Date of Award

2017

Document Type

Open Access Thesis

Department

Biological Sciences

Sub-Department

College of Arts and Sciences

First Advisor

Joseph Quattro

Abstract

The Gulf of Mexico (GOM) is an important spawning ground for many commercially important fish species including yellowfin, skipjack, and blackfin tunas. In particular, it is an essential spawning habitat for Atlantic bluefin tuna, whose stock status is of great international concern. It is vital to the appropriate conservation management of these species to determine both the location of their spawning grounds and the genetic diversity found within them. Fish eggs are a fisheries-independent source of spawning information that can provide more accurate estimates of spawning sites compared to larvae. This study describes population diversity and reproductive life histories in Thunnus and Katsuwonus using fish eggs that were collected during the National Marine Fisheries Service’s (NMFS) 2011 spring larval survey in the northern Gulf of Mexico. Of 12,731 eggs surveyed genetically from 121 different sites, 38 Thunnus thynnus, 49 Thunnus albacares, 192 Thunnus atlanticus, and 15 Katsuwonus pelamis were identified. T.thynnus and K.pelamis had very high haplotypic diversity (h=.995 and h=.946, respectively), while T.albacares and T.atlanticus had relatively lower haplotypic diversity (h=.288 and h=.454). Phylogenetic and molecular diversity analyses for each species revealed that bluefin and skipjack tunas display aggregate spawning at relatively few sites, while yellowfin and blackfin individuals spawn independently at multiple sites. All species were found throughout the GOM apart from bluefin tuna which was only identified along the northern-most edge of the GOM within the continental shelf and slope.

Rights

© 2017, Katrina C. Hounchell

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