Sakhalin State University (SakhGU) DISTRIBUTION AND ABUNDANCE OF GRAY WHALES IN NORTHEAST SAKHALIN COASTAL WATERS IN JULY-SEPTEMBER 2015

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1 Sakhalin State University (SakhGU) DISTRIBUTION AND ABUNDANCE OF GRAY WHALES IN NORTHEAST SAKHALIN COASTAL WATERS IN JULY-SEPTEMBER 2015 SURVEY REPORT UNDER THE 2015 GRAY WHALE MONITORING PROGRAM OFF THE NORTHEAST COAST OF SAKHALIN ISLAND V.A. Vladimirov (Council on Marine Mammals), I.A. Timokhin (Moscow State University) and S.A. Tyurin (LGL Eko) Prepared for Exxon Neftegas Limited and Sakhalin Energy Investment Company Ltd. Yuzhno-Sakhalinsk 2016

2 Sakhalin State University (SakhGU) APPROVED BY SakhGU Provost, I.G. Minervin, DISTRIBUTION AND ABUNDANCE OF GRAY WHALES IN NORTHEAST SAKHALIN COASTAL WATERS IN JULY-SEPTEMBER 2015 SURVEY REPORT UNDER THE 2015 GRAY WHALE MONITORING PROGRAM OFF THE NORTHEAST COAST OF SAKHALIN ISLAND V.A. Vladimirov (Council on Marine Mammals), I.A. Timokhin (Moscow State University) and S.A. Tyurin (LGL Eko) Prepared for Exxon Neftegas Limited and Sakhalin Energy Investment Company Ltd. Yuzhno-Sakhalinsk

3 2015 PROGRAM OF GRAY WHALE MONITORING OFF THE NORTHEAST COAST OF SAKHALIN ISLAND The gray whale surveys consisted of: 1. Onshore vehicle-based surveys: The 2015 onshore distribution surveys were conducted by 13 groups of SakhGU observers. Each group worked at the same survey station during the entire field season. S.P. Starodymov managed the work of all groups at the Odoptu-Piltun (north) site, and I.O. Tarasov at the Astokh-Chayvo (south) site (both from ENL). Party responsible for work execution: Sakhalin State University (SakhGU). 2. Vessel-based surveys: Igor Maksimov research vessel: A.Yu. Yakovlev (Institute of Marine Biology, team lead), A.V.Baklanov, M.S. Kornienko, A.S. Tischuk (all from SakhGU). High-speed passenger vessel Polar Piltun: V.E. Zhukov, candidate of biological sciences (team leader), V.Ya, Kavun candidate of biological sciences, E.B. Lebedev, A. Pogonyshev, E. Sazonov (all from SakhGU) Party responsible for work execution Institute of Marine Biology (IMB), Far East Branch of the Russian Academy of Sciences, and SakhGU. Director of gray whale distribution monitoring research V.A Vladimirov., candidate of biological sciences (Regional Public Organization Council on Marine Mammals ). I

4 TABLE OF CONTENTS EXECUTIVE SUMMARY INTRODUCTION Main objectives of the program for monitoring the distribution of gray whales off the northeast coast of Sakhalin island using vessel-based and shore-based surveys STUDY METHODOLOGY SURVEY EFFORTS AND MATERIALS COLLECTED Shore-based surveys Vessel-based surveys SURVEY RESULTS Gray whale distribution and abundance Piltun feeding area Shore-based surveys Changes in the simultaneous number of whales in the Piltun area Spatial distribution of whales and its seasonal variations Whale distribution by distance from shore and water depths Offshore feeding area Total number of gray whales in the feeding group in Sakhalin waters Size of whale pods Piltun area Offshore Area Sightings of other marine mammal species DISCUSSION OF RESULTS CONCLUSION ACKNOWLEDGEMENTS REFERENCES APPENDIX APPENDIX APPENDIX APPENDIX II

5 LIST OF TABLES Table 3-1. Number of onshore vehicle-based surveys of gray whales in the Piltun area in August-September 2015 and overall results... 5 Table 4-1. Distribution of gray whales in the Piltun area according to distance from shore in August-September 2015 (based on complete synchronized shore-based surveys) Table 4-2. Distribution of gray whales in the Piltun area according to water depth in August- September 2015 (based on complete synchronized shore-based surveys) Table 4-3. Sizes of gray whale pods recorded in the Piltun feeding area in 2015 (according to data from all shore-based surveys) Table 4-4. Size of gray whale pods recorded in the Offshore feeding area in 2015 (according to data from all vessel-based surveys) III

6 LIST OF FIGURES Fig Locations of survey stations of gray whale shore-based surveys in the Piltun feeding area and planned transects of their vessel-based surveys in the Offshore feeding area in Fig Seasonal variations of number of gray whales recorded simultaneously in the Piltun area in August-September of 2015 (based on complete synchronized shorebased surveys)... 8 Fig Seasonal variations in gray whale spatial distribution in the Piltun feeding area in August-September of 2015 according to complete synchronized shore-based surveys (density of whales per 1 km 2 )... 9 Figure 4-3. Seasonal variations in gray whale quantitative distribution by sections in Piltun area waters in August-September of 2015 (based on complete synchronized shorebased surveys) Figure 4-4. Distribution of gray whales in the Piltun area by distance from shore in August-September 2015 (based on complete synchronized shore-based surveys) Figure 4-5. Distribution of gray whales in the Piltun area by sea depth in August- September of 2015 (based on complete synchronized shore-based surveys) Figure 4-6. Distribution of gray whales in the Offshore feeding area in July-August 2015 (based on complete vessel-based surveys) Figure 4-7. Sightings of other marine mammal species in the waters of the northeastern Sakhalin in July-September of 2015 (based on shore-based and vessel-based surveys) Figure 5-1. Year-to-year variations in gray whale distribution in the Piltun and Offshore feeding areas in (based on combined shore-based and vessel-based survey data) Figure 5-2. Consolidated data on changing numbers of gray whales in the East Sakhalin feeding area in IV

7 EXECUTIVE SUMMARY This report presents the results of vessel-based and shore-based surveys in the summer and fall of 2015 under the Joint ENL-SEIC gray whale monitoring program off the northeast coast of Sakhalin Island. The2015 distribution survey data shows that maximum concurrent number of gray whales recorded off the coast of northeast Sakhalin in 2015 reached 107 individuals, which was 40% higher than in 2014 (75 whales) and just 16% lower than the highest number recorded in the entire monitoring period (127 individuals in 2012). The gray whale distribution in the Piltun feeding area in August-September of 2015 was typical for this area as in the vast majority of previous years when the monitoring was conducted, the animals stayed in the central part of the area at a distance of up to 2 km from shore and at water depths of up to 10 m, with an especially high concentration (averaging 73% of whales during the season) in the waters adjacent to the mouth of Piltun Bay. The highest concentration of gray whales in the Offshore feeding area was observed in its southeast part where water depths reach m. During the entire season, another smaller aggregation of whales was observed in the northern part of the Piltun area, averaging 13.8% of the number of whales in the area; they stayed mainly in the waters located at a distance of 5-10 km from shore at depths of m, which may be related, as the results of 2015 benthos studies show, to the increased concentration of the sand lance (Ammodytes hexapterus) the gray whales highly preferred food item. Survey data obtained during the 2015 Joint ENL-SEIC gray whale distribution monitoring program indicate that the number of gray whales feeding in eastern Sakhalin is within the range of numbers observed in previous years. No obvious anomalies in the distribution or seasonal variations of the number of gray whales were found during the 2015 vessel-based and shore-based surveys that could be interpreted as signs of anthropogenic impact. 1

8 1. INTRODUCTION The gray whale surveys whose results are presented in this report took place in July-September 2015 under the 2015 Program for Gray Whale Monitoring off the Northeast Coast of Sakhalin Island, which was duly endorsed by the Russian Ministry of Natural Resources and Ecology, the Federal Service for Supervision of Natural Resources Development (Rosprirodnadzor), and the Federal Fishing Agency (Rosrybolovstvo). Funding and logistical support for all the activities were provided by Exxon Neftegas Limited (ENL) and Sakhalin Energy Investment Company, Ltd. (SEIC), respective operators of the Sakhalin 1 and Sakhalin 2 oil and gas projects Main objectives of the program for monitoring the distribution of gray whales off the northeast coast of Sakhalin island using vessel-based and shorebased surveys 1. Determine spatial and temporal characteristics of gray whale distribution in the Piltun and Offshore feeding areas; 2. Assess the seasonal and year-to-year variations in gray whale distribution in the Piltun and Offshore feeding areas; 3. Determine the total number of whales during the main feeding period in the Piltun and Offshore feeding areas; 4. Gather data on the distribution and abundance of other marine mammal species identified during observations. 2. STUDY METHODOLOGY The methods of collecting field materials during vessel-based and shore-based surveys, laboratory processing and analysis of data, and mapping have been sufficiently tested and have remained practically unchanged for a number of years. All of them have been thoroughly described in the pertinent sections of the 2012 report on the Program for Monitoring Gray Whales off the Northeast Coast of Sakhalin (Fadeyev, 2012). A slight difference of the 2015 shore-based surveys was that observations from the survey stations (SS) were conducted by a permanent group of observers who worked at the same station for the entire season rather than by mobile groups driving from one survey station to another, as in previous years. This modification in the survey arrangement was because the same groups were simultaneously involved in the ENL Whale Impact Monitoring and Mitigation Program during Seismic Surveys Performed by ENL in the Sakhalin-1 License Blocks in the Summer and Fall of 2015, during which the adjacent nearshore water areas were surveyed multiple times during daylight hours. The methodology of performing 2

9 observations remained unchanged, which is why the results are completely comparable with the results of monitoring in previous years. The locations of the survey stations from which shore-based observations of whales were performed in the Piltun feeding area in 2015 and the traverses of vessel-based surveys in the Offshore area are shown in Figure 2-1. The locations of most of the shorebased survey stations have not changed since 2013, although four low-lying coastal survey stations in the southern half of the Piltun area that were washed away by winter storms (Nos and 13) were moved to the nearest elevated points (descriptions of all the survey stations are given in Appendix 1). Vessel transects of the surveys in the Offshore area were shifted by one transect south in 2015, so that transects 2-7 were surveyed instead of transects 1-6, because whales were seen farther south than the most southern transect line. 3

10 Survey stations Onshore/offshore infrastructure facilities Vessel-based survey transects Subsea pipelines ENL SEIC License blocks ENL SEIC Odoptu Odoptu License Block SEA OF OKHOTSK Kilometers Piltun Bay LGL Eko LLC, December 2015 PA-B Platform Piltun-Astokh License Block Piltun Lighthouse PA-A Platform (Molikpaq) SAKHALIN ISLAND Chayvo OPF Val Yastreb Rig Chayvo Bay Orlan Platform Chayvo License Block Berkut Platform Arkutun-Dagi License Block RUSSIA Bering Sea Sea of Okhotsk Sakhalin Work Area Nyisky Bay JAPAN Pacific Ocean Nogliki Fig Locations of survey stations of gray whale shore-based surveys in the Piltun feeding area and planned transects of their vessel-based surveys in the Offshore feeding area in

11 3. SURVEY EFFORTS AND MATERIALS COLLECTED 3.1. Shore-based surveys The 2015 field work of shore-based distribution surveys of gray whales in the Piltun feeding area lasted 61 days (August 1 through September 30). Because of bad weather during a large part of the field work season, only 13 complete synchronized surveys (August 2 to September 16) were performed in the area. In addition, 14 complete non-synchronized surveys were conducted in one of the sections (13 surveys in the Astokh-Chayvo section and 1 survey in the Odoptu-Piltun section), but it was not possible to conduct accurate surveys in the other section due to weather conditions (Table 3-1). In 36 cases, surveys that had been started in the areas had to be interrupted due to worsening weather conditions (reduced visibility, high seas or precipitation). Altogether, 541 sightings of lone gray whales or pods were recorded during the shore-based surveys in 2015, and the total number of animals sighted was 602 (Table 3-1). Table 3-1. Number of onshore vehicle-based surveys of gray whales in the Piltun area in August-September 2015 and overall results Odoptu-Piltun section (survey stations 1 8) Complete surveys Partial surveys Total number of Month Number of whale recorded n n sightings whales August September Total: Astokh Chayvo section (survey stations 9 13) Month Complete surveys Partial surveys Number of whale Total number of n n sightings recorded whales August September Total: T o t a l Complete surveys Partial Total number Month Number of whale synchronous asynchronous surveys of recorded sightings n n n whales August September Total: Note: The number of gray whale pods or single gray whale sightings, and whale count includes all recorded whales and whale pods, including whales sighted outside the 1-minute sector scanning periods ("out of scan"). Complete surveys within a section are those during which monitoring was performed at all survey stations (survey stations 1 8 in the Odoptu-Piltun section and 9 13 in the Astokh- Chayvo section); complete synchronous surveys in the entire area are defined as synchronized complete surveys carried out in both sections; asynchronous surveys are complete surveys 5

12 performed within these sections at different times. Partial surveys are those that for some reason were not carried out at all survey stations. In addition to gray whales, 35 animals of three other cetacean species and 2 pinnipeds (northern sea lions, which are included in the RF Red Book) were recorded during shore-based surveys; information on all of them is presented in Section 4.2 of this report and in Appendix Vessel-based surveys In 2015, vessel-based distribution surveys of gray whales and other marine mammals were conducted under the Joint ENL- SEIC Program in the Offshore feeding area using the Polar Piltun high-speed passenger ship starting from the second 10 days of July through the end of August. Two complete surveys were conducted on July 11 and August 29. The surveys planned for September were not performed due to adverse weather conditions. In addition, two complete surveys were done from the Igor Maksimov research vessel (July 21 and August 24).as part of the ENL Whale Impact Monitoring and Mitigation Program during Seismic Surveys Performed by ENL in the Sakhalin -1 License Blocks During the July 11 survey, three sightings of groups and individual whales were recorded (total of 5 individuals), in the July 21 survey there were 20 sightings (31 individuals), in the August 24 survey there were 26 sightings (67 animals), and in the August 29 survey there were 14 sightings (42 individuals). Two more gray whales were sighted on July 20 during an incomplete survey from Igor Maksimov. Altogether, 147 gray whales and 19 animals of 5 more marine mammal species were recorded during the special vessel-based surveys in 2015 (Polar Piltun observation data are presented in Appendix 3, and Igor Maksimov data will be included in another report). More detailed information on the gray whales recorded in the Offshore area in 2015 during vessel-based surveys is given in Sections and of this report, and information on the other marine mammals is given in Section

13 4. SURVEY RESULTS 4.1. Gray whale distribution and abundance Piltun feeding area Shore-based surveys On the whole, the weather conditions in August-September, 2015 were hardly conducive to visual shore-based observations. A more or less complete series of synchronized surveys could only be conducted over the entire local water area, and a representative pattern of seasonal variations in distribution and simultaneous whale numbers could only be obtained during the 25-day period from August 23 to September 16 (the survey results are given in Appendix 4) Changes in the simultaneous number of whales in the Piltun area As far as can be judged from the data obtained, during the period from August 20 to mid-september when it proved possible to conduct a series of more or less regular surveys, the simultaneous number of gray whales in the Piltun area recorded during these surveys was fairly unstable, showing a slight trend toward a gradual decrease (Fig. 4-1); on average, it was 29.3 individuals during the last 10 days of August and 23.6 individuals from September 1 to September 16. Looking at the seasonal change in the number of whales using the results of two more headcounts in very early August, we can probably assume that the number of gray whales concentrated in the Piltun area increased until late August and then started to decrease, which is common for this area at the end of the feeding season, although we cannot be completely sure of this as it was impossible to perform surveys after September 16 due to the onset of windy weather. The average number of gray whales recorded simultaneously during the August- September period in 2015 in the Piltun area was 25.7 individuals, and their highest number was 40 individuals (August 24), which is the lowest number during the entire monitoring period (since 2003). 7

14 Max whales (August 24) Number Whales Date Fig Seasonal variations of number of gray whales recorded simultaneously in the Piltun area in August-September of 2015 (based on complete synchronized shore-based surveys) Spatial distribution of whales and its seasonal variations The number of gray whales that were simultaneously present in the Piltun feeding area in August-September, 2015 was relatively low, and they actually stayed only in the central and northern parts of the area during this period. The whale distribution maps that were constructed based on a density analysis of the shore-based survey results demonstrate that the vast majority of animals were located in the area from survey station 7 to survey station 10 during the entire observation period, with an especially high concentration near the Piltun bay mouth generally in the area of survey stations 8 and 9 (Fig. 4-2). Simultaneously, another small congregation of whales, localized on the northern periphery of the Offshore area, north of survey station 4, was seen during the entire observation period, especially in late summer/early fall. The majority of animals typically stayed here in the area in water depths exceeding 20 m (Fig. 4-2). 8

15 Aug Aug Sep Aug 01-Sep 16 SEA OF OKHOTSK SEA OF OKHOTSK SEA OF OKHOTSK SEA OF OKHOTSK Rosneft Rosneft Rosneft Rosneft Odoptu Odoptu Odoptu Odoptu Piltun Bay Piltun Bay Piltun Bay Piltun Bay PA-B Drilling Platform PA-B Drilling Platform PA-B Drilling Platform PA-B Drilling Platform Piltun Lighthouse Piltun Lighthouse Piltun Lighthouse Piltun Lighthouse PA-A Drilling Platform (Molikpaq) PA-A Drilling Platform (Molikpaq) PA-A Drilling Platform (Molikpaq) PA-A Drilling Platform (Molikpaq) Chayvo OPF Yastreb Rig Berkut Drilling Platform Chayvo OPF Yastreb Rig Berkut Drilling Platform» Chayvo OPF Yastreb Rig» Berkut Drilling Platform Chayvo OPF Yastreb Rig» Berkut Drilling Platform Chayvo Bay Orlan Drilling Platform Chayvo Bay Orlan Drilling Platform Chayvo Bay Orlan Drilling Platform Chayvo Bay Orlan Drilling Platform Average number of whales per km 2 : - onshore survey stations - onshore/offshore infrastructure facilities km Fig Seasonal variations in gray whale spatial distribution in the Piltun feeding area in August-September of 2015 according to complete synchronized shore-based surveys (density of whales per 1 km 2 ) 9

16 % of number of whales Season periods Segments of water area between survey stations Average number of whales in segments of water area % of whales in the water area full season Figure 4-3. Seasonal variations in gray whale quantitative distribution by sections in Piltun area waters in August-September of 2015 (based on complete synchronized shorebased surveys) The quantitative parameters of gray whale distribution over the Piltun feeding area, as shown in Fig. 4-3, numerically reflect the above spatial distribution of the animals. Confirming the pattern shown on the distribution maps, they demonstrate that in general during the observation period, the vast majority of whales were concentrated in the water area adjacent to the Piltun bay mouth, between survey stations 7 and 10 (the average for the observation period was 73%, with variations during half-month periods from 65.8% to 86.5% of all individuals). During the entire observation period, an average of 13.8% of whales stayed within the small northern congregation north of survey station 4 with a peak of 15.4% in the second half of August. 10

17 Whale distribution by distance from shore and water depths The distribution of gray whales by distance from the island coast, as calculated on the basis of shore-based surveys, indicates that, in general, the overwhelming number of whales in the Piltun feeding area (77.8% on average) remained within 2 km from water line over the entire observation season in However, there was a significant difference in gray whale distribution by distance from shore in different water areas: the average number of whales within 2 km from coastal line was 63.1% in the northern, Odoptu-Piltun area and 91.4% in the southern, Astokh-Chayvo area (Table 4-1, Figure 4-4). There was also a major difference between the sectors in terms of the numbers of whales staying at a significant distance (over 3 km) from shore: in the first sector the average during the season was 31.9%, and in the second sector only 6.9%. Particularly noticeable was the difference between the sectors in terms of gray whale presence at distances from shore exceeding 5 km: in the Odoptu-Piltun sector there were almost 22% of whales, while in the Astokh-Chayvo sector there were only 1.7% of whales. During the period from August through September the number of whales in this most seaward zone of the water area grew most noticeably in the northern sector (from 10.2% to 38.7%). Table 4-1. Distribution of gray whales in the Piltun area according to distance from shore in August-September 2015 (based on complete synchronized shore-based surveys) Distance (km) Number of whales in each part of the season (%) Aug Aug Sep August September Total Odoptu-Piltun sector > Astokh-Chayvo sector > Piltun area as a whole > The distribution of gray whales by water depths in the Piltun feeding area in 2015 in general corresponded to their distribution by distance from shore, since distance from shore and depth are correlated. Most of the animals (76.0%) remained in 11

18 water depths of no more than 10 m for the entire season, and their primary concentration (54.8% on average) was observed at depths of 0-5 m (Table 4-2, Figure 4-5). Such whale distribution by depth was most pronounced in the shallower Astokh- Chayvo sector, where an average of 92.0% of the animals remained in this zone with minor monthly variations (94.4% in August and 90.3% in September). In the deeper Odoptu- Piltun sector the concentration of whales in August and during the entire season was slightly higher in the zone of 6-10 meter isobath lines (42.9% and 34.4%, respectively), but in September a considerable number of the animals migrated from this zone to an even deeper ( 11 m) part of this water area, which caused the proportional concentration of whales there to almost double - from 30.6% to 58.0% (Table 4-2). This increase was most noticeable in the deepest area (21-25 and especially >25 m) - from 10.2% to 17.7% and from 5.1% to 16.1%, respectively). Table 4-2. Distribution of gray whales in the Piltun area according to water depth in August- September 2015 (based on complete synchronized shore-based surveys) Depth (m) Number of whales in each part of the season (%) Aug Aug Sep August September Total Odoptu-Piltun sector > Astokh-Chayvo sector > Piltun area as a whole >

19 % of total number of whales Odoptu-Piltun section Astokh Chayvo section Piltun area Distance to shore (km) Figure 4-4. Distribution of gray whales in the Piltun area by distance from shore in August- September 2015 (based on complete synchronized shore-based surveys). Odoptu-Piltun section Astokh Chayvo section Piltun area % of total number of whales Sea depth (m) Figure 4-5. Distribution of gray whales in the Piltun area by sea depth in August- September of 2015 (based on complete synchronized shore-based surveys) 13

20 Offshore feeding area As mentioned in Section 3.1 above, four special gray whale surveys were conducted in the Offshore feeding area in 2015, making it possible to accurately calculate their distribution density throughout the water area and to prepare a corresponding map (Figure 4-6). Onshore/offshore infrastructure facilities Special survey transect in the Offshore feeding area (2015) Number of whales per km 2 < 0,25 0,26-0,5 0,51-1 1,1-2 > 2 Orlan Platform Berkut Platform Kilometers Universal Transverse Mercator Zone 54 (CM 141 E) WGS 1984 SAKHALIN ISLAND RUSSIA Sea of Okhotsk Work Area Bering Sea Nyisky Bay Sakhalin Nogliki JAPAN Pacific Ocean Figure 4-6. Distribution of gray whales in the Offshore feeding area in July-August 2015 (based on complete vessel-based surveys) The map shows that during the entire period covered by the surveys (from July 11 through August 29), whales were concentrated in the southeastern part of the Offshore area, almost all of them staying in water depths ranging from 50 to 65 m. 14

21 There were no noticeable changes to the nature of their distribution throughout the feeding area during the observations conducted for nearly one and a half months: most of the animals kept to a more or less dense congregation centered in the eastern half of transect 5 (Figure 4-6) Total number of gray whales in the feeding group in Sakhalin waters The highest number of whales in the Piltun area (40 animals) was recorded during a shore-based survey on August 24. The highest number of whales in the Offshore area (67 animals) was recorded during a vessel-based survey on the same day. These simultaneous surveys actually preclude the possibility of double recording or under-recording of whales due to their migration from one area to another during the time between the surveys in the two areas. Therefore, it would be quite appropriate to simply add up these highest numbers to obtain an estimate of the maximum concurrent number of gray whales present in the two feeding areas during the peak feeding season. As a result, the maximum concurrent number of gray whales recorded in 2015 in the northeastern Sakhalin waters during the shore-based and vessel-based surveys under the ENL-SEIC joint monitoring program is 107. It should be noted that this number only reflects the maximum number of gray whales present at the same time in the northeastern Sakhalin waters and recorded during the surveys. Actually, during the feeding season many more animals likely approach the island s shores, and, for various reasons do not remain there for an extended period of time.. Therefore, the figures obtained during the one-day surveys do not always reflect the total number of gray whales visiting this area during the period of observations. The photo-identification ( photo ID ) data provide a more accurate estimate of the number of gray whales likely to be present in the feeding areas of eastern Sakhalin during the main feeding period of According to the photo ID data a total of 171 whales visited the northeastern Sakhalin waters in June-October 2015 (Yakovlev et al., 2015). Since some animals probably migrated from the eastern Sakhalin area, the number of gray whales present at the same time near the Sakhalin shores that were recorded during the surveys was only 62.6% of their total recorded number in

22 Size of whale pods Piltun area Gray whale pod size observations in the Piltun feeding area conducted in August- September 2015 during the shore-based surveys showed that during this period gray whales were mostly seen as single individuals (in 89.7% of cases) accounting for 80.6% of all recorded animals (Table 4-3). The frequency of pods of two was 9.4%, and they accounted for a total of 16.9% of all whales sighted. Sightings of pods of three were much less frequent (0.9% of all sightings, accounting for a total of 2.5% of whales). Larger pods were not sighted. The average number of whales per pod was 1.11 individuals. The frequencies of sightings of lone whales and various pods in the Piltun feeding area in 2015 were quite close to the sighting frequencies for , demonstrating the low variability of this figure over the years. 16

23 Table 4-3. Sizes of gray whale pods recorded in the Piltun feeding area in 2015 (according to data from all shore-based surveys) Month Pod size (number of individuals) n % of the % of the % of the % of the % of the % of the number of number of number of number of number of number of sightings individuals sightings individual s sightings individuals August September Season total: Note: n number of recorded pods Table 4-4. Size of gray whale pods recorded in the Offshore feeding area in 2015 (according to data from all vessel-based surveys) Pod size (number of individuals) Month n % of the % of the % of the % of the % of the % of the % of the % of the % of the % of the % of the % of the % of the % of the % of the % of the number of number of number of number of number of number of number of number of number of number of number of number of number of number of number of number of sightings individuals sightings individuals sightings individuals sightings individuals sightings individuals sightings individuals sightings individuals sightings individuals July August Season 65 total: Note: n number of recorded pods 17

24 Offshore Area During the four surveys conducted in July and August, there were 65 sightings of the gray whales resulting in the recording of 147 individuals. Thus, the average number of whales in a group for the entire season totaled 2.3 individuals. Lone animals were observed most often 44.6% of sightings and 19.7% of the total number of the recoded individuals, further in descending order were pairs 29.3% of sightings (25.9% individuals) and pods of 3 and 4 whales 13.9% of sightings (18.4% individuals) and 4.6% of sightings (8.2% individuals), respectively (Table 4-4). Larger pods (of 5, 6, 7, 10 and 13 individuals) were observed one time each, making up in total only 7.7% of sightings but comprising 27.9% of all recorded whales. However, the above data should be treated with caution since the series of data acquired in the Offshore area was not too large Sightings of other marine mammal species During the vessel-based surveys conducted in the waters of the north-eastern Sakhalin in July-August 2015, the following marine mammal species were recorded along with the gray whales in the waters of the Offshore area and adjacent areas far from shore: 2 solitary minke whales Balaenoptera acutorostrata, 1 killer whale Orcinus orca, 8 harbor porpoises Phocoena phocoena (6 singles and 1 pair), 7 northern fur seals Саllorhinus ursinus (4 singles and 1 group of 3 individuals) and 1 eared seal Eumetopias jubatus. The location of all animals is shown in Figure 4-7, and other information is given in Appendix 3. According to the shore-based survey data, animals of 3 additional cetacean species were encountered along with the gray whales in the Piltun area in August- September of 2015: 4 lone minke whales, 12 harbor porpoises (4 singles and 4 pairs) and 13 killer whales - 2 groups of 3 individuals, 3 pairs and 1 lone animal (1 group of three individuals and 1 group of two individuals, sighted on September 21 near survey station 1, were, most probably, a temporarily-separated group of 5 whales). Of pinnipeds, the eared seals were recorded during the season as follows: 2 eared seals on August 23 near survey station 2 and on August 8 near survey station 3. The distribution of all cetacean and pinnipeds registered along with the gray whales in the waters of the Piltun feeding area is shown in Figure 4-7, while information on the dates and exact coordinates for all sightings is provided in Appendix 2. 18

25 Minke whale Killer whale (Orca) Harbor porpoise Northern fur seal Northern sea lion - Onshore survey stations Special survey transect in the Offshore feeding area (2015) Onshore/offshore infrastructure facilities Kilometers Universal Transverse Mercator Zone 54 (CM 141 E) WGS 1984 Odoptu Piltun Bay PA Platform SEA OF OKHOTSK Piltun Lighthouse PA-A Platform (Molikpaq) SAKHALIN ISLAND Chayvo OPF Yastreb Rig Val Chayvo Bay Orlan Platform Berkut Platform RUSSIA Bering Sea Sea of Okhotsk Work Area Sakhalin Nyisky Bay Pacific Ocean Nogliki JAPAN Figure 4-7. Sightings of other marine mammal species in the waters of the north-eastern Sakhalin in July-September of 2015 (based on shore-based and vessel-based surveys) In addition to the above marine mammal species, 3 Phocidae species spotted seal or earless seal (Phoca largha, Ph. vitulina largha), bearded seal or leporine seal (Erignathus barbatus) and ringed seal or marbled seal (Pusa hispida ochotensis) are encountered in the waters off northeastern Sakhalin everywhere, all year round and in fairly large numbers. 19

26 Because all three listed species are common in the waters off northeastern Sakhalin, they are not specifically counted under the gray whale monitoring program because it would be very time-consuming, would require revising the observation methodology, and could be done only to the disadvantage of the main monitoring objective. 20

27 5. DISCUSSION OF RESULTS On the whole, the general distribution of the gray whales in the Piltun feeding area in August-September of 2015 was typical of this water area. During those two months, which happen to be the main feeding period for these animals, the vast majority of them (averaging 73.0% over the season and varying in each half-month segment from 65.8 to 86.5%) remained within a confined water area immediately adjacent to the Piltun Bay mouth (between SS No. 7 and No. 10). At the same time, 2015 was also marked by the appearance and presence over the entire survey period of another small, localized aggregation of whales on the northern periphery of the feeding area, north of survey station 4, where up to 15.4% of all whales present in the area and 13.8% of the season s average were concentrated in the second half of August. The characteristic feature of this northern mini-aggregation was the presence of the majority of the whales there (over 60% during the season), in the water area stretching for a distance of over 5 km from the shore beyond the 20-m isobath (Figure 4-2), while, overall for the Piltun feeding area, the majority of the whales (on average at least 76%) remained within 2 km from the coastal line in waters no more than 10 m deep during the entire 2015 survey season (Figures 4-4 and 4-5). In July-August of 2015 the gray whales concentrated in the Offshore feeding area in its southeastern part in water depths up to m. The pattern of gray whale distribution in this area was virtually the same as in 2014, although compared to previous monitoring years, the feeding aggregation shifted in the southeastern direction. An analysis of the data acquired over the 12-years of monitoring gray whale distribution (Figure 5-1) allows certain conclusions to be drawn with regard to general gray whale distribution patterns in the areas of their summer-fall feeding offshore northeastern Sakhalin. Thus, in the coastal Piltun feeding area, the whales kept to its central part at a distance of up to 2 km from the shore in depths up to m during the overwhelming majority of the monitoring years, forming especially high concentrations (exceeding 70-80%, and sometimes even higher) in the vicinity of the mouth of Piltun Bay. However, in certain years, the distribution of gray whales here would change sharply and the main aggregation of whales would shift to the northern part of the area, where a large foraging aggregation would form over 2-3 feeding seasons, also spreading over the zone in water depths of over 20 m. A similar situation, in particular, occurred in and, to some degree, in 2006 (Figure 5-1), when the majority (up to 70%) of all gray whales of the East Sakhalin feeding group concentrated in the North Piltun aggregation. Clearly a great number of whales relocated there from the Offshore area, which was abruptly abandoned (in , 21

28 the surveys counted between 49 and 83 whales, and in only between 9 and 26 - Figure 5-2). The main purpose of the gray whales arrival in the waters offshore northeast Sakhalin is to feed. Therefore, the nature of their distribution over the water areas is primarily driven by the abundance and availability of prey. Analysis of the relevant benthos data gathered under the monitoring program indicated that the typical distribution of gray whales in the coastal Piltun area over its waters (with the majority of whales concentrating in the central part of the area) is driven by the distribution of amphipod biomass, among which Monoporeia affinis is predominant (Fadeyev, 2004, 2006, 2012, 2013; Fadeyev, 2011). However, the appearance of an unusually abundant aggregation of gray whales in the north Piltun area in was apparently driven (based on the same data) by the large spawning clusters of the bottom-dwelling sand lance Ammodytes hexapterus, being a highly-sought-after prey of gray whales and certain other baleen whales (Zimushko et Lenskaya, 1970; Tackaberry et Robbins, 2011). The results of 2015 benthos studies show that the highest concentrations of sand lance are also identified in the northern part of the Piltun area, and its average biomass is five times more that in 2014 (Ivin, 2016). Thus, the formation of a small whale concentration over the deepwater zone in the north of the Piltun area in 2015 may be fully related to the occurrence of sand lance. As far as the Offshore feeding area is concerned, the gray whales feed there primarily on a different amphipod species (Ampelisca eschrichtii) that maintains a different lifestyle and a different reproduction rate. Therefore, in the Offshore feeding area the whales do not form spatially stable aggregations existing at the same place over many years and even decades (like in the Piltun area), but are defined by а slownomad type of feeding pattern, gradually moving from one feeding area to another while depleting the food supply in the former (Figure 5-1). In the summer-fall of 2015, the gray whales remained within the same feeding range where they were observed the previous year. 22

29 Okha Okha Okha Okha Okha Okha Okha Okha Okha Okha Okha Sea of Okhotsk Piltun feeding area Lighthouse Chayvo Bay Offshore feeding area Nyisky Bay Nogliki Km Number of whales per km 2 based on the density analysis data: Whales not included in the density analysis: - Shore-based survey stations - Drilling rigs and platforms - Seabed pipelines Figure 5-1. Year-to-year variations in gray whale distribution in the Piltun and Offshore feeding areas in (based on combined shore-based and vessel-based survey data) 23

30 When considering the abundance of gray whales in the waters off Northeast Sakhalin, it should be noted that the data on the recorded number of gray whales obtained from visual shore-based observations in the Piltun feeding area and vesselbased observations in the Offshore Feeding Area refer to the one-time number of whales present in the waters as of the time of observation and does not provide any information about the total number of animals who visited the areas during the observation season, because that number depends primarily on the rate of whale rotation, i.e. the rate at which some whales leave the area and others arrive. By contrast, the concurrent photo-id studies provide data about the number of whales who visited the feeding area during the season and who were recorded by photos and videos, but fail to provide any information about the nature and duration of the whales presence in the area (for example, if there are no subsequent photos of the same individual, it does not mean that the individual was not actually present in the area, because the chance of it staying unnoticed is quite high). Another important factor is the rate at which the photos and videos are taken (the number of survey crews and survey days). In view of the above, it is very important to compare the data obtained from visual observations and photo-id in order to evaluate the whale abundance situation in the feeding area during the season. This makes it possible to estimate the number of whales present in the monitored waters during any given year (i.e. the absolute number observed) and how consistently they were present. The 2015 photo-id surveys put the number of gray whales that visited the waters off of Northeast Sakhalin during the summer/fall season at 171 (Yakovlev et al., 2016) which is 25% higher than in 2014 (137 individuals) and is the highest number on record for the entire monitoring period (Fig. 5-2). This estimate may have been affected by the increased photo-id effort in At the same time, the highest recorded number of whales that were present in the Piltun and Offshore feeding areas at the time of synchronized surveys was almost one-third fewer (107 individuals). As indicated by similar comparisons of gray whale abundance in previous years, similar differences between the photo-identification and visual observation numbers has also occurred in previous years (Figure 5-2). 24

31 Number Whales Years Figure 5-2. Consolidated data on changing numbers of gray whales in the East Sakhalin feeding area in Note; 1 - Maximum concurrent number of whales recorded in the Piltun Feeding Area (from shore-based surveys); 2 - Maximum concurrent number of whales recorded in the Offshore Feeding Area (from vesselbased surveys); 3 - Maximum total number of whales recorded in both feeding areas (from simultaneous shorebased and vessel-based surveys); 4 Total number of whales recorded in the waters off of Northeast Sakhalin from photo-id surveys (Yakovlev et al., 2015). In , the number of gray whales obtained from shore-based surveys in the Piltun area and simultaneous surveys in the entire eastern Sakhalin feeding area were greater than those obtained through photo-id (which does not at all guarantee total recording of all animals present in the water area). This suggests that in these years, the overwhelming majority of gray whales that came to the Piltun area (and offshore northeast Sakhalin) for feeding remained there for the entire season, did not migrate to any other areas, and were therefore recorded during one-time surveys. A similar situation took place in , when the survey figures were just a little lower than those from the photo-id, giving grounds to assume that few of the whales that came to the eastern Sakhalin feeding area migrated to other areas. The steady presence of gray whales in the offshore areas of Sakhalin and their high abundance there in , and in particular in (also in 2004), indicate that feeding resources, primarily in the key Piltun feeding area, were sufficient to feed that number of animals over the entire season. However, the number of gray whales recorded through visual observations for and partially for 2009 was lower than the estimate numbers from photo-id data (the fact that the number of photo-identified whales in 2008 had been underestimated was mentioned above, therefore, its coincidence with the survey-based number can be 25

32 ignored). The unexpected significant difference in the data obtained may have been related to the whales' migration in the mid-2000s from the eastern Sakhalin area to the eastern Kamchatka area, where they formed another small feeding area in Olga Bay (Vladimirov et al., 2009; Tyurneva et al., 2010). In the summer-fall season, the overwhelming majority of gray whales from the eastern Sakhalin feeding grouping that previously fed only in the offshore waters of the northeast Sakhalin continued to come there, but later many of them migrated to eastern Kamchatka, while some animals migrated in both directions between the two feeding areas within the season (Tyurneva et al., 2010). The resulting decrease in the number of one-time recorded whales off East Sakhalin may have caused the survey numbers to be significantly lower than those obtained from photo-id, which recorded all whales sighted during the season. Probably, a similar situation clearly developed in the most recent years as well. The only difference is that the exact area of whale migration from the eastern Sakhalin feeding grouping is not yet known, because according to V.V. Vertyankin (Kronotsky Biosphere Nature Reserve) no increase in whale numbers was noted in the eastern Kamchatka area. We can only suppose that the most probable area where whales found alternative summer and fall feeding areas is the shallow Shelikhov Bay in the northern part of the Sea of Okhotsk, where whalers observed large groupings of gray whales in the 19th century. To summarize the above, we can state that the numbers of the East-Sakhalin feeding group of gray whales are currently at an all-time high for the monitoring period, having reached 170-plus individuals (based on the photo-id estimate). However, in the past few years there has been a process of the whales arriving in Sakhalin's coastal waters to migrate to other, as yet unknown feeding areas. This is evidenced by the decreasing onetime number of whales recorded in the key Piltun feeding area (the maximum numbers dropped from 48 to 40 individuals, and the average numbers for the season dropped from 34.6 to 25.7 individuals compared to 2014). However, a similar situation occurred in the mid-2000 s, indicating that such phenomena can be regarded as natural variations in the abundance of animals in natural populations, and can develop into a new growth phase just as quickly. Significant fluctuations in the abundance of gray whales have been observed in the Offshore area as well, and most often they are opposite to the whale population fluctuations observed in the Piltun Area (2003/2004 to 2009/2010, and 2014/2015, - Fig. 5-2). In 2015, for example the number of whales recorded from surveys in the Offshore area increased and came close to the highest numbers recorded previously in 2001 and 2008, thus offsetting the continued overall decrease in whale population in the near-shore Piltun Area. These data indicate that there is a regular and fairly intense process of offsetting redistribution of gray whales between the two feeding areas located off northeast Sakhalin. In general, based on the monitoring results obtained in 2015 under the joint ENL and SEIC monitoring program, it seems reasonable to conclude that the number of gray 26

33 whales feeding off the shore of northeastern Sakhalin Island in 2015 is within the range of numbers observed in previous years. The type of whale distributions in both feeding areas (Piltun and Offshore) is consistent with the average distribution from multi-year observations, while the year-on-year fluctuations in the number of whales in the feeding waters are due to natural, ecosystem-determined causes. They are also affected by migrations whose intensity varies due to changes in the environment. There are no visible anomalies in the distribution or seasonal variations of gray whale abundance recorded by shore-based and vessel-based surveys that could be interpreted as indicating a human impact on them. 27