Conserving Atlantic Bluefin Tuna with Spawning Sanctuaries
Atlantic bluefin tuna populations in both the western and eastern Atlantic Ocean are currently at very low levels (ICCAT 2010a; 2010b), and additional management measures are needed to rebuild their populations (Armsworth et al. 2010; Block et al. 2005; Druon 2010; Hurry et al. 2008; ICCAT 2007; MacKenzie et al. 2009; Safina and Klinger 2008; Teo et al. 2007a; Teo and Block 2010). The prohibition of certain fishing activities at specific times or in specific areas, known as “time and area closures” in fisheries management parlance, are tools commonly used to protect crucial genetic and biological diversity, restore population structure (e.g., age and sex distribution) and spawning stocks, and reduce bycatch (Pelletier et al. 2008).
Globally, pelagic fishes (Goodyear 1999), mollusks (Dredge 1992) and reef fishes (Galal et al. 2002) have been managed with closures because they protect specific size classes, sexes or individual species from excessive fishing mortality. For example, North Atlantic swordfish have been successfully protected by time and area closures and have recently been declared rebuilt by the U.S. National Marine Fisheries Service (NMFS 2009a), see box below. Recent research suggests that closure of spawning areas for Atlantic bluefin tuna, used specifically to protect spawning fish (Beets and Friedlander 1998; Heyman et al. 2005; Nemeth 2005; Sala et al. 2001), may be a viable tool to help rebuild their depleted populations (Armsworth et al. 2010; Block et al. 2005; Druon 2010; ICCAT 2007; Teo et al. 2007a; Teo and Block 2010).