Knowlton Amy R.

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Knowlton
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Amy R.
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  • Presentation
    Don’t assume it’s ghost gear : accurate gear characterization is critical for entanglement mitigation [poster]
    (Woods Hole Oceanographic Institution, 2017-10-25) Henry, Allison G. ; Barco, Susan G. ; Cole, Tim ; Johnson, Amanda ; Knowlton, Amy R. ; Landry, Scott ; Mattila, David K. ; Moore, Michael J. ; Robbins, Jooke ; van der Hoop, Julie ; Asmutis-Silvia, Regina
    Entanglement is a significant conservation and welfare issue which is limiting the recovery of a number of marine species, including marine mammals. It is therefore important to reliably identify the causes of these events, including the nature of the entangling gear in order to reduce or prevent them in the future. A recently published review of marine debris assessed 76 publications and attributed a total of 1805 cases of cetacean entanglements in “ghost gear”, of which 78% (n=1413) were extracted from 13 peer reviewed publications. We examined the 13 publications cited in the review and found that the specific gear type or status of gear involved in the reported events was rarely mentioned beyond the fact that it was fishing related. This is likely due to the fact that determinations of debris as the entangling material are very difficult. In fact, in reviewing 10 years of large whale entanglement records for the U.S., the authors of another study reported that Hawaii was the only region in which any entangling gear was positively identified as ghost gear. The assumption that entangling gear is marine debris unless otherwise stated is dangerous because it could impact efforts to modify or restrict risk-prone fishing in key marine mammal habitats. Entanglement in actively fished gear poses a very real threat, and claims that only lost or abandoned fishing gear is responsible for entanglements can undermine conservation efforts.
  • Presentation
    Entanglements of North Atlantic right whales increase as their distribution shifts in response to climate change: The need for a new management paradigm [poster]
    (Woods Hole Oceanographic Institution, 2019-12-09) Pendleton, Daniel ; Pettis, Heather M. ; Hamilton, Philip K. ; Knowlton, Amy R. ; Landry, Scott ; Moore, Michael J. ; McLellan, William A. ; Corkeron, Peter ; Kraus, Scott D.
    Detection rate of severely injured or entangled NARWs began to increase around 2004 - 2007.
  • Article
    Larger females have more calves: influence of maternal body length on fecundity in North Atlantic right whales
    (Inter Research, 2022-05-12) Stewart, Joshua D. ; Durban, John W. ; Europe, Hollis ; Fearnbach, Holly ; Hamilton, Philip K. ; Knowlton, Amy R. ; Lynn, Morgan S. ; Miller, Carolyn A. ; Perryman, Wayne L. ; Tao, Brandon W. H. ; Moore, Michael J.
    North Atlantic right whales (NARW) are critically endangered and have been declining in abundance since 2011. In the past decade, human-caused mortalities from vessel strikes and entanglements have been increasing, while birth rates in the population are at a 40 yr low. In addition to declining abundance, recent studies have shown that NARW length-at-age is decreasing due to the energetic impacts of sub-lethal entanglements, and that the body condition of the population is poorer than closely related southern right whales. We examined whether shorter body lengths are associated with reduced fecundity in female NARW. We compared age-corrected, modeled metrics of body length with 3 metrics of fecundity: age at first reproduction, average inter-birth interval, and the number of calves produced per potential reproductive year. We found that body length is significantly related to birth interval and calves produced per reproductive year, but not age at first reproduction. Larger whales had shorter inter-birth intervals and produced more calves per potential reproductive year. Larger whales also had higher lifetime calf production, but this was a result of larger whales having longer potential reproductive spans, as body lengths have generally been declining over the past 40 yr. Declining body sizes are a potential contributor to low birth rates over the past decade. Efforts to reduce entanglements and vessel strikes could help maintain population viability by increasing fecundity and improving resiliency of the population to other anthropogenic and climate impacts.
  • Article
    Blubber thickness in right whales Eubalaena glacialis and Eubalaena australis related with reproduction, life history status and prey abundance
    (Inter-Research, 2011-10-05) Miller, Carolyn A. ; Reeb, Desray ; Best, Peter B. ; Knowlton, Amy R. ; Brown, Moira W. ; Moore, Michael J.
    The high variability in reproductive performance of North Atlantic right whales Eubalaena glacialis compared to southern right whales Eubalaena australis may reflect differences in lipid reserves. Amplitude-mode ultrasound was used to measure the thickness of right whale integument (epidermis and blubber, herein referred to as blubber thickness) in E. glacialis in the Bay of Fundy, Canada for 5 summer seasons and in E. australis off the South African coast for 2 austral winter seasons. E. glacialis had significantly thinner blubber layers (mean ±1 SD = 12.23 ± 2.16 cm, n = 172) than E. australis (16.13 ± 3.88 cm, n = 117), suggesting differing levels of nutrition between the 2 species. Blubber was thickest in females measured 3 to 6 mo prior to the start of pregnancy (E. glacialis), thinner during ­lactation (E. glacialis, E. australis) and then thicker with time after weaning (E. glacialis). These results suggest that lipids in blubber are used as energetic support for reproduction in female right whales. Blubber thickness increased in calves during suckling (E. glacialis, E. australis) but sub­sequently decreased after weaning (E. glacialis). Juvenile and adult male E. glacialis blubber thicknesses were compared between years of differing prey Calanus finmarchicus abundances (data from Pershing et al. 2005; ICES J Mar Sci 62:1511–1523); during a year of low prey abundance whales had significantly thinner blubber than during years of greater prey abundance. Taken together, these results suggest that blubber thickness is indicative of right whale energy balance and that the marked fluctuations in North Atlantic right whale reproduction have a nutritional component.
  • Preprint
    Ropeless fishing to prevent large whale entanglements: Ropeless Consortium report
    (Elsevier, 2019-06-22) Myers, Hannah J. ; Moore, Michael J. ; Baumgartner, Mark F. ; Brillant, Sean W. ; Katona, Steven K. ; Knowlton, Amy R. ; Morissette, Lyne ; Pettis, Heather M. ; Shester, Geoff ; Werner, Timothy B.
    The 2017 North Atlantic right whale (NARW) unusual mortality event and an increase in humpback whale entanglements off the U.S. West Coast have driven significant interest in ropeless trap/pot fishing. Removing the vertical buoy lines used to mark traps on the sea floor and haul them up would dramatically reduce or eliminate entanglements, the leading cause of NARW mortality, while potentially allowing fishermen to harvest in areas that would otherwise need to be closed to protect whales. At the first annual Ropeless Consortium meeting, researchers, fishing industry representatives, manufacturers, conservationists, and regulators discussed existing and developing technological replacements for the marking and retrieval functions of buoy lines. Fishermen and NGO partners shared their experience demonstrating ropeless systems and provided feedback to improve the designs. U.S. and Canadian federal regulators discussed prospects to use ropeless fishing gear in areas closed to fishing with vertical lines, as well as other options to reduce entanglements, and a Massachusetts official shared additional regulatory considerations involved in ropeless fishing in state waters. Sustainable seafood experts discussed consumer market advantages and endangered, threatened, and protected species impacts in sustainability standards and certifications. Moving forward, there is an immediate need to (1) work with industry partners to iteratively test and improve ropeless retrieval and marking systems to adapt them to the specific conditions of the relevant trap/pot fisheries, (2) create data sharing and communications protocols for ropeless gear location marking, and (3) develop regulatory procedures and enforcement capacity to allow legal ropeless gear use.
  • Article
    Characterizing the duration and severity of fishing gear entanglement on a North Atlantic right whale (Eubalaena glacialis) using stable isotopes, steroid and thyroid hormones in baleen
    (Frontiers Media, 2018-05-15) Lysiak, Nadine S. J. ; Trumble, Stephen J. ; Knowlton, Amy R. ; Moore, Michael J.
    North Atlantic right whales (Eubalaena glacialis) are highly endangered and frequently exposed to a myriad of human activities and stressors in their industrialized habitat. Entanglements in fixed fishing gear represent a particularly pervasive and often drawn-out source of anthropogenic morbidity and mortality to the species. To better understand both the physiological response to entanglement, and to determine fundamental parameters such as acquisition, duration, and severity of entanglement, we measured a suite of biogeochemical markers in the baleen of an adult female that died from a well-documented chronic entanglement in 2005 (whale Eg2301). Steroid hormones (cortisol, corticosterone, estradiol, and progesterone), thyroid hormones (triiodothyronine (T3) and thyroxine (T4)), and stable isotopes (δ13C and δ15N) were all measured in a longitudinally sampled baleen plate. This yielded an 8-year profile of foraging and migration behavior, stress response, and reproduction. Stable isotopes cycled in annual patterns that reflect the animal's north-south migration behavior and seasonally abundant zooplankton diet. A progesterone peak, lasting approximately 23 months, was associated with the single known calving event (in 2002) for this female. Estradiol, cortisol, corticosterone, T3, and T4 were also elevated, although variably so, during the progesterone peak. This whale was initially sighted with a fishing gear entanglement in September 2004, but the hormone panel suggests that the animal first interacted with the gear as early as June 2004. Elevated δ15N, T3, and T4 indicate that Eg2301 potentially experienced increased energy expenditure, significant lipid catabolism, and thermal stress approximately 3 months before the initial sighting with fishing gear. All hormones in the panel (except cortisol) were elevated above baseline by September 2004. This novel study illustrates the value of using baleen to reconstruct recent temporal profiles and as a comparative matrix in which key physiological indicators of individual whales can be used to understand the impacts of anthropogenic activity on threatened whale populations.
  • Article
    Fatally entangled right whales can die extremely slowly
    (IEEE, 2006-09) Moore, Michael J. ; Bogomolni, Andrea L. ; Bowman, Robert ; Hamilton, Philip K. ; Harry, Charles T. ; Knowlton, Amy R. ; Landry, Scott ; Rotstein, David S. ; Touhey, Kathleen M.
    Unlike smaller marine mammals that lack the mass and power to break free from serious entanglements in fixed fishing gear, right whales can do so, but they are not always rope free. The remaining rope can gradually constrict one or more body parts and the resulting debilitation and ultimate death can take many months. Thus the practices that lead to these mortalities need to be viewed not only as a conflict between the cultural and socioeconomic value of a fishery versus a potential species extinction process, but also in terms of an extreme animal welfare issue.
  • Preprint
    Rebuttal to published article “A review of ghost gear entanglement amongst marine mammals, reptiles and elasmobranchs” by M. Stelfox, J. Hudgins, and M. Sweet
    ( 2016-11) Asmutis-Silvia, Regina ; Barco, Susan G. ; Cole, Tim ; Henry, Allison G. ; Johnson, Amanda ; Knowlton, Amy R. ; Landry, Scott ; Mattila, David K. ; Moore, Michael J. ; Robbins, Jooke ; van der Hoop, Julie
    We reviewed the findings of the recently published article by Stelfox et al. (2016): “A review of ghost gear entanglement amongst marine mammals, reptiles and elasmobranchs” published in this journal (Volume 111, pp 6–17) and found that they are both flawed and misleading as they do not accurately reflect the prevalence of “ghost gear” cases reported in the literature. While we commend the authors for recognizing the importance of attempting to quantify the threat and for recommending more comprehensive databases, the methods, results and conclusions of this review have not advanced the understanding of the issue. As authors of the papers on whale entanglements in the North Atlantic that were reviewed by Stelfox et al. (2016) and others who are knowledgeable about the topic, we provide specific comments regarding misrepresentations of both the source of entanglement (e.g., actively fished gear versus “ghost gear”) and the number of reported entanglements for whale species included in the North Atlantic.
  • Article
    Morphometry, gross morphology and available histopathology in North Atlantic right whale (Eubalaena glacialis) mortalities (1970-2002)
    (International Whaling Commission, 2023-03-15) Moore, Michael J. ; Knowlton, Amy R. ; Kraus, Scott D. ; McLellan, William A. ; Bonde, Robert K.
    Fifty-four right whale mortalities have been reported from between Florida, USA and the Canadian Maritimes from 1970 to 2002. Thirty of those animals were examined: 18 adults and juveniles, and 12 calves. Morphometric data are presented such that prediction of body weight is possible if the age, or one or more measurements are known. Calves grew approximately linearly in their first year. Total length and fluke width increased asymptotically to a plateau with age, weight increased linearly with age, weight and snout to blowhole distance increased exponentially with total length, whereas total length was linearly related to fluke width and flipper length. Among the adults and juveniles examined in this study, human interaction appeared to be a major cause of mortality, where in 14/18 necropsies, trauma was a significant finding. In 10/14 of these, the cause of the trauma was presumed to be vessel collision. Entanglement in fishing gear accounted for the remaining four cases. Trauma was also present in 4/12 calves. In the majority of calf mortalities (8/12) the cause of death was not determined. Sharp ship trauma included propeller lacerations inducing multiple, deep lacerations that often incised vital organs including the brain, spinal cord, major airways, vessels and musculature. Blunt ship trauma resulted in major internal bruising and fractures often without any obvious external damage. In at least two cases fatal gear entanglements were extremely protracted: where the entanglements took at least 100 and 163 days respectively to be finally lethal. The sum of these findings show two major needs: (1) that extinction avoidance management strategies focused on reducing trauma to right whales from ship collisions and fishing gear entanglement are highly appropriate and need to be continued and; (2) that as mitigation measures continue to be introduced into shipping and fishing industry practices, there is a strong effort to maximise the diagnostic quality of post-mortem examination of right whale mortalities, to ensure an optimal understanding of resultant trends.
  • Article
    Decreasing body size is associated with reduced calving probability in critically endangered North Atlantic right whales
    (Royal Society of Chemistry, 2024-02-28) Pirotta, Enrico ; Tyack, Peter L. ; Durban, John W. ; Fearnbach, Holly ; Hamilton, Philip K. ; Harris, Catriona M. ; Knowlton, Amy R. ; Kraus, Scott D. ; Miller, Carolyn A. ; Moore, Michael J. ; Pettis, Heather M. ; Photopoulou, Theoni ; Rolland, Rosalind M. ; Schick, Robert S. ; Thomas, Len
    Body size is key to many life-history processes, including reproduction. Across species, climate change and other stressors have caused reductions in the body size to which animals can grow, called asymptotic size, with consequences for demography. A reduction in mean asymptotic length was documented for critically endangered North Atlantic right whales, in parallel with declines in health and vital rates resulting from human activities and environmental changes. Here, we tested whether smaller body size was associated with lower reproductive output, using a state-space model for individual health, survival and reproduction that quantifies the mechanistic links between these processes. Body size (as represented by the cube of length) was strongly associated with a female's calving probability at each reproductive opportunity. This relationship explained 62% of the variation in calving among reproductive females, along with their decreasing health (20%). The effects of decreasing mean body size on reproductive performance are another concerning indication of the worsening prospects for this species and many others affected by environmental change, requiring a focus of conservation and management interventions on improving conditions that affect reproduction as well as reducing mortality.
  • Article
    Assessing North Atlantic Right whale health: a review of threats, and development of tools critical for conservation of the species
    (Inter Research, 2021-02-25) Moore, Michael J. ; Rowles, Teresa K. ; Fauquier, Deborah A. ; Baker, Jason T. ; Biedron, Ingrid S. ; Durban, John W. ; Hamilton, Philip K. ; Henry, Allison G. ; Knowlton, Amy R. ; McLellan, William A. ; Miller, Carolyn A. ; Pace, Richard M., III ; Pettis, Heather M. ; Raverty, Stephen A. ; Rolland, Rosalind M. ; Schick, Robert S. ; Sharp, Sarah M. ; Smith, Cynthia R. ; Thomas, Len ; van der Hoop, Julie M. ; Ziccard, Michael H.
    Whaling decimated North Atlantic right whales (Eubalaena glacialis - NARW) since the 11th century and southern right whales (E. australis - SRW) since the 19th century. Today, NARWs are critically endangered and decreasing, whereas SRWs are recovering. We review NARW health assessment literature, NARW Consortium databases, and efforts and limitations to monitor individual and species health, survival, and fecundity. Photographs are used to track individual movement and external signs of health such as evidence of vessel and entanglement trauma. Post mortem examinations establish cause of death and determine organ pathology. Photogrammetry is used to assess growth rates and body condition. Samples of blow, skin, blubber, baleen and feces quantify hormones that provide information on stress, reproduction, and nutrition, identify microbiome changes, and assess evidence of infection. We also discuss models of the population consequences of multiple stressors, including the connection between human activities (e.g., entanglement) and health. Lethal and sublethal vessel and entanglement trauma have been identified as major threats to the species. There is a clear and immediate need for expanding trauma reduction measures. Beyond these major concerns, further study is needed to evaluate the impact of other stressors, such as pathogens, microbiome changes, and algal and industrial toxins, on NARW reproductive success and health. Current and new health assessment tools should be developed and used to monitor the effectiveness of management measures, and will help determine whether they are sufficient for a substantive species recovery.