Concord, MA, United States
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Packard G.E.,Woods Hole Oceanographic Institution | Kukulya A.,Woods Hole Oceanographic Institution | Austin T.,Woods Hole Oceanographic Institution | Dennett M.,Woods Hole Oceanographic Institution | And 5 more authors.
OCEANS 2013 MTS/IEEE - San Diego: An Ocean in Common | Year: 2013

We present results from field experiments in which a REMUS-100 autonomous underwater vehicle (AUV) tracked multiple tagged sharks in the open ocean over periods of several hours. The Oceanographic Systems Laboratory (OSL) developed an algorithm that allows the vehicle to use information from an active transponder to provide a three dimensional track of the animal with high spatial and high temporal resolution. Field studies were conducted in the spring and summer of 2012. Two basking sharks and four white sharks were tagged and tracked for 1-3 hours. Here we present the engineering developments required to create the system. © 2013 MTS.


Kukulya A.L.,Woods Hole Oceanographic Institution | Stokey R.,Woods Hole Oceanographic Institution | Littlefield R.,Woods Hole Oceanographic Institution | Jaffre F.,Woods Hole Oceanographic Institution | And 2 more authors.
MTS/IEEE OCEANS 2015 - Genova: Discovering Sustainable Ocean Energy for a New World | Year: 2015

Little is known about deep-water predatory attacks and behavior of white sharks (Carcharodon carcharias). Revealing how ocean predators operate and forage within their environment is fundamental to the protection of the species and their ecosystem. It is very difficult to quantify habitat use and behavior of large marine animals that may range widely and are not easy to observe directly, such as sharks. Studies of shark foraging ecology and feeding behavior are extremely difficult as predation events are rarely witnessed. Also, these studies often cannot identify the habitat in which a shark feeds, making definition of critical habitats difficult [1]. Currently, satellite and acoustic tags are used to follow the migration of white sharks, however this method limits information acquisition about detailed behaviors therefore leaving gaps in scientists understanding of dynamic movement of marine animals. Recent developments in fine-scale spatial 3D tracking and imaging of large sharks with an Autonomous Underwater Vehicle (AUV) have given scientists a never before seen view into hunting and foraging behaviors of these animals in the wild [2]. While tracking pelagic predators is no longer a novel idea, improved imaging sensors and navigation capabilities continue to evolve thus making observations of behaviors in deep water even more possible. Significant improvements have been made in hardware and software capabilities from lessons learned while tracking basking sharks and white sharks in Cape Cod in 2012 using a specially modified Remote Environmental Monitoring UnitS REMUS AUV known as SharkCam developed in the Oceanographic Systems Lab (OSL) at the Woods Hole Oceanographic Institution (WHOI. The capabilities and field results from a second expedition taken place near Guadalupe Island, Mexico from November 2013 are presented in this paper. The REMUS SharkCam system consists of a 100-meter depth rated vehicle outfitted with a circular Ultra Short BaseLine (USBL) receiver array for omni-directional tracking of a tagged animal. The vehicle interrogates the tag, and the round trip travel time of the response is then used to determine the range to the animal. This response is then beam-formed to determine the bearing relative to the vehicle, and the vehicle's compass is used to transform this into an absolute bearing. From this, the location in earth coordinates (latitude/longitude) can be determined. A second response from the tag is time delayed proportional to depth. The time delta between the two responses is used to determine the depth of the animal. This combination allows precise location of the tagged animal in three-dimensional space never before possible from an underwater vehicle. In the 2012 field trials we conducted to track great white sharks off of Chatham, MA, it was found that maintaining a solid track on the shark proved to be challenging. There were two hypotheses as to why this was the case. First, when the shark towed the transponder, the orientation of the transponder changed from its normal upright orientation to horizontal, and the torroidal beam pattern of the bottom mounted transducer become vertical, not horizontal. The vehicle was in an acoustic dead zone. The second hypothesis was that when the shark moved quickly, the Doppler shift of the signal caused the beamformer signal match to fail. A significant improvement to real-time tracking was the development of a shipboard tracking system (STS) that enabled operators to track the tagged shark and the REMUS AUV separately, allowing for long term tracking of the animal if the AUV needed to be recovered due to battery depletion or mechanical faults. It also enabled operators to know how well the system was working in real time by providing depth, range and bearing back to the ship. © 2015 IEEE.


News Article | June 17, 2016
Site: www.techtimes.com

Marine conservationists in Massachusetts spotted a great white shark they had once tagged swimming in the waters of Cape Cod on Thursday morning, June 16. According to the Atlantic White Shark Conservancy, the visitor turned out to be "Scratchy," a 13-foot male great white that was fitted with an electronic tracker on to monitor its activity in August. However, he was first identified by the Massachusetts Marine Fisheries Department back in 2014. Conservationists gave the ocean predator the nickname because of the many scratches on his side, likely as a result of encounters with seals. While great white sharks are not known to frequent the waters of the Atlantic Ocean, the state marine fisheries division said several of the ocean predators have been seen swimming around Monomoy Island, which is located off the coast of Chatham, Cape Cod. The area is known for its large population of gray seals. Marine researchers have identified and tagged as many as 80 great white sharks off the coast of Cape Cod from 2009 to 2015. Because of Cape Cod's growing seal population, scientists believe the region could very well become a new hub for predatory great white sharks. Owen Nichols, a marine biologist who has studied seals for 15 years, said the marine mammals have experienced a population boom over the last few decades. Nichols explained that seals were virtually exterminated from Cape Cod waters right up until the 1960s. He said that what is happening right now is that the marine mammals are beginning to recolonize the region, which could bring a resurgence of seals. Before the implementation of the Marine Mammal Protection Act in 1972, seal sightings in the region were very rare. The marine mammals were often hunted by locals before they were declared protected by the federal government. However, the return of the seals in droves is also attracting many sharks to the area to look for food. Researchers say they have spotted 68 great white sharks around Cape Cod in 2014. This figure ballooned to 140 individual sharks in 2015. The hordes of seals are also a cause of concern for local fishermen as they have been consuming too many of available fish stock in the region. Earlier in the week, a team from the National Geographic Magazine, including wildlife photographer Brian Skerry, scoured the murky green waters of Cape Cod to capture images of the great whites in the area. The ocean predators are the subject of an upcoming article on the magazine, which is set to focus on the region as a potential gathering area for great whites. © 2016 Tech Times, All rights reserved. Do not reproduce without permission.


Legare B.,Texas Parks and Wildlife Department | Kneebone J.,Massachusetts Marine Fisheries | DeAngelis B.,The Nature Conservancy | Skomal G.,Massachusetts Marine Fisheries
Marine Biology | Year: 2015

Shark nursery areas are widely regarded as essential habitats for the growth and survival of young individuals. The effective management and protection of shark nursery habitat are contingent upon a clear understanding of how individual species utilize such habitat both spatially and temporally. Although shark nurseries have been identified in the Caribbean, this information is generally lacking. From 2006 to 2012, we used passive acoustic telemetry to monitor the presence, movements, and habitat use of 65 juvenile blacktip sharks (Carcharhinus limbatus) and 42 juvenile lemon sharks (Negaprion brevirostris) within Fish Bay and Coral Bay, two shark nurseries in St. John, United States Virgin Islands. Both species were present in each bay during all months of the year, but abundance peaked during the summer (June–September). Although telemetry data indicated that blacktip and lemon sharks moved throughout each embayment, each species exhibited strong site fidelity to core areas across all years of the study. Habitat partitioning was observed in both nurseries as blacktip sharks generally occurred in areas characterized by water depths of 1.5–6 m with seagrass and sand/mud substrate, while lemon sharks remained in close proximity to or within shallow (<1 m), mangrove-fringed seagrass habitat. Blacktip sharks were also observed to exhibit greater activity space during the nighttime hours (1900–0659 h) within Coral Bay. The results of this study indicate that Fish Bay and Coral Bay are nursery areas that warrant designation as essential fish habitat and exemplify the need for additional focused management measures. © 2015, Springer-Verlag Berlin Heidelberg.


Kneebone J.,University of Massachusetts Dartmouth | Chisholm J.,Massachusetts Marine Fisheries | Skomal G.B.,Massachusetts Marine Fisheries
Marine Ecology Progress Series | Year: 2012

The sand tiger shark Carcharias taurus is a large coastal species that has endured marked declines in its western North Atlantic population over the past 30 yr. In the face of these declines, identification of nursery areas for this species is of particular importance to ensure the implementation of protective measures that will maximize survival of young individuals to maturity. Passive acoustic telemetry was used to assess the emergence of Plymouth, Kingston, Duxbury (PKD) Bay, Massachusetts, USA, as a seasonal nursery for juvenile sand tigers that migrate north from southern parturition grounds. Seasonal residency, habitat use, and site fidelity of 73 acoustically tagged juvenile sand tigers (78 to 108 cm fork length) were monitored within PKD Bay during 4 seasonal periods from 2008 to 2011. Eight individuals were tracked in multiple years, with 2 individuals returning to PKD Bay in 3 consecutive years. Sand tigers remained in PKD Bay for periods of 1 to 124 d and displayed a high degree of site fidelity to 2 core habitats during each year of the study. Weekly activity space estimates were relatively constant throughout each yearly monitoring period, with a general increase prior to emigration of sharks from the embayment. Emigration of sharks from PKD Bay was significantly related to both day length and water temperature. Collectively, these results suggest that PKD Bay constitutes a seasonal nursery area for juvenile sand tigers and warrants the extension of juvenile sand tiger essential fish habitat north of Cape Cod, Massachusetts, USA. © Inter-Research 2012.


Kneebone J.,University of Massachusetts Dartmouth | Chisholm J.,Massachusetts Marine Fisheries | Bernal D.,University of Massachusetts Dartmouth | Skomal G.,Massachusetts Marine Fisheries
Fisheries Research | Year: 2013

Current shark fishery management regulations in the US Atlantic, as well as other regions worldwide, mandate the release of sand tigers (. Carcharias taurus) captured in recreational fisheries. To examine the efficacy of this strategy as a conservation tool, the physical and physiological effects of capture stress and post-release survivorship were examined in juvenile sand tigers angled on conventional rod and reel tackle with offset circle hooks. Analysis of blood samples obtained immediately after capture (. n=. 84) indicated that, relative to minimally stressed captive individuals, juvenile sand tiger blood biochemistry is disturbed after brief (<7. min) angling events. Serial blood sampling of five captive sharks subjected to a 3. min simulated rod and reel angling event revealed rapid and significant disruptions in blood biochemistry with physiological recovery within 12-24. h. Post-release monitoring of 65 sharks surgically implanted with acoustic tags demonstrated high degrees of immediate (99%), short- (82%), and long-term post-release survivorship (75%). Physiological disruptions did not appear to reduce immediate survivorship (5 days post capture), however, sharks hooked internally had lower rates of survival 50-100 days following release. Overall, these results suggest that juvenile sand tigers are able to cope with and survive the physiological stress associated with brief rod and reel capture, but physical trauma associated with hook location can impair post-release survival. Regardless, mandatory release appears to be a viable management strategy for juvenile sand tigers captured in rod and reel fisheries. © 2013 Elsevier B.V.


Kneebone J.,University of Massachusetts Dartmouth | Chisholm J.,Massachusetts Marine Fisheries | Skomal G.,Massachusetts Marine Fisheries
Marine Biology | Year: 2014

To date, movement patterns of juvenile sand tigers (Carcharias taurus) along the east coast of the USA have been loosely defined. Given the magnitude of the purported decline in the sand tiger population in the western North Atlantic (WNA), characterization of the species' movement patterns throughout this broad area is essential for the effective management and recovery of this population. Using passive acoustic telemetry, pop-up satellite archival transmitting tags, and conventional fishery-dependent tag/recapture data, seasonal movements of juvenile sand tigers (ages 0-2 years; <125 cm fork length) were monitored between Maine and Florida along the US east coast from 2007 to 2013. Collectively, tag data indicated that juvenile sand tigers undergo extensive seasonal coastal migrations moving between summer (June-October) habitat (Maine to Delaware Bay) and winter (December-April) habitat (Cape Hatteras to central Florida) during the spring (April-June) and fall/early winter (October-December). Juvenile sand tigers occurred in a wide range of temperatures (9.8-26.9 °C) throughout the year, but spent the majority of their time in water from 12 to 20 °C. Given the extensive movements and continuous utilization of relatively shallow (<80 m) nearshore waters exhibited by these relatively small individuals throughout their first years of life, it is imperative that precautions be taken to limit negative effects of anthropogenic interactions on this species (i.e., fisheries bycatch, coastal degradation) in an effort to rebuild and sustain the WNA population. © 2014 Springer-Verlag Berlin Heidelberg.

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