Berchok Catherine L.

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Berchok
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Catherine L.
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  • Article
    Long-term passive acoustic recordings track the changing distribution of North Atlantic right whales (Eubalaena glacialis) from 2004 to 2014
    (Nature Publishing Group, 2017-10-18) Davis, Genevieve E. ; Baumgartner, Mark F. ; Bonnell, Julianne M. ; Bell, Joel ; Berchok, Catherine L. ; Bort Thornton, Jacqueline ; Brault, Solange ; Buchanan, Gary ; Charif, Russell A. ; Cholewiak, Danielle ; Clark, Christopher W. ; Corkeron, Peter ; Delarue, Julien ; Dudzinski, Kathleen ; Hatch, Leila ; Hildebrand, John ; Hodge, Lynne ; Klinck, Holger ; Kraus, Scott D. ; Martin, Bruce ; Mellinger, David K. ; Moors-Murphy, Hilary ; Nieukirk, Sharon ; Nowacek, Douglas P. ; Parks, Susan E. ; Read, Andrew J. ; Rice, Aaron N. ; Risch, Denise ; Širović, Ana ; Soldevilla, Melissa ; Stafford, Kathleen M. ; Stanistreet, Joy ; Summers, Erin ; Todd, Sean ; Warde, Ann M. ; Van Parijs, Sofie M.
    Given new distribution patterns of the endangered North Atlantic right whale (NARW; Eubalaena glacialis) population in recent years, an improved understanding of spatio-temporal movements are imperative for the conservation of this species. While so far visual data have provided most information on NARW movements, passive acoustic monitoring (PAM) was used in this study in order to better capture year-round NARW presence. This project used PAM data from 2004 to 2014 collected by 19 organizations throughout the western North Atlantic Ocean. Overall, data from 324 recorders (35,600 days) were processed and analyzed using a classification and detection system. Results highlight almost year-round habitat use of the western North Atlantic Ocean, with a decrease in detections in waters off Cape Hatteras, North Carolina in summer and fall. Data collected post 2010 showed an increased NARW presence in the mid-Atlantic region and a simultaneous decrease in the northern Gulf of Maine. In addition, NARWs were widely distributed across most regions throughout winter months. This study demonstrates that a large-scale analysis of PAM data provides significant value to understanding and tracking shifts in large whale movements over long time scales.
  • Article
    Monitoring Alaskan Arctic shelf ecosystems through collaborative observation networks
    (Oceanography Society, 2022-04-28) Danielson, Seth L. ; Grebmeier, Jacqueline M. ; Iken, Katrin ; Berchok, Catherine L. ; Britt, Lyle ; Dunton, Kenneth ; Eisner, Lisa B. ; Farley, Edward V. ; Fujiwara, Amane ; Hauser, Donna D.W. ; Itoh, Motoyo ; Kikuchi, Takashi ; Kotwicki, Stan ; Kuletz, Kathy J. ; Mordy, Calvin W. ; Nishino, Shigeto ; Peralta-Ferriz, Cecilia ; Pickart, Robert S. ; Stabeno, Phyllis J. ; Stafford, Kathleen M. ; Whiting, Alex V. ; Woodgate, Rebecca
    Ongoing scientific programs that monitor marine environmental and ecological systems and changes comprise an informal but collaborative, information-rich, and spatially extensive network for the Alaskan Arctic continental shelves. Such programs reflect contributions and priorities of regional, national, and international funding agencies, as well as private donors and communities. These science programs are operated by a variety of local, regional, state, and national agencies, and academic, Tribal, for-profit, and nongovernmental nonprofit entities. Efforts include research ship and autonomous vehicle surveys, year-long mooring deployments, and observations from coastal communities. Inter-program coordination allows cost-effective leveraging of field logistics and collected data into value-added information that fosters new insights unattainable by any single program operating alone. Coordination occurs at many levels, from discussions at marine mammal co-management meetings and interagency meetings to scientific symposia and data workshops. Together, the efforts represented by this collection of loosely linked long-term monitoring programs enable a biologically focused scientific foundation for understanding ecosystem responses to warming water temperatures and declining Arctic sea ice. Here, we introduce a variety of currently active monitoring efforts in the Alaskan Arctic marine realm that exemplify the above attributes.
  • Article
    Associations between North Pacific right whales and their zooplanktonic prey in the southeastern Bering Sea
    (Inter-Research, 2013-09-17) Baumgartner, Mark F. ; Lysiak, Nadine S. J. ; Esch, H. Carter ; Zerbini, Alexandre N. ; Berchok, Catherine L. ; Clapham, Phillip J.
    Due to the seriously endangered status of North Pacific right whales Eubalaena japonica, an improved understanding of the environmental factors that influence the species’ distribution and occurrence is needed to better assess the effects of climate change and industrial activities on the population. Associations among right whales, zooplankton, and the physical environment were examined in the southeastern Bering Sea during the summers of 2008 and 2009. Sampling with nets, an optical plankton counter, and a video plankton recorder in proximity to whales as well as along cross-isobath surveys indicated that the copepod Calanus marshallae is the primary prey of right whales in this region. Acoustic detections of right whales from sonobuoys deployed during the cross-isobath surveys were strongly associated with C. marshallae abundance, and peak abundance estimates of C. marshallae in 2.5 m depth strata near a tagged right whale ranged as high as 106 copepods m-3. The smaller Pseudocalanus spp. was higher in abundance than C. marshallae in proximity to right whales, but significantly lower in biomass. High concentrations of C. marshallae occurred in both the surface and bottom layers of the highly stratified water column, but there was no evidence of diel vertical migration. Instead, occurrence of C. marshallae in the bottom layer was associated with elevated near-bottom light attenuance and chlorophyll fluorescence, suggesting C. marshallae may aggregate at depth while feeding on resuspended phytodetritus. Despite the occasional presence of strong horizontal gradients in hydrographic properties, no association was found between C. marshallae and either fronts or phytoplankton distribution.
  • Article
    Exploring movement patterns and changing distributions of baleen whales in the western North Atlantic using a decade of passive acoustic data
    (Wiley, 2020-05-25) Davis, Genevieve E. ; Baumgartner, Mark F. ; Corkeron, Peter ; Bell, Joel ; Berchok, Catherine L. ; Bonnell, Julianne M. ; Bort Thornton, Jacqueline ; Brault, Solange ; Buchanan, Gary ; Cholewiak, Danielle ; Clark, Christopher W. ; Delarue, Julien ; Hatch, Leila ; Klinck, Holger ; Kraus, Scott D. ; Martin, Bruce ; Mellinger, David K. ; Moors-Murphy, Hilary ; Nieukirk, Sharon ; Nowacek, Douglas P. ; Parks, Susan E. ; Parry, Dawn ; Pegg, Nicole ; Read, Andrew J. ; Rice, Aaron N. ; Risch, Denise ; Scott, Alyssa ; Soldevilla, Melissa ; Stafford, Kathleen M. ; Stanistreet, Joy ; Summers, Erin ; Todd, Sean ; Van Parijs, Sofie M.
    Six baleen whale species are found in the temperate western North Atlantic Ocean, with limited information existing on the distribution and movement patterns for most. There is mounting evidence of distributional shifts in many species, including marine mammals, likely because of climate‐driven changes in ocean temperature and circulation. Previous acoustic studies examined the occurrence of minke (Balaenoptera acutorostrata ) and North Atlantic right whales (NARW; Eubalaena glacialis ). This study assesses the acoustic presence of humpback (Megaptera novaeangliae ), sei (B. borealis ), fin (B. physalus ), and blue whales (B. musculus ) over a decade, based on daily detections of their vocalizations. Data collected from 2004 to 2014 on 281 bottom‐mounted recorders, totaling 35,033 days, were processed using automated detection software and screened for each species' presence. A published study on NARW acoustics revealed significant changes in occurrence patterns between the periods of 2004–2010 and 2011–2014; therefore, these same time periods were examined here. All four species were present from the Southeast United States to Greenland; humpback whales were also present in the Caribbean. All species occurred throughout all regions in the winter, suggesting that baleen whales are widely distributed during these months. Each of the species showed significant changes in acoustic occurrence after 2010. Similar to NARWs, sei whales had higher acoustic occurrence in mid‐Atlantic regions after 2010. Fin, blue, and sei whales were more frequently detected in the northern latitudes of the study area after 2010. Despite this general northward shift, all four species were detected less on the Scotian Shelf area after 2010, matching documented shifts in prey availability in this region. A decade of acoustic observations have shown important distributional changes over the range of baleen whales, mirroring known climatic shifts and identifying new habitats that will require further protection from anthropogenic threats like fixed fishing gear, shipping, and noise pollution.
  • Article
    Visual and passive acoustic observations of blue whale trios from two distinct populations
    (Wiley, 2019-09-03) Schall, Elena ; Di Iorio, Lucia ; Berchok, Catherine L. ; Filún, Diego ; Bedriñana-Romano, Luis ; Buchan, Susannah J. ; Van Opzeeland, Ilse ; Sears, Richard ; Hucke-Gaete, Rodrigo
    Blue whale populations from both hemispheres are thought to undertake annual migrations between high latitude feeding grounds and low latitude breeding grounds (Mackintosh, 1966). For individuals of some populations these predetermined movements to and from wintering areas where calving occurs have been confirmed through photo‐identification, satellite‐tracking, and passive acoustic monitoring (Burtenshaw et al., 2004; Mate, Lagerquist, & Calambokidis, 1999; Sears & Perrin, 2002; Stafford, Nieukirk, & Fox, 1999a). However, for many blue whale populations no clear migratory behavior has been reported and locations of respective breeding grounds remain unclear (e.g., Hucke‐Gaete, Osman, Moreno, Findlay, & Ljungblad, 2004; Samaran et al., 2013; Stafford, Chapp, Bohnenstiel, & Tolstoy, 2011; Thomisch et al., 2016). On feeding grounds in the Gulf of St. Lawrence and along the coast of California, blue whales have been observed to form female–male pairs during summer, which can remain stable up to over several weeks, with the number of pairs increasing towards the end of summer (Sears & Perrin, 2002; Calambokidis, unpublished data;1 RS, unpublished data). These pairs are sometimes joined by a second male, forming a blue whale trio, which often is observed to engage in surface active behaviors lasting several minutes (Sears & Perrin, 2002; RS, unpublished data). The formation of blue whale trios is probably related to reproductive competition between male escorts and female choice (RS, unpublished data). Blue whale males produce population‐specific songs likely functioning as reproductive advertisement (Edds‐Walton, 1997; Oleson et al. 2007a; Stafford, Fox, & Clark, 1998). Several studies have reported song year‐round in low‐, mid‐, and high‐latitude waters, frequently with high song production rates during summer on the feeding grounds (e.g., Barlow et al., 2018; Buchan, Stafford, & Hucke‐Gaete, 2015; Samaran, Adam, & Guinett, 2010; Širović et al., 2004; Stafford, Nieukirk, & Fox, 1999b; Thomisch et al., 2016). Therefore, breeding activities in blue whales may be more opportunistic, i.e., not restricted to the breeding season or to a specific habitat.
  • Article
    The Pacific water flow branches in the eastern Chukchi Sea
    (Elsevier, 2023-11-10) Pickart, Robert S. ; Lin, Peigen ; Bahr, Frank B. ; McRaven, Leah T. ; Huang, Jie ; Pacini, Astrid ; Arrigo, Kevin Robert ; Ashjian, Carin J. ; Berchok, Catherine L. ; Baumgartner, Mark F. ; Cho, Kyoungho ; Cooper, Lee W. ; Danielson, Seth L. ; Dasher, Doug H. ; Fuiwara, Amane ; Gann, Jeanette C. ; Grebmeier, Jacqueline M. ; He, Jiangfeng ; Hirawake, Toru ; Itoh, Motoyo ; Juranek, Laurie ; Kikuchi, Takashi ; Moore, G. W. Kent ; Napp, Jeffrey M. ; John Nelson, R. ; Nishino, Shigeto ; Statscewich, Hank ; Stabeno, Phyllis J. ; Stafford, Kathleen M. ; Ueno, Hiromichi ; Vagle, Svein ; Weingartner, Thomas J. ; Williams, Bill ; Zimmermann, Sarah L.
    The flow of Pacific-origin water across the Chukchi Sea shelf impacts the regional ecosystem in profound ways, yet the two current branches on the eastern shelf that carry the water from Bering Strait to Barrow Canyon – the Alaskan Coastal Current (ACC) and Central Channel (CC) Branch – have not been clearly distinguished or quantified. In this study we use an extensive collection of repeat hydrographic sections occupied at three locations on the Chukchi shelf, together with data from a climatology of shipboard velocity data, to accomplish this. The data were collected predominantly between 2010 and 2020 during the warm months of the year as part of the Distributed Biological Observatory and Arctic Observing Network. The mean sections show that mass is balanced for both currents at the three locations: Bering Strait, Point Hope, and Barrow Canyon. The overall mean ACC transport is 0.34 ± 0.04 Sv, and that of the CC Branch is 0.86 ± 0.11 Sv. The dominant hydrographic variability at Bering Strait is seasonal, but this becomes less evident to the north. At Barrow Canyon, the dominant hydrographic signal is associated with year-to-year variations in sea-ice melt. Farther south there is pronounced mesoscale variability: an empirical orthogonal function analysis at Bering Strait and Point Hope reveals a distinct ACC mode and CC Branch mode in hydrography and baroclinic transport, where the former is wind-driven. Finally, the northward evolution in properties of the two currents is investigated. The poleward increase in salinity of the ACC can be explained by lateral mixing alone, but solar heating together with wind mixing play a large role in the temperature evolution. This same atmospheric forcing also impacts the northward evolution of the CC Branch.