84 



Abstract — Short-duration (5- or 10- 

 day) deployments of pop-up satellite 

 archival tags were used to estimate 

 survival of white marlin \Tetrapturus 

 albidus) released from the western 

 North Atlantic recreational fishery. 

 Forty-one tags, each recording tem- 

 perature, pressure, and light level 

 readings approximately every two 

 minutes for 5-day tags (n = 5) or four 

 minutes for 10-day tags (« = 36), were 

 attached to white marlin caught with 

 dead baits rigged on straight-shank 

 ("J") hooks (rc = 21) or circle hooks 

 (?i=20) in offshore waters of the U.S. 

 Mid-Atlantic region, the Dominican 

 Republic, Mexico, and Venezuela. 

 Forty tags (97.8%) transmitted data 

 to the satellites of the Argos system, 

 and 33 tags (82.5%) transmitted data 

 consistent with survival of tagged ani- 

 mals over the deployment duration. 

 Approximately 61% (range: 19-95%) 

 of all archived data were successfully 

 recovered from each tag. Survival was 

 significantly (P<0.01) higher for white 

 marlin caught on circle hooks (100%) 

 than for those caught on straight- 

 shank ("J") hooks (65%). Time-to- 

 death ranged from 10 minutes to 64 

 hours following release for the seven 

 documented mortalities, and five ani- 

 mals died within the first six hours 

 after release. These results indicate 

 that a simple change in hook type 

 can significantly increase the sur- 

 vival of white marlin released from 

 recreational fishing gear. 



Application of pop-up satellite archival tag 



technology to estimate postrelease survival 



of white marlin iTetrapturus albidus) 



caught on circle and straight-shank ("J") hooks 



in the western North Atlantic recreational fishery 4 



Andrij Z. Horodysky 



John E. Graves 



Virginia Institute of Marine Science 



College of William and Mary 



Route 1 208 Greate Rd. 



Gloucester Point, Virginia 23062 



E mail address (for J. E. Graves, contact author): graves(S>vims edu 



Manuscript submitted 20 January 2004 

 to the Scientific Editor's Office. 

 Manuscript approved for publication 

 2 August 2004 by the Scientific Editor. 



Fish. Bull. 103:84-96 (2005). 



Atlantic white marlin (Tetrapturus 

 albidus Poey, 1860) are targeted by a 

 directed recreational fishery and occur 

 as incidental bycatch in commercial 

 fisheries throughout the warm pelagic 

 waters of the Atlantic Ocean. Total 

 reported recreational and commercial 

 landings of white marlin peaked at 

 4911 metric tons (t) in the mid-1960s, 

 declined steadily during the next 15 

 years, and have since fluctuated with- 

 out trend between 1000 and 2000 t 

 despite substantial increases in fish- 

 ing effort (ICCAT, 2003). Recent popu- 

 lation assessments conducted by the 

 Standing Committee for Research and 

 Statistics (SCRS) of the International 

 Commission for the Conservation of 

 Atlantic Tunas (ICCAT) indicate that 

 the Atlantic-wide white marlin stock 

 is currently at historically low levels 

 and has been severely overexploited 

 for over three decades (ICCAT, 2003). 

 In the 2002 white marlin assessment, 

 the 2001 biomass was estimated to 

 be less than 12% of that required for 

 maximum sustainable yield (MSY) 

 under the continuity case (ICCAT, 

 2003). Current harvest is estimated to 

 be more than eight times the replace- 

 ment yield (ICCAT, 2003). 



In response to the overfished status 

 of white marlin, ICCAT has adopted 

 binding international recommendations 

 to decrease overall Atlantic landings of 

 this species by 67% from 1996 or 1999 

 levels (whichever is greater) through 

 the release of all live white marlin 

 from commercial pelagic longline and 

 purse-seine gears (ICCAT, 2001). How- 



ever, even these dramatic reductions 

 may be ineffective in rebuilding the 

 white marlin stock. Goodyear (2000) 

 estimated that a 60% decrease from 

 1999 fishing mortality levels would be 

 required to halt the reduction of At- 

 lantic blue marlin (Makaira nigricans). 

 Because white marlin experience high- 

 er levels of fishing-induced mortality, 

 it is expected that the reduction in 

 mortality required to stabilize this 

 stock will be even greater. 



Management measures within the 

 United States, established by the At- 

 lantic Billfish Fishery Management 

 Plan (FMP) (NMFS, 1988) and sub- 

 sequent Amendment 1 (NMFS, 1999), 

 have also been implemented to reduce 

 white marlin fishing mortality. U.S. 

 commercial fishermen have been pro- 

 hibited from landing or possessing 

 all Atlantic istiophorids since 1988. 

 Dead discards of white marlin from 

 the U.S. commercial pelagic longline 

 fishery peaked at 107 t in 1989, and 

 have decreased to 40-60 t over the 

 last several years (White Marlin 

 Status Review Team 1 ). Management 



♦Contribution 2610 from the Virginia 

 Institute of Marine Science, College of 

 William and Mary, Gloucester Point, VA 

 23062. 



1 White Marlin Status Review Team. 

 2002. Atlantic white marlin status 

 review document, 49 p. Report to 

 the National Marine Fisheries Ser- 

 vice. Southeast Regional Office, 

 September 3, 2002. www.nmfs.gov/ 

 prot_res/readingrm/Candidate_Plus/ 

 wh it e„m a rl in/ whm_status_review.pdf 



