Epibiotic fauna of the Antarctic minke whale as a reliable indicator of seasonal movements

Abstract

Antarctic minke whales, Balaenoptera bonaerensis, breed in tropical and temperate waters of the Southern Hemisphere in winter and feed in Antarctic grounds in the austral summer. These seasonal migrations could be less defined than those of other whale species, but the evidence is scanty. We quantitatively describe the epibiotic fauna of Antarctic minke whales and explore its potential to trace migrations. Seven species were found on 125 out of 333 examined Antarctic minke whales captured during the last Antarctic NEWREP-A expedition in the Southern Ocean: the amphipod Balaenocyamus balaenopterae (prevalence = 22.2%), the copepod Pennella balaenoptera (0.6%); three coronulid, obligate barnacles, Xenobalanus globicipitis (11.1%), Coronula reginae (8.7%), C. diadema (0.9%); and two lepadid, facultative barnacles, Conchoderma auritum (9.0%) and C. virgatum (0.3%). Species with prevalence > 8% exhibited a modest increase in their probability of occurrence with whale body length. Data indicated positive associations between coronulid barnacles and no apparent recruitment in Antarctic waters. All specimens of X. globicipitis were dead, showing progressive degradation throughout the sampling period, and a geographic analysis indicated a marked drop of occurrence where the minimum sea surface temperature is < 12 °C. Thus, field detection -with non-lethal methodologies, such as drones- of coronulid barnacles, especially X. globicipitis, on whales in the Southern Ocean could evince seasonal migration. Future investigations on geographical distribution, growth rate, and degradation (for X. globicipitis) could also assist in timing whales’ migration.

Migratory movements of fin whales from the Gulf of St. Lawrence challenge our understanding of the Northwest Atlantic stock structure

“…In other species, such as pinnipeds and beluga ( Delphinapterus leucas ), an increase in skin temperature was shown to stimulate the moult 63 , 64 . Diatoms and ectoparasites grow and disappear on the skin of baleen whales in different habitats and temperatures 5 , 65 , 66 . However, it remains unknown whether skin regeneration could trigger the large-scale and short-duration southerly movements observed in some individuals during early winter in our study.…”

Yasunaga et al. (2022) meets the ethics code of Marine Mammal Science, and the journal's decision to publish the paper is correct

“…Importantly, these data and samples are now considered "historical" and must be used to learn more about the biology of whales and contribute to the conservation and management of the whale species involved. Indeed, several studies using these data and samples have been published recently in international journals (Nishimura et al, 2021;Taguchi et al, 2023;Ten et al, 2022;Uchida et al, 2021). Perhaps most importantly, these data and sample sets have also been used to calibrate nonlethal methodologies (e.g., Goto et al, 2020;Inoue et al, 2019).…”