Impacts of lost fishing gear on coral reef sessile invertebrates in the Florida Keys National Marine Sanctuary Mark Chiappone a, * , Helga Dienes a , Dione W. Swanson b , Steven L. Miller a a Center for Marine Science and NOAA’s National Undersea Research Center, University of North Carolina at Wilmington, 515 Caribbean Drive, Key Largo, FL 33037, USA b Division of Marine Biology and Fisheries, Rosenstiel School of Marine and Atmospheric Science, University of Miami, 4600 Rickenbacker Causeway, Miami, FL 33149, USA Received 8 March 2002; received in revised form 10 February 2004; accepted 30 April 2004 Abstract The Florida Keys coral reef ecosystem supports multimillion-dollar commercial and recreational fisheries. The ecological effects caused by fishing gear that is lost when cut or broken after snagging on the bottom is a growing concern to managers and scientists. Few data exist, however, to assess the impacts of lost fishing gear to benthic organisms and habitat structure. In this study, 63 offshore coral reef and hard-bottom sites were surveyed during 2001 to quantify the impacts of lost fishing gear to coral reef sessile invertebrates. Lost hook-and-line fishing gear accounted for 87% of all debris (N ¼ 298 incidences) encountered and was responsible for 84% of the 321 documented impacts to sponges and benthic cnidarians, predominantly consisting of tissue abrasion causing partial individual or colony mortality. Branching gorgonians (Octocorallia) were the most frequently affected (56%), followed by milleporid hydrocorals (19%) and sponges (13%). Factors affecting the impacts of lost fishing gear include sessile invertebrate density, the density of lost fishing gear, and gear length. While lost hook-and-line fishing gear is ubiquitous in the Florida Keys, less than 0.2% of the available milleporid hydrocorals, stony corals, and gorgonians in the habitats studied are adversely affected in terms of colony abrasions and partial mortality. Ó 2004 Elsevier Ltd. All rights reserved. Keywords: Fishing gear; Florida Keys; Marine pollution; Protected areas; Stratified sample design 1. Introduction Fishing is the most widespread exploitative activity on coral reefs and poses significant threats to the bio- diversity and condition of marine ecosystems (Jennings and Polunin, 1996). Marine fishery resources on a global scale are under intensive pressure from fishing (Botsford et al., 1997), and from the perspectives of fisheries managers, environmentalists and scientists, there is general agreement than habitat degradation is the most important threat to the long-term recovery of exploit- able fisheries stocks (Benaka, 1999). Fishing can influ- ence the population structure of species by affecting their abundance, size, growth and mortality, but can also modify species interactions such as competition and predation by altering structural complexity (Russ, 1991; Auster and Langton, 1999). Various ecological effects occur when traps and bottom trawls are deployed, but impacts may also occur when large numbers of anglers use hook-and-line gear to fish (Jennings and Lock, 1996; Jones and Syms, 1998). Derelict fishing gear can destroy benthic organisms and entangle both benthic and mobile fauna, including endangered species (Donohue et al., 2001). While the direct and indirect effects of fishing on marine ecosystems are a growing concern (Dayton et al., 1995; Jennings and Polunin, 1996), the extent and pos- sible effects of lost fishing gear and other debris on or- ganisms and ecological processes is still largely unknown in many coastal ecosystems. The exceptions to this pattern are a breadth of studies evaluating the effects of mobile fishing gear on benthic habitat structure (Auster and Langton, 1999; Benaka, 1999). * Corresponding author. Tel.: +1-305-451-0233; fax: +1-305-453- 9719. E-mail address: chiapponem@uncwil.edu (M. Chiappone). 0006-3207/$ - see front matter Ó 2004 Elsevier Ltd. All rights reserved. doi:10.1016/j.biocon.2004.04.023 Biological Conservation 121 (2005) 221–230 www.elsevier.com/locate/biocon BIOLOGICAL CONSERVATION