Ayana Johnson, Ph.D. 2011
IGERT Fellow Marine Biodiversity and Conservation
photo credit: Doug Clevenger for Post Modern co.
Ayana is a CMBC OCEAN LEADER and now the Director of Science and Solution for the Waitt Foundation
NSF Profile Video of Ayana - March 2009
Thesis: Fish, Fishing, Diving and the Management of Coral Reefs
My dissertation is a multi-disciplinary attempt to understand
how coral reef resources can be managed sustainably. I began by examining the
peer-reviewed literature on artisanal reef fisheries, identifying gaps in
knowledge, and proposing a set of priority areas for future research.
Ecological examinations of trap fishing and gill nets followed. Fish trap bycatch (i.e. incidental or unwanted catch) can be reduced by 80%, without
reducing catch value, via the inclusion of escape gaps that allow juveniles and
narrow-bodied species to escape. However, high catch of ecologically important
herbivores remains a concern. The use of gill nets is unsustainable because
they cause habitat damage, have substantial bycatch, and capture the few
remaining apex predators present on Caribbean coral reefs. The second half of
the dissertation is a tripartite presentation of the results of interviews with
177 fishers and 211 professional SCUBA divers on Curaçao and Bonaire. First, I showed
that fishers are well aware of the declining state of coral reef health,
whereas divers have a so-called “shifted baseline,” with dramatically lower
expectations for reef abundance and productivity. Then, employing experimental
behavioral economics, I determined that fishers have significantly higher
discount rates than divers, and that these rates are negatively correlated with
support for regulations to manage fishing and diving. Lastly, I contemplated
how to reconcile ecosystem requirements with stakeholder preferences, and
developed a sustainable management plan for the coral reefs of Curaçao and
Johnson, Ayana Elizabeth. 2010. Reducing bycatch in coral reef trap fisheries: escape gaps as a step towards sustainability. Marine Ecology Progress Series. Vol 415: 201-209.
The overarching objective of my dissertation was to examine options for sustainable management of coral reef resources via research conducted on Curaçao and Bonaire. The two eastern Caribbean islands have similar coral reef ecosystems, strong fishing traditions, thriving dive tourism industries, and socio-political histories, but have divergent histories of resource conservation. Curaçao has only recently begun to manage its marine resources in earnest, whereas Bonaire has had a marine park and fisheries regulations for decades, and is internationally renowned for its conservation efforts and ethos. However, both islands have experienced dramatic degradation of their coral reefs and fish populations in the last half-century. Using these islands as case studies, this dissertation focuses on fishing, and to a lesser extent SCUBA diving, and attempts to diagnose hindrances to sustainable resource use and suggest remedies for them.
Trends, current understanding, and future directions for artisanal coral reef fisheries research
Artisanal coral reef fisheries provide food and employment to hundreds of millions of people in developing countries, making their sustainability a priority for users, management, and research. Many of these fisheries are ecologically degraded and not yielding the full potential of socioeconomic returns. To help inform priority areas for future research, I present a literature review that evaluates past and current research effort and trends on coral reef fi sheries. A search of the peer-reviewed literature returned 364 articles, each of which was examined to identify the types of data presented and the types of management recommendations made. Main trends in the literature were a decline in experimental studies and in studies that report time series and fish catch biomass, density, and diversity, but an increase in papers containing stakeholder interview data. Key future research priorities are: (1) effectiveness of management approaches, (2) limits to sustainable extraction, (3) effects of climate change, (4) food security, (5) the role of aquaculture, (6) access to and control of fishery resources, (7) relationships between economic development and fishery exploitation, (8) alternative livelihoods, and (9) integration of ecological and socioeconomic research. Focusing on these areas will provide decision-makers with the necessary information to develop sustainable solutions.
Reducing bycatch in coral reef trap fisheries: escape gaps as a step towards sustainability
Widespread use of minimally selective fish traps has contributed to the overfishing of Caribbean coral reefs. Traps typically target high-value fish such as groupers and snappers, but they also have high bycatch of ecologically important herbivores (parrotfish and surgeonfish) and non-target species. One strategy for reducing this bycatch is to retrofit traps with rectangular escape gaps that allow juveniles and narrow-bodied species to escape. On the shallow reefs of Curaçao, Netherlands Antilles, I compared the catch of traditional Antillean chevron traps (the control) to the catch of traps with short escape gaps (20 × 2.5 cm), traps with tall escape gaps (40 × 2.5 cm), and traps with a panel of large aperture mesh. With data from 190 24-h trap sets, the mean number of fish caught was 11.84 in control traps, 4.88 in short gap traps, 4.43 in tall gap traps, and 0.34 in large mesh traps. Escape gaps reduce the bycatch by ~80%, key herbivores by ~55%, and butterflyfish by ~85%. Escape gaps reduce neither the catch of high-value fish, nor the total market value of the catch. Therefore, using escape gaps could make trap fishing more sustainable without reducing fishermen’s revenues.
Gill net use on Caribbean coral reefs is unsustainable
Gill nets are commonly used on coral reefs around the world, yet little research has been published on their catches or the ecological effects of their use. On Curaçao, I documented the catch of 13 gill net sets by two groups of fishers. The mean catch quantity was 10.4 fish, the mean catch mass was 5.7 kg, and the mean catch value was 31.7 USD after a mean soak time of 15.3 hours. The documented attributes of gill net use – catch of the few remaining pelagic predators on coral reefs, catch of rare species, bycatch, and benthic damage – make it very unpopular with the large majority of the fishing community as well as with the SCUBA diving community. Because few people are financially dependent on gill net fishing, gill nets have detrimental effects on coral reef ecology, and there is broad public support for regulation to restrict gill net use, this situation is an opportunity to act for reef conservation by prohibiting use of gill nets. An island-wide buyout of gill nets to compensate inconvenienced fishers may be appropriate and would complement a ban.
Shifting baselines in artisanal coral reef fisheries
Understanding stakeholders’ perceptions of environmental problems is critical to designing palatable solutions. I interviewed 177 fishers and 211 professional SCUBA divers in Curaçao and Bonaire to assess their understanding of the extent and causes of the degradation of the coral reefs where they fish and dive. Fishers are well aware of the declining health of the nearshore ecosystem regardless of age and years of fishing. In contrast, divers were generally less aware of reef degradation, although older and more experienced divers were more likely to have perceived a decline. Thus, divers have a shifted baseline compared with fishers. Fishers were more likely to blame the degradation on external factors such as changes in climate, currents, or industrial fishing offshore, whereas divers tended to blame fishing and coastal development. These divergent perspectives have important implications for management. Fishers have properly diagnosed the problem but generally deny culpability and are resistant to fishing restrictions. Divers have a limited understanding of the problem, but overwhelmingly support most restrictions on marine resource use. Reconciling these opposing views will be essential for the lasting protection and wise use of the reef ecosystems of these islands.
Time preferences and the management of coral reef fisheries
To investigate whether there is a relationship between how individuals make financial decisions and how they make decisions about the use of natural resources, I conducted a time preference experiment with 161 fishers and 195 divers on the Caribbean islands of Curaçao and Bonaire. I found that divers have significantly higher individual discount factors (IDFs) than fishers, and the majority of interviewees exhibited neither present nor future bias. For divers, there was a significant positive correlation between mean IDF and support of regulations to manage fishing and diving, but there was no equivalent relationship for fishers. This implies that conservation views are influenced by multiple factors, and that individuals’ preferred approaches to managing coral reefs are not necessarily formed using the same metrics as financial decisions. These results have implications for determining appropriate management strategies, incentivizing conservation, and the understanding the appropriateness of property rightsbased management.
A socioeconomically informed approach to managing fishing and diving on Caribbean coral reefs
The coral reef ecosystems of Curaçao and Bonaire are substantially degraded relative to their historical conditions. Both islands should substantially augment their reef management in order to prevent further resource degradation and loss of the associated ecosystem services. Based on extensive socioeconomic interviews with fishers and professional SCUBA divers, I present the most socially-palatable management steps, discuss economic and socio-cultural drivers of fisher and diver behavior, and recommend four principles with which to frame a more sustainable management structure: (1) effort and capacity reduction, (2) gear-based management, (3) marine reserves, and (4) simplicity and enforceability. Within this, specific steps that should be taken in order to support long-term sustainable use of the coral reefs, include: (1) cap the numbers of fishers, divers, and dive shops; (2) reduce latent fishing capacity via boat buyouts; (3) transition to hook-and-line fishing only and ban gill net use immediately; (4) establish large no-fishing and no-diving zones; and (5) enact simple and easily enforceable regulations with few caveats. While these measures may seem draconian, they are necessary to safeguard fishing and diving as important sources of employment and leisure.
This collection of, perhaps seemingly disparate, projects grew out of my desire to develop a holistic understanding of the complexities of coral reef management. At its root, the overfishing of coral reefs can be considered a simple problem: there are too many people and too few fish for harvest to continue at its present rate. But the details are important. Reef resources are critical to the welfare, nutrition, and cultural heritage of hundreds of millions of people, making it critical to grapple with how to conserve both fish and fishing communities. By integrating the results of my multi-disciplinary research – fieldwork on fish traps and gill nets, socioeconomic interviews, time preference elicitation, and a review of the literature – I put forth management recommendations for Curaçao and Bonaire. The case study presented here is not a unique case. Coral reef ecosystems colliding with fishing, tourism, development, and population growth are the norm. Hopefully, the fishing gear research, examination of fishers’ and divers’ shifted baselines, application of behavioral economics to coral reef management, identification of priorities for future research, management recommendations, and conclusions throughout this dissertation will be applicable to other islands and other resource management challenges, and will be applied