Shark Ecology

Shark Ecology

Habitat use, connectivity, migratory routes and status of shark populations

This project is currently Active

In the Galapagos, sharks are of great importance to the local economy. The marine tourism industry, which heavily relies on shark sightings, provides employment to 37% of the local active workforce. It has been estimated that on average a live shark is worth USD$360,105 per year to the local economy.

Thanks to the protection the Marine Reserve gives to the marine ecosystem and all plant and animal species within its boundaries, the Galapagos are one of the few sites around the world where shark populations remain healthy, providing a unique opportunity for researchers to study their populations. At the Charles Darwin Foundation (CDF), we carry out various projects focusing on increasing our understanding of sharks and their relationship with their environment with the aim of providing a strong scientific basis for the development of effective management plans that will ensure their long-term protection.

Our Research Team

Pelayo Salinas de León

Principal Investigator

Pelayo has led the research projects in fisheries and sharks of the CDRS since August 2012. Prior to working in Galapagos, he completed his PhD in marine biology at the University of Wellington in...

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Denisse is an Ecuadorian marine biologist who graduated with a Master of Studies (Marine Biology & Geographic Information Systems) from the University of Western Australia. Initially, she came to...

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Megan Cundy

Project Assistant

Megan is an Australian marine scientist with a Bachelor of Science (First class Honors) from Curtin University in Australia. Her Honors thesis compared the sampling efficacy, advantages and...

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Magdalena was born in Germany, but grew up all over Latin America. In 2016, after completing her bachelor’s degree in Biology at Justus-Liebig-University in Germany, she came to the Galapagos to...

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Project Details

It is estimated that over 100 million sharks are fished every year around the world, mostly for their fins. This overfishing is the main cause behind a decline of about 90% in shark populations globally since the start of industrial scale fishing in the 60s and 70s. However, the Galapagos, particularly the northern islands of Darwin and Wolf, provide a refuge for the largest shark biomass on Earth. This is largely thanks to the protection that the Galapagos Marine Reserve (GMR) affords to marine ecosystems within its boundaries.

Galapagos Shark in Wolf, Galapagos
Galapagos Shark in Wolf, Galapagos. Photo by: Pelayo Salinas, CDF.

The Sharks Project focuses on the most common shark species found inside the GMR, including hammerheads, Galapagos sharks, tiger sharks, blacktips, whitetip reef sharks, silky sharks, and whale sharks. We evaluate the status of their populations, study their movement patterns to understand their migratory routes and evaluate the effectiveness of the marine reserve in protecting various shark species. Based on the information collected in our studies we can also uncover local distribution patterns and levels of connectivity among populations at a regional level. Furthermore, we can use this information as a reference point to study the effects of climate change on these species.

To carry out our studies, we used a variety of sampling methods including:

  • Diver Operated stereo-Video (stereo-DOVs) and baited remote underwater video systems (stereo-BRUVs) used to characterize fish and shark communities and to estimate their relative abundance
  • Stable isotope analysis which allow us to determine what and where sharks feed
  • Genetic analysis which we used to determine the level of connectivity between difference populations of a given shark species
  • Acoustic and satellite tags enable us to uncover habitat use and movement patterns of sharks inside and outside the GMR
  • The use of Remotely Operated Vehicles (ROVs), manned submersibles and Deep-Sea drop cameras to study deep water species.
Installing satellite tags
Installing satellite tags. Photo by: Pelayo Salinas, CDF.

We expect the results of our studies contribute to the design and implementation of management and conservation plans for shark populations within the GMR and across the region.

The main goal of this project is to evaluate the effectiveness of the Galapagos Marine Reserve in protecting shark populations under a changing climate, and to uncover spatial usage and regional connectivity patterns of the main shark species in the archipelago.

The specific objectives of our project are:

  • To evaluate the effectiveness of the GMR in protecting the assemblages of sharks and predatory fish, and to assess the impact of ENSO cycles to their populations.
  • To compare the composition of shark communities inhabiting the Tropical Eastern Pacific (TEP) region.
  • To assess site fidelity and study habitat use in tiger sharks (Galeocerdo cuvier), and to evaluate the importance of the green sea turtle (Chelonia mydas) in their diet.
  • Identify and characterize the migratory and connectivity patterns, within the GMR and the wider TEP region, of tiger (G. cuvier) and hammerhead (Sphyrna lewini) sharks.
  • Provide information to the Galapagos National Park Directorate (GNPD) about the status of shark populations with the aim to contribute to the development of management plans for the Marine Reserve that will result in the protection of the diversity and health of these communities.
  • Raise awareness about the importance of sharks in marine ecosystems through education campaigns directed to the local community, particularly to children and young people.

Our results

From underwater censuses using stereo cameras in 2013 and 2014, we found that Darwin and Wolf (DW), the two northernmost islands within the GMR, harbor the largest shark biomass on the planet. In our study, we identified several species of sharks, including hammerhead (S. lewini), galapagos (C. galapagensis) and blacktip (C. limbatus) sharks. This high concentration of sharks is possible due to the nutrient-rich currents reaching these islands, making them highly productive areas. Additionally, the total ban on shark fishing within the GMR helps in maintaining a high density of sharks in the area. However, illegal fishing continues to pose a threat to these apex predators within the GMR. Thus, ongoing protection is necessary if we are to protect the high biomass and diversity of northern Galapagos.

Comparison of fish biomass recorded at Darwin and Wolf (DW) islands and other oceanic islands around the world. Figure from: Salinas-de-León et al, 2016. PeerJ.1911.
Comparison of fish biomass recorded at Darwin and Wolf (DW) islands and other oceanic islands around the world. Figure from: Salinas-de-León et al, 2016. PeerJ.1911.

Through the use of satellite tags on tiger sharks (Galeocerdo cuvier) between 2014 and 2017, we found these sharks show a resident pattern, as they spent over 90% of their time within the boundaries of the GMR. This pattern is unusual in this species because they tend to be highly migratory elsewhere in the world. However, the high abundance of food in the Galapagos, particularly of green sea turtles, is likely the main driver behind the residency pattern found at the GMR. Additionally, analyses of their movements allowed us to establish that they have a tendency to gather around green turtle nesting beaches, their preferred prey item in the archipelago.

Concentrated use areas in red (core areas, 50% of detections), intermediate use in orange (75% of detections), and wider home range area in yellow (95% of detections) of G. cuvier. Map from: Salinas-de-León et al (in review), FCD.
Concentrated use areas in red (core areas, 50% of detections), intermediate use in orange (75% of detections), and wider home range area in yellow (95% of detections) of G. cuvier. Map from: Salinas-de-León et al (in review), FCD.

An in-depth understanding of the patterns of distribution and abundance of sharks, as well as of the biological and environmental variables that influence said patterns, is necessary to develop and evaluate conservation and management plans. In 2015, we deployed baited remote underwater stereo-video systems (stereo-BRUVS) at 48 sites across the GMR. This allowed us to identify spatio-temporal patterns in the composition of shark assemblages within the GMR.

We found a total of 877 sharks of 10 species, which represents just over 1% of all marine animals identified in these videos. The highest abundance (number of individuals) of sharks was found at Darwin and Wolf islands. However, the highest diversity (number of species) of sharks was found at Isabela, Floreana, Santa Cruz and the Daphne islets. The most common shark species across the GMR were the galapagos, hammerhead, blacktip and whitetip, which represented 83% of sharks identified in our videos. These species occupy similar habitats which is why we usually find them together.

We also found sharks did not distribute themselves evenly across the archipelago. Instead, changes in environmental variables, such as seawater temperature, are highly influential in their distribution. Finally, although we found some differences in shark distribution between seasons, they were not big enough to be considered significantly different by our analysis.

Relative abundance of eight species of sharks across sites sampled in 2015. Figure from: Acuña-Marrero et al, 2018. MEPS 593:73-95.
Relative abundance of eight species of sharks across sites sampled in 2015. Figure from: Acuña-Marrero et al, 2018. MEPS 593:73-95.

Thanks to a collaborative effort between the Charles Darwin Foundation, the Galapagos National Park Directorate and Ocean Exploration Trust, we were able to go on expedition on board the E/V Nautilus in June 2015. During this expedition, we explored deep-sea environments within the GMR. Using two Remotely Operated Vehicles (ROVs), we investigated the sea floor around the Iguanas-Pinguinos hydrothermal vent located at a depth of 1.5 km, north of Darwin Island.
We found 157 egg cases from Bathyraja spinosissima, a deep-sea skate, in the area surrounding a vent. The egg cases pictured below were in various states of development, and most of them were found within a 150 m radius of active vents.
Seawater temperature measurements confirmed that the temperature increased as the distance to the vent decreased. This suggests that B. spinosissima is using the warmer area around the vents to incubate its egg cases, which can take as long as 1,500 days (just over 4 years) to hatch.

Since egg cases were found in higher quantities around the hydrothermal vents, we can conclude that this is the first record of these habitats being used as nurseries (areas hosting a great number of juveniles). Due to the long incubation period of these species, these skates are particularly vulnerable to changes in their environment. For this reason, it is necessary to give these areas the highest possible level of protection against human intervention.

The red dot in the map shows the location of the Iguanas-Pingüinos hydrothermal vent. The area surrounding this vent at a depth of 1.5 km was explored using ROVs. On the right, egg cases from B. spinosissima found during the June 2015 expedition are shown. Figure from: Salinas-de-León et al., 2018. Scientific Reports 8:1788.
The red dot in the map shows the location of the Iguanas-Pingüinos hydrothermal vent. The area surrounding this vent at a depth of 1.5 km was explored using ROVs. On the right, egg cases from B. spinosissima found during the June 2015 expedition are shown. Figure from: Salinas-de-León et al., 2018. Scientific Reports 8:1788.

To foster support for shark conservation campaigns, it is of vital importance that we understand the attitudes of local communities towards sharks. To evaluate the public’s perceptions of sharks within the GMR, our team surveyed residents and visitors over 15 years of age in Puerto Ayora (largest human settlement in the archipelago) between October and November 2015.

Based on survey responses, we identified that the aesthetic value, environmental role and their perceived dangerousness were the variables with the biggest influence on the public’s attitude towards sharks.
We also found attitudes varied based on gender, occupation and island residency status. Despite this variability, we found a strong positive correlation between positive attitudes towards sharks and tolerance/support for shark conservation programs.
Our recommendation is for shark conservation policies go in hand with the promotion of positive attitudes towards these animals.

Outreach and Education 

Promoting positive attitudes towards sharks in children of Galapagos. Photo from: Juan Manuel García, CDF.
Promoting positive attitudes towards sharks in children of Galapagos. Photo from: Juan Manuel García, CDF.

Our education campaign “Protect the Fins and the Ocean Wins” was carried out in 2016 on the four inhabited islands of the archipelago: Santa Cruz, Isabela, San Cristobal and Floreana. The main objectives were to change the negative perceptions about sharks and to promote the Galapagos as a model for sustainable co-existence between humans and these animals.

We visited schools to teach children about the importance of sharks in maintaining the health of marine ecosystems, and supporting the local human communities. Overall, we reached more than 1,500 children aged between 9 and 12 years.
In 2017, thanks to the support from Save Our Seas Foundation, we created the Marine Education project. This scheme does not only base itself on scientific information, but it also offers opportunities to experience and explore the marine world to members of the local community. This way they can learn about the marine ecosystems surrounding their islands, and the sharks that inhabit them.

The Charles Darwin Foundation’s Van Straelen Interpretation Center was renovated in 2018, and a permanent exhibition called “Marine World” was set up. This display presents information about the ecological role and anatomy of sharks, the species that inhabit the archipelago, as well as results obtained from our 2016 educational campaign to local, national and international visitors.

Moreover, we created the ‘Sharks Ambassadors’ club, which has more than 50 members, who are local students aged between 12 and 17 years. This program teaches the ambassadors about methodologies that our scientists use to study sharks and other marine species. The club also offers them the opportunity to learn more practical skills, such as species identification while snorkeling. The Shark Ambassadors are empowered to develop activities that promote the conservation of local marine ecosystems so that they can become positive agents of change in their communities.

Shark ambassadors, teachers, naturalist guide and members of the Sharks Project during a fieldtrip in November 2017. Photo from: Daniel Unda, CDF.
Shark ambassadors, teachers, naturalist guide and members of the Sharks Project during a fieldtrip in November 2017. Photo from: Daniel Unda, CDF.

Keywords: Sharks, Galapagos Marine Reserve, conservation, Tropical Eastern Pacific

Bibliographical References

  • Acuña-Marrero, D., Zimmerhackel, J.S., Mayorga, J. and Hearn, A. (2013). First record of three shark species, Odontaspis ferox, Mustelus albipinnis and Centrophorus squamosus, from the Galápagos Islands. Marine Biodiversity Records, 6.
  • Acuña-Marrero, D., Jiménez, J., Smith, F., Doherty Jr., P. F., Hearn, A. R., Green, J. R., … Salinas-de-León, P. (2014). Whale Shark (Rhincodon typus) Seasonal Presence, Residence Time and Habitat Use at Darwin Island, Galapagos Marine Reserve. PloS One, 9(12), e115946.
  • Salinas de León, P., Acuña-Marrero, D., Rastoin, E., Friedlander, A. M., Donovan, M. K., & Sala, E. (2016). Largest global shark biomass found in the northern Galápagos Islands of Darwin and Wolf. PeerJ, 4, e1911. https://doi.org/10.7717/peerj.1911
  • Acuña-Marrero, D., Smith, A. N. H., Hammerschlag, N., Hearn, A. R., Anderson, M. J., Calich, H., … Salinas-de-León, P. (2017). Residency and movement patterns of an apex predatory shark (Galeocerdo cuvier) at the Galapagos Marine Reserve. PloS One, 12(8), e0183669. https://doi.org/10.1371/journal.pone.0183669
  • Pazmiño, D. A., Maes, G. E., Simpfendorfer, C. A., Salinas-de-León, P., & Van Herwerden, L. (2017). Genome-wide SNPs reveal low effective population size within confined management units of the highly vagile Galapagos shark (Carcharhinus galapagensis). Conservation Genetics, 18(5), 1151–1163. https://doi.org/10.1007/s10592-017-0967-1
  • Salinas-de-León, P., Hoyos-Padilla, E. M., & Pochet, F. (2017). First observation on the mating behaviour of the endangered scalloped hammerhead shark Sphyrna lewini in the Tropical Eastern Pacific. Environmental Biology of Fishes, 100(12), 1603–1608. https://doi.org/10.1007/s10641-017-0668-0
  • Acuña-Marrero, D., Smith, A. N. H., Salinas-de-León, P., Harvey, E. S., Pawley, M. D. M., & Anderson, M. J. (2018). Spatial patterns of distribution and relative abundance of coastal shark species in the Galapagos Marine Reserve. Marine Ecology Progress Series, 593, 73–95. https://doi.org/10.3354/meps12505
  • Acuña-Marrero, D., Cruz-Modino, R. de la, Smith, A. N. H., Salinas-de-León, P., Pawley, M. D. M., & Anderson, M. J. (2018). Understanding human attitudes towards sharks to promote sustainable coexistence. Marine Policy, 91(May 2017), 122–128. https://doi.org/10.1016/j.marpol.2018.02.018
  • Arnés-Urgellés, C., Hoyos-Padilla, E.M., Pochet, F. & Salinas-de-León, P. (2018). First observation on the mating behaviour of the marbled ray, Taeniurops meyeni, in the Tropical Eastern Pacific. Environmental Biology of Fishes, 101(12), pp.1693-1699.
  • Cerutti-Pereyra, F., Yánez, A.B., Ebert, D.A., Arnés-Urgellés, C. & Salinas-de-León, P. (2018). New record and range extension of the Deepsea Skate, Bathyraja abyssicola (Chondrichthyes: Arhynchobatidae), in the Galapagos Islands. Journal of the Ocean Science Foundation, 30, pp.85-89.
  • Salinas-de-León, P., Phillips, B., Ebert, D., Shivji, M. S., Cerutti-Pereyra, F., Ruck, C., … Marsh, L. (2018). Deep-sea hydrothermal vents as natural egg-case incubators at the Galapagos Rift. Scientific Reports, 8(1), 1788. https://doi.org/10.1038/s41598-018-20046-4

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