Spatial ecology of Carcharias taurus in the northwestern Mid-Atlantic coastal ocean

De Haulsee,Lm Brown,Bm Wetherbee,Mw Breece,Da Fox,Mj Oliver

doi:10.3354/meps12592

Abstract

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 597:191-206 (2018) - DOI: https://doi.org/10.3354/meps12592 Spatial ecology of Carcharias taurus in the northwestern Mid-Atlantic coastal ocean D. E. Haulsee1,*, M. W. Breece1, L. M. Brown2, B. M. Wetherbee3, D. A. Fox2, M. J. Oliver1 1College of Earth, Ocean and the Environment, University of Delaware, Lewes, DE 19958, USA 2Department of Agriculture and Natural Resources, Delaware State University, Dover, DE 19901, USA 3Department of Biological Sciences, University of Rhode Island, Kingston, RI 02811, USA *Corresponding author: dhaulsee@udel.edu ABSTRACT: The sand tiger shark Carcharias taurus is a highly migratory coastal species with declining populations worldwide. This species exhibits many behaviors that make coastal sharks difficult to manage, including aggregatory behavior, sexual segregation, and large-scale migrations through shallow coastal waters with many opportunities for human interactions. Sand tigers from the Western North Atlantic subpopulation are known to seasonally inhabit Delaware Bay and surrounding coastal waters. This region has been recommended as a habitat area of particular concern for the Western North Atlantic sand tiger population, and increased understanding of their movements and habitat requirements will facilitate management efforts. We developed models to predict sand tiger occupancy using spatially dynamic environmental predictors. Our models predicted sand tiger (juveniles, adult males, adult females, and all sharks combined) occurrences in 2 study regions, the Delaware Bay and the western Mid-Atlantic coastal ocean. Sea surface temperature, day of year, water depth, and remote sensing reflectance at 555 nm were the most important environmental predictors of occurrence, and correctly predicted 80-89% of sand tiger acoustic telemetry records in the 2 study regions. Our models predicted differences in the timing and location of occurrences among juveniles and adults, as well as areas where these life history stages overlap in the Mid-Atlantic coastal ocean. Our hope is that a daily forecast of sand tiger occurrence from our modeling efforts could be useful for conservation and management efforts in this important region, as well as for studying the spatial and behavioral ecology of this important top predator. KEY WORDS: Acoustic telemetry · Generalized additive mixed model · Predictive habitat modeling · Species distribution · Sand tiger shark · Carcharias taurus Full text in pdf format Supplementary material PreviousNextCite this article as: Haulsee DE, Breece MW, Brown LM, Wetherbee BM, Fox DA, Oliver MJ (2018) Spatial ecology of Carcharias taurus in the northwestern Mid-Atlantic coastal ocean. Mar Ecol Prog Ser 597:191-206. https://doi.org/10.3354/meps12592 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 597. Online publication date: June 11, 2018 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2018 Inter-Research.

Highlights

The removal of sharks from the ocean negatively affects the health of the ecosystems, as these top predators serve an important role in structuring the food web through consumptive and non-consumptive effects (Stevens et al 2000, Myers & Worm 2003, Burkholder et al 2013, Bornatowski et al 2014)
Adult sharks seem to be reacting to water temperature, moving north into the Mid-Atlantic coastal ocean only when surface waters warm to approximately 18°C
We observed a similar pattern in the rapid emigration of juveniles and adults from the Delaware Bay and coastal ocean, represented by the steep slope of the density plots of sand tiger presence (Fig. 2)

Summary

Introduction

The removal of sharks from the ocean negatively affects the health of the ecosystems, as these top predators serve an important role in structuring the food web through consumptive and non-consumptive effects (Stevens et al 2000, Myers & Worm 2003, Burkholder et al 2013, Bornatowski et al 2014) For these reasons, there is much concern about declining shark populations worldwide, and managers are making efforts to enact meaningful conservation and management strategies to reverse these trends (Topelko & Dearden 2005, Kinney & Simpfendorfer 2009). Passive acoustic telemetry is commonly used to monitor the movements and migrations of marine animals (Heupel et al 2006, Donaldson et al 2014, Hussey et al 2015) This technique allows researchers to monitor numerous individuals of species large enough to carry a transmitter into the detection range of moored acoustic receiving arrays (Jackson 2011, Kneebone et al 2012, Haulsee et al 2015). Even though remotely sensed temperature and color are measured on the surface of the ocean, a growing number of studies have documented their value in predicting marine species distributions (Adams et al 2016, Breece et al 2016, Hazen et al 2017)

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Results

Conclusion