March 5, 2025
A study published in the journal Fish and Fisheries this month revealed that fisheries could reduce shark death by requiring the release of threatened sharks caught as bycatch by at least three times. Known as retention bans, the practice requires that fishermen release certain sharks that are endangered or unwanted rather than retain them for their fins, or some other use not intended as food.
Scientists at the the University of California, Santa Barbara’s Bren School, analyzed almost 150 different shark species, caught in large commercial fisheries including longline, purse seine and around FADS. The data estimated mortality rates for an additional 341 species that lacked direct studies on bycatch. Modeling different policy scenarios, the researchers concluded that retention bans could reduce shark mortality by three times on average. However, the reduction is still not enough to ensure the sustainability of heavily fished species, such as mako and silky sharks, or extremely endangered species like the oceanic whitetip.
Once hooked or netted, some species of sharks are far more vulnerable to death after capture than others. Some small sharks and several threatened species, including hammerhead sharks and thresher sharks, had particularly high mortality rates. Deep-sea species also have lower survival due to the extreme temperature and pressure changes they experience when brought up from deepwater.
The bans by themselve will not be enough to save many sharks, the authors conclude. Additional conservation measures, such as restricting certain fishing areas, setting catch quotas, and regulating fishing gear, must be implemented to ensure long-term population stability.
Retention bans, which prohibit the keeping of caught sharks, are a crucial tool in protecting endangered shark species.
Here’s how retention bans contribute:
- Reducing Mortality:
- The primary benefit is a significant reduction in shark mortality. By requiring that caught sharks be released, retention bans prevent them from being killed and landed. This is especially important for slow-reproducing species that are vulnerable to overfishing.
- Even if sharks are caught as bycatch (unintentionally), a retention ban mandates their release, giving them a chance to survive.
- Protecting Vulnerable Species:
- Many shark species are slow-growing, late to mature, and have few offspring. This makes them highly susceptible to overfishing. Retention bans provide a critical layer of protection for these vulnerable populations.
- Endangered or threatened shark species are often specifically targeted by retention bans, ensuring that their populations have a chance to recover.
- Supporting Sustainable Fisheries:
- While retention bans may seem to restrict fishing activities, they can actually contribute to the long-term sustainability of fisheries.
- By preventing the depletion of shark populations, retention bans help ensure that these species remain a part of the ecosystem, which can benefit other commercially important fish species.
- Data Collection:
- Often, retention bans are coupled with requirements to report catches. This allows scientists to gather valuable data on shark populations, distribution, and behavior, which can inform conservation efforts.
Retention bans are a proactive measure to safeguard endangered sharks by prioritizing their survival and promoting the health of marine ecosystems.
Nearly one-third of all shark species are now threatened with extinction, primarily due to overfishing. This loss is not just the sharks, but creates a significant disruption to marine ecosystems and ocean health. Sharks play a vital role in maintaining healthy marine ecosystems. As apex predators, they regulate prey populations and ensure balance within the food web.
By protecting shark populations, retention bans help preserve the ecological integrity of marine ecosystems, including species humans rely upon.
Feitosa, L.M., Caughman, A.M., D’Costa, N.G., Orofino, S., Burns, E.S., Schiller, L., Worm, B. and Bradley, D. (2025), Retention Bans Are Beneficial but Insufficient to Stop Shark Overfishing. Fish Fish. https://doi.org/10.1111/faf.12892