Preliminary Evaluation of Potential Impacts Associated with Small Cetacean Remote Biopsy Sampling by Controlled Testing on Stranded Common Bottlenose Dolphins (<i>Tursiops truncatus</i>)

To explore the potential macroscopic tissue effects of select remote biopsy tools to common bottlenose dolphins (Tursiops truncatus), carcasses were darted and their traumatic effects on the anatomy in target and non-target areas of the body were described. In total, 87 samples were collected (target area, n = 19; non-target area, n = 68) within standardized grid partitions from five carcasses of sub-adult to adult age classes with a range of body condition scores. We broadly classified impacts penetrating completely through the blubber into muscle or deeper internal tissues as over-penetrations (n = 51/87, 59%). For samples collected in the defined target area, there was a low number of over-penetrations (n = 5/51; 10%). However, for samples collected in the defined, non-target areas, a much higher number of over-penetrations occurred (n = 45/51 88%). A visual examination of some samples indicated that sample length and appearance may not be reliable guides to assess the penetration depth of the wounds. These preliminary results suggest samples collected in non-targeted areas could pose much higher risk to the individual. We encourage other researchers considering the use of remote biopsy tools to conduct similar assessments prior to field sampling to better understand the potential consequences of misplaced samples with a view towards continually improving remote biopsy tools and techniques for the benefit of cetacean welfare

Preliminary Evaluation of Potential Impacts Associated with Small Cetacean Remote Biopsy Sampling by Controlled Testing on Stranded Common Bottlenose Dolphins (Tursiops truncatus)

To explore the potential macroscopic tissue effects of select remote biopsy tools to common bottlenose dolphins (Tursiops truncatus), carcasses were darted and their traumatic effects on the anatomy in target and non-target areas of the body were described. In total, 87 samples were collected (target area, n = 19; non-target area, n = 68) within standardized grid partitions from five carcasses of sub-adult to adult age classes with a range of body condition scores. We broadly classified impacts penetrating completely through the blubber into muscle or deeper internal tissues as over-penetrations (n = 51/87, 59%). For samples collected in the defined target area, there was a low number of over-penetrations (n = 5/51; 10%). However, for samples collected in the defined, non-target areas, a much higher number of over-penetrations occurred (n = 45/51 88%). A visual examination of some samples indicated that sample length and appearance may not be reliable guides to assess the penetration depth of the wounds. These preliminary results suggest samples collected in non-targeted areas could pose much higher risk to the individual. We encourage other researchers considering the use of remote biopsy tools to conduct similar assessments prior to field sampling to better understand the potential consequences of misplaced samples with a view towards continually improving remote biopsy tools and techniques for the benefit of cetacean welfare

A Common Bottlenose Dolphin (Tursiops Truncatus) Prey Handling Technique For Marine Catfish (Ariidae) In The Northern Gulf Of Mexico

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

Injurious catfish spines found during the necropsy of a single bottlenose dolphin (176 cm male, SEUS ID No. SER13-1180, MMPL1312).

<p>Injurious catfish spines found during the necropsy of a single bottlenose dolphin (176 cm male, SEUS ID No. SER13-1180, MMPL1312).</p

Dorsal fin matches for bottlenose dolphin sightings associated with severed catfish heads.

<p>X = dorsal fin match.</p

Bottlenose dolphin sightings (n = 13) associated with catfish decapitation in the nGoMx.

<p>MSS = Mississippi Sound, PCB = Pensacola Bay coast, SJB = Saint Joseph Bay, SAR = Sarasota Bay and west Florida coast.</p

Bottlenose dolphin interacts with a hardhead catfish (<i>Ariopsis felis</i>) near Palma Sola Bay, FL (SAR).

<p>The dorsal and pectoral spines of the fish appear locked in their defensive positions.</p

Severed catfish head (<i>B</i>.<i>marinus</i>) found near dolphins demonstrating foraging behavior near Palma Sola Bay, FL (SAR).

<p>Severed catfish head (<i>B</i>.<i>marinus</i>) found near dolphins demonstrating foraging behavior near Palma Sola Bay, FL (SAR).</p

Severed catfish head from the 7 May 2015 sighting (MSS).

<p>Linear epidermal tears at right are typical of dolphin rake marks and are near the point of amputation in each SCH.</p