Tuesday, September 21, 2021

Dazzling Dolphins in Decline: Conflicts between Conservation and Fisheries

 Guest post by recent UTSC MEnvSc graduate, Samantha Lalonde

How do some people seem to know which career they are going to pursue seemingly before they can even walk? Do they just wake up one morning and decide that they want to be a dentist? In my case, I had no idea what I wanted to do all throughout primary school and most of high school. Then, I was presented with a life-changing opportunity.

 In high school, I was offered the chance to volunteer in the Amazon rainforest in Peru with Operation Wallacea3, a conservation research organization. I lived on a riverboat in the Pacaya Samiria National Reserve4 where I completed field surveys of birds, reptiles, fish, and plants with local and international researchers. I quickly realized that I enjoyed doing field work and studying populations of species. But it was one particular morning, while we were gliding peacefully along the narrow river in our small boat, that I realized that I wanted to pursue studies in conservation. A sound broke the silence; the unmistakable sound of a dolphin breaching the surface of the water to breath. It was then that I was introduced to the dazzling pink river dolphin. I had never even heard of these unique charismatic animals until embarking on this trip. But I couldn’t imagine how anyone, after seeing these creatures, could ever harm them.

After pursuing a degree in environmental science and studying the complex ecological, social, and economic factors surrounding conservation science, I now understand that life isn’t as simple as I thought it was in that moment. People have differing beliefs, priorities, and opportunities for education. All of this to say that the Amazonian river dolphins are in decline, and I’m here to explain to past me (and present you since you’re here) why their conservation isn’t such a clear-cut matter.

Boto river dolphin – Mr Devotor / Charismatic Planet1  

Tucuxi river dolphin – Gregory R. Mann / Ocean Treasures2  

The Amazon basin is home to two dolphin species – the boto or Amazon river dolphin and the tucuxi dolphin. The boto dolphin is larger and completely pink, compared to the tucuxi dolphin, which has a pale pink stomach. The International Union for Conservation of Nature5 (IUCN), an organization working on conservation and sustainable use of natural resources, has assessed both dolphin species under the IUCN Red List6. The IUCN Red List provides information on global species habitat and ecology as well as threats they are facing. Tucuxi was classified as “Data Deficient” in 20107, meaning that there is limited information on the threats, ecology, and population trends for this species. Up until recently, the boto dolphin was also listed as “Data Deficient”, but in 2018, it was uplisted to “Endangered”8 due to studies showing large declines in their numbers.

The uplisting of the boto dolphin to “Endangered” by the IUCN was in part influenced by a study by da Silva and colleagues9 in 2018 that looked at long term changes in river dolphin populations. In this study, dolphin surveys were completed monthly from 1994 to 2017 in one of the largest conservation areas of the Brazilian Amazon – the Mamirauá Sustainable Development Reserve (MSDR). Despite being legally protected8 (bans on commercial fishing in the reserve), the number of botos counted during the surveys halved every 10 years, and the number of tucuxi every 9 years. Why was this happening? The areas in which the researchers were doing their surveys had not significantly increased in human population, food sources for the dolphins were still abundant, and the region had not been affected by dams or mining. The researchers concluded that there was no other obvious reason for declines in dolphin populations other than fishery-related mortality. They noted that the human population in Amazonia is growing rapidly, and so too is their demand for fish. The use of gillnets (a wall of netting that hangs in the water column) was found to have greatly increased during the two decades that the researchers study took place.

Gillnets catch fish that swim into it and catch them by their gills S. Maugeri / FAO10

A recently published study by another group of researchers, Campbell and colleagues11, looked into how fisheries and river dolphins are interacting in the Peruvian Amazon. They used questionnaires that asked about fishing habits, fisher interactions with dolphins, and fisher perceptions and beliefs regarding boto and tucuxi dolphins. Community members who were not directly involved in fishing were also given questionnaires to gather information about beliefs and perceptions about river dolphins and the selling of dolphin body parts.

Most fishers interviewed by the researchers had a negative perception of river dolphins and stated that they had had conflicts with dolphins in their fishing areas. The biggest problems they reported were dolphins getting tangled up in their nets and damaging fishing gear, dolphins stealing fish, and boto dolphins being aggressive towards their boats. These have economic impacts for fishers.

A big problem in dolphin conservation is dolphin by-catch, where fishers are trying to catch specific types of fish but unintentionally also catch dolphins. The study estimated a minimum of 182 dolphins being unintentionally caught per year across the fishers they surveyed. Given this, there may be upwards of 2,000 dolphins being bycaught over the entire area they sampled when you take into account the estimated 9735 fishers working in the area. Even this is a conservative estimate, given that the catching of dolphins is illegal, and so the fishers who filled out the questionnaires likely reported fewer catches than they would have otherwise. Bycaught dolphins may be released alive, dead, or kept and sold as bait or for traditional use. A third of fishers reported knowing someone who used dolphin parts as bait, and 56% of community member reported knowing where dolphin parts were sold. However, only 26% of community members stated that they knew that river dolphins were a legally protected species. River dolphins are primarily used as bait for the rapidly expanding piracatinga (catfish) fishery in South America, despite this practice being illegal.

In 2015, the Brazilian government announced a 5-year prohibition12 on the sale and trade of piracatinga with the intention of putting an end to dolphin hunting. River dolphin conservation is challenging because these fishers have no economic alternatives and there is limited presence of governmental organizations and strategies to help deal with this13. Fishing is practiced by most families living by the river in these areas to meet basic needs and is also one of the leading economic activities in the Amazon. The annual revenue of fishing activities is approximately 80 million USD in the Peruvian Amazon basin11. It is not surprising then, that the fishers in the state of Amazonas immediately pushed for a reduced length of the ban14.  Additionally, in their paper, da Silva and colleagues saw no improvement in dolphin numbers from 2015 to 2017, and suggested that this ban was widely ignored9.

I have come a long way since that first glimpse into conservation science all those years ago in Peru. I know now that when we see these types of debates, we have to remember that conservation is complex, and everyone has different opportunities, perceptions, and priorities. Conservation isn’t just about counting animals from a riverboat. Efforts to safeguard species have to consider the ecological, economic, and social factors surrounding an issue to truly be effective. In this case, clear and enforceable regulations have to be put in place by the government to protect river dolphins. The 5-year ban on piracatinga sale, for example, expired in January 2020 and has not been renewed15. Research into population trends must continue, as well as ways to decrease bycatch. Finally, increased efforts must be put into decreasing the economic reliance of fishers on the sales of river dolphins for bait in the Amazon basin.

Although the thought of juggling all these components of conservation can seem daunting at times, the challenge and the reward of successful conservation and management are worth the effort. I can only hope that more people will rise to the challenge to help the animal that ignited my passion for wildlife conservation all those years ago.


1.        Mr Devotor. The Facts of Amazon River Dolphins. https://www.charismaticplanet.com/facts-amazon-river-dolphins/ (2019).

2.        Mann, G. R. Tucuxi Dolphin. 2019 http://otlibrary.com/tucuxi-dolphin/.

3.        Operation Wallacea. Conservation Research Expeditions. https://www.opwall.com/ (2020).

4.        PROMPERU. Pacaya Samiria Nature Reserve. https://www.peru.travel/en/attractions/pacaya-samiria-national-reserve.

5.        IUCN. International Union for Conservation of Nature . https://www.iucn.org/ (2020).

6.        IUCN Red List. The IUCN Red List of Threatened Species. https://www.iucnredlist.org/ (2020).

7.        Secchi, E. Sotalia fluviatilis. The IUCN Red List of Threatened Species 2012. e.T190871A17583369. https://dx.doi.org/10.2305/IUCN.UK.2012.RLTS.T190871A17583369.en (2020).

8.        da Silva, V. et al. Inia geoffrensis. The IUCN Red List of Threatened Species 2018: e.T10831A50358152. https://dx.doi.org/10.2305/IUCN.UK.2018-2.RLTS.T10831A50358152.en (2018).

9.        Da Silva, V. M. F., Freitas, C. E. C., Dias, R. L. & Martin, A. R. Both cetaceans in the Brazilian Amazon show sustained, profound population declines over two decades. PLoS One 13, e0191304 (2018).

10.      Maugeri, S. fishing with bottom gillnets. FOOD AND AGRICULTURE ORGANIZATION OF THE UNITED NATIONS FAO http://www.fao.org/3/X6935E/X6935E00.htm (1980).

11.      Campbell, E. et al. Coexisting in the Peruvian Amazon: Interactions between fisheries and river dolphins. J. Nat. Conserv. 56, 125859 (2020).

12.      IUCN – SSC Cetacean Specialist Group. Amazon dolphins as fish bait: Brazil introduces a moratorium on piracatinga fishing. https://iucn-csg.org/amazon-dolphins-as-fish-bait-brazil-introduces-a-moratorium-on-piracatinga-fishing/ (2019).

13.      Trujillo, F., Crespo, E., Van Damme, P. A. & Usma, J. S. The Action Plan for South American River Dolphins 2010-2020. (WWF, Fundación Omacha, WDS, WDCS, Solamac, 2010).

14.      InfoAmazonia. Pescadores do Amazonas querem reduzir tempo da moratória da piracatinga (EN: Fishermen from Amazonas want to reduce the moratorium on piracatinga). 2015 https://infoamazonia.org/pt/2015/03/amazon-fishermen-want-to-reduce-time-of-moratorium-on-piracatinga-fish/#!/story=post-12510&loc=-4.389559200000014,-64.55674760000001,7.

15.      Mongabay - EcoWatch. Brazil’s Amazon River Dolphin Faces Extinction After Fishing Moratorium Ends. https://www.ecowatch.com/amazon-river-dolphin-2646191674.html?rebelltitem=1#rebelltitem1 (2020).

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