Application of a multi-disciplinary approach to reveal population structure and Southern Ocean feeding grounds of humpback whales

Riekkola, Leena; Zerbini, Alexandre N.; Andrews, Olive; Andrews‐Goff, Virginia; Baker, C. Scott; Chandler, David; Childerhouse, Simon; Clapham, Phillip J.; Dodémont, Rémi; Donnelly, David; Friedlaender, Ari S.; Gallego, Ramón; Garrigue, Claire; Ivashchenko, Yulia V.; Jarman, Simon; Lindsay, Rebecca; Pallin, Logan; Robbins, Jooke; Steel, Debbie; Tremlett, James; Vindenes, Silje; Constantine, Rochelle

doi:10.1016/j.ecolind.2018.02.030

Cited by 60 publications

(84 citation statements)

References 84 publications

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“…However, our pregnancy rates are much higher than expected for a population that is believed to be growing at a rate of only 3.4% per year [ 60 ]. Similarly high observations of annual reproduction and overall pregnancy rates were made among humpbacks sampled of the Kermadec Islands in Oceania [ 72 ]. The east Australian population of humpbacks is projected to be recovering at or near the estimated physiological limit of the species (approx.…”

Section: Discussionmentioning

confidence: 83%

High pregnancy rates in humpback whales (Megaptera novaeangliae) around the Western Antarctic Peninsula, evidence of a rapidly growing population

et al. 2018

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Antarctic humpback whales are recovering from near extirpation from commercial whaling. To understand the dynamics of this recovery and establish a baseline to monitor impacts of a rapidly changing environment, we investigated sex ratios and pregnancy rates of females within the Western Antarctic Peninsula (WAP) feeding population. DNA profiling of 577 tissue samples (2010–2016) identified 239 males and 268 females. Blubber progesterone levels indicated 63.5% of the females biopsied were pregnant. This proportion varied significantly across years, from 36% in 2010 to 86% in 2014. A comparison of samples collected in summer versus fall showed significant increases in the proportion of females present (50% to 59%) and pregnant (59% to 72%), consistent with demographic variation in migratory timing. We also found evidence of annual reproduction among females; 54.5% of females accompanied by a calf were pregnant. These high pregnancy rates are consistent with a population recovering from past exploitation, but appear inconsistent with recent estimates of WAP humpback population growth. Thus, our results will help to better understand population growth potential and set a current baseline from which to determine the impact of climate change and variability on fecundity and reproductive rates.

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Section: Discussionmentioning

confidence: 83%

High pregnancy rates in humpback whales (Megaptera novaeangliae) around the Western Antarctic Peninsula, evidence of a rapidly growing population

et al. 2018

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“…Sei whales are sighted in north‐eastern New Zealand waters, with one individual frequently sighted in the Hauraki Gulf (R. Constantine, unpublished data). Humpback whales typically migrate through New Zealand waters as they move between Antarctic feeding grounds and Oceania breeding grounds (Constantine, Russell, Gibbs, Childerhouse, & Baker, ; Dawbin, ), stopping briefly at the northern Kermadec Islands in social aggregations (Riekkola et al, ) and near Fiordland where some foraging occurs before they complete their southern migration to Antarctic waters (Gales et al, ). Killer whales range widely throughout all New Zealand offshore and nearshore waters feeding on a variety of benthic and demersal prey (Visser, ), typical of the species' global distribution and habitat use patterns (Ford, ).…”

Section: Discussionmentioning

confidence: 99%

Modelling the spatial distribution of cetaceans in New Zealand waters

Stephenson

Goetz

Sharp

et al. 2020

Diversity and Distributions

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Aim Cetaceans are inherently difficult to study due to their elusive, pelagic and often highly migratory nature. New Zealand waters are home to 50% of the world's cetacean species, but their spatial distributions are poorly known. Here, we model distributions of 30 cetacean taxa using an extensive at‐sea sightings dataset (n > 14,000) and high‐resolution (1 km2) environmental data layers. Location New Zealand's Exclusive Economic Zone (EEZ). Methods Two models were used to predict probability of species occurrence based on available sightings records. For taxa with <50 sightings (n = 15), Relative Environmental Suitability (RES), and for taxa with ≥50 sightings (n = 15), Boosted Regression Tree (BRT) models were used. Independently collected presence/absence data were used for further model evaluation for a subset of taxa. Results RES models for rarely sighted species showed reasonable fits to available sightings and stranding data based on literature and expert knowledge on the species' autecology. BRT models showed high predictive power for commonly sighted species (AUC: 0.79–0.99). Important variables for predicting the occurrence of cetacean taxa were temperature residuals, bathymetry, distance to the 500 m isobath, mixed layer depth and water turbidity. Cetacean distribution patterns varied from highly localised, nearshore (e.g., Hector's dolphin), to more ubiquitous (e.g., common dolphin) to primarily offshore species (e.g., blue whale). Cetacean richness based on stacked species occurrence layers illustrated patterns of fewer inshore taxa with localised richness hotspots, and higher offshore richness especially in locales of the Macquarie Ridge, Bounty Trough and Chatham Rise. Main conclusions Predicted spatial distributions fill a major knowledge gap towards informing future assessments and conservation planning for cetaceans in New Zealand's extensive EEZ. While sightings datasets were not spatially comprehensive for any taxa, these two best available approaches allow for predictive modelling of both more common, and of rarely sighted, cetacean species with limited available information.

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“…However, the extensive longitudinal movements (>1500 km) observed from east to west of the Coral Sea further question the scale at which the humpback whale may move during the breeding season. Longitudinal movements were characterized by transit-like parameters, typically observed during migration: low residence time, high swimming speeds and oriented travelling 10,11,[36][37][38] . Two males moved between the well-known breeding grounds of southeastern New Caledonia, and the presumed breeding grounds of Capel and Kelso, located at a distance of about 850 km.…”

Section: Discussionmentioning

confidence: 99%

Horizontal and vertical movements of humpback whales inform the use of critical pelagic habitats in the western South Pacific

Derville

Torres

Zerbini

et al. 2020

Sci Rep

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Humpback whales (Megaptera novaeangliae) are known for their nearshore distribution during the breeding season, but their pelagic habitat use patterns remain mostly unexplored. From 2016 to 2018, 18 humpback whales were equipped with depth-recording satellite tags (SPLASH10) to shed light on environmental and social drivers of seamount association around new caledonia in the western South Pacific. Movement paths were spatially structured around shallow seamounts (<200 m). Indeed, two males stopped over the Lord Howe seamount chain during the first-ever recorded longitudinal transit between New Caledonia and the east coast of Australia. Residence time significantly increased with proximity to shallow seamounts, while dive depth increased in the vicinity of seafloor ridges. Most of the 7,986 recorded dives occurred above 80 m (88.5%), but deep dives (>80 m, max 616 m) were also recorded (11.5%), including by maternal females. Deep dives often occurred in series and were characterized by U-shapes suggesting high energy expenditure. This study provides new insights into the formerly overlooked use of pelagic habitats by humpback whales during the breeding season. Given increasing anthropogenic threats on deep sea habitats worldwide, this work has implications for the conservation of vulnerable marine ecosystems.

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Application of a multi-disciplinary approach to reveal population structure and Southern Ocean feeding grounds of humpback whales

Cited by 60 publications

References 84 publications

High pregnancy rates in humpback whales (Megaptera novaeangliae) around the Western Antarctic Peninsula, evidence of a rapidly growing population

High pregnancy rates in humpback whales (Megaptera novaeangliae) around the Western Antarctic Peninsula, evidence of a rapidly growing population

Modelling the spatial distribution of cetaceans in New Zealand waters

Horizontal and vertical movements of humpback whales inform the use of critical pelagic habitats in the western South Pacific

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