded sea lions seen on haulouts, and similar data are collected on reproductive status. Ultimately, all of this information is collated at the completion of the field season and combined into a single Steller sea lion brand resight database.

All the data received from occasional respondents—fishermen, hunters, local residents, etc.—are also entered in this database. Data on the branded sea lion encounters along the coast of Hokkaido (Japan) are regularly provided by students of Hokkaido University and biologists from the Hokkaido National Fisheries Research Institute. There are currently more than 100,000 records about encounters of 2,648 branded Steller sea lions in the database.  (continued)
 

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