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Conservation

How just 3% saves 50%: Small expansions of protected areas in “shark hot spots” could save HALF of currently endangered Sharks, Skates, and Rays

The Great Hammerhead is one of the many imperiled species around the world in need of protection. (Photo from Discovery Communications)

SHARKBITES SATURDAY

Article: Davidson, Lindsay N K, and Nicholas K Dulvy. “Global Marine Protected Areas for Avoiding Extinctions.” Nature Ecology and Evolution 1.January (2017): 1–6. Web.
doi:10.1038/s41559-016-0040

The struggle is real, folks

The struggle is real for many chondrichthyan (sharks, skates, and rays) species threatened with extinction due to overfishing, primarily for the shark-fin trade and sometimes, unintended catch. Shark finning is the process by which sharks are caught, usually by the hundreds on long-line hooks; their fins are then sliced off and they are tossed overboard to drown or bleed to death. Studies have shown that between 70-100 million sharks are killed for their fins every year, and many more shark finning deaths go unreported due to illegal fishing. This rate is unsustainable (not to mention, brutal) and is already showing consequences via dwindling population numbers of particular species up to 90%. This decline will ultimately have major impacts on the rest of the marine ecosystem, and ultimately our own food sources as well.

Fig. 1. The main differences between Skates (Rajiformes) and Rays (Mylobatiformes).
Ocean Treasures Library, www.otlibrary.org

How can we protect Sharks?

The Convention on Biological Diversity has proposed a target goal called Aichi Target 12, which states that “by 2020, the extinction of known threatened species has been prevented and their conservation status, especially of those most in decline, has been improved and sustained.” How do we achieve this goal? One of the many ways is by establishing marine protected areas.

There are a number of marine protected areas (MPAs) across the globe designated for the protection of marine life, 29% of which are designated specifically for shark conservation (Figure 2a). However, many of these areas are not properly enforced due to funding, resources, laws regarding the level of protection, socio-economic human concerns, and targets which are not achievable within the timeframe allotted.

Currently, 24 countries around the world have designated their entire economic exclusive zone (EEZ) (200 nautical miles from the coast) as a Shark Sanctuary, which prohibits all shark fishing within these waters. Many other countries have established laws banning certain types of shark fishing, such as strictly finning sharks without taking the entire shark, fishing for particular species, or limits on the number of sharks fishermen can take. However, there are still countries which do not have any laws regarding the fishing of sharks, many of which have vulnerable species in their waters that are subject to heavy fishing pressures.

Therefore, this target is simply not feasible unless major action is taken to expand and strengthen these marine protected areas. In addition, the vast majority of open ocean is international, and therefore has no governing authority to create or enforce protected areas.

So how do scientists and policy-makers decide where to propose a marine protected area to protect these vulnerable species? How large do they need to be to protect an adequate number of the population for sustainability?

The study

Fig 2. a) A graph of the currently designated Shark marine protected areas, in comparison to the total around the globe. Currently, 29% have been designated specifically for shark conservation. b) This graph shows the number of each Order of chondrichthyans listed on the “IUCN Red Lists”. c) Shows the percentage of the imperiled endemic species of chondrichthyans currently protected within no-take MPAs.

The Earth to Ocean Research Group at Simon Fraser University in British Columbia, Canada set out to find answers to these questions by using information obtained from The International Union for the Conservation of Nature (IUCN) Red lists. These “Red Lists” categorize species based on population status as “Critically Endangered”, “Endangered”, “Vulnerable”, and “Data-deficient, but believed to be vulnerable or endangered”. These lists also include what is known about each species habitat range and migratory routes.

The results: a game of niches

The 2017 study found that there are 99 chondrichthyan species on the current IUCN Red List! (Figure 2b). They found that only 12 species of these sharks, skates, and rays were protected within MPAs; and of those 12 species, only 10% of their migratory range is protected from fishing (Figure 2c). This leaves the rest of their migration routes, and those of the 87-other vulnerable species of sharks, skates, and rays unprotected.

The researchers then set out to find out how much the MPA network would need to be expanded to cover 100% of the territories for the imperiled species on the red list. They discovered that this could be accomplished by expanding MPA reserves to 13% of the economic exclusive zones; however, this would require the expansion in over 70 countries, which is a very difficult task. Currently, the world is having trouble even reaching Aichi Target 11’s goal of 10% of each EEZ protected by 2020, let alone 13%.

So, then the scientists looked at scientific research for hot spots, or areas with the greatest numbers of threatened and endemic species. Endemic means species that live in one specific habitat or niche and are therefore most vulnerable to extinction because of their preference for only one area. They identified hotspots spanning 12 countries within four regions. The inclusion of these hotspots in MPAs would cover over half of the population of each of the 99 imperiled endemic species (Figure 3b). This would require only a 3% expansion of the global EEZs to be designated as no-take marine reserves for Sharks from the current status, which is more achievable toward the Aichi Target 12 goal. (Figure 3a)

However, the study also found that while half of these countries have established shark fishing regulations (which are arguably variable in management and enforcement), four of the countries on the list- Taiwan, Indonesia, Brazil, and Argentina- are not only hot spots for imperiled and endemic species, but are also within the top 10 Shark Fishing countries in the world. This poses a huge conflict of interest in regards to the conservation of sharks, skates, and rays, which would need to be managed much differently in order to meet the Aichi Target 12 goals or the proposed 3% expansion of the global EEZs.

Fig 3. a) A map of the prime areas to designate marine protected areas to protect 50% of the imperiled species within 12 countries. b) The number of imperiled endemic species with migratory routes through the Economic Exclusive Zones of each country, represented by color. Warmer colors represent a higher density of imperiled, native chondrichthyan species. The four regions with the highest numbers include South America, the Indo-Pacific, Western Indian Ocean, and the Western Pacific Ocean. (Davidson and Dulvy, 2017)

Why do we care about fishermen-infested waters?

So, what does this mean for these sharks who swim in fishermen-infested waters? It means that we, as scientists and policy-makers, need to approach conservation by taking into account the human perspectives related to MPAs and biodiversity hotspots. Many of these countries rely on the industry of shark fishing for their livelihoods, usually for sale and trade to Asiatic countries who use shark fins to make soup that is a status symbol in many Asian cultures. Whether we introduce alternative forms of livelihood, or limit the amount of fishing to a sustainable level, the proper inclusion of humans in the design and execution of marine protected areas is essential for success. Such consideration of both sharks and humans in MPA design and implementation could make it possible to protect at least half of the 99 imperiled and endemic sharks, skates, and rays from the threat of extinction, which this study suggests could be achieved with just a 3% expansion of marine reserves within global EEZs to include more shark hotspot regions.

Protecting chondrichthyans is in everyone’s best interest, as these creatures are vital to functioning marine ecosystems and food-webs which feed people around the globe, even those that hunt them for their fins.

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