Optimizing enforcement and compliance in offshore marine protected areas: a case study from Cocos Island, Costa Rica A DRIAN A RIAS ,R OBERT L. P RESSEY ,R HONDDA E. J ONES J ORGE G. Á LVAREZ -R OMERO and J OSHUA E. C INNER Abstract Illegal exploitation of resources is a cause of environmental degradation worldwide. The effectiveness of conservation initiatives such as marine protected areas relies on users’ compliance with regulations. Although com- pliance can be motivated by social norms (e.g. peer pressure and legitimacy), some enforcement is commonly necessary. Enforcement is expensive, particularly in areas far from land, but costs can be reduced by optimizing enforcement. We present a case study of how enforcement could be optimized at Cocos Island National Park, Costa Rica, an offshore protected area and World Heritage Site. By analysing patrol records we determined the spatial and temporal distribution of illegal fishing and its relationship to patrol effort. Illegal fishing was concentrated on a seamount within the Park and peaked during the third year-quarter, probably as a result of oceanographic con- ditions. The lunar cycle in conjunction with the time of year significantly influenced the occurrence of incursions. The predictability of illegal fishing in space and time facilitates the optimization of patrol effort. Repeat offenders are common in the Park and we suggest that unenforced regulations and weak governance are partly to blame. We provide recommendations for efficient distribution of patrol effort in space and time, establishing adequate governance and policy, and designing marine protected areas to improve compliance. Our methods and recommendations are applicable to other protected areas and managed natural resources. Keywords Cocos Island, Costa Rica, illegal fishing, long- lining, lunar phase, marine reserve, patrol, poaching Introduction O ffshore marine protected areas are an emerging ap- proach to marine conservation and fisheries management (Game et al., 2009; Graham & McClanahan, 2013). Their effectiveness, as for near-shore protected areas, relies heavily on compliance by fishermen (Campbell et al., 2012; Edgar et al., 2014). Even remote locations are not safeguarded from illegal fishing because fishermen will travel long distances to target commercially valuable species (Berkes et al., 2006); for example, in the Chagos Archipelago, a remote area in the Indian Ocean with few inhabitants, illegal fishing has resulted in a significant decline in sharks (Graham et al., 2010). Ensuring compliance offshore is challenging. Patrolling large and distant tracts of ocean is logistically difficult and financially expensive, and therefore detection rates for illegal activity are low. Additionally, important factors for compliance, such as social norms (e.g. peer pressure and legitimacy) and legislation, may be absent or lack sup- port offshore. Although voluntary compliance is desirable (Ostrom, 1990; Hønneland, 2000; Arias & Sutton, 2013), not all people comply voluntarily; typically some degree of enforcement is necessary (Tyler, 1990; Hønneland, 2000). However, enforcement is perhaps the most expensive man- agement activity in both terrestrial and marine protected areas (Robinson et al., 2010; Ban et al., 2011). With limited funds for conservation, optimizing enforcement can make management more cost-effective. There is a common misconception that enforcement involves only patrolling but it actually encompasses detec- tion, arrest/citation, prosecution and conviction (Sutinen, 1987; Akella & Cannon, 2004); it can be described heuris- tically as a four-link chain. The first link, probability of detection, is mainly technical and field-based, relying on factors such as equipment, and number and skills of wardens. The remaining links (probabilities of arrest/ citation, prosecution and conviction) tend to rely progress- ively more on legal and political constructs. The probability of arrest depends partly on field equipment (e.g. a boat’s capacity to pursue) but also on what legally constitutes non- compliance and evidence. The probability of prosecution involves the capacity of the legal and institutional system to undertake proceedings against non-compliance, under- lining the importance of strong institutions and coord- ination between them. Conviction, and its associated penalties, rests on the judiciary and its probability depends on the quality of evidence and the overall capacity of the enforcement system (Akella & Cannon, 2004). Ultimately ADRIAN ARIAS (Corresponding author), ROBERT L. PRESSEY,JORGE G. ÁLVAREZ- ROMERO and JOSHUA E. CINNER Australian Research Council Centre of Excellence for Coral Reef Studies, James Cook University, Townsville, QLD 4811, Australia. E-mail adrian.arias@my.jcu.edu.au RHONDDA E. JONES School of Marine and Tropical Biology, James Cook University, Townsville, Australia Received 25 October 2013. Revision requested 27 January 2014. Accepted 29 April 2014. First published online 4 August 2014. Oryx, 2016, 50(1), 18–26 © 2014 Fauna & Flora International doi:10.1017/S0030605314000337 https://doi.org/10.1017/S0030605314000337 Published online by Cambridge University Press