{"id":2896,"date":"2019-07-23T04:39:18","date_gmt":"2019-07-23T04:39:18","guid":{"rendered":"http:\/\/blogs.oregonstate.edu\/gemmlab\/?p=2896"},"modified":"2019-07-23T04:39:26","modified_gmt":"2019-07-23T04:39:26","slug":"applying-novel-methods-in-conservation-physiology-to-understand-cases-of-large-whale-mortalities","status":"publish","type":"post","link":"https:\/\/dev.blogs.oregonstate.edu\/gemmlab\/2019\/07\/23\/applying-novel-methods-in-conservation-physiology-to-understand-cases-of-large-whale-mortalities\/","title":{"rendered":"Applying novel methods in conservation physiology to understand cases of large whale mortalities"},"content":{"rendered":"\n

By Alejandro Fern\u00e1nez Aj\u00f3, PhD student at NAU and GEMM Lab research technician<\/strong><\/p>\n\n\n\n

Although\ncommercial whaling is currently banned and several whale populations show\nevidence of recovery, today\u00b4s whales are exposed to a variety of other human\nstressors (e.g., entanglement in fishing gear, vessel strikes, shipping noise,\nclimate change, etc.; reviewed in Hunt et al., 2017a). The recovery and\nconservation of large whale populations is particularly important to the\noceanic environment due to their key ecological role and unique biological\ntraits, including their large body size, long lifespan and sizable home ranges\n(Magera et al., 2013; Atkinson et al., 2015; Thomas and Reeves, 2015). Thus,\nscientists must develop novel tools to overcome the challenges of studying\nwhale physiology in order to distinguish the relative importance of the different\nimpacts and guide conservation actions accordingly (Ayres et al., 2012; Hunt et\nal., 2013).<\/p>\n\n\n\n

To this end,\nbaleen hormone analysis represents a powerful tool for retrospective assessment\nof patterns in whale physiology (Hunt et al., 2014, 2016, 2017a, 2017b, 2018;\nLysiak et. al., 2018; Fern\u00e1ndez Aj\u00f3 et al., 2018; Rolland et al., 2019).\nMoreover, hormonal panels, which include multiple hormones, are helping to\nbetter clarify and distinguish between the physiological effects of different\nsources of anthropogenic and environmental stressors (Ayres et al., 2012;\nWasser et al., 2017; Lysiak et al., 2018; Romero et al., 2015).<\/p>\n\n\n\n

What is Baleen?<\/strong> Baleen is a stratified epithelial tissue consisting of long, fringed plates that grow downward from the upper jaw, which collectively form the whale\u00b4s filter-feeding apparatus (Figure 1<\/strong>). This tissue accumulates hormones as it grows. Hormones are deposited in a linear fashion with time so that a single plate of baleen allows retrospective assessment and evaluation of a whales\u2019 physiological condition, and in calves baleen provides a record of the entire lifespan including part of their gestation. Baleen samples are also readily accessible and routinely collected during necropsy along with other samples and relevant information. <\/p>\n\n\n\n

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Figure 1:<\/strong> Top: A baleen plate from a southern right whale calf (Source: Fern\u00e1ndez Aj\u00f3 et al. 2018). Bottom: A southern right whale with mouth open exposing its baleen (photo credit: Stephen Johnson). <\/figcaption><\/figure>\n\n\n\n

Why are the\nSouthern Right Whales calves (SRW) dying in Patagonia?<\/strong><\/p>\n\n\n\n

I am a Fulbright Ph.D. student in the Buck Laboratory<\/a>  at Northern Arizona University since Fall 2017, a researcher with the Whale Conservation Institute of Argentina (Instituto de Conservaci\u00f3n de Ballenas<\/a>) and Field Technician for the GEMM Lab over the summer. I focus my research on the application and development of novel methods in conservation physiology to improve our understanding of how physiological parameters are affected by human pressures that impact large whales and marine mammals. I am especially interested in understanding the underlaying causes of large whale mortalities with the aim of preventing their occurrence when possible. In particular, for my Ph.D. dissertation, I am studying a die-off case of Southern Right Whale (SRW) calves, Eubalaena australis<\/em>, off Peninsula Vald\u00e9s (PV) in Patagonia-Argentina (Figure 2<\/strong>).<\/p>\n\n\n\n

Prior to\n2000, annual calf mortality at PV was considered normal and tracked the\npopulation growth rate (Rowntree et al., 2013). However, between 2007 and 2013,\n558 whales died, including 513 newborn calves (Sironi et al., 2018). Average\ntotal whale deaths per year increased tenfold, from 8.2 in 1993-2002 to 80 in\n2007-2013. These mortality levels have never before been observed for the\nspecies or any other population of whales (Thomas et al., 2013, Sironi et al.,\n2018).<\/p>\n\n\n\n

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Figure 2:<\/strong> Study area, the red dots along the shoreline indicate the location where the whales were found stranded at Pen\u00ednsula Vald\u00e9s in 2018 (Source: The Right Whale Program Research Report 2018, Sironi and Rowntree, 2018) <\/figcaption><\/figure>\n\n\n\n

Among several hypotheses proposed to explain these elevated calf mortalities, harassment by Kelp Gulls, Larus dominicanus,<\/em> on young calves stands out as a plausible cause and is a unique problem only seen at the PV calving ground. Kelp gull parasitism on SRWs near PV was first observed in the 1970\u2019s (Thomas, 1988). Gulls primarily harass mother-calf pairs, and this parasitic behavior includes pecking on the backs of the whales and creating open wounds to feed on their skin and blubber. The current intensity of gull harassment has been identified as a significant environmental stressor to whales and potential contributor to calf deaths (Mar\u00f3n et al., 2015b; Fern\u00e1ndez Aj\u00f3 et al., 2018). <\/p>\n\n\n\n

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