101 Abstract—The longfin mako (Isurus paucus) is a poorly studied oceanic Horizontal and vertical movements of longfin shark taken in fisheries throughout makos (Isurus paucus) tracked with satellite- its worldwide range in temperate and tropical waters. Satellite-linked linked tags in the northwestern Atlantic Ocean tags were deployed to investigate the movements of 2 mature males, 1 one tagged in the northeastern Gulf Robert E. Hueter (contact author) of Mexico (GOM) and the other off John P. Tyminski1 northern Cuba. Horizontal tracks John J. Morris1 estimated by using likelihood meth- 2 ods were similar for these sharks; Alexei Ruiz Abierno comparable movements were docu- Jorge Angulo Valdes2,3 mented from the GOM, through the Straits of Florida and the Ba- Email address for contact author: [email protected] hamas, and into the open Atlantic Ocean where they converged on the 1 Center for Shark Research Mid-Atlantic Bight. Depth and tem- Mote Marine Laboratory perature ranges were 0–1767 m and 1600 Ken Thompson Parkway 4.0–28.8°C. A diel pattern of vertical Sarasota, Florida 34236 movement was evident for both in- 2 Centro de Investigaciones Marinas dividuals, along with regular forays Universidad de la Habana from cold daytime depths to warmer Calle 16, No. 114 e/ 1ra y 3ra near-surface waters, possibly as an Miramar, Playa, La Habana CP 11300, Cuba adaptation for thermoregulation. The vertical movements of longfin 3 School of Natural Resources and Environment makos allow them to exploit verti- University of Florida cally migrating prey but these move- P.O. Box 116455 ments increase their vulnerability to Gainesville, Florida 32611 pelagic longlining. The horizontal movements of these sharks reveal the limited benefit of areas current- ly closed to pelagic longlining off The shark genus Isurus comprises and de Anda-Fuente, 2012). Despite the southeastern United States and 2 species with similar morphologi- its large size (to at least 417 cm in also indicate the connectivity of U.S., cal features, the shortfin mako (I. total length [TL]; Gilmore, 1983), Cuban, Mexican, and Bahamian wa- oxyrinchus) and the longfin mako the longfin mako is an understudied ters for this species. Because of the (I. paucus) (Compagno, 2001). The species, partly because of its relative vulnerability of longfin makos to longfin mako is a global oceanic spe- rarity, its pelagic nature, and observ- overexploitation, improved biological cies that inhabits both tropical and ers’ confusion with its congener, the information is needed for accurate stock assessments and appropri- subtropical waters (Compagno, 2001) shortfin mako (Castro, 2011). ate management and conservation but also ranges into temperate seas The longfin mako is not directly measures. (Queiroz et al., 2006; Bustamante et targeted in any fishery, but is taken al., 2009; Mucientes et al., 2013). In as bycatch throughout its range in the western Atlantic Ocean, the long- tropical and temperate waters by fin mako has been documented in the pelagic longline fisheries that tar- Gulf Stream off the eastern United get swordfish (Xiphias gladius), tuna States, off Cuba’s northern coast, as species (Thunnus spp.), and other far south as southern Brazil (Com- shark species (Reardon et al., 2006; Manuscript submitted 15 April 2016. pagno, 2001), and as far north as Mucientes et al., 2013; Frédou et al., Manuscript accepted 29 November 2016. Georges Bank (Kohler et al., 1998). 2015). In a study of shark bycatch in Fish. Bull.: 115:101–116 (2017). In the Gulf of Mexico (GOM), long- the small-scale, pelagic longline fish- Online publication date: 20 December 2016. fin makos have been observed in- ery of northwest Cuba, Guitart Man- doi: 10.7755/FB.115.1.9 frequently but have been reported day (1975) reported that the longfin in the northern GOM off the Mis- mako was the sixth most common The views and opinions expressed or implied in this article are those of the sissippi River and south of Panama shark by weight of the 11 shark spe- author (or authors) and do not necessarily City, Florida (Killam and Parsons, cies reported; a more recent study of reflect the position of the National 1986) and in the southern GOM off this fishery ranked the longfin mako Marine Fisheries Service, NOAA. Tabasco, Mexico (Wakida-Kusunoki higher in landings (Aguilar et al., 102 Fishery Bulletin 115(1) 2014). Fins of longfin makos are of desirable quality GOM, were captured and tagged with pop-up satel- and have been reported in the Hong Kong (Clarke et lite archival tags to track their horizontal and vertical al., 2006), Chilean (Sebastian et al., 2008), and Indone- movements. In 2012, a male longfin mako (LFM1) was sian fin trades (Sembiring et al., 2015). Consequently, captured during an overnight pelagic longline set de- in some fisheries but not in the Cuban fishery, this spe- ployed on 27 April in the northeastern GOM (28.40°N, cies may be finned and discarded at sea; hence, land- 85.84°W) from the RV Weatherbird II of the Florida ings of longfin makos may be underreported (Reardon Institute of Oceanography. In 2015, a second male long- et al., 2006). Given the apparent declines in some fin mako (LFM2) was captured during an overnight populations of the shortfin mako (Baum et al., 2003; pelagic longline set deployed from an artisanal Cuban Dulvy et al., 2008), it is likely that populations of the fishing vessel on 13 February off Cojimar in northwest longfin mako have been affected by intensive pelagic Cuba (23.26°N, 81.98°W). longline fisheries (Reardon et al., 2006). Because of its When LFM1 was captured in 2012, the sea-surface rarity, low reproductive potential, and bycatch-induced temperature (SST) was 25.3°C and depth to the bot- mortality, the longfin mako is listed as vulnerable in tom was approximately 334 m. The gear targeted pe- the IUCN Red List of Threatened Species (Reardon et lagic fish species and consisted of 26 km of mainline al., 2006) and in 2008 was added to Appendix II of the with 30-m gangions composed of 136-kg monofilament Convention on the Conservation of Migratory Species of connected through a 9/0 nickel-plated swivel to 1 m of Wild Animals (Kyne et al., 2012). In U.S. waters, reten- 0.8-mm stainless steel cable. The 202 hooks deployed tion of longfin makos has been prohibited for both com- were 18/0 circle hooks with zero offset and were baited mercial and recreational fishermen since 2000 under with Spanish mackerel (Scomberomorus maculatus) the National Marine Fisheries Service (NMFS) fishery or little tunny (Euthynnus alletteratus) and were sus- management plan for sharks that inhabit the Atlantic pended at depths 30–60 m below the surface. Chemical Ocean and adjacent waters (NMFS1). In an ecological glow sticks (Chemilures,2 World Plastics, San Carlos, risk assessment of shark species caught in Atlantic CA) were attached to the gangions approximately 2 pelagic longline fisheries, Cortés et al. (2015) ranked m above each baited hook as a fish attractant. Upon the vulnerability of the longfin mako among species at haulback of the gear the following morning on 28 April, highest risk and highlighted the need for better basic one longfin mako was among the catch. The captured biological information for this shark. shark was lifted out of the water and brought on deck Satellite-linked tagging technologies have provided with a specially designed cradle to support the shark’s researchers with effective tools for revealing home body weight (Grace et al., 2007). The animal remained ranges, movement and migration routes, and habitat- within this cradle for measuring and tagging proce- use patterns of marine predators (Hammerschlag et al., dures, during which time its gills were irrigated with 2011). Most lamnid species have been studied by using seawater from a hose inserted into its mouth. satellite tracking. These species include the shortfin The shark was tagged with a pop-up satellite ar- mako (Loefer et al., 2005; Stevens et al., 2010; Rog- chival tag (Mk10; Wildlife Computers, Redmond, WA). ers et al., 2015), white shark (Carcharodon carcharias) The tag archived measurements of ambient tempera- (Bruce et al., 2006; Weng et al., 2007; Nasby-Lucas et ture, pressure, and light level at 3-s intervals and al., 2009), porbeagle (Lamna nasus) (Pade et al., 2009; summarized these data into 8-h periods to facilitate Saunders et al., 2011; Francis et al., 2015), and salmon data transmission. The tag was programmed to detach shark (L. ditropis) (Weng et al., 2005, 2008). However, after 90 d on the shark, float to the sea surface, and there are no detailed reports of satellite-tracked long- transmit a summary of its archived data by way of the fin makos from any part of the global range of this Argos satellite system with time-at-depth and time-at- species. Conventional tagging results in U.S. waters, temperature histograms in 14 user-defined bins. Black although sparse, indicate movement of longfin makos antifouling paint (EP-2000; ePaint Company, East Fal- from the eastern GOM into the western North Atlantic mouth, MA) before deployment had been applied to the Ocean, likely through the Straits of Florida (Kohler et tag, excluding its sensors and label. At deployment, al., 1998). We are the first to use satellite tracking as the tag was inserted into the shark’s dorsal muscula- a means of assessing the behavior, ecology, and vulner- ture just below the first dorsal fin by using a stainless ability to fisheries of this species. steel dart (Type SSD; 34.0 × 8.5 mm; Hallprint Pty. Ltd., Hindmarsh Valley, Australia) attached to a 15-cm tether composed of 55-kg coated, braided wire (Berkley, Materials and methods Spirit Lake, IA).