Evidence for Infanticide in Bottlenose Dolphins of the Western North Atlantic

Nine bottlenose dolphin (Tursiops truncatus) calves that stranded in Virginia in 1996 and 1997 died of severe blunt-force trauma. Injuries were concentrated on the head and chest and multiple rib fractures, lung lacerations, and soft tissue contusions were prominent. Skeletal and/or soft tissue trauma occurred bilaterally in all of the calves. One had a bite wound across the left mandible that exhibited deep punctures consistent with the tooth placement in an adult bottlenose dolphin. The lesions were not compatible with predation, boat strike, fisheries interactions, rough-surf injury, or blast injury. However, they were similar to traumatic injuries described in stranded bottlenose dolphin calves and harbor porpoises (Phocoena phocoena) in Great Britain attributed to violent dolphin interactions. The evidence suggests that violent dolphin behavior was the cause of the trauma in the nine calves reported here and that infanticide occurs in bottlenose dolphins of the western North Atlantic

Likely locations of sea turtle stranding mortality using experimentally-calibrated, time and space-specific drift models

This is an accepted manuscript of the published article. Sea turtle stranding events provide an opportunity to study drivers of mortality, but causes of strandings are poorly understood. A general turtle carcass oceanographic drift model was developed to estimate likely mortality locations from coastal sea turtle stranding records. Key model advancements include realistic direct wind forcing on carcasses, temperature driven carcass decomposition and the development of mortality location predictions for individual strandings. We applied this model to 2009-2014 stranding events within the Chesapeake Bay, Virginia. Predicted origin of vessel strike strandings were compared to commercial vessel data, and potential hazardous turtle-vessel interactions were identified in the southeastern Bay and James River. Commercial fishing activity of gear types with known sea turtle interactions were compared to predicted mortality locations for stranded turtles with suggested fisheries-induced mortality. Probable mortality locations for these strandings varied seasonally, with two distinct areas in the southwest and southeast portions of the lower Bay. Spatial overlap was noted between potential mortality locations and gillnet, seine, pot, and pound net fisheries, providing important information for focusing future research on mitigating conflict between sea turtles and human activities. Our ability to quantitatively assess spatial and temporal overlap between sea turtle mortality and human uses of the habitat were hindered by the low resolution of human use datasets, especially those for recreational vessel and commercial fishing gear distributions. This study highlights the importance of addressing these data gaps and provides a meaningful conservation tool that can be applied to stranding data of sea turtles and other marine megafauna worldwide

Consequences of drift and carcass decomposition for estimating sea turtle mortality hotspots

Sea turtle strandings provide important mortality information, yet knowledge of turtle carcass at-sea drift and decomposition characteristics are needed to better understand and manage where these mortalities occur. We used empirical sea turtle carcass decomposition and drift experiments in the Chesapeake Bay, Virginia, USA to estimate probable carcass oceanic drift times and quantify the impact of direct wind forcing on carcass drift. Based on the time period during which free-floating turtle carcasses tethered nearshore were buoyant, we determined that oceanic drift duration of turtle carcasses was highly dependent on water temperature and varied from 2 to 15 days during typical late spring to early fall Bay water conditions. The importance of direct wind forcing for turtle carcass drift was assessed based on track divergence rates from multiple simultaneous deployments of three types of surface drifters: bucket drifters, artificial turtles and turtle carcass drifters. Turtle drift along-wind leeway was found to vary from 1 to 4% of wind speed, representing an added drift velocity of approximately 0.03–0.1 m/s for typical Bay wind conditions. This is comparable to current speeds in the Bay (0.1–0.2 m/s), suggesting wind is important for carcass drift. Estimated carcass drift parameters were integrated into a Chesapeake Bay oceanographic drift model to predict carcass drift to terrestrial stranding locations. Increased drift duration (e.g., due to low temperatures) increases mean distance between expected mortality events and stranding locations, as well as decreases overall likelihood of retention in the Bay. Probable mortality hotspots for the peak month of strandings (June) were identified off coastal southeastern Virginia and within the lower Bay, including the Bay mouth and lower James River. Overall, results support that sea turtle drift time is quite variable, and varies greatly depending on water and air temperature as well as oceanic conditions. Knowledge of these parameters will improve our ability to interpret stranding events around the globe

Rebuttal to published article “A review of ghost gear entanglement amongst marine mammals, reptiles and elasmobranchs” by M. Stelfox, J. Hudgins, and M. Sweet

Author Posting. © The Author(s), 2016. This is the author's version of the work. It is posted here under a nonexclusive, irrevocable, paid-up, worldwide license granted to WHOI. It is made available for personal use, not for redistribution. The definitive version was published in Marine Pollution Bulletin 117 (2017): 554-555, doi:10.1016/j.marpolbul.2016.11.052.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

Don’t assume it’s ghost gear : accurate gear characterization is critical for entanglement mitigation [poster]

Presented at the Society for Marine Mammology 22nd Biennial Marine Mammal Conference, Halifax, Nova Scotia, October 23-27, 2017Entanglement 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.2017-10-2

Loggerhead turtle Caretta caretta density and abundance in Chesapeake Bay and the temperate ocean waters of the southern portion of the Mid-Atlantic Bight

Funding was provided by the NOAA Species Recovery Grants to States program (Award #NA 47200033) issued to the Virginia Department of Game and Inland Fisheries which contracted with the Virginia Aquarium & Marine Science Center Foundation. Additional funding for tags and turtle capture was also provided by US Fleet Forces Command as well as the Virginia Aquarium Batten Collaborative Research Fund and Batten Professional Development Fund.We conducted aerial surveys of sea turtles in 2011 and 2012, incorporating corrections for perception and availability bias in Chesapeake Bay and near-shore continental shelf waters of the Mid-Atlantic Bight off the US states of Virginia and Maryland. Results of these surveys and ancillary research to determine surface times for loggerhead turtles provide us with a new baseline population estimate for turtles in the region. Prior surveys were conducted in Chesapeake Bay in the mid-1980s and early 2000s, and in ocean waters in the late 1970s and early 1980s. Although comparison of density estimates not corrected for availability between prior surveys and this effort suggests that the population of sea turtles, especially loggerhead turtles, is higher than previous estimates, differences between surveys may be the result of survey methodologies and cannot be assumed to be true changes in density. Surface time for availability corrections was calculated using dive summaries from satellite telemetry on 27 loggerhead turtles tracked between 2011 and 2015. We calculated stratified seasonal availability corrections for bay and ocean waters based on assumed differences in turtle behavior and water clarity between the 2 habitats. For each habitat, we provided seasonal corrections for 3 detection depth bins (shallow, moderate, and deep) to account for differences in sub-surface detection ranges. Differences and trends toward differences among availability corrections underscore the need to better understand the many variables that affect surface time for sea turtles in temperate waters, and the effect that availability has on abundance and density estimates.Publisher PDFPeer reviewe

Strandings as indicators of marine mammal biodiversity and human interactions off the coast of North Carolina

The adjacency of 2 marine biogeographic regions off Cape Hatteras, North Carolina (NC), and the proximity of the Gulf Stream result in a high biodiversity of species from northern and southern provinces and from coastal and pelagic habitats. We examined spatiotemporal patterns of marine mammal strandings and evidence of human interaction for these strandings along NC shorelines and evaluated whether the spatiotemporal patterns and species diversity of the stranded animals reflected published records of populations in NC waters. During the period of 1997–2008, 1847 stranded animals were documented from 1777 reported events. These animals represented 9 families and 34 species that ranged from tropical delphinids to pagophilic seals. This biodiversity is higher than levels observed in other regions. Most strandings were of coastal bottlenose dolphins (Tursiops truncatus) (56%), harbor porpoises (Phocoena phocoena) (14%), and harbor seals (Phoca vitulina) (4%). Overall, strandings of northern species peaked in spring. Bottlenose dolphin strandings peaked in spring and fall. Almost half of the strandings, including southern delphinids, occurred north of Cape Hatteras, on only 30% of NC’s coastline. Most stranded animals that were positive for human interaction showed evidence of having been entangled in fishing gear, particularly bottlenose dolphins, harbor porpoises, short-finned pilot whales (Globicephala macrorhynchus), harbor seals, and humpback whales (Megaptera novaeangliae). Spatiotemporal patterns of bottlenose dolphin strandings were similar to ocean gillnet fishing effort. Biodiversity of the animals stranded on the beaches reflected biodiversity in the waters off NC, albeit not always proportional to the relative abundance of species (e.g., Kogia species). Changes in the spatiotemporal patterns of strandings can serve as indicators of underlying changes due to anthropogenic or naturally occurring events in the source populations

Fin whale (Balaenoptera physalus) mitogenomics: A cautionary tale of defining sub-species from mitochondrial sequence monophyly

The advent of massive parallel sequencing technologies has resulted in an increase of studies based upon complete mitochondrial genome DNA sequences that revisit the taxonomic status within and among species. Spatially distinct monophyly in such mitogenomic genealogies, i.e., the sharing of a recent common ancestor among con-specific samples collected in the same region has been viewed as evidence for subspecies. Several recent studies in cetaceans have employed this criterion to suggest subsequent intraspecific taxonomic revisions. We reason that employing intra-specific, spatially distinct monophyly at non-recombining, clonally inherited genomes is an unsatisfactory criterion for defining subspecies based upon theoretical (genetic drift) and practical (sampling effort) arguments. This point was illustrated by a re-analysis of a global mitogenomic assessment of fin whales, Balaenoptera physalus spp., published by Archer et al. (2013), which proposed to further subdivide the Northern Hemisphere fin whale subspecies, B. p. physalus. The proposed revision was based upon the detection of spatially distinct monophyly among North Atlantic and North Pacific fin whales in a genealogy based upon complete mitochondrial genome DNA sequences. The extended analysis conducted in this study (1676 mitochondrial control region, 162 complete mitochondrial genome DNA sequences and 20 microsatellite loci genotyped in 380 samples) revealed that the apparent monophyly among North Atlantic fin whales reported by Archer et al. (2013) to be due to low sample sizes. In conclusion, defining sub-species from monophyly (i.e., the absence of para- or polyphyly) can lead to erroneous conclusions due to relatively 'trivial' aspects, such as sampling. Basic population genetic processes (i.e., genetic drift and migration) also affect the time to the most recent common ancestor and hence the probability that individuals in a sample are monophyletic

Fin whale (Balaenoptera physalus) mitogenomics: A cautionary tale of defining sub-species from mitochondrial sequence monophyly

© The Authors, 2019. This article is distributed under the terms of the Creative Commons Attribution-Noncommercial-Share Alike 4.0 International License. The definitive version was published in Molecular Phylogenetics and Evolution (2019), doi:10.1016/j.ympev.2019.02.003.The advent of massive parallel sequencing technologies has resulted in an increase of studies based upon complete mitochondrial genome DNA sequences that revisit the taxonomic status within and among species. Spatially distinct monophyly in such mitogenomic genealogies, i.e., the sharing of a recent common ancestor among con-specific samples collected in the same region has been viewed as evidence for subspecies. Several recent studies in cetaceans have employed this criterion to suggest subsequent intraspecific taxonomic revisions. We reason that employing intra-specific, spatially distinct monophyly at non-recombining, clonally inherited genomes is an unsatisfactory criterion for defining subspecies based upon theoretical (genetic drift) and practical (sampling effort) arguments. This point was illustrated by a re-analysis of a global mitogenomic assessment of fin whales, Balaenoptera physalus spp., published by Archer et al. (2013), which proposed to further subdivide the Northern Hemisphere fin whale subspecies, B. p. physalus. The proposed revision was based upon the detection of spatially distinct monophyly among North Atlantic and North Pacific fin whales in a genealogy based upon complete mitochondrial genome DNA sequences. The extended analysis conducted in this study (1,676 mitochondrial control region, 162 complete mitochondrial genome DNA sequences and 20 microsatellite loci genotyped in 358 samples) revealed that the apparent monophyly among North Atlantic fin whales reported by Archer et al. (2013) to be due to low sample sizes. In conclusion, defining sub-species from monophyly (i.e., the absence of para- or polyphyly) can lead to erroneous conclusions due to relatively “trivial” aspects, such as sampling. Basic population genetic processes (i.e., genetic drift and migration) also affect the time to the most recent common ancestor and hence the probability that individuals in a sample are monophyletic.We are grateful to Hanne Jørgensen, Anna Sellas, Mary Beth Rew and Christina Færch-Jensen for technical assistance. We thank Drs. P. E. Rosel and K. D. Mullin (U.S. National Marine Fisheries Service Southeast Fisheries Science Center) and members of the U.S. Northeast and Southeast Region Marine Mammal Stranding Network and its response teams, including the International Fund for Animal Welfare, the Marine Mammal Stranding Center, Mystic Aquarium, the Riverhead Foundation for Marine Research and Preservation (K. Durham) and the Marine Mammal Stranding Program of the University of North Carolina Wilmington for access to fin whale samples from the western North Atlantic. We thank Gisli Vikingsson for providing samples. We are indebted to Dr. Eduardo Secchi for facilitating data sharing. Data collection in the Southern Ocean was conducted under research projects Baleias (CNPq grants 557064/2009-0 and 408096/2013-6), INTERBIOTA (CNPq 407889/2013-2) and INCT-APA (CNPq 574018/2008-5), of the Brazilian Antarctic Program and a contribution by the research consortium ‘Ecology and Conservation of Marine Megafauna – EcoMega-CNPq’. MAS was supported through a FCT Investigator contract funded by POPH, QREN European Social Fund, and Portuguese Ministry for Science and Education. Data collection in the Azores was funded by TRACE-PTDC/MAR/74071/2006 and MAPCET-M2.1.2/F/012/2011 [FEDER, COMPETE, QREN European Social Fund, and Proconvergencia Açores/EU Program]. Fin whale illustration herein is used with the permission of Frédérique Lucas. We acknowledge the Center for Information Technology of the University of Groningen for IT support and access to the Peregrine high performance-computing cluster