1. Cover Page – Characterization of the Catch by Swordfish Buoy Gear
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1. Cover Page – Characterization of the Catch by Swordfish Buoy Gear in Southeast Florida NOAA Cooperative Research Program Grant Number: NA07NMF4540075 Award Period: 8/1/2007 to 8/31/2009 (reflecting “no-cost” extension granted 7/31/2008) David Kerstetter, Ph.D.* (Project Principal Investigator) and Shannon Bayse Nova Southeastern University Oceanographic Center 8000 North Ocean Drive Dania Beach, FL 33004 *Corresponding Author: [email protected] December 2009 2. Abstract – This project had the goal of characterizing the target catch and bycatch species and disposition within the directed swordfish fishery in southeast Florida that utilizes the so- called “swordfish buoy gear” (SBG). All fieldwork was completed by the end of August 2009 as expected with the “no-cost” extension granted in 2008. The preliminary analyses of the collected data indicate that catch-per-unit-effort (CPUE) for catch and bycatch is much higher for SBG than pelagic longline gear. The fishery encounters very little bycatch, and those animals that are captured by the gear are almost always alive at gear retrieval and subsequent release. This project did not encounter any marine mammals, sea turtles, or sea birds. The descriptions of the behavior of the fishing gear itself, such as effective fishing depths and relationships of effective fishing depths with gear configuration indicate that the gear fishes somewhat shallower than simple additions of the lengths of the gear sections would indicate. The various iterations of the field datasheet that captures all of the fishing activities (deployment, “tending”, and retrieval) and gear characteristics has also been provided as an Appendix to this final report. 3. Introduction – Large expanses of waters traditionally fished by the U.S. pelagic longline fishery have been closed in recent years to protect populations of sea turtles and other bycatch species. For example, the Florida East Coast (FEC) Closed Area was closed in 2000, in large part, to reduce the catch of juvenile swordfish by the pelagic longline fleet. Other areas closed to pelagic longline operations include the DeSoto Canyon in the Gulf of Mexico (again, due to juvenile swordfish) and the traditional winter fishing grounds of the Windward Passage (in part due to geo-political concerns over fishing in foreign Exclusive Economic Zones). However, all of these areas once allowed the U.S. pelagic longline fleet access to some of the most fertile fishing grounds in the western Atlantic Ocean for swordfish and other highly migratory species (HMS) such as yellowfin and bigeye tunas. Closing these areas was compounded with gear restrictions, with the result that the U.S. share of the North Atlantic catch of swordfish has dropped from an average of 28.9% of the North Atlantic total harvest between 1985-1994 to only a 22.9% average from 2000-2004 (ICCAT, 2006), or a drop of over half from the catches in the late 1980s. (Although dated, these same trends hold true today.) These regulatory actions have also resulted in growing pressure at the International Commission for the Conservation of Atlantic Tunas (ICCAT) from other harvesting nations to revise the U.S. allocation of the total allowable catch of this swordfish stock. While recent actions during the 2009 ICCAT annual meeting ended without changing the current U.S. quota on the North Atlantic swordfish stock, such challenges to the U.S. quota share are likely in the future. Changes in the U.S. swordfish fisheries that would enable U.S. vessels to approach or catch its annual international quota of swordfish would also help preserve the important conservation advocacy role of the United States within ICCAT. Many of the public proposals to increase catch rates for the U.S. fishery have addressed reopening parts of these closed areas to pelagic longline gear, and on-going research in the FEC is showing mixed results in terms of bycatch interactions (D. Kerstetter, unpubl. data). These proposals have generally resulted in fierce opposition from both recreational anglers and conservation organizations, which prefer the status quo of leaving these areas closed to pelagic longline gear altogether. One less controversial alternative to reopening the closed areas to pelagic longline fishing operations would be to adopt another type of fishing gear altogether. Swordfish buoy gear (SBG; Figure 1) is one such alternative that has developed in south Florida during approximately the past ten years. This gear type uses a small number of branch lines (≤ five historically, now one or two by regulation) attached to a 150-200 m length of 3.2-3.5 mm monofilament or braided nylon mainline. This mainline is then attached between a large lighted inflatable float or a “hi-flyer” radar-reflecting buoy to allow the gear to be monitored by the vessel during the nighttime fishing operations. Branch line construction is essentially similar to that of the pelagic longline fleet: approximately 15-20 m of 1.8 mm monofilament, with a snap swivel at one end and the hook at the other. Some configurations use a small, leaded swivel approximately 1.5 m above the hook to reduce potential torsion and entangling of the branch lines during the “soak” period of the fishing activities. Despite having some characteristics of a so-called “vertical longline” (Figure 1; also see Bjordal and Løkkeborg, 1996), each SBG section (“piece”) of gear is believed to function much more like a small segment of pelagic longline gear. Another difference is that vertical longline gear is more commonly used for reef-associating fishes or on volcanic, steep-slope areas (Sainsbury, 1966), although occasionally the gear is also used for large pelagic fishes, such as tunas (e.g., Dagorn et al., 2001). Because SBG is currently classified as “handgear” under federal regulations, rather than a modified form of pelagic longline, the use of J-style hooks is not prohibited. There is currently very little scientific information available regarding the SBG fishery in south Florida or its catches. Some small, recreational-type vessels may only deploy two or three pieces of gear, although some of these vessels are reportedly setting up to 12 pieces per night (pers. comm., S. Carl, formerly of Hi-Liner Fishing Tackle, Inc.). Large pelagic longline vessels, which pass through the Florida Straits seasonally as they move from the winter grounds in the Caribbean to the summer Grand Banks fishery, have reportedly tried setting up to 60 pieces per night (pers. comm., G. O’Neill, Carol Ann Sword Corp.), albeit with minimal success. Rising fuel costs have prompted some of the larger vessels that would normally travel to the Grand Banks to reconfigure their fishing plans for the summer to stay within 200 miles of the coast (pers. comm., G. Johnson, Pocahontas, Inc.). Given the increased pressure in the remaining open fishing grounds for traditional pelagic longline gear, and that 71 (39.2%) of all directed swordfish permit holders are located in Florida (NMFS, 2008), some of these smaller longline vessels may choose to remain in the closed area of the Florida Straits with SBG instead. This research project had two specific goals: Goal 1: To describe the nature of the catch by SBG gear in the Florida Straits. The gear type would be characterized through the described length (and weight, if retained species) of the catch. Additional analyses will compare the catch of this fishery with that of the recreational rod-and-reel swordfish fishery and the now-closed commercial pelagic longline fishery in the FEC closed area. Goal 2: To use electronic monitoring equipment to determine the physical parameters of the SBG gear type. In addition to the documentation of the catch and bycatch for SBG fishing gear, this proposed work would also use electronic monitoring equipment to determine the effective fishing depths and times. The determination of how the elapsed minutes since hooking would allow both a time of hooking and the amount of time that caught animals are attached to the gear during medium-scale operations. TDRs would be downloaded after each night’s fishing operations have concluded. The use of TDRs will allow the characterization of the envelope of the gear, i.e., the depths at which the gear is found during the fishing operations. Determining this parameter would allows the description of the theoretical overlap of the SBG gear type with its swordfish target species. Optimally, this could be maximized for species (or even juvenile versus adult) and therefore allow for the development of a more efficient gear type for the harvestable adult swordfish. The larger goal of this study was to provide the basis for monitoring the catches within the swordfish buoy gear fishery absent a dedicated, mandatory logbook program. Although such a logbook program was subsequently implemented during the course of this project, these results still provide the best available data on catches, catch rates, and bycatch information for the fishery absent an independent fisheries observer program. 4. Methods – The research conducted under this grant used several different commercial fishing vessels in the swordfish buoy gear fishery. Although the original proposal was to use the F/V Kristin Lee for the majority of the work, this vessel was frequently being used in the pelagic longline fishery and thus was unavailable for the majority of the SBG sets (see previous semi-annual reports). The use of the larger vessel was intended to permit the collection of data far more efficiently by both being able to monitor and fish many more buoys than a smaller vessel and utilizing the radio beacon buoys already aboard from past commercial pelagic longline operations. We were able to obtain an exempted fishing permit for the F/V Kristin Lee to allow the vessel to fish with swordfish buoy gear within the Florida East Coast (FEC) Closed Area of the Florida Straits, although the conditions of the permit required that the hydraulic system to the main longline spool be disconnected.