Marine & Environmental Sciences Faculty Articles

Swordfish Xiphias gladius Diet in the Florida Straits

Document Type

Article

Publication Date

3-26-2020

Publication Title

Bulletin of Marine Science

Keywords

Diet, Florida, Stomach contents, Swordfish, Xiphias gladius

ISSN

0007-4977

First Page

1

Last Page

20

Abstract

Swordfish Xiphias gladius inhabit the Florida Straits year-round and provide a significant role in the food web as top-level predators. However, little is known about the diet composition and thus ecological role of swordfish in Florida. This study investigated swordfish diet by analyzing stomach contents of 131 swordfish in the Florida Straits from April 2007 to December 2008. Identifiable species included 13 teleost species, 3 cephalopod species, and 1 crustacean species. Cephalopods dominated the swordfish diet by weight (72.4%) and number (69.9%), and ranked highest in importance in the diet by the index of relative importance (IRI; 81.5%). Teleosts occurred the most (99.1%) but represented the second highest importance in diet by weight (25.2%), number (26.3%), and IRI (17.6%). Illex sp. was the prey with the greatest dietary importance, followed by unidentifiable ommastrephid squids. Stomach fullness index values ranged from 0 (empty) to 8.98 (mean = 0.37). A positive significant correlation between swordfish length and prey length was found (r² = 0.104, P = 0.037), and no significant correlations were found between swordfish weight and prey weight (r² = −0.075, P = 0.065). This is the first study to report a comprehensive diet of swordfish inhabiting waters in the Florida Straits region and suggests swordfish may be opportunistic feeders, altering their diet when abundance or presence of prey changes.

ORCID ID

0000-0002-4440-8767

ResearcherID

I-5396-2012

DOI

10.5343/bms.2019.0097

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