Entity

Time filter

Source Type

New Bedford, MA, United States

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. Source


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. Source


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. Source


News Article | June 17, 2016
Site: http://www.techtimes.com/rss/sections/earth.xml

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.

Discover hidden collaborations