Conservation has become a more popular topic in recent years, with younger generations taking an interest in the well being of endangered species as well as endangered natural resources throughout the world. The blue shark has been listed as a Near Threatened species on the IUCN (International Union for Conservation of Nature) Red List since 2018, and is one of the many animals in need of conservation efforts. It is one of the most easily recognizable shark species due to its brilliant blue color, as well as its extra-long pectoral fins. The fins of the blue shark (Prionace glauca) are highly sought after in the shark fin trade.
Population Data and the Blue Shark
The blue shark is a pelagic species, meaning it lives in the open ocean and is highly mobile. This shark is found in temperate and tropical waters around the world, and off of every continent except Antarctica. Though exact numbers of global blue shark populations have not been definitively established, new studies can help determine population sizes in different areas, giving scientists a closer look at this shark’s ecology.
Low Numbers in the Mediterranean Sea
Between the Gulf of Lion and Malta, blue shark population sizes are small, which makes them more vulnerable to fishing events and high mortality rates. In these particular areas, this species is listed as Critically Endangered (CR) by the IUCN. The blue sharks in this region are classified as “low stock”, and unfortunately, the Mediterranean currently has the highest percentage of threatened chondrichthyans (other cartilaginous fishes including the blue shark) in the world: 53% of the species here are threatened with extinction. Blue shark fishing is unregulated in the Mediterranean sea, making them a highly vulnerable species.
Collecting Data Samples with Non-Lethal Fishing Techniques
Recreational fishermen acting as citizen scientists recently used no-kill line-fishing to help collect samples from blue sharks to identify the genetics and demographics of this species in the Gulf of Lion and the Ligurian Sea in the Mediterranean. These processes allow scientists to create a catalogue of blue sharks in the area, identifying size and gender (establishing age and maturity), as well as plotting GPS coordinates. This information helps to determine how many individuals are present in a particular region and which ones have reached reproductive maturity, providing a clearer picture of the blue shark population. Population dynamics change depending on how many males and females are present, and which of those individuals are capable of mating, with hopes of new pups being born and for populations to increase. If a population is identified and subsequently monitored, there are more opportunities for protection and conservation.
Blue Shark Demographics in the Mediterranean
Between the Gulf of Lion and the Ligurian Sea, the average total length of blue sharks observed in this study measured between 4.25 ft/1.2m) (approx. 2 years old) and 7ft/2m (approx. 5 years old).
This concludes one of two things:
- These juveniles are younger than or are just reaching this species’ estimated age of maturity; or
- They are reaching sexual maturity at smaller sizes, possibly due to the limited space of the Mediterranean Sea (being a smaller body of water compared to the open ocean), or even restrictions on food availability in the area.
Protecting the Blue Shark Today
In November 2022, the blue shark was added to Appendix II of the Convention on International Trade in Endangered Species (CITES) at the 2022 Conference of the Parties (COP19). Adding the blue shark to this agreement shows ambition to regulate the trade of this animal to protect intrinsic populations in its natural habitat. Unfortunately, CITES parties can allow trade to continue if it is “certified” that it does not harm the species’ survival in the wild.
In November 2023, the International Commission for the Conservation of Atlantic Tunas (ICCAT) met and proposed reducing catch quotas for heavily fished blue sharks. An agreement to reduce North Atlantic catch by 23% was met, highlighting intentions to maintain a healthy stock of this species. However, the conclusion of this meeting does not require that all sharks be brought to land with their fins naturally attached. This issue has remained unaddressed for over 15 years.
It is clear that we still have much work to do in protecting the blue shark.
What Can You Do?
There are many ways you can help the blue and other endangered shark species. You can:
- Donate to organizations like Shark Angels fighting for the protection and conservation of sharks around the world
- Write to your local legislators to encourage them to establish conservation areas and to ban shark fishing and finning
- Sign petitions, speak out, and educate others about how important sharks are for the survival of our planet
- Go “shark-free” and avoid buying goods made with shark products such as squalene (shark cartilage & shark liver oil)
- Adopt A Shark with Shark Angels to help support efforts to raise awareness of critical issues facing sharks and protect these and other threatened species!
Written by Candace Drabeck, Everglades University student majoring in Marine Resources and Management and Shark Angels Intern.