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The Good, the Bad, and the Rocky...Reefs Long-term ecological monitoring of rocky reefs in the Gulf of California

Understanding the difference between the impacts of human activity and natural trends is difficult to say the least. As a means of accomplishing such a task, the Gulf of California Marine Program (GCMP) undertakes annual surveys of reefs and mangrove forests, to record the biological characteristics in the Gulf of California (GoC). This underwater monitoring effort was established in 1998 and includes population counts and species biodiversity data as well as descriptive summaries of the role of organisms in various marine ecosystems. Using the data, the GCMP is able to gauge the health of a reef ecosystem and evaluate whether conservation measures, such as Marine Protected Areas (MPAs), are working effectively. The GCMP provides stakeholders with analyzed, ready-to-use data, useful for advising fishery management and strengthening collaborations.

Patience Pays Off With Long-Term Ecological Monitoring (LTEM) LTEM projects aid to understand the effects of human activities on natural systems. This is key to conservation because how organisms respond to changes in the environment greatly ranges, and understanding these behaviors assists in predicting ecological reactions to different pressures. LTEM projects are not only crucial to the adaptability of ecosystems and how they change in space and time, but they also provide insight into fishery and habitat management plans. With the GCMP long-term dataset, it is possible to map and track changes in populations and ecosystems over time which would otherwise be impossible with short-term data. Throughout the report, keep in mind:

The Good

The Bad


Strong Communities For Strong Reefs

Through collaborations between the GCMP and local diving, sport fishing operators and other institutions, local ecological monitoring in the Gulf of California has become highly efficient and effective at benefitting all of the parties involved. The GCMP’s LTEM program holds monitoring workshops to build capacity and improve data collection, providing participants with highly valuable skills and creating a lasting support network to the program. Combined with other collaborators, this large network not only strengthens the ability to monitor, but also increases interest and environmental awareness within the region. To further foster marine stewardship, the GCMP developed a monitoring protocol guide in 2013 that highlights the key information necessary to conduct successful monitoring campaigns. The guide allows the GCMP and other groups to maintain consistent data collection, learn about monitoring issues and solutions, and apply their skills to other rocky reef ecosystems.


Playing Doctor: Measuring Reef Health The GCMP has developed the Reef Health Index (RHI) to help assess the well-being of rocky reefs and to track changes in their community. Total fish biomass and the effect of fishing pressure in protected areas can all be calculated and analyzed using data collected from the GCMP’s LTEM program. In addition, the RHI suggests thresholds of fish biomass that can maintain a sustainable population, and may be used to understand local fishing catch limitations. By tracking species populations, the GCMP is also able to conclude that low numbers of species and higher densities of benthic invertebrates (such as seastars and sea urchins) reflect higher levels of fishing.2 Thus, long-term monitoring helps evaluate the health of reefs around the region and to maintain sustainable reefs productivities.

Reef Health Index (RHI): measures

+ well-being of reef

to calculate


 changes in community

to inform

total fish biomass

fishing pressure



sustainable fish thresholds

local catch limits


One Decade, One Reserve

The biodiversity and abundance of species in Cabo Pulmo make it an ideal destination for SCUBA diving and snorkeling activities. However, the region has not always been this way. Though designated as a protected marine park in 1995, Cabo Pulmo showed both low biodiversity and abundance of organisms. The community then voted to have a strict no-fishing rule, and in the ten years that followed, Cabo Pulmo’s top predator biomass increased by 1070% and total fish biomass grew 463%.3 Today, Cabo Pulmo is more than just a vacation hotspot: it is one of the most renowned and successful Marine Protected Areas (MPAs) in the world. Working with a range of different, international research partners, the GCMP’s LTEM program generates valuable information that helps to track ecological growth and improve the management of the park.


Larvae: The Lost Link for Marine Connectivity

fishing zones

marine protected areas

release sites only

release sites with genetic samples

When planning no-take marine reserves, understanding the journey of eggs is crucial to determining whether the reserves are self-sustaining or not. The GCMP set to answer exactly that: By using the GCMP’s LTEM data of 33 sites from 2008 to 2010 and analyzing fishery catch data, GCMP researchers identified where leopard grouper (Mycteroperca rosacea) larvae come from.4 With computer modeling, the GCMP also collaborated in a simulation of the path of floating eggs in relation to the local marine reserve. This model provides insight into which species will increase in biomass, what areas will benefit from protection, and suggests management and location guidelines of no-take reserves within the Northern Gulf. 4

no-take zone

Example Study Area: Around the Midriff Islands in the Gulf of California. Using GCMP’s LTEM data, researchers created a model that provided insight into how best to implement marine protected areas, no-take zones and fishing zones (Moreno-Baez et al., 2010; Moreno-Båez et al., 2012).



The Early Years: Protecting Juveniles and their Nurseries

1,500 63

The number of fishable yellow snapper (Lutjanus argentiventris) in the GoC is determined by the availability of nursery habitat (where young snappers develop) and climate conditions.5 Knowing where fish like to live and keeping tabs on these habitats could allow fisheries managers to plan ahead and adjust fishing effort to habitat availability. From 1998 to 2015, the GCMP has conducted more than 1,500 surveys in 63 mangrove sites to calculate the abundance of juveniles and habitat shifts of the yellow snapper.6 The GCMP concluded that mangroves house yellow snappers as juveniles, but the stock greatly decreases as the distance between a reef and a mangrove site increases. This information can help managers adjust fishing pressure in light of changes in population distributions and changing climate.


Rocky reef health index



When Good Intentions Are Not Enough Established as a National Park in 1996, Loreto Bay (LBNP) lacked management enforcement until 2003. As a marine park, it was split in two: a no-take zone restricting fishing activity, only 0.7% of the park, and a multi-use zone allowing fishing. From 1998 to 2010, the GCMP monitored fourteen reef sites inside and eight sites outside the park and concluded that the amount of fish was the same in both zones.7 More than 15 years as a protected area, the LBNP has failed to improve the status of its reefs: the current state of the park mirrors its 1996 conditions. This may be due to the rise of recreational fishing rise in the park (over 400%!) and weak enforcement, allowing illegal fishing activities to persist.7 Only with constant and methodical monitoring was this failure to improve uncovered, suggesting the LBNP management plans need to be reconsidered.

Loreto Bay National Park: 1996


possible factors

ď…¸ unhealthy status of reef

ď…¸ unhealthy status remained the same

400% + recreational fishing rise


weak enforcement


Relying on and Destroying Rocky Reefs: the Human Paradox


With 75% of the globe’s reefs near human settlements and with those populations expected to double in the next 50 to 100 years, the GCMP collaborated in a research that investigated the impact of human activity on reef ecosystem functions in 2011.9 This human activity includes, but is not limited to, coastal development, overuse of marine resources, and human pollution such as agricultural runoff. The study found that higher diversity systems may be more vulnerable to human activities as more species are exposed to human threats. As a result, the ecosystem’s ability to generate goods, services, and revenue is undercut, negatively affecting the reliant economy overall. Having such knowledge at hand motivates management and helps minimize the human pressures in coastal regions under pressure.


Reefs at Risk

68% Using the GCMP’s Reef Health Index (RHI), which has been constructed from 15 years of LTEM data, the GCMP evaluates the current health of reefs across the Gulf. Scores represent differences from the average health of the Gulf’s rocky reefs and range from highly degraded to highly preserved. Using this index, the GCMP found that 80% of all the reefs in the GoC are considered unhealthy. While 95% of the Cabo Pulmo reefs and 93% of Marias reefs had healthy RHI values, 71% of reefs in other MPAs and 64% of open access reefs were categorized as unhealthy.2 Locating the reefs most at risk and identifying the most important factors influencing reef health are key to making informed management decisions and to understanding what will ensue if the health of a reef further deteriorates. 12


Exposed and Vulnerable


At present, only approximately 5% of the Gulf of California is a no-take zone, leaving the majority of the Gulf vulnerable to overfishing and human overexploitation.8 In 1999, the GCMP’s LTEM program conducted a baseline survey of more than 80 sites in the Gulf of California. Using this survey, the GCMP identified specific areas that need protection: at least 20% of the coastal habitats, all rare coral and sea grass habitats, at least half of all mangroves habitats, and all of the sites where economically valuable key species reproduce.1 This work outlined the first proposal of a network containing 24 marine reserves in the GoC, all connected by biological and ecological processes. Unfortunately, only one of these 24 areas (Cabo Pulmo National Park) has been protected at 100%; the rest of them remain as open to unregulated fisheries or as MPAs that do not receive enough enforcement to protect their reefs (such as Loreto Bay National Park).


Fishing Smaller in Species and Size Shifts in fishing catch are not always clear—changes can be slow and hard to detect. To map the change in catch over the last 30 years, the GCMP interviewed fishermen, analyzed fisheries statistics, and conducted underwater surveys in the GoC from 1998 to 2001. The researchers concluded that these habitats were “fished down”—fisheries shifted from targeting larger and longer-lived predators to smaller and shorter-lived fish.10 Using LTEM data, the GCMP ranked the GoC’s reefs by fishing pressure (number of fishing boats in the area). This allowed fisheries’ impacts on the population and size of the targeted species to be determined: the average catch length of fish in the GoC decreased by 45 cm from 1970 to 2000—in the 1980s alone, the size dropped 33 cm!10 This marked shift affects not just the targeted species, but also the entire underwater and coastal community.

Shifting baseline idea:






Over the past 17 years, the GCMP has worked at gathering a lot of long term data for coastal and marine ecosystems, but there is much more we need to accomplish in the years to follow. We now plan to implement our Reef Health Index along the entire Mexican Pacific coast to evaluate environmental changes caused by human activity. This will help us identify areas of high priority for future conservation efforts. Conservation of marine ecosystems require the constant generation of scientific data, over long periods and large scales. This allows us to identify changes in marine community structures, functions, and general health. For these reasons, our principle objective is to continue our annual surveys for a variety of marine ecosystems including mangroves and rocky reefs for years to come. Additionally, dissemination and open access of our data continues to be a crucial component of our monitoring program. Making our data and findings available to the public via interactive stories, such as those published on dataMares ( will continue to be a priority and aim for each monitoring year. Having this electronic communication platform allows us to inform the general public about the importance of these delicate ecosystems and how their health affects local coastal communities. 31% of the stories currently published on dataMares use the GCMP’s LTEM data and tackle topics ranging from mangroves to reef health. These stories attract over 11,000 hits in both English and Spanish, while to date the overall website has been explored by over 420,000 visitors. Transparency in our work aids in not only educating the public, but also in building trust among stakeholders. Collaboration among all parties is critical to efficiently achieving conservation and sustainability within the region.


Above all, the success of the GCMP’s monitoring program would not be attainable without our supporters. It is only because of our funders that we are able to dive deeper, expand monitoring areas, and put forth a collective effort towards conservation of the Gulf of California. Together, the GCMP and its partners undertake ecological and social issues within the region to make a tangible difference in the relationship between humans and the environment.

We would like to thank The Walton Family Foundation, The Leona M. and Harry B. Helmsley Charitable Trust Foundation, Fondo Mexicano para la Conservaciรณn de la Naturaleza A.C., The David and Lucile Packard Foundation, WWW Foundation, International Community Foundation, and Comision Nacional de Areas Naturales Protegidas for their support of the program that has allowed field research, analysis tools, and information dissemination.

WWW Foundation Rhodes Family


Bibliography 1

Sala, E., O. Aburto-Oropeza, G. Paredes, I.Parra, J. C. Barrera, & P. K. Dayton. (2002). A General Model for Designing Networks of Marine Reserves. Science: 298 (5600), 1991-1993. doi: 10.1126/science.1075284


Aburto-Oropeza, O., E. Ezcurra, J. Moxley, A. Sánchez-Rodríguez, I. Mascareñas-Osorio, C. Sánchez-Ortiz, et al. (2015). A framework to assess the health of rocky reefs linking geomorphology, community assemblage, and fish biomass. Ecological Indicators, 52, 53–361. doi:10.1016/j.ecolind.2014.12.006


Aburto-Oropeza, O., B. Erisman, G. R. Galland, I. Mascareñas-Osorio, E. Sala,& E. Ezcurra. (2011). Large Recovery of Fish Biomass in a NoTake Marine Reserve. PLoS One, 6(8), e23601. doi: 10.1371/journal.pone.0023601.t002


Munguia-Vega, A., Jackson, A., Marinone, S. G., Erisman, B., Moreno-Baez, M., Girón-Nava, A., et al. (2014). Asymmetric connectivity of spawning aggregations of a commercially important marine fish using a multidisciplinary approach. PeerJ, 2, e511. peerj.511


Aburto-Oropeza, O., Sala, L. E., Paredes, G., Mendoza, A., & Ballesteros, E. (2007). Predictability of reef fish recruitment in a highly variable nursery habitat. Ecology, 88(9), 2220–2228.


Aburto-Oropeza, O, Dominguez-Guerrero I, Cota-Nieto J, Plomozo-Lugo T. (2009). Recruitment and ontogenetic habitat shifts of the yellow snapper (Lutjanus argentiventris) in the Gulf of California. Marine Biology. 156:2461-2472.


Rife, A.N., O. Aburto-Oropeza, P. A. Hastings, B. Erisman, F. Ballantyne, J. Wielgus, et al. (2013). Long-term effectiveness of a multi-use marine protected area on reef fish assemblages and fisheries landings. Journal of Environmental Management, 117(C), 276–283. doi: 10.1016/j. jenvman.2012.12.029


The David and Lucile Packard Foundation. Gulf of California Subprogram: 2012-2016 Strategy. 2013. uploads/2013/04/GOC-Subprogram-Strategy-2012_2016.pdf


Mora, C., Aburto-Oropeza, O., Ayala Bocos, A., Ayotte, P. M., Banks, S., Bauman, A. G., et al. (2011). Global Human Footprint on the Linkage between Biodiversity and Ecosystem Functioning in Reef Fishes. PLoS Biology, 9(4), e1000606. pbio.1000606.g004


Sala, E., Aburto-Oropeza, O., Reza, M., Paredes, G., & López-Lemus, L. G. (2004). Fishing down coastal food webs in the Gulf of California. Fisheries, 29(3), 19–25. 19

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The Good, the Bad and the Rocky-Reefs  

Understanding the difference between the impacts of human activity and natural trends is difficult to say the least. As a means of accomplis...

The Good, the Bad and the Rocky-Reefs  

Understanding the difference between the impacts of human activity and natural trends is difficult to say the least. As a means of accomplis...