Mercury levels in humpback whales, and other Southern Ocean marine megafauna

AbstractHumpback whales are thought to undertake annual migrations between their low latitude breeding grounds and high latitude feeding grounds. However, under specific conditions, humpback whales sometimes change their migratory destination or skip migration overall. Here we document the surprising persistent presence of humpback whales in the Atlantic sector of the Southern Ocean during five years (2011, 2012, 2013, 2017, and 2018) using passive acoustic data. However, in the El Niño years 2015 and 2016, humpback whales were virtually absent. Our data show that humpback whales are systematically present in the Atlantic sector of the Southern Ocean and suggest that these whales are particularly sensitive to climate oscillations which have profound effects on winds, sea ice extent, primary production, and especially krill productivity.

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A description and summary of the Antarctic Humpback Whale Catalogue

J. Cetacean Res. Manage. ◽

10.47536/jcrm.vi.307 ◽

2020 ◽

pp. 95-99

Author(s):

Judith Allen ◽

Carole Carlson ◽

Peter T. Stevick

Keyword(s):

South America ◽

Southern Ocean ◽

Antarctic Peninsula ◽

Humpback Whale ◽

Humpback Whales ◽

Western Coast ◽

Long Distance ◽

Dorsal Fin ◽

Feeding Area ◽

The Antarctic

The Antarctic Humpback Whale Catalogue (AHWC) is an international collaborative project investigating movement patterns of humpback whales in the Southern Ocean and corresponding lower latitude waters. The collection contains records contributed by 261 researchers and opportunistic sources. Photographs come from all of the Antarctic management areas, the feeding grounds in southern Chile and also most of the known or suspected low-latitude breeding areas and span more than two decades. This allows comparisons to be made over all of the major regions used by Southern Hemisphere humpback whales. The fluke, left dorsal fin/flank and right dorsal fin/flank collections represent 3,655, 413 and 407 individual whales respectively. There were 194 individuals resighted in more than one year, and 82 individuals resighted in more than one region. Resightings document movement along the western coast of South America and movement between the Antarctic Peninsula and western coast of South America and Central America. A single individual from Brazil was resighted off South Georgia, representing the first documented link between the Brazilian breeding ground and any feeding area. A second individual from Brazil was resighted off Madagascar, documenting long distance movement of a female between non-adjacent breeding areas. Resightings also include two matches between American Samoa and the Antarctic Peninsula, documenting the first known feeding site for American Somoa and setting a new long distance seasonal migration record. Three matches between Sector V and eastern Australia support earlier evidence provided by Discovery tags. Multiple resightings of individuals in the Antarctic Peninsula during more than one season indicate that humpback whales in this area show some degree of regional feeding area fidelity. The AHWC provides a powerful non-lethal and non-invasive tool for investigating the movements and population structure of the whales utilising the Southern Ocean Sanctuary. Through this methodical, coordinated comparison and maintenance of collections from across the hemisphere, large-scale movement patterns may be examined, both within the Antarctic, and from the Antarctic to breeding grounds at low latitudes.

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Large-scale spatial variabilities in the humpback whale acoustic presence in the Atlantic sector of the Southern Ocean

Royal Society Open Science ◽

10.1098/rsos.201347 ◽

2020 ◽

Vol 7 (12) ◽

pp. 201347

Author(s):

Elena Schall ◽

Karolin Thomisch ◽

Olaf Boebel ◽

Gabriele Gerlach ◽

Stefanie Spiesecke ◽

...

Keyword(s):

Southern Ocean ◽

High Latitude ◽

Large Scale ◽

Austral Summer ◽

Humpback Whale ◽

Humpback Whales ◽

Stock Management ◽

Atlantic Sector ◽

Acoustic Activity ◽

Passive Acoustic

Southern Hemisphere humpback whales ( Megaptera novaeangliae ) inhabit a wide variety of ecosystems including both low- and high-latitude areas. Understanding the habitat selection of humpback whale populations is key for humpback whale stock management and general ecosystem management. In the Atlantic sector of the Southern Ocean ( ASSO ), the investigation of baleen whale distribution by sighting surveys is temporally restricted to the austral summer. The implementation of autonomous passive acoustic monitoring, in turn, allows the study of vocal baleen whales year-round. This study describes the results of analysing passive acoustic data spanning 12 recording positions throughout the ASSO applying a combination of automatic and manual analysis methods to register humpback whale acoustic activity. Humpback whales were present at nine recording positions with higher acoustic activities towards lower latitudes and the eastern and western edges of the ASSO . During all months, except December (the month with the fewest recordings), humpback whale acoustic activity was registered in the ASSO . The acoustic presence of humpback whales at various locations in the ASSO confirms previous observations that part of the population remains in high-latitude waters beyond austral summer, presumably to feed. The spatial and temporal extent of humpback whale presence in the ASSO suggests that this area may be used by multiple humpback whale breeding populations as a feeding ground.

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New insights into prime Southern Ocean forage grounds for thriving Western Australian humpback whales

Scientific Reports ◽

10.1038/s41598-019-50497-2 ◽

2019 ◽

Vol 9 (1) ◽

Cited By ~ 4

Author(s):

Sophie Bestley ◽

Virginia Andrews-Goff ◽

Esmee van Wijk ◽

Stephen R. Rintoul ◽

Michael C. Double ◽

...

Keyword(s):

Southern Ocean ◽

Humpback Whale ◽

Humpback Whales ◽

Western Boundary ◽

Boundary Current ◽

Austral Spring ◽

Partial Explanation ◽

Migration Pathways ◽

Western Australian ◽

Feeding Grounds

Abstract Humpback whale populations migrate extensively between winter breeding grounds and summer feeding grounds, however known links to remote Antarctic feeding grounds remain limited in many cases. New satellite tracks detail humpback whale migration pathways from Western Australia into the Southern Ocean. These highlight a focal feeding area during austral spring and early summer at the southern Kerguelen plateau, in a western boundary current where a sharp northward turn and retroflection of ocean fronts occurs along the eastern plateau edge. The topographic steering of oceanographic features here likely supports a predictable, productive and persistent forage ground. The spatial distribution of whaling catches and Discovery era mark-recaptures confirms the importance of this region to Western Australian humpback whales since at least historical times. Movement modelling discriminates sex-related behaviours, with females moving faster during both transit and resident periods, which may be a consequence of size or indicate differential energetic requirements. Relatively short and directed migratory pathways overall, together with high-quality, reliable forage resources may provide a partial explanation for the ongoing strong recovery demonstrated by this population. The combination of new oceanographic information and movement data provides enhanced understanding of important biological processes, which are relevant within the context of the current spatial management and conservation efforts in the Southern Ocean.

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

Scientific Reports ◽

10.1038/s41598-021-02612-5 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

M. C. C. Marcondes ◽

T. Cheeseman ◽

J. A. Jackson ◽

A. S. Friedlaender ◽

L. Pallin ◽

...

Keyword(s):

Southern Ocean ◽

High Latitude ◽

Prey Availability ◽

Humpback Whale ◽

Humpback Whales ◽

West Antarctic ◽

Breeding Populations ◽

Commercial Whaling ◽

Feeding Area ◽

New Evidence

AbstractHumpback 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.

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