Nowacek
Douglas P.
Nowacek
Douglas P.
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ArticleLong-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.
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ArticleThe relationship among oceanography, prey fields, and beaked whale foraging habitat in the Tongue of the Ocean(Public Library of Science, 2011-04-27) Hazen, Elliott L. ; Nowacek, Douglas P. ; St. Laurent, Louis C. ; Halpin, Patrick N. ; Moretti, David J.Beaked whales, specifically Blainville's (Mesoplodon densirostris) and Cuvier's (Ziphius cavirostris), are known to feed in the Tongue of the Ocean, Bahamas. These whales can be reliably detected and often localized within the Atlantic Undersea Test and Evaluation Center (AUTEC) acoustic sensor system. The AUTEC range is a regularly spaced bottom mounted hydrophone array covering >350 nm2 providing a valuable network to record anthropogenic noise and marine mammal vocalizations. Assessments of the potential risks of noise exposure to beaked whales have historically occurred in the absence of information about the physical and biological environments in which these animals are distributed. In the fall of 2008, we used a downward looking 38 kHz SIMRAD EK60 echosounder to measure prey scattering layers concurrent with fine scale turbulence measurements from an autonomous turbulence profiler. Using an 8 km, 4-leaf clover sampling pattern, we completed a total of 7.5 repeat surveys with concurrently measured physical and biological oceanographic parameters, so as to examine the spatiotemporal scales and relationships among turbulence levels, biological scattering layers, and beaked whale foraging activity. We found a strong correlation among increased prey density and ocean vertical structure relative to increased click densities. Understanding the habitats of these whales and their utilization patterns will improve future models of beaked whale habitat as well as allowing more comprehensive assessments of exposure risk to anthropogenic sound.
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ArticleRecent scientific publications cast doubt on North Atlantic right whale future(Frontiers Media, 2016-08-17) Kraus, Scott D. ; Kenney, Robert D. ; Mayo, Charles A. ; McLellan, William A. ; Moore, Michael J. ; Nowacek, Douglas P.
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ArticleExploring 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.
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ArticleDoes the marine biosphere mix the ocean?(Sears Foundation for Marine Research, 2006-07) Dewar, William K. ; Bingham, Rory J. ; Iverson, R. L. ; Nowacek, Douglas P. ; St. Laurent, Louis C. ; Wiebe, Peter H.Ocean mixing is thought to control the climatically important oceanic overturning circulation. Here we argue the marine biosphere, by a mechanism like the bioturbation occurring in marine sediments, mixes the oceans as effectively as the winds and tides. This statement is derived ultimately from an estimated 62.7 TeraWatts of chemical power provided to the marine environment in net primary production. Various approaches argue something like 1% (.63 TeraWatts) of this power is invested in aphotic ocean mechanical energy, a rate comparable to wind and tidal inputs.
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ArticleSwimming kinematics and efficiency of entangled North Atlantic right whales(Inter-Research, 2017-01-12) van der Hoop, Julie ; Nowacek, Douglas P. ; Moore, Michael J. ; Triantafyllou, Michael S.Marine mammals are streamlined for efficient movement in their relatively viscous fluid environment and are able to alter their kinematics (i.e. fluke stroke frequency, amplitude, or both) in response to changes in force balance. Entanglement in fishing gear adds significant drag and buoyant forces that can impact swimming behaviors across a range of timescales. We deployed biologging tags during the disentanglement of 2 North Atlantic right whales Eubalaena glacialis to (1) examine how their kinematics changed in response to drag and buoyancy from entanglement in fishing gear, and (2) calculate resultant changes in swimming efficiency for one individual. We observed variable responses in dive behavior, but neither whale appeared to exploit added buoyancy to reduce energy expenditure. While some of the observed changes in behavior were individually specific, some swimming kinematics were consistently modulated in response to high drag and buoyancy associated with entangling gear, affecting thrust production. In high drag and buoyancy conditions, fluke strokes were significantly shorter and more variable in shape, and gliding was less frequent. Thrust and efficiency significantly differed among dive phases. Disentanglement reduced thrust coefficients ~4-fold, leading to 1.2 to 1.8-fold lower power (W). Ideal propulsive efficiency was significantly lower when entangled, though we detected no difference in observed propulsive efficiency between the conditions. Similar to carrying heavy objects or changing shoes, we present another condition where animals perceive unique movement constraints over seconds to minutes and develop compensatory strategies, altering their movement accordingly.
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ArticleNorth Atlantic right whales (Eubalaena glacialis) ignore ships but respond to alerting stimuli(Royal Society, 2003-12-03) Nowacek, Douglas P. ; Johnson, Mark P. ; Tyack, Peter L.North Atlantic right whales were extensively hunted during the whaling era and have not recovered. One of the primary factors inhibiting their recovery is anthropogenic mortality caused by ship strikes. To assess risk factors involved in ship strikes, we used a multi-sensor acoustic recording tag to measure the responses of whales to passing ships and experimentally tested their responses to controlled sound exposures, which included recordings of ship noise, the social sounds of conspecifics and a signal designed to alert the whales. The whales reacted strongly to the alert signal, they reacted mildly to the social sounds of conspecifics, but they showed no such responses to the sounds of approaching vessels as well as actual vessels. Whales responded to the alert by swimming strongly to the surface, a response likely to increase rather than decrease the risk of collision.
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ArticleDissipation processes in the Tongue of the Ocean(John Wiley & Sons, 2016-05-14) Hooper, James A. ; Baringer, Molly O. ; St. Laurent, Louis C. ; Dewar, William K. ; Nowacek, Douglas P.The Tongue of the Ocean (TOTO) region located within the Bahamas archipelago is a relatively understudied region in terms of both its biological and physical oceanographic characteristics. A prey-field mapping cruise took place in the fall between 15 September 2008 and 1 October 2008, consisting of a series of transects and “clovers” to study the spatial and temporal variability. The region is characterized by a deep scattering layer (DSL), which is preyed on by nekton that serves as the food for beaked whale and other whale species. This study marks the first of its kind where concurrent measurements of acoustic backscatter and turbulence have been conducted for a nekton scattering layer well below the euphotic zone. Turbulence data collected from a Deep Microstructure Profiler are compared to biological and shear data collected by a 38 kHz Simrad EK 60 echo sounder and a hydrographic Doppler sonar system, respectively. From these measurements, the primary processes responsible for the turbulent production in the TOTO region are assessed. The DSL around 500 m and a surface scattering layer (SSL) are investigated for raised ε values. Strong correlation between turbulence levels and scattering intensity of prey is generally found in the SSL with dissipation levels as large as ∼10−7 W kg−1, 3 orders of magnitude above background levels. In the DSL and during the diel vertical migration, dissipation levels ∼10−8 W kg−1 were observed.
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ArticleDiel changes in humpback whale Megaptera novaeangliae feeding behavior in response to sand lance Ammodytes spp. behavior and distribution(Inter-Research, 2009-12-03) Friedlaender, Ari S. ; Hazen, Elliott L. ; Nowacek, Douglas P. ; Halpin, Patrick N. ; Ware, Colin ; Weinrich, Mason T. ; Hurst, Thomas P. ; Wiley, David N.Humpback whales Megaptera novaeangliae have adopted unique feeding strategies to take advantage of behavioral changes in their prey. However, logistical constraints have largely limited ecological analyses of these interactions. Our objectives were to (1) link humpback whale feeding behaviors to concurrent measurements of prey using scientific echo-sounders, and (2) quantify how sand lance behavior influences the feeding behaviors and foraging ecology of humpback whales. To measure, in fine detail, the 3-dimensional orientation and movement patterns of humpback whales underwater, we used a multi-sensor tag attached via suction cups (DTAG). We tested the specific hypothesis that the diel movement patterns of sand lance between bottom substrate and the water column correlates to changes between surface and bottom feeding strategies of humpback whales on Stellwagen Bank, MA. We collected over 96 h of both day- and nighttime data from 15 whales in 2006, and recorded 393 surface and 230 bottom feeding events. Individual whales exhibit both surface and bottom feeding behaviors, switching from one to the other in relation to changing light and prey conditions. Surface feeding behaviors were individually variable in their constitution but ubiquitously biased towards daylight hours, when prey was most abundant in the upper portion of the water column. Bottom feeding behavior occurred largely at night, coincident with when sand lance descend to seek refuge in the substrate. Our data provide novel insights into the behavioral ecology of humpback whales and their prey, indicating significant diel patterns in foraging behaviors concurrent with changes in prey behavior.