Martin van Aswegen, Andy Szabo, Jens J Currie, Stephanie H Stack, Lewis Evans, Janice Straley, Janet Neilson, Christine Gabriele, Kelly Cates, Debbie Steel, Lars Bejder
{"title":"Maternal investment, body condition and calf growth in humpback whales.","authors":"Martin van Aswegen, Andy Szabo, Jens J Currie, Stephanie H Stack, Lewis Evans, Janice Straley, Janet Neilson, Christine Gabriele, Kelly Cates, Debbie Steel, Lars Bejder","doi":"10.1113/JP287379","DOIUrl":null,"url":null,"abstract":"<p><p>Given recent declines in North Pacific humpback whale (Megaptera novaeangliae) reproductive output and calf survival, there is additional urgency to better understand how mother-calf pairs allocate energy resources across their migratory cycle. Here, unoccupied aerial system (UAS; or drone) photogrammetry was used to quantify the body size and condition (BC) of humpback whales on their Hawai'i (HI) breeding and Southeast Alaska (SEAK) feeding grounds. Between 2018 and 2022, we collected 2410 measurements of 1659 individuals. Rates of change in body volume (BV) and length (BL) were quantified using 803 repeat measurements of 275 individuals. On average, HI mothers lost 0.106 m<sup>3</sup> or 96.84 kg day<sup>-1</sup> while fasting, equivalent to 2641 MJ day<sup>-1</sup> or 830 kg of krill and 424 kg of Pacific herring daily. HI calf BV and BL increased by 0.035 m<sup>3</sup> and 2.6 cm day<sup>-1</sup>, respectively. In SEAK, maternal BV increased by 0.015 m<sup>3</sup> or 14.54 kg day<sup>-1</sup> (367 MJ day<sup>-1</sup>), while calf BV and BL increased by 0.039 m<sup>3</sup> and 0.93 cm day<sup>-1</sup>, respectively. Maternal investment in calf growth correlated with both female BL and BC, with larger females producing larger, faster-growing calves. Finally, using 330 measurements from 156 females, we quantified differences in BC increase over four feeding seasons. Lactating females exhibited an average BC increase of 6.10%, half that of unclassified females (13.51%) and six times lower than pregnant females (37%). These findings represent novel insights into the life history of humpback whales across their migratory cycle, providing key baseline data for bioenergetic models elucidating the effects of anthropogenic disturbance and rapidly changing ocean ecosystems. KEY POINTS: On average, Hawai'i (HI) mothers lost 0.106 m<sup>3</sup> or 96.84 kg day<sup>-1</sup>, equivalent to 2641 MJ day<sup>-1</sup>. Over a 60 day period, this corresponded to an estimated mean energetic cost of 158 GJ, or ≈50 tons of krill or ≈25 tons of Pacific herring, surpassing the total energetic cost of gestation estimated for humpback whales of similar length. In Southeast Alaska (SEAK), maternal body volume (BV) increased by just 0.015 m<sup>3</sup> or 14.54 kg day<sup>-1</sup> (367 MJ day<sup>-1</sup>). Further, SEAK lactating females showed the slowest rates of growth in body width and condition over a 150 day period compared to non-lactating females. Maternal investment in calf growth correlated with both maternal length and body condition, with larger females producing larger, faster-growing calves. In HI, however, the ratio between maternal BV lost and calf BV gained (conversion efficiency) was relatively low compared to other mammals.</p>","PeriodicalId":50088,"journal":{"name":"Journal of Physiology-London","volume":" ","pages":""},"PeriodicalIF":4.7000,"publicationDate":"2024-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of Physiology-London","FirstCategoryId":"3","ListUrlMain":"https://doi.org/10.1113/JP287379","RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"NEUROSCIENCES","Score":null,"Total":0}
引用次数: 0
Abstract
Given recent declines in North Pacific humpback whale (Megaptera novaeangliae) reproductive output and calf survival, there is additional urgency to better understand how mother-calf pairs allocate energy resources across their migratory cycle. Here, unoccupied aerial system (UAS; or drone) photogrammetry was used to quantify the body size and condition (BC) of humpback whales on their Hawai'i (HI) breeding and Southeast Alaska (SEAK) feeding grounds. Between 2018 and 2022, we collected 2410 measurements of 1659 individuals. Rates of change in body volume (BV) and length (BL) were quantified using 803 repeat measurements of 275 individuals. On average, HI mothers lost 0.106 m3 or 96.84 kg day-1 while fasting, equivalent to 2641 MJ day-1 or 830 kg of krill and 424 kg of Pacific herring daily. HI calf BV and BL increased by 0.035 m3 and 2.6 cm day-1, respectively. In SEAK, maternal BV increased by 0.015 m3 or 14.54 kg day-1 (367 MJ day-1), while calf BV and BL increased by 0.039 m3 and 0.93 cm day-1, respectively. Maternal investment in calf growth correlated with both female BL and BC, with larger females producing larger, faster-growing calves. Finally, using 330 measurements from 156 females, we quantified differences in BC increase over four feeding seasons. Lactating females exhibited an average BC increase of 6.10%, half that of unclassified females (13.51%) and six times lower than pregnant females (37%). These findings represent novel insights into the life history of humpback whales across their migratory cycle, providing key baseline data for bioenergetic models elucidating the effects of anthropogenic disturbance and rapidly changing ocean ecosystems. KEY POINTS: On average, Hawai'i (HI) mothers lost 0.106 m3 or 96.84 kg day-1, equivalent to 2641 MJ day-1. Over a 60 day period, this corresponded to an estimated mean energetic cost of 158 GJ, or ≈50 tons of krill or ≈25 tons of Pacific herring, surpassing the total energetic cost of gestation estimated for humpback whales of similar length. In Southeast Alaska (SEAK), maternal body volume (BV) increased by just 0.015 m3 or 14.54 kg day-1 (367 MJ day-1). Further, SEAK lactating females showed the slowest rates of growth in body width and condition over a 150 day period compared to non-lactating females. Maternal investment in calf growth correlated with both maternal length and body condition, with larger females producing larger, faster-growing calves. In HI, however, the ratio between maternal BV lost and calf BV gained (conversion efficiency) was relatively low compared to other mammals.
期刊介绍:
The Journal of Physiology publishes full-length original Research Papers and Techniques for Physiology, which are short papers aimed at disseminating new techniques for physiological research. Articles solicited by the Editorial Board include Perspectives, Symposium Reports and Topical Reviews, which highlight areas of special physiological interest. CrossTalk articles are short editorial-style invited articles framing a debate between experts in the field on controversial topics. Letters to the Editor and Journal Club articles are also published. All categories of papers are subjected to peer reivew.
The Journal of Physiology welcomes submitted research papers in all areas of physiology. Authors should present original work that illustrates new physiological principles or mechanisms. Papers on work at the molecular level, at the level of the cell membrane, single cells, tissues or organs and on systems physiology are all acceptable. Theoretical papers and papers that use computational models to further our understanding of physiological processes will be considered if based on experimentally derived data and if the hypothesis advanced is directly amenable to experimental testing. While emphasis is on human and mammalian physiology, work on lower vertebrate or invertebrate preparations may be suitable if it furthers the understanding of the functioning of other organisms including mammals.