Distribution and Habitat Associations of Billfish and Swordfish Larvae across Mesoscale Features in the Gulf of Mexico

Abstract

Ichthyoplankton surveys were conducted in surface waters of the northern Gulf of Mexico (NGoM) over a three-year period (2006–2008) to determine the relative value of this region as early life habitat of sailfish (Istiophorus platypterus), blue marlin (Makaira nigricans), white marlin (Kajikia albida), and swordfish (Xiphias gladius). Sailfish were the dominant billfish collected in summer surveys, and larvae were present at 37.5% of the stations sampled. Blue marlin and white marlin larvae were present at 25.0% and 4.6% of the stations sampled, respectively, while swordfish occurred at 17.2% of the stations. Areas of peak production were detected and maximum density estimates for sailfish (22.09 larvae 1000 m−2) were significantly higher than the three other species: blue marlin (9.62 larvae 1000 m−2), white marlin (5.44 larvae 1000 m−2), and swordfish (4.67 larvae 1000 m−2). The distribution and abundance of billfish and swordfish larvae varied spatially and temporally, and several environmental variables (sea surface temperature, salinity, sea surface height, distance to the Loop Current, current velocity, water depth, and Sargassum biomass) were deemed to be influential variables in generalized additive models (GAMs). Mesoscale features in the NGoM affected the distribution and abundance of billfish and swordfish larvae, with densities typically higher in frontal zones or areas proximal to the Loop Current. Habitat suitability of all four species was strongly linked to physicochemical attributes of the water masses they inhabited, and observed abundance was higher in slope waters with lower sea surface temperature and higher salinity. Our results highlight the value of the NGoM as early life habitat of billfishes and swordfish, and represent valuable baseline data for evaluating anthropogenic effects (i.e., Deepwater Horizon oil spill) on the Atlantic billfish and swordfish populations.

Deepwater Horizon crude oil impacts the developing hearts of large predatory pelagic fish

“…In the decades following the last major US oil spill (the 1989 Exxon Valdez spill in Alaska), developing fish embryos have been shown to be especially vulnerable to the toxicity of crude oil (4). The northern Gulf provides critical spawning and rearing habitats for a range of commercially and ecologically important pelagic fish species, and the timing of oil release into the ecosystem from the damaged Deepwater Horizon/MC252 well coincided with the temporal spawning window for bluefin and yellowfin tunas, mahi mahi, king and Spanish mackerels, greater and lesser amberjack, sailfish, blue marlin, and cobia (5)(6)(7)(8)(9)(10)(11)(12)(13). Yellowfin tuna (Thunnus albacares) and greater amberjack (Seriola dumerili) contribute to important commercial fisheries (48,960,000 pounds in 2010 and 4,348,000 pounds in 2004, respectively) (14,15).…”

Fish Resources of the Gulf of Mexico

“…Because no spawning-capable adults have been captured in this region, it is unlikely that blue marlin spawn in the Loop Current in the northeastern Gulf of Mexico (Brown-Peterson et al 2008). Strong histological evidence supports the lack of spawning in the northern Gulf of Mexico east of the Mississippi River, which is augmented by the failure to capture blue marlin larvae in areas not associated with the Loop Current Kraus et al 2011;Rooker et al 2012). Thus, the likelihood of blue marlin spawning in the northern Gulf of Mexico is slim, although the northern Gulf of Mexico supports an active recreational fishery for blue marlin from May through September (Brown-Peterson et al 2008).…”

“…Blue marlin tag/recapture data from the Gulf of Mexico indicate that seasonal movements may occur between the Gulf of Mexico (summer) and the Bahamas (winter). Several data sources indicate that the Gulf of Mexico may serve as important spawning and/or nursery habitat for blue marlin (Brown-Peterson et al 2008;Rooker et al 2012). Blue marlin larvae were found in a 2005 fishery-independent survey in the areas from 27 to 28 N to 90 to 94 W in July (Rooker et al 2012).…”

“…Several data sources indicate that the Gulf of Mexico may serve as important spawning and/or nursery habitat for blue marlin (Brown-Peterson et al 2008;Rooker et al 2012). Blue marlin larvae were found in a 2005 fishery-independent survey in the areas from 27 to 28 N to 90 to 94 W in July (Rooker et al 2012). This seems to suggest that blue marlin can spawn in the northern Gulf of Mexico (Brown-Peterson et al 2008;Kraus et al 2011).…”

“…However, larvae mainly are present near the western margin of Loop Current on the continental shelf in relatively warm waters (>27 C). The presence of young blue marlin larvae along the boundary of the Loop Current may be a result of transport from Caribbean/Straits of Florida spawning events (Kraus et al 2011;Rooker et al 2012). Because no spawning-capable adults have been captured in this region, it is unlikely that blue marlin spawn in the Loop Current in the northeastern Gulf of Mexico (Brown-Peterson et al 2008).…”