100 million sharks are killed each year

Have you been hearing this statistic in the news and wondered where it came from?

Until now there had been rough estimates of the number of sharks killed each year, but no one had really worked the numbers.

In this study, “Global catches, exploitation rates, and rebuilding options for sharks”, nicknamed the "100 million sharks killed each year" paper, we did some serious number crunching.

How?

We used all the data we could get our hands on to estimate the global catch and mortality of sharks in the year 2000 and 2010.

We incorporated reported and unreported landings (what fishers caught and brought back to shore), discards (what fishers caught and threw back to sea), and shark finning practices (where fishers kept only the fins, and threw back the rest of the shark).

Summing across these, and considering survivorship of the sharks that are discarded (most don’t live), we found that approximately 1.44 million metric tons and 1.41 million tons were killed in 2000 and 2010, respectively.

Using the average weights of sharks by species, we translated these figures into annual mortality estimates, finding that around 100 million sharks were killed in 2000 and 97 million sharks in 2010 — given uncertainties in the datasets, the range is somewhere between 63 and 273 million sharks per year.

Further, to assess the sustainability of these rates, we examined the exploitation rate for sharks as a group. By comparing two independent mortality estimates with an estimate of total global biomass, the calculated exploitation rates ranged between 6.4% and 7.9% of sharks killed per year. This exceeds the average rebound rate (how quickly they can reproduce) for many shark species, further explaining the ongoing declines shark populations.

Who cares?

The consequences of our findings suggest that the impact of unsustainable catch and mortality rates would drive shark populations towards extinction, with impacts that extend across marine ecosystems. This highlights the necessity of a drastic reduction in global shark mortality to facilitate the rebuilding of depleted populations and the restoration of marine ecosystems with functional top predators.

So, what's the big takeaway?

The number of sharks that are killed each year needs to seriously be cut back.

This paper is a call to action, a wake-up call to protect sharks and their role in the ecosystem to keep our oceans healthy.

Outcomes?

The outcomes of this paper have played a pivotal role in driving positive changes and fostering proactive conservation efforts.

In response to the alarming statistics on shark mortality, there has been a notable increase in anti-finning policies. These measures aim to ensure that more sharks are landed intact, discouraging the cruel and unsustainable practice of shark finning. By implementing and reinforcing anti-finning policies, authorities and stakeholders work towards reducing the wasteful and detrimental impact on shark populations.

Additionally, the paper has influenced the establishment of Shark Sanctuaries and other area-based conservation measures. These initiatives create designated zones where sharks are safeguarded from overfishing and exploitation, providing crucial safe havens for their populations. Shark Sanctuaries serve as effective tools in preserving the biodiversity of marine ecosystems by maintaining healthy shark populations and contributing to overall ecological balance.

Moreover, the findings of the paper have contributed to the advocacy for CITES listings to prevent unsustainable international trade of threatened shark species. By placing certain shark species under the protection of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES), international regulations are implemented to curb the trade of these threatened species. Such listings serve as a mechanism to ensure that global commerce does not further endanger already vulnerable shark populations.

The outcomes of this paper have also catalyzed positive changes in shark conservation by promoting advocacy, education, and rallying to support the protection of sharks.

These efforts collectively contribute to a more sustainable and responsible approach to managing and preserving shark populations on a global scale, but more work is needed to make sure these efforts are working and having the intended effect.

eManta: Global Threats to Manta Rays

Have you ever realized that manta rays — the majestic black and white rays that are often features of nature documentaries — are targeted by fishers for their rays and gills (‘gill rakers’ to be exact)?

In the eManta project — Global Population Trends and Human Use Patterns of Manta and Mobula Rays — we evaluated the global threats to manta rays to understand the protections that they need.

*Tip: Do an internet search for “manta gill rakers” to see what we’re talking about!

**NOTE: When we began the project, there was only one named species. By the time we finished, there were three named species. And, shortly after publication, manta rays merged with Mobula rays, or devil rays. This shows how much we’re still learning about even the largest charismatic megafauna, imagine how little we know about the lesser known species.

Project Overview?

People love to dive with manta rays. Tourists fly around the world just to see them. So alarms rang when they started to disappear, and that’s when we were recruited to help.

Like sharks, manta rays reproduce very slowly and are vulnerable to overfishing.

Our eManta project was set up and solicited observations and insights from local, experts in 90 regions of the world.

This comprehensive effort aimed to understand the distribution and threats faced by Mobulidae and we gathered information from 200 to 62,000 dives per region.

Key Findings?

• Mobulids, comprising eleven species, exhibit globally and regionally restricted distributions, congregating in specific hotspots with low sighting frequencies (<1% of dives).

• Nearly half (47%) of the surveyed regions reported declining Mobulid sightings over the past decade, indicating the urgent need for conservation measures.

• While Mobulid ecotourism is prevalent in many regions (45% reported), only 32% of these areas have some layers of protection, emphasizing the need for improved conservation policies.

• Mobulids are being fished and sold in local markets in 16% and 12% of regions, respectively, particularly in areas adjacent to mobulid abundance hotspots and ecotourism regions.

• With the exception of only two countries, fishing and selling of Mobulid rays is not being reported — this means that IUU fishing (illegal, unreported, unregulated fishing) combined with international trade is a threat.

Implications for Conservation?

Our findings underscore the urgent need for improved conservation and monitoring efforts.

Identifying regions where ecotourism and exploitation are in conflict can guide prioritized conservation actions.

The eManta project is also a beacon for participatory and citizen science, and the need for timely, ongoing, scalable research that keeps pace with business and exploitation.

Outcomes?

The discrepancy between the number of countries reporting catch Mobulid rays and those that were actually catching them, suggested widespread unreported and unregulated (IUU) fishing of mantas. This finding was pivotal for advocating for their listing on the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES).

Shark Sanctuaries: Country-Sized Havens for Sharks and Rays

Have you ever wondered about those 'Shark Sanctuaries' you've been hearing about?

You're not alone!

We just published two companion papers — A global overview of shark sanctuary regulations and their impact on shark fisheries and Global evaluation of shark sanctuaries — that delved into Shark Sanctuaries. The first describes what they are and are not, where they are, and their potential to fulfill their goals of protecting sharks and rays from fishing. The second evaluated Shark Sanctuary policies from local perspectives.

What are Shark Sanctuaries?

We defined them as countries where commercial shark fishing is completely banned AND where it is prohibited to possess sharks or shark parts. At the time of publication, Shark Sanctuaries covered fifteen coastal countries spanning the Atlantic, Indian, and Pacific Oceans.

Why?

In response to the rapid declines in shark and ray populations, fifteen countries took a bold step by establishing Shark Sanctuaries since 2009. These areas, covering more than 3% of the world's oceans, aim to protect sharks from fishing and trade. However, despite their widespread adoption, there has been little empirical evaluation of their effectiveness.

How?

For the review, we first read all the policies that comprised the Shark Sanctuary to determine exactly what was and wasn’t allowed and looked for all potential loopholes that could be exploited. For example: Was research allowed to target sharks? What were the penalties? Were traditional and artisanal exceptions made? Did they explicitly define what sharks were and did it include rays? How did they handle transshipments — where the sharks could be landed at sea on another non-fishing vessel (skirting the rule altogether)? Were certain gears that are particularly bad for sharks, or used to target sharks, forbidden? etc.

Then, we used the Sea Around Us fishing data to explore historical fishing, and shark fishing, in each of the Shark Sanctuary countries, which told us which countries would be effected by the Shark Sanctuary and how it might change where and how they fish. For example, a country with high shark catch ratio suggests they were targeting sharks in the sanctuary, and therefore they would need to modify where and how they fish.

The evaluation, was based on a global diver survey that provided a comprehensive snapshot of the conditions within these sanctuaries.

We gathered insights from 438 divers in 38 countries who contributed observations based on a total of 667,033 individual dives. It set a baseline for shark populations (diversity, abundance, occurrence), human interactions, public awareness, and threats. The findings were then compared with observations from 23 other non-sanctuary countries.

Key Findings:

From the review:

We found that although Shark Sanctuaries have the intended effect of reducing shark mortality, there is an urgent need to address bycatch within Shark Sanctuary regulations, and that baseline data are needed to monitor and assess sanctuary effectiveness.

From the evaluation:

• Shark sanctuaries showed less severe declines in shark populations compared to non-sanctuaries, signifying a positive impact on shark conservation.

• Sanctuaries reported fewer instances of sharks being sold in markets, indicating a potential reduction in shark-related commerce.

• Shark Sanctuaries experienced lower overall fishing threats, suggesting a positive influence on curbing harmful fishing practices.

• While some Shark Sanctuaries address direct fishing, there remains significant challenges in addressing bycatch, ghost gear, marine debris, and habitat destruction, which also threaten sharks.

• Participants in Shark Sanctuaries were more optimistic about local shark populations' survival, but emphasized the need for additional conservation efforts.

Implications:

Our results suggest that Shark Sanctuaries can contribute positively to shark conservation. However, the evaluation highlights the need for a more holistic approach. Sanctuaries alone might not be sufficient, as challenges such as bycatch and habitat destruction persist. Urgently needed are higher-resolution data on shark abundance and incidental catch to guide targeted conservation efforts and optimize sanctuary benefits.

Program Evaluation Measures:

Together, our papers highlight the importance of program evaluation within Shark Sanctuaries. Are they working? Under what conditions do they work best? How do Shark Sanctuaries compare to other conservation strategies, like protected areas that cover all species, time-area closures that only protect small areas for a short period of time, or anti-finning policies?

While sanctuaries may reduce shark mortality, addressing bycatch and collecting baseline data become critical components of effective conservation strategies.

In conclusion, these evaluations offer valuable insights into the potential of Shark Sanctuaries as conservation tools and underscore the urgency ongoing assessments to ensure they safeguard sharks in the long-term.

Together, the global eOceans® community is understanding and rebuilding many aspects of the ocean — protected areas, endangered and culturally valued species, blue economy. Learn more about these fields with links listed below.

MARINE PROTECTED AREAS

Marine Protected Areas (MPAs) and other effective area-based conservation measures (OECMS) are needed to protect and restore the ocean — from climate change, biodiversity loss, habitat destruction, destructive fishing practices, etc. They need to perform. Here, we provide a list of papers to learn more about MPAs, MPA performance, methods for data collection and analysis, and other MPA related works.

**For clarity, we only include OPEN ACCESS papers here, but suggest using “Google Scholar” or other reputable search engines to find relevant studies.

BLUE ECONOMY

After centuries of misuse with reliance on the ocean for a livable planet, there is an urgent need to protect and restore ocean health. Concurrently, there is also a push to exploit the perceived untapped wealth of the ocean’s services. These competing interests have elevated the urgency of deliberate marine spatial planning (MSP), with judicial innovations and investments and rigorous rejection of “bluewashed” activities to ensure that both endeavors succeed. That is the Blue Economy.

**For clarity, we only include OPEN ACCESS papers here, but suggest using “Google Scholar” or other reputable search engines to find relevant studies.

Endangered Species

Many species have faced an alarming declines in number and biomass — becoming endangered — due to a multitude of threats, including overfishing, habitat destruction, and climate change. These stem from a lack of data, misinformation, disinformation, and effective lobbying against science-based decision making. Recovering these species is crucial as they play pivotal roles in maintaining the delicate balance of marine ecosystems. The lower they go, the more time, money, and resources it takes to recover them. There are many more species than we can include here.

**For clarity, we only include OPEN ACCESS papers here, but suggest using “Google Scholar” or other reputable search engines to find relevant studies.

Participatory Science

Participatory science (aka “citizen science) is the way forward. It not only facilitates data collection, fosters public engagement and understanding in marine conservation, but it also, essentially, expands what is known about the ocean and the conservation strategies that are needed. Participatory science empowers communities to actively steward their ocean spaces and collaborative enable capacity sharing, fostering a deeper understanding of the ocean and the need for collective action.

**For clarity, we only include OPEN ACCESS papers here, but suggest using “Google Scholar” or other reputable search engines to find relevant studies.