Application of photo identification approach to white whales in Moroshechnaya and Hayruzovo estuaries

Application of photo identification approach to white whales in Moroshechnaya and Hayruzovo estuaries

16 June 2014

The research was conducted in the common estuary of the Belogolovaya and Khairyuzova rivers, near the village of Ust-Khairyuzovo from July 30 – August 31, 2010, and in the estuary of the Moroshechnaya River (from August 17 – September 13, 2011), which is lo-cated 40 km southward from the common estuary.

 


Estuaries of rivers in western Kamchatka are actively used by beluga whales to fatten up during summer and autumn, due to fish that go practically nonstop to their spawning locations through these estuaries. The research was done under the Beluga White Whale Program conducted by the Severtsov Institute of Ecology and Evolution of the Russian Academy of Sciences, with the support of the Russian Geographical Society (the program is part of the Permanent expedi-tion of Russian Academy of Science studying Red Book animals and other focus species of Russia). As part of the Program, we had the opportunity to conduct photo ID studies of beluga whale aggregations in the Moroshechnaya and Khairyuzova river estuaries. The method of photo identification was used in order to provide the basis for the further work and to make a preliminary estimation of the aggregation size. We set ourselves the tasks: to create a photo catalog of individually identified beluga whales, to describe the main types of natural marks belonging to particular individuals, and to track the routes of local migrations of animals. Also, we planned to assess the practicability of the photo ID method in beluga whale research and the limitations of this method for examining this species.

 

Beluga whales were photographed from a boat and from the shore, using a Nikon D80 camera with 18-200 mm lens. We photographed dorsal and lateral sides of the animals‘ bodies seen above the surface of water. Because of belugas‘ color pattern, we manually corrected automatic exposure settings (one or two steps, depending on lighting conditions). While taking photos, we simultaneously counted the total number of belugas in the group visually and recorded the general pattern of the animals‘ behavior. The photographs were edited, using ACDSee Pro 3 software. Beluga whales that possessed a set of unique distinguishing features were assigned a unique number. Then we cre-ated a photo catalog that consisted of photos of these uniquely marked animals. Good-quality photos of animals that did not possess any marked distinguishing features that might serve for their identification in the future were kept in view for future but were not included in the catalog.


Due to the solid, mostly monochrome color and lack of pronounced dorsal fin, photo ID of beluga whales is only possible using natural marks that animals receive during their lives. Mainly those are skin injuries caused by interactions with other marine mammals or objects, including injuries of anthropogenic origin, as well as marks of diseases that they had in the previous years. Among the distinctive natural marks observed by us were skin scarring, such as single small scars or multiple long and short scars that were usually parallel or sometimes ran through the whole length of the animal‘s body. There were round/oval skin lesions raised above the surface of the skin; most frequently, the skin lesions were single, though some individuals had multiple lesions. Also we found such skin defects as sunken oval spots and single funnel-like lesions; these defects might have formed after biopsy samples were taken from these animals or the marks may be scars from bullet wounds. Multi-year observations are needed in order to assess whether various skin lesions persist for a long time. Accord-ing to scientific papers, most of the marks disappear just after one or two molts.


In the estuary of the Moroshechnaya River, we saw several beluga whales that had distinct black splotches and stripes on their backs and heads.

 

The stripes were rather durable: belugas with this color pattern were spotted during the entire period of observations. We suppose that these stripes on animals‘ bodies were left by the clay on the bottom of the river. Several times, we saw beluga whales accidentally scrape the ventral or lateral sides of their bodies badly against the bottom, when the animals were chasing salmon. No doubt, these natural marks greatly simplified identification of some individuals within one season. Gray and dark gray calves were especially easy to identify by their distinct scar pat-terns and peeling parts of the skin, but unfortunately, such marks are very nondurable, and they can hardly be used with certainty for identification of the same animal in the following year. Researchers who tried the photo ID method before to identify the White Sea beluga whales do not use the photo ID method any more with gray-colored animals due to great altera-bility of their skin pattern.


Based on natural marks, we identified 173 beluga whales in the estuary of Belogolovaya and Khairyuzova rivers and 130 beluga whales in the Moroshechnaya River. Over 80% animals were spotted only once over the entire observation period. Re-sightings of identified individuals most frequently occurred in particular parts of the estuary. Supposedly, these particular locations are the areas where females and young animals come to fatten up. There were no repeated sightings in the area in between the Belogolovaya-Khairyuzova estuary and the Moroshechnaya estuary; this can be explained both by low migration activity of the animals during the fat-tening period and by small number of identified animals compared to the total number of belugas in the aggregations.


Comparing the number of animals that were counted visually and the number of animals that were individually identified we found that this method was quite inefficient with beluga whales: we identified only 15% of the sighted animals due to their unique marks. Some of the reasons for inefficiency of the photo ID method are as follows: the proportion of white and light gray animals that do not yet possess a unique pattern of scars or marks was high; beluga whales were quite timid and did not allow a boat to approach close to them so that researchers could take their pho-tographs. A special type of avoidance of humans that greatly hampered our work was that belugas changed their surfacing patterns. The animals took advantage of their flexible necks, raising only the blow hole and the occipital region of their head above the surface to breathe. Conversely, photographing beluga whales from shore was successful and allowed us to take photos of all the animals that were located at a dis-tance of several hundred meters; this allowed us to precisely count the number of individuals in particular parts of their aquatic habitat and determine the frequency of use of these locations.

 

Due to the small number of identified animals, we cannot use this data to estimate the proportion of individuals or groups of individuals using particular fattening areas. Perhaps, as data accumulate, we will be able to use the photo ID counting method based on repeated sightings of individual beluga whales. But even so, precision of the photo ID method will need to be verified and adjusted by other counting methods, such as aerial surveys or visual observations, like it was done in a photo ID study conducted by Cher-netsky and co-authors.


Thus, we can arrive at a conclusion that the use of the photo ID method in respect to the beluga whales inhabiting the Tigilsky District in the western Kamchatka is quite complicated. Considerable limitations are imposed by the appearance of the animals that lack pronounced unique color patterns or body shape and their timid behavior (active avoidance of humans). Even the natural marks described above have the property of changing over time. In view of the above-mentioned facts, before we are able to use the results of the photo ID studies in our further work, we will need longterm efforts and collecting a large amount of information, as was shown by the experi-ence of Russian and international researchers.

 

Tarasyan K.K., Shulezhko T.S., Glazov D.лю., Rozhnov V.V.

 

A.N. Severtsov Institute of Ecology and Evolution, RAS, Moscow, Russia

 

Kamchatka Branch of Pacific Institute of Geography, FE RAS, Petropavlovsk-Kamchatsky, Russia

 

References:

 


Chernetsky A.D., Krasnova V.V. 2008. Photoidentification as a tool for studying a local stock of belugas (Delphinapterus leu-cas) in the White Sea. Pp. 129-132 in Marine mammals of the Holarctic. Collection of scientific papers. Odessa


Chernetsky A.D., Krasnova V.V., Bel‘kovich V.M. 2010. Results of beluga (Delphinapterus leucas) photo-ID on Solovetsky reproductive gathering in 2007-2009. Pp. 616-619 in Marine mammals of the Holarctic. Collection of scientific papers. Kaliningrad


McGuire T.L., Kaplan C.C. 2009. Photo-identification of beluga whales in Upper Cook Inlet, Alaska. Final Report of Field Activities in 2008. Report prepared by LGL Alaska Research Associates, Inc., Anchorage, AK, for Na-tional Fish and Wildlife Foundation, Chevron, and ConocoPhillips Alaska, Inc. 28 p.