Diet Analysis of Stranded Bottlenose Dolphins (<i>Tursiops truncatus</i>) in Virginia

<p>This study describes the diet of bottlenose dolphins (<em>Tursiops truncatus</em>) stranded in Virginia via stomach content analysis and considers factors such as proportion of numerical abundance and reconstructed mass, frequency of occurrence, average reconstructed prey size, prey diversity and quantity, and otolith degradation code. Fish size was estimated via regression equations established from local fish collected during the study that derive wet weight directly from otolith length or width. Squid size is estimated from previously published equations. Soniferous fishes dominated the diet, especially Atlantic croaker, spot, and seatrout spp., adding evidence to the theory that bottlenose dolphins passively listen for their prey. Noise pollution should be an important consideration for the conservation of this species. The diet was influenced by ontogenetic and seasonal changes. Prey that are relatively difficult to capture or not available to calves due to habitat, such as striped bass or longfin inshore squid, were absent in the diet of that age class. However, easy to capture prey, such as spot, became progressively less important with age. Seasonal variation in the diet was observed, with differences likely being due to changes in prey availability (due to seasonal migrations) and detectability (due to increased vocalizing during spawning) rather than changes in prey preference. Lastly, the stomachs of dolphins with external evidence of an entangling interaction contained a significantly higher proportion of recently ingested fish (using otolith code as a proxy) than those that did not. The presence of recently ingested prey is commonly referenced as an indicator of peracute underwater entrapment; however, this is the first study to quantitatively establish a significant relationship. The data presented in this study promise to enhance policy and management by establishing baseline information on natural history as well as a quantitatively assessed indicator for peracute underwater entrapment that can be referenced to study local shifts in natural history or incidence of bycatch.</p>

Name thesis:degree_name

Master of Science (MS)

Level thesis:degree_level

Thesis

Discipline thesis:degree_discipline

Biological Sciences

Year dc:date.available

2020

Author dc:creator

• Volker, Kristen Marie

Contributors dc:contributor

• Ian Bartol
• Holly Gaff
• Kent Carpenter
• Damon Gannon

• Bottlenose dolphin
• Bycatch
• Diet
• Soniferous fishes
• Stranding
• Tursiops truncatus
• Biology
• Ecology and Evolutionary Biology
• Marine Biology

Statement dc:rights

• <p>In Copyright. URI: <a href="http://rightsstatements.org/vocab/InC/1.0/">http://rightsstatements.org/vocab/InC/1.0/</a> This Item is protected by copyright and/or related rights. You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s).</p>

Identifier

9798641222868

OAI identifier oai:identifier

oai:digitalcommons.odu.edu:biology_etds-1113