The Southern Ocean Exchange: porous boundaries between humpback whale breeding populations in southern polar waters

Humpback whales (Megaptera novaeangliae) are a cosmopolitan species and perform long annual migrations between low-latitude breeding areas and high-latitude feeding areas. Their breeding populations appear to be spatially and genetically segregated due to long-term, maternally inherited fidelity to natal breeding areas. In the Southern Hemisphere, some humpback whale breeding populations mix in Southern Ocean waters in summer, but very little movement between Pacific and Atlantic waters has been identified to date, suggesting these waters constituted an oceanic boundary between genetically distinct populations. Here, we present new evidence of summer co-occurrence in the West Antarctic Peninsula feeding area of two recovering humpback whale breeding populations from the Atlantic (Brazil) and Pacific (Central and South America). As humpback whale populations recover, observations like this point to the need to revise our perceptions of boundaries between stocks, particularly on high latitude feeding grounds. We suggest that this “Southern Ocean Exchange” may become more frequent as populations recover from commercial whaling and climate change modifies environmental dynamics and humpback whale prey availability.

Contestation and norm change in whale and elephant conservation: Non-use or sustainable use?

Elephants and whales took center stage in the environmental movements of the 1980s. As flagship species, they were the poster children of global initiatives: international ivory trading and commercial whaling were banned in the 1980s in the context of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) and the International Whaling Commission (IWC), respectively. While the conservation of both species is contested, we observe a change of existing norms in one case but not in the other: A moratorium on commercial whaling remains in place. Meanwhile, a limited shift to sustainable use regarding ivory was passed in 1997/2000. We ask why norm change occurred in one case but not the other, given their similarities. We argue that the difference can be explained by the perceived legitimacy of the claims of norm challengers using arguments of “affectedness” and the breadth of issues covered by CITES. In contrast, other factors commonly discussed in norms research do not explain this puzzle: the relative power and strategies of norm advocates and challengers, and the degree of legalization. This shows the interplay of discursive aspects and concrete institutional opportunities for norm change, even in the face of otherwise inopportune conditions.

Fin whales of the Great Bear Rainforest: Balaenoptera physalus velifera in a Canadian Pacific fjord system

Fin whales (Balaenoptera physalus) are widely considered an offshore and oceanic species, but certain populations also use coastal areas and semi-enclosed seas. Based upon fifteen years of study, we report that Canadian Pacific fin whales (B. p. velifera) have returned to the Kitimat Fjord System (KFS) in the Great Bear Rainforest, and have established a seasonally resident population in its intracoastal waters. This is the only fjord system along this coast or elsewhere in which fin whales are known to occur regularly with strong site fidelity. The KFS was also the only Canadian Pacific fjord system in which fin whales were commonly found and killed during commercial whaling, pointing to its long-term importance. Traditional knowledge, whaling records, and citizen science databases suggest that fin whales were extirpated from this area prior to their return in 2005–2006. Visual surveys and mark-recapture analysis documented their repopulation of the area, with 100–120 whales using the fjord system in recent years, as well as the establishment of a seasonally resident population with annual return rates higher than 70%. Line transect surveys identified the central and outer channels of the KFS as the primary fin whale habitat, with the greatest densities occurring in Squally Channel and Caamaño Sound. Fin whales were observed in the KFS in most months of the year. Vessel- and shore-based surveys (27,311 km and 6,572 hours of effort, respectively) indicated regular fin whale presence (2,542 detections), including mother-calf pairs, from June to October and peak abundance in late August–early September. Seasonal patterns were variable year-to-year, and several lines of evidence indicated that fin whales arrived and departed from the KFS repeatedly throughout the summer and fall. Additionally, we report on the population’s social network and morphometrics. These findings offer insights into the dynamics of population recovery in an area where several marine shipping projects are proposed. The fin whales of the Great Bear Rainforest represent a rare exception to general patterns in this species’ natural history, and we highlight the importance of their conservation.

Multiple pygmy blue whale acoustic populations in the Indian Ocean: whale song identifies a possible new population

Blue whales were brought to the edge of extinction by commercial whaling in the twentieth century and their recovery rate in the Southern Hemisphere has been slow; they remain endangered. Blue whales, although the largest animals on Earth, are difficult to study in the Southern Hemisphere, thus their population structure, distribution and migration remain poorly known. Fortunately, blue whales produce powerful and stereotyped songs, which prove an effective clue for monitoring their different ‘acoustic populations.’ The DGD-Chagos song has been previously reported in the central Indian Ocean. A comparison of this song with the pygmy blue and Omura’s whale songs shows that the Chagos song are likely produced by a distinct previously unknown pygmy blue whale population. These songs are a large part of the underwater soundscape in the tropical Indian Ocean and have been so for nearly two decades. Seasonal differences in song detections among our six recording sites suggest that the Chagos whales migrate from the eastern to western central Indian Ocean, around the Chagos Archipelago, then further east, up to the north of Western Australia, and possibly further north, as far as Sri Lanka. The Indian Ocean holds a greater diversity of blue whale populations than thought previously.

Fine-scale habitat use by humpback whales (Megaptera novaeangliae) in Zavora Bay, Mozambique

Little is known about the humpback whales (Megaptera novaeangliae) of the East-African Coast genetic sub-unit (C1). With an estimated population size of 7000 whales, they demonstrate the resilience of the species after commercial whaling caused population numbers to decline drastically. Zavora Bay, Mozambique offers an ideal observation point of the passage of the whales during their annual migration towards the breeding ground of southern Africa and serves as an operating base to monitor this population. This study aimed at identifying the importance of Zavora Bay as part of this breeding ground and the core regions for humpback whale use within the study area. Results showed the waters off the coast of Zavora are actively used for breeding and do not merely serve as passage towards the wintering habitats. A mother-calf pair separation with a preference for shallower waters closer to shore was observed. Besides depth and distance to shore, slope also proved to have a significant influence on the distribution of adult humpback whales. Increased survey effort and more detailed investigation of the threats to humpback whales within the waters of Zavora are recommended.

In Pursuit of the White Whale of Cooperation

On 26 December 2018, Japan announced that it would withdraw from the International Whaling Commission (iwc) and indicated its intention to begin commercial whaling for the first time in 30 years. Despite the ethical and political outcry from several States, the legal ramifications of Japan’s withdrawal requires further analysis. This article examines the relationship between Japan and the iwc ex ante and ex post Japan’s withdrawal. Such an examination highlights the influence that Japan’s international duty to cooperate in the conservation and management of cetaceans might have across various international instruments. Japan is no longer bound by the recommendations and resolutions of the iwc; however, Japan remains a member of both the United Nations Convention on the Law of the Sea and the Convention on International Trade in Endangered Species of Wild Fauna and Flora. With this in mind, the article examines the interaction between these three international instruments as well as the influence that such interaction might have on Japan’s international obligation to cooperate in the conservation of cetaceans.

Sidney Holt on principles for the conservation of wild living resources, whaling in the Antarctic, and the Beverton–Holt stock–recruitment relationship

I review my interactions with Sidney Holt concerning principles for the conservation of wild living resources, the whaling case between Australia and Japan in the International Court of Justice, and the Beverton–Holt stock–recruitment relationship (BH-SRR). Holt and Lee Talbot published a monograph on principles for conservation in 1977; I lead the publication of an update ∼20 years later. I compare the two versions and discuss Holt’s contributions. Holt was active in the world-wide campaign to cease whaling and in efforts to have the Japanese special permit whaling programme in the Antarctic recognized as violating the moratorium on commercial whaling. I describe my involvement in the case and my interactions with him during oral arguments in the case and when the International Court of Justice rendered its decision that the Japanese programme of special permit whaling contravened the international treaty for the regulation of whaling because it was not for purposes of scientific research. In response to a paper of mine concerning steepness, Holt wrote to me that the BH-SSR is a one-, not two-, parameter function. I explain my current understanding of his reasoning, which involves how we use the SRR in fishery management.

Vladimir Arsen’ev and Whales in Russia’s Revolutionary Far East

This article examines the contributions the famous Far Eastern writer Vladimir Arsen’ev made to the development of the Russian/Soviet whaling industry in the 1920s. During that time Arsen’ev worked as a “specialist for marine mammal hunting” for Dal’rybokhota. He studied the whales of the Russian Far East and helped craft the Far Eastern Republic’s policy toward its subjects who wanted to start whaling. As someone with a deep knowledge of imperial-era environmental destruction and conservation, Arsen’ev helped develop measures designed to protect the region’s Indigenous people and fur-bearing animals while strengthening Russian sovereignty. He also advocated the wholesale slaughter of killer whales and ultimately failed to restrain destructive commercial whaling. However, in addition to adding a new chapter to Arsen’ev’s biography, his ideas about whales and whaling help us better understand the Far East’s environment history and especially the way imperial-era ideas around conservation survived into the Soviet period.

The collapse and recovery potential of carbon sequestration by baleen whales in the Southern Ocean

Limiting climate warming below 2°C requires both reducing anthropic greenhouse gas emissions and sequestering more atmospheric carbon. Natural Climate Solutions (NCS) rely on the ability of ecosystems to capture and store carbon. Despite the important role of marine megafauna on the ocean carbon cycle, its potential as a NCS has not yet been explored. Here, we quantify the amount of carbon potentially sequestered by five baleen whale species across the Southern Hemisphere between 1890 and 2100 through both the sinking of carcasses after natural death and the fertilisation of phytoplankton by nutrients in faeces. At their pre-exploitation abundances, the five whales could sequester 10.6 106 tonnes of carbon per year (tC.yr-1) but this natural carbon sink was reduced at 2 106 tC.yr-1 in 1965 due to commercial whaling. However, the restoration of whale populations could sequester 8.7 106 tC.yr-1 at the end of the 21st century suggesting an efficient but neglected NCS that remains to be estimated globally including all marine vertebrates.