The Effects of Derelict Blue Crab Traps on Marine Organisms in the Lower York River, Virginia

—Derelict (abandoned or lost) traps targeting blue crab Callinectes sapidus have the potential to affect the blue crab fishery and other marine-oriented species. We used sidescan sonar to locate derelict traps and assess their extent and accumulation rate. Experimental traps were monitored at four locations to calculate catch rates of marine organisms and trap degradation rates. In 2006, 635–676 derelict traps were identified in a 33.5-km area of the lower York River in Virginia’s portion of the Chesapeake Bay. Trap loss rates are estimated at 30%, resulting in the potential addition of over 100,000 traps annually to the Chesapeake Bay derelict trap population in Virginia. The top four species captured in the experimental traps were blue crab, Atlantic croaker Micropogonias undulates, oyster toadfish Opsanus tau, and white perch Morone americana. Experimental derelict traps captured 50.6 blue crabs trap 1 season 1 during April–November 2006 and 13.6 Atlantic croakers trap 1 season 1 during May–August 2006. There was no difference in catch rates between traps of different ages. Baiting traps to simulate entrapped fish (self-baiting) doubled the catch rate. Experimental derelict traps continued to capture organisms for at least 1 year, which suggests that derelict traps could affect blue crab populations. The number of derelict traps targeting blue crab Callinectes sapidus in the nation’s estuaries is unknown. Typically, traps become lost when buoy lines are severed by vessel propellers, lines break because of age, choice of buoy material is poor, traps are abandoned, traps are vandalized, or storms roll the traps, pulling the buoy below the surface. In Florida, Alabama, Mississippi, and Louisiana, estimates derived from calculations of trap loss suggest that derelict traps numbered at 605,000 in 1993, although Guillory and Perret (1998) stated that this number probably was an underestimate. Guillory et al. (2001), using an annual total of 1 million traps fished commercially and a 25% loss–abandonment rate, suggested that 250,000 derelict traps are added to the Gulf of Mexico annually. The blue crab is considered an important component of the Chesapeake Bay, both ecologically and economically. This species is considered the foremost benthic scavenger and predator (Baird and Ulanowicz 1989), and Chesapeake Bay stocks provided 80% of the U.S. blue crab catch in the 1950s (Miller et al. 2005). However, a steady decrease in landings has occurred over the last few decades (Miller 2001a, 2005). According to commercial landings, the Chesapeake Bay is still the nation’s largest source of blue crabs (30% in 2003), but Virginia has dropped to fourth (Miller et al. 2005). Nonetheless, the blue crab fishery still accounts for over US$200 million annually for the Chesapeake Bay region (Miller 2001b). Lost or abandoned (derelict) commercial fishing gear, including nets and traps, present safety, nuisance, and environmental effects in estuarine waters. Blue crabs and various fish species that are entrapped and die in derelict traps can act as an attractant to crabs, resulting in a self-baiting effect. Derelict fishing gear damages sensitive habitat and continues to capture both target and bycatch species, leading to reduced fitness and significant acute and delayed mortalities (High and Worlund 1979; Guillory 1993, 2001; Bullimore et al. 2001; Matsuoka et al. 2005). Animals captured in derelict traps experience starvation, cannibalism, infection, disease, or prolonged exposure to poor water quality (i.e., low dissolved oxygen; Van Engel 1982; Guillory 1993). The effect of derelict blue crab traps on diamondback terrapin Malaclemys terrapin and commercially important finfish has been documented (Smolowitz 1978; Guillory 1993; Guillory and Prejean 1997; Roosenburg et al. 1997). In the Gulf of Mexico, evidence that derelict traps contribute to significant mortalities in the blue crab fishery has prompted the development of removal strategies to reduce the ecological and economic impacts of derelict traps (Guillory et al. 2001). Information regarding the amount and effect of derelict traps in the Chesapeake Bay is limited. An examination of existing derelict trap data retrieved from Chesapeake Bay Multispecies Monitoring and Assessment Program (ChesMMAP; Bonzek and Latour 2005) trawl surveys shows the potential effect of derelict traps on nekton in Virginia waters. During surveys from April to October 2002–2005, 91 derelict * Corresponding author: [email protected] Received January 23, 2007; accepted December 17, 2007 Published online August 21, 2008 1194 North American Journal of Fisheries Management 28:1194–1200, 2008 Copyright by the American Fisheries Society 2008 DOI: 10.1577/M07-014.1 [Management Brief]