Eubalaena Japonica Research Articles

The world's smallest whale population?

The North Pacific right whale (Eubalaena japonica) was heavily exploited by both nineteenth century whaling and recent (1960s) illegal Soviet catches. Today, the species remains extremely rare especially in the eastern North Pacific. Here, we use photographic and genotype data to calculate the first mark-recapture estimates of abundance for right whales in the Bering Sea and Aleutian Islands. The estimates were very similar: photographic = 31 (95% CL 23-54), genotyping = 28 (95% CL 24-42). We also estimated the population contains eight females (95% CL 7-18) and 20 males (95% CL 17-37). Although these estimates may relate to a Bering Sea subpopulation, other data suggest that the total eastern North Pacific population is unlikely to be much larger. Its precarious status today-the world's smallest whale population for which an abundance estimate exists-is a direct consequence of uncontrolled and illegal whaling, and highlights the past failure of international management to prevent such abuses.

Right whale distribution in the Bering Sea revisited: A fresh look.

The North Pacific right whale (Eubalaena japonica) is one of the most endangered baleen whales in the world, with current abundance estimates of fewer than 40 individuals. As such, it has been the focus of intensive population monitoring studies. Long‐term passive acoustic monitoring is a useful tool for assessing distribution, habitat use, and population status of marine mammals. For Bering Sea right whales, past analyses of distribution were based on their stereotyped upsweep call. Results from sonobuoy recordings made during the 2008 and 2009 southeastern Bering Sea right whale cruises, however, found gunshot calls to be much more common. To assess whether inclusion of gunshot call detections will change our understanding of the spatial and temporal distribution of North Pacific right whales, we examined four years (2006–2009) of long‐term recordings made by the National Marine Mammal Laboratory and the Pacific Marine Environmental Laboratory at six different locations on the Bering Sea shelf. A comparison of the results using upsweeps, gunshots, and a combination of both will be presented. [Work supported by an Inter‐Agency Agreement from the Minerals Management Service.]

Right whale gunshot calls in the southeastern Bering Sea.

The eastern population of the North Pacific right whale (Eubalaena japonica) is critically endangered. Following extensive historical whaling in the 19th century and large illegal catches by the USSR in the 1960’s, it is likely that this population now numbers in the tens of animals. Little is known about the distribution, movements, migrations, or habitat use of this population, but the existing data suggest that it now occupies a reduced range compared to historical times. In 2007, NMML began conducting a multiyear study of the distribution, abundance, and habitat use of North Pacific right whales in the North Aleutian Basin and southeastern Bering Sea using aerial and vessel surveys. During the 2008 survey, directional sonobuoys were used 24 h a day to record right whale calls and obtain cross-bearings to the whales. Although previous work in the Bering Sea focused on detections of the right whale upsweep call, our findings suggest that the gunshot call is much more ubiquitous. Spatial and temporal trends of gunshot calls will be presented, and changes in gunshot call characteristics relative to observed surfacing sequences will be described. [Work supported by an interagency agreement from the Minerals Management Service.]

North Pacific right whale (Eubalaena japonica) seasonal and diel calling patterns from long‐term acoustic recordings in the southeastern Bering Sea, 2000–2006

AbstractWe assessed North Pacific right whale (Eubalaena japonica) seasonal and daily calling patterns in the southeastern Bering Sea (SEBS) using long‐term hydrophone recordings from October 2000 through January 2006. We detected right whale calls on the SEBS middle shelf (<100 m depth) as early as May, intermittently throughout summer and fall, and as late as December. Calls also were detected on one day in June 2005 on the SEBS slope (>1,000 m), but were not detected near Kodiak Island from April to August 2003. In months with calls, detections occurred on more days in July–October (≥6 d/mo), than from May to June or November to December (≤3 d/mo). Calls were clustered in time and were usually detected on 1–3 consecutive days with a median interval of 6.5 d for calls >1 d apart. Hourly calling rates were significantly higher at night than during the day. These data indicate that right whales occur in the SEBS later in the year than previously known, intermittently pass through the middle‐shelf study region, and usually remain there no longer than a few days. Right whale habitat use in the SEBS may intensify in mid‐summer through early fall based on higher monthly and daily call detection rates.

Seasonal variability and detection range modeling of baleen whale calls in the Gulf of Alaska, 1999–2002

Five species of large whales, including the blue (Balaenoptera musculus), fin (B. physalus), sei (B. borealis), humpback (Megaptera novaeangliae), and North Pacific right (Eubalaena japonica), were the target of commercial harvests in the Gulf of Alaska (GoA) during the 19th through mid-20th Centuries. Since this time, there have been a few summer time visual surveys for these species, but no overview of year-round use of these waters by endangered whales primarily because standard visual survey data are difficult and costly. From October 1999-May 2002, moored hydrophones were deployed in six locations in the GoA to record whale calls. Reception of calls from fin, humpback, and blue whales and an unknown source, called Watkins' whale, showed seasonal and geographic variation. Calls were detected more often during the winter than during the summer, suggesting that animals inhabit the GoA year-round. To estimate the distance at which species-diagnostic calls could be heard, parabolic equation propagation loss models for frequencies characteristic of each of each call type were run. Maximum detection ranges in the subarctic North Pacific ranged from 45 to 250 km among three species (fin, humpback, blue), although modeled detection ranges varied greatly with input parameters and choice of ambient noise level.

Acoustic detection and satellite-tracking leads to discovery of rare concentration of endangered North Pacific right whales

The North Pacific right whale, Eubalaena japonica, is one of the most endangered species of whale in the world. On 10 August 2004, two right whales were located in the Bering Sea using headings to right whale calls provided by directional sonobuoys. A satellite-monitored radio tag attached to one of these whales functioned for 40 days. Over the 40-day period, this whale moved throughout a large part of the southeast Bering Sea shelf, including areas of the outer-shelf where right whales have not been seen in decades. In September, multiple right whales were acoustically located and subsequently sighted by another survey vessel approaching a near-real-time position from the tag. An analysis of photographs confirmed at least 17 individual whales (not including the tagged whales). Genetic analysis of biopsy samples identified 17 individuals: 10 males and 7 females. The discovery of seven females was significant, as only one female had been identified in the past. Genetics also confirmed the presence of at least two calves. Although the future of this population is highly uncertain, the discovery of additional females and calves gives some hope that this most critically endangered of all whale populations may still possess the capacity to recover.

Population histories of right whales (Cetacea:Eubalaena) inferred from mitochondrial sequence diversities and divergences of their whale lice (Amphipoda:Cyamus)

Right whales carry large populations of three 'whale lice' (Cyamus ovalis, Cyamus gracilis, Cyamus erraticus) that have no other hosts. We used sequence variation in the mitochondrial COI gene to ask (i) whether cyamid population structures might reveal associations among right whale individuals and subpopulations, (ii) whether the divergences of the three nominally conspecific cyamid species on North Atlantic, North Pacific, and southern right whales (Eubalaena glacialis, Eubalaena japonica, Eubalaena australis) might indicate their times of separation, and (iii) whether the shapes of cyamid gene trees might contain information about changes in the population sizes of right whales. We found high levels of nucleotide diversity but almost no population structure within oceans, indicating large effective population sizes and high rates of transfer between whales and subpopulations. North Atlantic and Southern Ocean populations of all three species are reciprocally monophyletic, and North Pacific C. erraticus is well separated from North Atlantic and southern C. erraticus. Mitochondrial clock calibrations suggest that these divergences occurred around 6 million years ago (Ma), and that the Eubalaena mitochondrial clock is very slow. North Pacific C. ovalis forms a clade inside the southern C. ovalis gene tree, implying that at least one right whale has crossed the equator in the Pacific Ocean within the last 1-2 million years (Myr). Low-frequency polymorphisms are more common than expected under neutrality for populations of constant size, but there is no obvious signal of rapid, interspecifically congruent expansion of the kind that would be expected if North Atlantic or southern right whales had experienced a prolonged population bottleneck within the last 0.5 Myr.

Historic and current habitat use by North Pacific right whales Eubalaena japonica in the Bering Sea and Gulf of Alaska

ABSTRACT 1. To help define areas and ecological parameters critical to the survival and recovery of the remnant population of North Pacific right whales, habitat use was investigated by examining all available sighting and catch records in the south‐eastern Bering Sea (SEBS) and Gulf of Alaska (GOA) over the past two centuries. 2. Based on re‐analyses of commercial whaling records, search effort, and resultant catches and sightings, waters of the: (i) SEBS slope and shelf, (ii) eastern Aleutian Islands and (iii) GOA slope and abyssal plain were important habitat for North Pacific right whales through the late 1960s. 3. Since 1980, the only area where right whales have been seen consistently is on the SEBS middle shelf. However, acoustic detections and single sightings have been reported in all other regions except the SEBS slope and oceanic GOA (areas where little, if any, acoustic and visual effort has occurred). 4. Sightings since 1979 were in waters < 200 m deep which may simply reflect the paucity of search effort elsewhere. From the commercial whaling era to the late 1960s, right whales were commonly seen in waters > 2000 m deep, indicating that their distribution is not restricted to shallow continental shelves. 5. North Pacific right whale sightings through the centuries have been associated with a variety of oceanic features, and there is little in common in the bathymetry of these regions. These whales appear to have a greater pelagic distribution than that observed in the North Atlantic, which may be related to the availability of larger copepods across the SEBS and GOA.

Endangered right whales on the southeastern Bering Sea shelf.

The eastern North Pacific right whale ( Eubalaena japonica Gray) was nearly extirpated by whaling by the 1960s. Today it is the most endangered population of large whale ([1][1]). Their historical summer distribution included the Gulf of Alaska and the southeastern Bering Sea, and that of the