Continuous movement behavior of humpback whales during the breeding season in the southwest Indian Ocean: on the road again!

Abstract

BackgroundHumpback whales are known to undertake long-distance migration between feeding and breeding sites, but their movement behavior within their breeding range is still poorly known. Satellite telemetry was used to investigate movement of humpback whales during the breeding season and provide further understanding of the breeding ecology and sub-population connectivity within the southwest Indian Ocean (SWIO). Implantable Argos satellite tags were deployed on 15 whales (7 males and 6 females) during the peak of the breeding season in Reunion Island. A switching-state-space model was applied to the telemetry data, in order to discriminate between “transiting” and “localized” movements, the latter of which relates to meandering behavior within putative breeding habitats, and a kernel density analysis was used to assess the spatial scale of the main putative breeding sites.ResultsWhales were tracked for up to 71 days from 31/07/2013 to 16/10/2013. The mean transmission duration was 25.7 days and the mean distance travelled was 2125.8 km. The tracks showed consistent movement of whales from Reunion to Madagascar, demonstrating a high level of connectivity between the two sub-regions, and the use of yet unknown breeding sites such as underwater seamounts (La Perouse) and banks (Mascarene Plateau). A localized movement pattern occurred in distinct bouts along the tracks, suggesting that whales were involved in breeding activity for 4.3 consecutive days on average, after which they resume transiting for an average of 6.6 days. Males visited several breeding sites within the SWIO, suggesting for the first time a movement strategy at a basin scale to maximize mating. Unexpectedly, females with calf also showed extensive transiting movement, while they engaged in localized behavior mainly off Reunion and Sainte-Marie (East Madagascar).ConclusionsThe results indicated that whales from Reunion do not represent a discrete population. Discrete breeding sites were identified, thereby highlighting priority areas for conservation. The study is a first attempt to quantify movement of humpback whales within the southwestern Indian Ocean breeding range. We demonstrate a wandering behavior with stopovers at areas that likely represent key breeding habitat, a strategy which may enhance likelihood of individual reproductive success.Electronic supplementary materialThe online version of this article (doi:10.1186/s40462-017-0101-5) contains supplementary material, which is available to authorized users.

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

“…These seabed features have in common a relatively shallow depth at their summit (10 to 60 m), surrounding seabed of 1,500 to 2,000 m deep, and guyot shapes with flat summits of a surface ranging from 17 km 2 (Ellet) to 1,800 km 2 (Capel 73 ). Humpback whales have been tracked during the breeding season over similar offshore features, such as Penguin Bank, in Hawaii 39,74 or La Pérouse seamount in the western Indian Ocean 12 . Given their low latitude and/or proximity of these seamounts to known coastal breeding grounds, breeding activities were speculated 12 .…”

“…Humpback whales (Megaptera novaeangliae) were recently discovered to visit seamounts during the breeding season and spring migration period occurring in tropical and subtropical latitudes [10][11][12][13] . Humpback whales seasonally migrate from the polar feeding grounds where they spend the summer, to the tropical breeding grounds where they mate and give birth during the winter.…”

Whales in warming water: Assessing breeding habitat diversity and adaptability in Oceania's changing climate

“…The reasons for such extensive migrations are still debated but could be linked to increased calf fitness in warmer waters of the tropical and subtropical breeding grounds (Clapham, ). Although this hypothesis suggests a direct link between humpback whale life history and water temperature, it remains unclear how sea surface temperature (SST) drives distributions within breeding latitudes, as studies have shown both strong relationships (Bortolotto, Danilewicz, Hammond, Thomas, & Zerbini, ; Guidino, Llapapasca, Silva, Alcorta, & Pacheco, ; Rasmussen et al, ; Smith et al, ) and weak or no effects of this variable (Dulau et al, ; Trudelle et al, ). SST is dynamic, with complex changes through time as it fluctuates on multiple temporal scales (monthly, seasonally, annually) and follows patterns that may be stochastic, cyclic (e.g., El Niño Southern Oscillation [ENSO], Pacific Decadal Oscillation, Antarctic Oscillation [AAO]) or continuous (climate change).…”

“…The reasons for such extensive migrations are still debated but could be linked to increased calf fitness in warmer waters of the tropical and subtropical breeding grounds (Clapham, 2000). Although this hypothesis suggests a direct link between humpback whale life history and water temperature, it remains unclear how sea surface temperature (SST) drives distributions within breeding latitudes, as studies have shown both strong relationships (Bortolotto, Danilewicz, Hammond, Thomas, & Zerbini, 2017;Guidino, Llapapasca, Silva, Alcorta, & Pacheco, 2014;Rasmussen et al, 2007;Smith et al, 2012) and weak or no effects of this variable (Dulau et al, 2017;Trudelle et al, 2016).…”

Behaviour of endangered European eels in proximity to a dam during downstream migration: Novel insights using high accuracy 3D acoustic telemetry

“…However, greater accuracy (approx. 1 m) is required to elucidate patterns in fine‐scale behaviour (Løkkeborg, Fernö, & Jørgensen, ; Rillahan, Chambers, Howell, & Watson, ), home range movements and habitat selection (Andrews et al, ; Coates, Hovel, Butler, Klimley, & Morgan, ; Espinoza, Farrugia, & Lowe, ), and reproduction (Dulau et al, ).…”