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(Part 2 of 2) by Alexandra Smith, Blue Parks Intern

Featured Image: Reef Shark at Bikini Atoll, Marshall Islands © Kurt Cotoaga

Read Part 1 Today!


In our last blog, “Sharks Are in Trouble (Part 1 of 2),” we explored the latest evidence that shark populations around the world are in serious trouble. As a keystone species, sharks are crucial to healthy marine ecosystems, but they are currently threatened by overfishing. Fortunately, it’s not too late to turn the tide—if we act now.

How to Turn the Tide for Sharks

When Dr. Nathan Pacoureau and colleagues gathered global data from the IUCN Red List’s Index and the Convention on Biological Diversity’s Living Planet Index to assess global shark populations and associated threats, they discovered massive declines caused by an 18-fold increase in fishing pressure over the last five decades. These data are key in planning for effective fisheries management and global conservation goals. If the data show that enormous fishing activity causes enormous shark losses, then strict science-based measures could mitigate further fisheries impacts and prevent population collapse. [1] Management measures such as shark sanctuaries, protected areas, catch limits, and gillnet/longline restrictions are associated with a greater abundance of reef sharks. [2] Strict measures that minimize bycatch mortality and limit the trade of shark and ray species for human use are also promising solutions. [1] For example, white shark populations which have historically been declining are now recovering in several regions due to bans on retaining these sharks whether caught intentionally or unintentionally; and thanks to strictly enforced quotas, hammerhead populations are rebuilding in the Northwest Atlantic. [1]

Marine protected areas (MPAs) that are well-managed and located in suitable areas can also contribute to healthy shark populations by protecting the sharks from direct threats and conserving the broader ecosystem they inhabit. Both restricted fishing and protected habitat are tremendously important when protecting threatened shark populations. [3] A 2012 study of two MPAs in the Great Barrier Reef Marine Park in Australia found that two shark species (juvenile pigeye and adult spot tail) displayed long-term use of MPAs, demonstrating the conservation benefits these areas have for shark populations. [4] Similarly, a group of Australian researchers who studied shark populations before and after 8 years of strict enforcement of the no-take MPA Ashland Reef in Western Australia, found a significant increase in reef sharks. Their data show just how quickly these previously fished shark communities can recover in well-managed, fully protected MPAs. [5]

Marine spatial planning on the high seas (areas beyond the national jurisdiction of any one country) in particular, is critical because many shark species inhabit open ocean areas and migrate long distances. MPAs that are well-connected and part of a network are very important, considering that sharks are migratory creatures that require large areas in the open ocean. Despite the huge area of high seas on our planet, a recent study found that pelagic (open-ocean) sharks have limited space where they can take refuge from fisheries on the high seas. [6] These areas (Areas Beyond National Jurisdiction, or ABNJ) are more challenging to manage than areas within a country’s jurisdiction or Exclusive Economic Zone (EEZ), since management decisions require international collaboration. That said, there’s hope on the horizon for high seas protection. The world’s nations have spent years trying to update the Law of the Sea treaty at the UN to protect ocean habitats beyond any one nation’s control. The pandemic delayed the final intergovernmental conference intended to discuss the treaty, but when it reconvenes in 2021, Marine Conservation Institute will be working to ensure that the new High Seas Treaty has real teeth for protecting open ocean areas and sharks.

Despite the positive ecological benefits of conservation measures, some developing nations fear they may be at risk of economic losses or financial insecurity if they stop harvesting shark species. [1] So, while prohibiting the trade and consumption of shark meat alone may not be viable, there are sustainable alternatives that could be developed alongside conservation measures that could benefit the local economy while minimizing negative impacts on sharks. For example, people—especially tourists—value biodiversity, so shifting focus toward the biodiversity value of sharks in their ecosystem has the potential to be far more lucrative than selling sharks for their meat. [7] The ecotourism industry is just one example of how maintaining healthy, thriving sharks in the ocean can have more lasting economic value than dead sharks being sold as meat. Better fishery management could also prevent overexploited fish populations and degraded ecosystems from undermining the well-being of fishing-dependent communities. Even if these communities are fishing legally and sustainably, the rest of the world’s practices and climate change affect them greatly.

Shark at Parque Nacional Cabo Pulmo, Mexico. Photo ©Octavio Aburto

A Blue Spark brings the return of sharks

Marine protected areas are an impressive and well tested tool that can transform ecosystems back toward their flourishing, pre-human state. In the Cabo Pulmo marine reserve off of Baja California, just that has occurred. This area, like all others on the Gulf of California, is renowned for its productive, biodiverse ecosystem. Unfortunately, several decades of overfishing had severely depleted the flora and fauna there. Fish stocks dwindled, coral reefs became bleached dead zones, and sharks virtually disappeared. But since the marine reserve was established in 1995, the complete turn-around and restored health of the ecosystem is astounding. Fish biomass has increased by 460%, and predatory sharks and rays now frequently reproduce, feed, and inhabit the area. White-tipped reef sharks, tiger sharks, and bull sharks have all returned to the area. Cabo Pulmo has provided an ideal space for shark populations to rebound, and it became a Blue Spark in 2020, which means Marine Conservation Institute is working with its champions to support its progress toward Blue Park status. [8]

Concluding Remarks

Overfishing of sharks is happening at a much faster pace than fisheries management, protections, and trade regulations are being put in place. [1] Declining shark populations are a pressing issue and must be treated as such by local and national governments. One vital part of the solution is implementing marine protected areas. Since sharks are highly migratory species, ideally these protected areas should be part of an interconnected system, where sharks can take refuge in open ocean habitat, buffering the impacts of fishing and other human activities. This understanding is at the root of our work at Marine Conservation Institute and justifies our recent call to action – supporting the proposed expanded protections around the Galápagos Marine Reserve. Expanding the MPA area there will protect shark migration pathways in the Eastern Tropical Pacific, allowing sharks to more safely migrate between the Galápagos Marine Reserve and the Cocos Island National Park. Both are  Blue Parks that are important safe havens for threatened and endangered shark species), and creating an interconnected MPA system will allow safer movement between the two. [9]

While many shark and ray populations are in critical need, several examples of successful management and conservation action are reason to hope. With well-connected protected areas, sustainably managed fisheries, a sense of urgency, and a dedication to action, there is hope for the recovery of shark populations across the globe.


Sources:

1.Pacoureau, N. et al. (2021) Half a century of global decline in oceanic sharks and rays. Nature 589, 567–571.

2. MacNeil, M.A. et al. (2020)Global status and conservation potential of reef sharks. Nature 583: 801–806.

3. Birkmanis, C.A. et al. (2020) Shark conservation hindered by lack of habitat protection. Global Ecology and Conservation 21: e00862.

4. Knip, D.M. et al (2012) Evaluating marine protected areas for the conservation of tropical coastal sharks. Biological Conservation 148(1): 200-209.

5. Speed, C.W. et al (2018) Evidence for rapid recovery of shark populations within a coral reef marine protected area. Biological Conservation 220: 308-319.

6. Queiroz, N. et al. (2019) Global spatial risk assessment of sharks under the footprint of fisheries. Nature 572, 461–466.

7. National Geographic. “Reef Sharks Are in Major Decline Worldwide.” National Geographic Retrieved Feb 2021 from www.nationalgeographic.com/animals/article/sharks-coral-reefs-decline-worldwide. 

8. Aburto-Oropeza, O. et al. (2011) Large Recovery of Fish Biomass in a No-Take Marine Reserve. PLoS ONE 6(8): 1-7.

9. Marine Conservation Institute (2021) Expanded Protections for Galápagos, Ecuador. Retrieved March 2021 from https://marine-conservation.org/blue-sparks/projects/galapagos-expansion/