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Gray whales (Eschrichtius robustus) constitute an important part of the diet of Chukotka Native population, reaching 30% of consumed food for the inland Chukchas. Over one hundred licenses for whale hunting are issued on an annual basis. After the USSR collapse natives had to hunt whales near the shore from the small boats. The problem of "stinky" whales arose immediately, as the meat of some harvested species possessed a strong medicinal/chemical odour. The hypotheses explaining the phenomenon ranged from biotoxins, to oil spills. To understand the problem, various tissues of normal and stinky Gray whales were collected in 2020-2021 and analyzed using headspace solid phase microextraction with Gas Chromatography - Mass Spectrometry. Here, we show that dozens of smelly organic compounds were identified among over 500 compounds detected in the samples. The most interesting analytes related to the off odour are bromophenols. The most probable suspect is 2,6-dibromophenol with strong iodoformic odour, perfectly matching that of the "stinky" whales. Quantitative results demonstrated its levels were up to 500-fold higher in the "stinky" whales' tissues. The source of 2,6-dibromophenol is likely polychaetes, producing 2,6-dibromophenol and colonising near shore waters where whales feed. Therefore, the mystery of the stinky whales may be considered resolved., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

In zooplankton-feeding baleen whales, site fidelity on the feeding grounds is usually expressed at a relatively large scale: although the whales remain in the general area, they move broadly within it, covering tens of kilometers per day. The gray whale, Eschrichtius robustus, is the only dedicated bottom feeder among baleen whales and its largely infaunal and epibenthic invertebrate prey are more sedentary and therefore have a more predictable distribution than zooplankton. We analyzed movements of individually identified gray whales and humpback whales (Megaptera novaeangliae) in an Arctic feeding area to see if specialization on stationary benthic prey would result in finer-scale site fidelity than specializing in more mobile zooplankton prey in the same area. Compared to humpback whales, the number of feeding gray whales in Senyavin Strait, Eastern Chukotka over three study years was higher; however, the resighting rate between years was lower than for humpback whales in the same area over the same period. All humpback whales moved broadly within their feeding range, while individual gray whales tended to remain at specific locations, returning to these locations in subsequent years. Thus, the fine-scale site fidelity was higher for gray whales and this should be a consideration when estimating anthropogenic impacts—for example, the effects of shipping traffic, fishing, and aboriginal whaling. Gaining an understanding of whale movement patterns, including site fidelity, is crucial for the conservation and sustainable management of whales and their habitats, especially in light of increasing anthropogenic pressures in the warming Arctic. [ABSTRACT FROM AUTHOR]

Cetacean species are highly mobile, most of them regularly travelling over long distances, thereby presenting complex obstacles to their conservation. Identification of their critical habitats, specifically those parts of a cetacean's range that are essential for day‐to‐day survival and for maintaining a healthy population growth rate, is necessary for their effective protection.This study presents a summary of the data on cetacean sightings during surveys that covered substantial parts of the Russian Far East coastal waters from the Okhotsk Sea to Chukotka in order to determine important areas for particular cetacean species. Sixteen cetacean species were registered during the surveys, and for 12 of them with sufficient numbers of sightings, zones with maximum sighting rates were identified.Only 13% of all cetacean sightings and 22% of sightings of protected species occurred within marine protected areas (MPAs). The highest sighting rates for protected species were concentrated off north‐eastern Sakhalin Island, in the Shantar Area, in Anadyr Gulf, in Kresta Bay and in the waters off eastern Chukotka. The analysis of the distribution patterns of various cetacean species in Russian Far East seas provides a solid base for future conservation planning. Lack of specific MPAs for protection of cetaceans and associated biodiversity hinders marine conservation in Russian Far East seas.The study highlights the specific zones important for various cetacean species and suggests the extension of some existing MPAs and the creation of new MPAs for future spatial habitat protection measures. [ABSTRACT FROM AUTHOR]

Killer whales are top predators in marine trophic chains, and therefore their feeding preferences can substantially affect the abundance of species on the lower trophic levels. Killer whales are known to feed on many different types of prey from small fish to large whales, but a given killer whale population usually focuses on a specific type of prey. Stable isotope analysis is widely used to study whale diets, because direct observations are often impossible. Killer whale feeding habits in the western North Pacific are poorly studied, and the large‐scale stable isotope analysis provides a unique opportunity to gain insights into the trophic links of this top predator. In this study, we compare the δ13C and δ15N stable isotope values from killer whale skin samples obtained in different areas of the western North Pacific from fish‐eating (R‐type) and mammal‐eating (T‐type) killer whale ecotypes. The effect of ecotype was highly significant: both carbon and nitrogen stable isotope values were lower in R‐type whales than in T‐type whales. The geographical variation also affected killer whale stable isotope values due to both the differences in killer whale diet and the variation in baseline stable isotope values across the study areas. [ABSTRACT FROM AUTHOR]

The article reports an encounter with a North Pacific right whale in eastern Chukotka. It mentions that Pacific right whale was approached and photographs were taken of flukes and both sides of the animal's head for individual photo identification. It also mentions that abnormal travelling pattern could be related to the recent rapid increase in annual temperatures that has been reported to in annual temperatures that has been reported to and temperate marine species.

Humpback whales migrate seasonally from high latitude feeding areas to lower latitude breeding areas for mating and calving. In 2004-2006, a North Pacific basin-wide study called SPLASH was conducted as an international collaboration among various groups of researchers. The Russian Far East consists of multiple high latitude feeding areas and during SPLASH, 102 whales were identified and compared to catalogs from breeding areas. Our goal in this study was to further investigate the migratory destinations of whales from the Russian Far East using a total of 1,459 photographs of whales identified from 2004 to 2014. We compared the latest Russian catalog with the SPLASH catalog from wintering areas (2004-2006) and with two additional regional catalogs from Okinawa (1989-2006) and the northern Philippines (2000-2006). We found a total of 152 matches: 106 with Asian, 35 with Hawaiian, and 11 with Mexican breeding grounds. The match rate was higher in mainland Kamchatka and consisted mostly of whales from the Asian breeding ground. In the Commander Islands, the proportion of whales from Asia was twice that of Hawaii and six times higher than Mexico. The total match rate was low, supporting the hypothesis of some undiscovered humpback whale breeding location in the North Pacific. [ABSTRACT FROM AUTHOR]

Herring-eating killer whales debilitate herring with underwater tail slaps and likely herd herring into tighter schools using a feeding-specific low-frequency pulsed call ('herding' call). Feeding on herring may be dependent upon daylight, as the whales use their white underside to help herd herring; however, feeding at night has not been investigated. The production of feeding-specific sounds provides an opportunity to use passive acoustic monitoring to investigate feeding behaviour at different times of day. We compared the acoustic behaviour of killer whales between day and night, using an autonomous recorder deployed in Iceland during winter. Based upon acoustic detection of underwater tail slaps used to feed upon herring we found that killer whales fed both at night and day: they spent 50% of their time at night and 73% of daytime feeding. Interestingly, there was a significant diel variation in acoustic behaviour. Herding calls were significantly associated with underwater tail slap rate and were recorded significantly more often at night, suggesting that in low-light conditions killer whales rely more on acoustics to herd herring. Communicative sounds were also related to underwater tail slap rate and produced at different rates during day and night. The capability to adapt feeding behaviour to different light conditions may be particularly relevant for predator species occurring in high latitudes during winter, when light availability is limited. [ABSTRACT FROM AUTHOR]

Many social animals have cultural traditions that may shape their societies while the social structure can in turn influence how the culture is acquired. Killer whales possess culturally transmitted dialects. The divergence of dialects was thought to occur simultaneously and consistently with the gradual fission of matrilines. In this paper we compare the social associations across matrilineal units, Bayesian phylogeny of dialects and similarity of particular syllables to test whether dialects affect social structure and whether associations or common origin define similarity of call types. We found that neither phylogeny of dialects nor similarity of syllables was correlated to associations between matrilineal units, but similarity of syllables was correlated to phylogeny of dialects for four of the six syllables analysed. The complexity and fluidity of social ties between matrilineal units and the variation in cultural transmission patterns produce a complex relationship between the social network and the socially learned vocalizations. [ABSTRACT FROM AUTHOR]

Humpback whales feed on a variety of prey, but significant differences likely occur between regional feeding grounds. In this study, the diets of humpback whales were analyzed by comparing stable isotope ratios in animal tissues at three humpback whale feeding grounds in the Russian Far East: Karaginsky Gulf, Anadyr Gulf, and the Commander Islands. Anadyr Gulf is a neritic zone far from a shelf break, Karaginsky Gulf is a neritic zone close to a shelf break, and the Commander Islands represent an open oceanic ecosystem where whales feed off the shelf break. Samples from the Commander Islands had the lowest mean δ13C and δ15N values (mean ± SE: δ13C = −18.7 ± 0.1, δ15N = 10.4 ± 0.1) compared to the samples from Karaginsky Gulf (δ13C = −17.2 ± 0.1, δ15N = 12.7 ± 0.2) and Anadyr Gulf (δ13C= −17.8 ± 0.1, δ15N = 14.0 ± 0.4). The samples from Anadyr Gulf had the highest δ15N values, while the samples from Karaginsky Gulf had the highest δ13C values. Both δ13C and δ15N values differed significantly among all three areas. Our data support the hypothesis that humpback whales tend to feed on fish in neritic areas and on plankton in deep oceanic waters. [ABSTRACT FROM AUTHOR]