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The illegal harvest of marine species within exclusive economic zones can have a strong impact on the function of local ecosystems and livelihoods of coastal communities. The complexity of these problems is often overlooked in the development of solutions, leading to ineffective and sometimes harmful social and environmental outcomes. One-dimensional, oversimplified perspectives can lead to conservation prescriptions that exacerbate social stressors. This is particularly critical in the case of international illegal trade of endangered, high-value species, which generate a value chain in which artisanal fishers are the first operational and often the weakest link of an intricate web. We examined 2 illegal fisheries, totoaba (Totoaba macdonaldi) and sea cucumber (Isostichopus badionotus and Holothuria floridana), in Mexico. Although these are 2 separate and independent fisheries, important ecological (resource condition, fishery impacts at the ecosystem level) and social (governance, markets) similarities improve understanding of their complexity. Our findings are relevant globally and show the need for interdisciplinary decision-making groups, community engagement, and the development of demand reduction measures.

Coastal marine ecosystems provide livelihoods for small-scale fishers and coastal communities around the world. Small-scale fisheries face great challenges since they are difficult to monitor, enforce, and manage, which may lead to overexploitation. Combining territorial use rights for fisheries (TURF) with no-take marine reserves to create TURF-reserves can improve the performance of small-scale fisheries by buffering fisheries from environmental variability and management errors, while ensuring that fishers reap the benefits of conservation investments. Since 2012, 18 old and new community-based Mexican TURF-reserves gained legal recognition thanks to a regulation passed in 2012; their effectiveness has not been formally evaluated. We combine causal inference techniques and the Social-Ecological Systems framework to provide a holistic evaluation of community-based TURF-reserves in three coastal communities in Mexico. We find that, overall, reserves have not yet achieved their stated goals of increasing the density of lobster and other benthic invertebrates, nor increasing lobster catches. A lack of clear ecological and socioeconomic effects likely results from a combination of factors. First, some of these reserves might be too young for the effects to show (reserves were 6–10 years old). Second, the reserves are not large enough to protect mobile species, like lobster. Third, variable and extreme oceanographic conditions have impacted harvested populations. Fourth, local fisheries are already well managed, and while reserves may protect populations within its boundaries, it is unlikely that reserves might have a detectable effect in catches. However, even small reserves are expected to provide benefits for sedentary invertebrates over longer time frames, with continued protection. These reserves may provide a foundation for establishing additional, larger marine reserves needed to effectively conserve mobile species.

Territorial Use Rights in Fisheries (TURFs) are gaining renewed attention as a potential tool for sustainable fisheries management in small-scale fisheries. This growing popularity comes despite the fact that there are still unresolved questions about the most effective TURF designs. One of the key questions is the role of TURF size in their efficacy both from ecological and social standpoints. This study explores the expected effects of existing TURF sizes on yields for TURF systems in Chile, México and Japan. The expected effect of larval dispersal and adult movement on yields was simulated for TURFs in each system. The results show that the analyzed TURF systems fall into three main categories: (a) TURFs that are of adequate size to eliminate the expected negative effects of both adult and larval movement, (b) TURFs that are large enough to eliminate the expected negative effects of adult movement, but not the effects of larval dispersal, and c) TURFs that are too small to eliminate the expected impacts on yield of both adult and larval movement. These analyses suggest that either existing models of TURF performance are incomplete or that there is significant scope for improved performance with altered TURF designs. Considering these alternatives, empirical evidence from the TURFs deemed too small suggests that complementary management tools can enhance TURF performance when natural or social constraints prevent the construction of TURFs of optimal size.

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Small-scale fisheries collectively have a large ecological footprint and are key sources of food security, especially in developing countries. Many of the data-intensive approaches to fishery management are infeasible in these fisheries, but one strategy that has rapidly emerged to overcome these challenges is the establishment of Territorial User Rights for Fisheries (TURFs). TURFs establish exclusive fishing zones for groups of stakeholders, which eliminates the race to fish with other groups. A key design challenge however is setting the size of TURFs-too large and the number of stakeholders sharing them impedes collective action; too small and the movement of target fish species in and out of the TURFs effectively removes the community's exclusive access. Here, we assess the size of 137 TURFs from across the globe in relation to these design challenges. We project that roughly two thirds of TURFs in our sample are already sized ideally to overcome the challenges posed by movement and group size. However, for most of the remaining TURFs, we project that all possible sizes would either be too small to overcome the movement challenge or too large to overcome the collective action challenge. Our results suggest that these fisheries, which target mobile species in densely populated regions, may need additional interventions to be successful. This article is protected by copyright. All rights reserved.

Territorial use rights in fisheries (TURFs) are coastal territories assigned to fishermen for the exclusive extraction of marine resources. Recent evidence shows that the incentives that arise from these systems can improve fisheries sustainability. Although research on TURFs has increased in recent years, important questions regarding the social and ecological dynamics underlying their success remain largely unanswered. In particular, in order to create new successful TURFs, it is critical to comprehend how fish movement over different distances affects the development of sustainable fishing practices within a TURF. In theory, excessive spillover outside a TURF will generate incentives to overharvest. However, many TURFs have proven successful even when targeted species move over distances far greater than the TURF's size. A common attribute among some of these successful systems is the presence of inter‐TURF cooperation arrangements. This raises the question of how different levels and types of cooperation affect the motivations for overharvesting driven by the movement of fish outside the TURF. In this paper, we examine equilibrium yields under different levels of inter‐TURF cooperation (from partial to full) and varying degrees of asymmetry across TURFs of both biological capacity and benefit‐sharing. We find that partial cooperation can improve yields even with an unequal distribution of shared benefits and asymmetric carrying capacity. However, cooperation arrangements are unstable if the sharing agreement and biological asymmetries are misaligned. Remarkably, we find that asymmetry in the system can lead to the creation of voluntary no‐take zones.