Development and Trial of Deep-set Buoy Gear for Swordfish, Xiphias gladius, in the Southern California Bight

Fishery interactions with nontarget species (including U.S. federally protected sea turtles and marine mammals) have severely impacted U.S. west coast swordfi sh, Xiphias gladius, fi sheries and have hindered the development of alternative domestic operations. This study used swordfi sh depth distribution data to aid in the design of deep-set fi shing gear to target swordfi sh in the Southern California Bight (SCB). To minimize nontarget interactions, the deep-set gear was designed to fi sh at depths between 270 and 320 m during daylight hours. The deep-set buoy gear (DSBG) confi guration consisted of a vertical mainline (2.2 mm monofi lament) affi xed with a 4 kg weight and two 8 m gangions (1.8 mm monofi lament), each rigged with an 18/0 circle hook and baited with mackerel, Scomber spp., or squid, Illex spp., or Dosidicus gigas. Surface fl oatation included a 36 cm diameter (21 kg) longline fl oat and two smaller (3 kg) strike indicator fl oats. Experimental fi shing trials were conducted using ten individual pieces of DSBG deployed simultaneously. Soak duration was maintained at 4 h/set and the gear was hauled immediately upon detection of a strike. Gear trials were conducted within the SCB from August to January of the 2011 and 2012 swordfi sh seasons from both research and cooperative fi shing vessels. From 54 sets (4,320 hookhours), 14 swordfi sh were captured without any interactions with bycatch/nontarget species of concern (i.e., sea turtles and marine mammals). Additional species captured during the trials included: bigeye thresher sharks, Alopias superciliosus (7); opah, Lampris guttatus (2); blue sharks, Prionace glauca (2); and common thresher shark, Alopias vulpinus (1). These data suggest that deep-set fi shing operations can selectively target swordfi sh during the day within the SCB and provide a basis for further testing using commercial applications. Introduction Several management concerns have been raised over swordfi sh, Xiphias gladius, fi sheries and their interactions with nontarget species (Carretta et al., 2003; Gilman et al., 2006). Within the U.S. west coast Exclusive Economic Zone (EEZ), swordfi sh are landed domestically by the California Drift Gillnet (DGN) fi shery and, to a lesser extent by a small southern California-based harpoon fl eet (Bedford and Hagerman, 1983). The remaining domestic demand for swordfi sh is met annually by imports from the Hawaii shallow-set longline fi shery and from foreign longline fl eets (Bartram and Kaneko, 2004; PFMC, 2011). Off California, DGN interactions with nontarget species of concern (e.g., marine mammals, Physeteridae, and sea turtles, Dermochelyidae) have spurred numerous restrictions that have directly affected local fi shermen through time and area closures (including the ~200,000 nmi2 Pacifi c Leatherback Closure Area (PLCA)) and mandated gear and operational modifi cations (Hanan et al., 1993; Carretta et al., 2003; PFMC, 2011; Benson et al.1). Despite recent information that suggests a healthy and underexploited population of north Pacifi c swordfi sh (Brodziak and Ishimura2), a consistent decline in DGN participation and ex-vessel revenues has ensued over the past 30 years. In 2012, DGN operations reached historic lows in both landings and participation, with fl eet operations restricted to the Southern 1Benson, S., H. Dewar, P. Dutton, C. Fahy, C. Heberer, D. Squires, and S. Stohs. 2009. Swordfi sh and leatherback use of temperate habitat (SLUTH): Workshop Report. In H. Dewar (Editor), U.S. Dep. Commer., NOAA, SWFSC Admin. Rep. LJ-09-06, La Jolla, Calif. 2Brodziak, J., and G. Ishimura. 2010. Stock assessment of North Pacifi c swordfi sh (Xiphias gladius) in 2009. U.S. Dep. Commer., NOAA, NMFS, Pacifi c Islands Fish. Sci. Cent., Admin. Rep. H-10-01, 37 p. California Bight (SCB), a relatively small portion of the former fi shery range (PFMC, 2013). These declines have resulted in adverse economic impacts on ports and associated businesses located adjacent to the PLCA (e.g., Morro Bay and Monterey) and have consolidated effort to a small geographic region that has been shown to historically fl uctuate in swordfi sh landings (Bedford and Hagerman, 1983). Commensurate with the decline of DGN operations off California, traditional harpoon fi sheries have also dwindled, with effort and landings also reaching their lowest points in over three decades (PFMC, 2013). This decline has occurred despite the openaccess nature of the harpoon fi shery and the local market void produced by the reduction of DGN operations. Several factors account for the decline in the harpoon industry, including the rise in operational costs (i.e., fuel prices), inconsistent catch rates, and the lack of new entrants into the fi shery. Because harpoon operations require relatively calm conditions, this fi shery has historically been limited to the waters of the SCB with landings

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