Extended Movements of Common Bottlenose Dolphins (Tursiops truncatus) Along the Northern Gulf of Mexico's Central Coast

Balmer, Brian C.; Sinclair, Carrie; Speakman, Todd; Quigley, Brian M.; Barry, Kevin P.; Cush, Carolyn; Hendon, Michael; Mullin, Keith D.; Ronje, Errol I.; Rosel, Patricia E.; Schwacke, Lori H.; Wells, Randall S.; Zolman, Eric S.

doi:10.18785/goms.3301.08

Cited by 15 publications

(19 citation statements)

References 13 publications

(15 reference statements)

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“…The large UDs of Coastal dolphins (936 ± 426 km 2 ; mean ± SD ; Table ) create a logistical challenge for a comprehensive assessment of the SC‐GA Coastal Stock's ranging pattern. In addition to health assessment/satellite tagging locations targeting coastal waters, photo‐ID comparisons between projects/field sites (e.g., Balmer et al, , Urian, ) and survey effort including both coastal and BSE waters (e.g., Laska, Speakman, & Fair, , Silva, ) can provide data essential in determining ranging patterns, site fidelity, and stock discreteness of the SC‐GA Coastal Stock.…”

Section: Discussionmentioning

confidence: 99%

“…However, historical photo-ID effort was primarily in BSE waters. The 2015 health assessment was conducted in September when the Southern Migratory Coastal Stock was hypothesized to be farther north off North Carolina (Hayes et al, 2017;Silva, 2016;Urian, 2016 Balmer et al, 2016, Urian, 2016 and survey effort including both coastal and BSE waters (e.g., Laska, Speakman, & Fair, 2011, Silva, 2016 can provide data essential in determining ranging patterns, site fidelity, and stock discreteness of the SC-GA Coastal Stock.…”

Section: Stock Structurementioning

confidence: 99%

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Ranging patterns, spatial overlap, and association with dolphin morbillivirus exposure in common bottlenose dolphins (Tursiops truncatus) along the Georgia, USA coast

Balmer

Zolman

Rowles

et al. 2018

Ecology and Evolution

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During 2013–2015, an outbreak of dolphin morbillivirus (DMV) occurred in the western North Atlantic, which resulted in the stranding of over 1,600 common bottlenose dolphins (Tursiops truncatus). There are currently five coastal and 10 bay, sound, and estuary dolphin stocks along the U.S. Atlantic coast, yet there is very limited understanding of which stocks were exposed to DMV during the recent outbreak, or how DMV was transmitted across stocks. In order to address these questions, information is needed on spatial overlap and stock interactions. The goals of this project were to determine ranging patterns, prevalence of DMV, and spatial overlap of the South Carolina‐Georgia (SC‐GA) Coastal Stock, and adjacent Southern Georgia Estuarine System (SGES) Stock. During September 2015, a health assessment and telemetry study was conducted in which 19 dolphins were captured, tested for antibodies to DMV, and satellite tagged. Dolphins were classified into one of three ranging patterns (Coastal, Sound, or Estuary) based upon telemetry data. Coastal dolphins (likely members of the SC‐GA Coastal Stock) had a significantly higher prevalence of positive DMV antibody titers (0.67; N = 2/3), than Sound and Estuary dolphins (likely members of the SGES Stock) (0.13; N = 2/16). These results suggest that the SC‐GA Coastal Stock may have experienced greater exposure to DMV as compared to the SGES Stock. However, due to the small size of the SGES Stock and its exposure to high levels of persistent contaminants, this stock may be particularly vulnerable to DMV infection in the future.

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Section: Discussionmentioning

confidence: 99%

Section: Stock Structurementioning

confidence: 99%

Ranging patterns, spatial overlap, and association with dolphin morbillivirus exposure in common bottlenose dolphins (Tursiops truncatus) along the Georgia, USA coast

Balmer

Zolman

Rowles

et al. 2018

Ecology and Evolution

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“…Balmer et al [93] first suggested the movement of three individual dolphins (including two in this study) found to travel between Destin, FL and MSS as potentially identifying with the Gulf of Mexico Northern Coastal Stock of bottlenose dolphins, as defined by the NMFS for marine mammal management purposes [94]. Few photo-ID studies have surveyed the coastal waters delineated by the Gulf of Mexico Northern Coastal Stock boundaries, thus the low number of catfish decapitation events observed may be in-part representative of less survey effort in those waters.…”

Section: Discussionmentioning

confidence: 99%

A common bottlenose dolphin (Tursiops truncatus) prey handling technique for marine catfish (Ariidae) in the northern Gulf of Mexico

et al. 2017

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Few accounts describe predator-prey interactions between common bottlenose dolphins (Tursiops truncatus Montagu 1821) and marine catfish (Ariopsis felis Linnaeus 1766, Bagre marinus Mitchill 1815). Over the course of 50,167 sightings of bottlenose dolphin groups in Mississippi Sound and along the Florida coast of the Gulf of Mexico, severed catfish heads were found floating and exhibiting movements at the surface in close proximity to 13 dolphin groups that demonstrated feeding behavior. These observations prompted a multi-disciplinary approach to study the predator-prey relationship between bottlenose dolphins and marine catfish. A review was conducted of bottlenose dolphin visual survey data and dorsal fin photographs from sightings where severed catfish heads were observed. Recovered severed catfish heads were preserved and studied, whole marine catfish were collected and examined, and stranding network pathology reports were reviewed for references to injuries related to fish spines. Photographic identification analysis confirms eight dolphins associated with severed catfish heads were present in three such sightings across an approximately 350 km expanse of coast between the Mississippi Sound and Saint Joseph Bay, FL. An examination of the severed catfish heads indicated interaction with dolphins, and fresh-caught whole hardhead catfish (A. felis) were examined to estimate the presumed total length of the catfish before decapitation. Thirty-eight instances of significant trauma or death in dolphins attributed to ingesting whole marine catfish were documented in stranding records collected from the southeastern United States of America. Bottlenose dolphins typically adhere to a ram-feeding strategy for prey capture followed by whole prey ingestion; however, marine catfish skull morphology may pose a consumption hazard due to rigid spines that can puncture and migrate through soft tissue, prompting a prey handling technique for certain dolphins, facilitating consumption of the posterior portion of the fish without the head.

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“…Seasonal fluctuations in abundance of dolphins in BSE along the GoM coast have been attributed to dolphins from coastal stocks periodically venturing into BSE waters (e.g. Hubard et al 2004, Balmer et al 2008, Conn et al 2011, and the tagged dolphins from St. Joe Bay apparently support that hypothesis (Balmer et al 2016). From photo-ID studies in Choctawhatchee and Pensacola Bays (easternmost bays within the area most affected by the DWH oil spill), 650 individual dolphins were identified; 88% were considered resident, and the remainder were considered transients on the basis of resightings (Shippee 2014).…”

mentioning

confidence: 95%

“…Of 10 bottlenose dolphins radio-tagged in Matagorda Bay, Texas, 7 exhibited confined movements near the tagging site, while 3 (tag life 21−59 d) ranged into adjacent bays, with 1 animal spending about half its time outside Matagorda Bay (Lynn & Würsig 2002). Of 23 bottlenose dolphins radio-tagged near St. Joe Bay, Florida, 19 remained fully or predominantly in the focal survey region (Balmer et al 2008), while 1 dolphin travelled about 100 km to Destin, Florida, and 2 were sighted in Mississippi Sound, more than 300 km from St. Joe Bay (Balmer et al 2016). It was sub sequent ly proposed that the latter 3 dolphins be longed to the coastal stock, despite having been tagged or photoidentified in an estuary.…”

mentioning

confidence: 99%

Assigning stranded bottlenose dolphins to source stocks using stable isotope ratios following the Deepwater Horizon oil spill

Hohn¹,

Thomas²,

Carmichael³

et al. 2017

Endang. Species. Res.

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The potential for stranded dolphins to serve as a tool for monitoring free-ranging populations would be enhanced if their stocks of origin were known. We used stable isotopes of carbon, nitrogen, and sulfur from skin to assign stranded bottlenose dolphins Tursiops truncatus to different habitats, as a proxy for stocks (demographically independent populations), following the Deepwater Horizon oil spill. Model results from biopsy samples collected from dolphins from known habitats (n = 205) resulted in an 80.5% probability of correct assignment. These results were applied to data from stranded dolphins (n = 217), resulting in predicted assignment probabilities of 0.473, 0.172, and 0.355 to Estuarine, Barrier Island (BI), and Coastal stocks, respectively. Differences were found west and east of the Mississippi River, with more Coastal dolphins stranding in western Louisiana and more Estuarine dolphins stranding in Mississippi. Within the Estuarine East Stock, 2 groups were identified, one predominantly associated with Mississippi and Alabama estuaries and another with western Florida. δ 15 N values were higher in stranded samples for both Estuarine and BI stocks, potentially indicating nutritional stress. High probabilities of correct assignment of the biopsy samples indicate predictable variation in stable isotopes and fidelity to habitat. The power of δ 34 S to discriminate habitats relative to salinity was essential. Stable isotopes may provide guidance regarding where additional testing is warranted to confirm demographic independence and aid in determining the source habitat of stranded dolphins, thus increasing the value of biological data collected from stranded individuals.

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Extended Movements of Common Bottlenose Dolphins (Tursiops truncatus) Along the Northern Gulf of Mexico's Central Coast

Cited by 15 publications

References 13 publications

Ranging patterns, spatial overlap, and association with dolphin morbillivirus exposure in common bottlenose dolphins (Tursiops truncatus) along the Georgia, USA coast

Ranging patterns, spatial overlap, and association with dolphin morbillivirus exposure in common bottlenose dolphins (Tursiops truncatus) along the Georgia, USA coast

A common bottlenose dolphin (Tursiops truncatus) prey handling technique for marine catfish (Ariidae) in the northern Gulf of Mexico

Assigning stranded bottlenose dolphins to source stocks using stable isotope ratios following the Deepwater Horizon oil spill

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