Seasonal residency, habitat use, and site fidelity of juvenile sand tiger sharks Carcharias taurus in a Massachusetts estuary

Abstract

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.

Habitat selection of a coastal shark species estimated from an autonomous underwater vehicle

“…Sand tigers were captured and acoustically tagged between 2007 and 2012 as part of projects carried out by Delaware State University, University of Rhode Island, University of Massachusetts and the Massachusetts Division of Marine Fisheries (Kneebone et al 2012); our study takes advantage of those ongoing tagging efforts. At the time of this study, there were 292 telemetered sand tigers in the western North Atlantic Ocean, from the projects mentioned above, serving as potential targets for detection by acoustic receivers.…”

“…pdf.) (tag details provided by: Atlantic Cooperative Telemetry [ACT] Network, Lori Brown pers comm, Kneebone et al 2012). All sand tigers were internally tagged unless otherwise noted.…”

“…Studies identifying mesoscale habitat use commonly use acoustic telemetry or visual sightings records to document species locations in the coastal ocean and estuaries (Heithaus et al 2006, Torres et al 2008, Huijbers et al 2012, Kneebone et al 2012. The coastal ocean presents additional challenges in habitat selection studies due to its physical dynamics.…”

“…Currents, tides, freshwater inputs, nutrient loading and patchy prey distribution create an environment that varies on scales much smaller than those in the open ocean (Epifanio & Garvine 2001). Within these mesoscale study regions, environmental conditions are measured using temperature loggers at fixed points (Kneebone et al 2012), bathymetry maps and sediment type (Heithaus et al 2006, Torres et al 2008, or point source measurements of temperature, salinity, turbidity, and dissolved oxygen recorded near sightings of animals (Torres et al 2008). In addition, auditory, olfactory and visual cues at smaller scales have been shown to affect juvenile reef fish habitat association in a laboratory setting (Huijbers et al 2012), and studies have shown that salmonids use chemical cues in the water for natal stream homing behavior (Scholz et al 1976, Dittman & Quinn 1996.…”

Movements of the reef manta ray (Manta alfredi) in the Red Sea using satellite and acoustic telemetry

“…These results highlight the importance of accurately delineating movements of individuals at scales relevant to species conservation. Advances in electronic tagging equipment provide a range of tracking technologies that enable assessment of the movement and habitat use of marine species ranging from hours (Carey et al 1990) to years (Block et al 2001) and across individual estuaries (Kneebone et al 2012) to ocean basins (Skomal et al 2009). …”