Sampling cetacean blubber using retrievable projectiles (biopsy hereafter) has facilitated a wealth of knowledge on inter alia: migration, life-history, trophic ecology, population structure and pollutant burden. Although observable behavioural responses in humpback whales (Megaptera novaeangliae) are usually mild or moderate (Noren and Mocklin, 2012), biopsy sampling is invasive and ought to be employed judiciously. Christiansen et al. (2020) compellingly argue that blubber lipid-content measurements could inform health and life-history assessments of humpback whales. They aimed to determine a relationship between blubber lipid-content (biopsy) and body shape (aerial photogrammetry). This is a laudable goal: validation of aerial photogrammetry for measuring internal body condition by proxy, would present a less-invasive alternative to biopsy sampling. However, it has previously been shown that the lipid content of biopsy samples is not representative of blubber in situ (Ryan et al., 2013). Therein, the blubber lipid content of a dead fin whale (Balaenoptera physalus) was estimated, comparing biopsy samples with control samples excised by scalpel. Percentage lipid content (mean±s.d.) was significantly lower and more variable for biopsies (37±6.6%, n=15) than controls (81±1.2%, n=3). The large discrepancy is likely a result of the biopsy dart rupturing adipocytes, precluding the use of biopsies for estimating blubber lipid-content (Ryan et al., 2013). I argue that this sampling effect could explain why Christiansen et al. (2020) did not find a relationship between metrics of internal and external body condition. Moreover, I discourage further use of biopsy sampling for measuring blubber lipid content due to sampling biases (Kershaw et al., 2019; Krahn et al., 2004; Ryan et al., 2013). This is especially relevant to longitudinal studies where repeat sampling increases the potential for adverse effects on the welfare of individual whales.
Lipid content of whale blubber cannot be measured using biopsies
Announcing the 2024 JEB Outstanding Paper Prize shortlist and winner
Every year JEB celebrates early-career researchers through the Outstanding Paper Prize. We recognise the shortlisted ECRS that contributed to 11 remarkable studies published in 2024 and congratulate the winner, Elise Laetz, from University of Groningen. See how else JEB supports and promotes ECRs.
Inside the Intergovernmental Panel on Climate Change with Hans-Otto Pörtner
During the past two decades, Hans-Otto Pörtner has steered climate change policy as a co-Chair of IPCC Working Group II. He tells us about the experience in this Perspective.
Photosynthesis turns symbiotic sea anemone's tentacles toward sun
Snakelocks sea anemones point their tentacles, packed with symbiotic algae, toward the sun so their lodgers can photosynthesize, and now Vengamanaidu Modepalli & colleagues have discovered that photosynthesis by the algae guides their host's tentacles towards the sun.
History of our journals
As our publisher, The Company of Biologists, turns 100 years old, read about JEB’s history and explore the journey of each of our sister journals: Development, Journal of Cell Science, Disease Models & Mechanisms and Biology Open.
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