Future Directions in Research on Bryde's Whales

Rochelle Constantine,Gwenith S Penry,Sharon L Nieukirk,Takashi Iwata

doi:10.3389/fmars.2018.00333

Abstract

One of the lesser known species of baleen whales, the Bryde’s whale, also known as Eden’s whale (Balaenoptera edeni edeni and B. edeni brydei), although hunted as part of a North Pacific Japanese research programme , was not heavily exploited by commercial whaling and remains a data deficient species. Their taxonomic status is not fully resolved and they are often mistaken for other species leading to uncertainty about their true distribution, behavior and conservation status. Some populations are critically endangered, whilst others are small but have high genetic diversity suggesting wider connectivity. The species’ unpredictable coastal and offshore global distribution throughout warm-temperate waters has led to populations with unknown genetic variation, and facing different threats. Few areas are well-studied, but each study reveals often contrasting movement patterns, foraging strategies and vocal repertoires; there are considerable knowledge gaps for Bryde’s whales. There are few Bryde’s populations with abundance estimates but they typically number in the mid- to high-hundreds of individuals, with other populations small, <100 mature individuals, and exposed to high levels of anthropogenic impacts. Future research should focus on understanding the diversity within and between populations. Here, we suggest an integrative, comparative approach towards future work on Bryde’s whales, including acoustic monitoring, trophic interactions, telemetry tools, understanding their novel behaviors, and resolving their species status. This will inform conservation management of this unusual species of whale vulnerable to anthropogenic impacts.

Highlights

PLASTICITY IN FORAGING BEHAVIORSBalaenopteridae including Bryde’s whales employ a foraging strategy, lunge feeding, characterized by the engulfment of a large volume of water at high speed and subsequent filtering with the mouth closed (Goldbogen et al, 2017)
One of the lesser known species of baleen whales, the Bryde’s whale, known as Eden’s whale (Balaenoptera edeni edeni and B. edeni brydei), hunted as part of a North Pacific Japanese research programme1, was not heavily exploited by commercial whaling and remains a data deficient species
When combined with ecological and morphological data, there is strong evidence to suggest the two forms could be separated at the species level and perhaps even disconnected from their coastal and oceanic descriptors that can lead to incorrect species assignment [e.g., the New Zealand coastal population is B. e. brydei, the offshore form (Wiseman, 2008)]

Summary

PLASTICITY IN FORAGING BEHAVIORS

Balaenopteridae including Bryde’s whales employ a foraging strategy, lunge feeding, characterized by the engulfment of a large volume of water at high speed and subsequent filtering with the mouth closed (Goldbogen et al, 2017). Bryde’s whales commonly use lunge feeding behaviors throughout their range (e.g., Miyazaki and Wada, 1978; Best et al, 1984; Tershy, 1992; Anderson, 2005; Steiner et al, 2008; Alves et al, 2010; Penry et al, 2011; Lodi et al, 2015; Iwata et al, 2017). Bryde’s whales have a wide array of novel behaviors to catch prey, perhaps more than any other species of baleen whale They forage at the sea-surface and at depth, during day-time and night-time, and feed on pelagic and mesopelagic prey. Ascertaining how the novel foraging behaviors are developed and transmitted, especially between mothers and calves and between wider ranging populations of whales would change our traditional thoughts about baleen whales

THREATS AND CONSERVATION

CONCLUSIONS