Do Sharks Get Terminal Illnesses?

Do sharks get terminal illnesses?

Check out this answer from Consensus:

Sharks are vulnerable to a range of terminal illnesses, including bacterial, fungal, and parasitic infections, as well as injuries related to human activities. Understanding these diseases and their impacts is crucial for the conservation and management of shark populations. Further research and diagnostic sampling are needed to better characterize the host-pathogen interactions in sharks and develop effective strategies to mitigate these threats.

Sharks, often perceived as apex predators with few natural threats, are not immune to diseases and terminal illnesses. This article explores various documented cases of terminal illnesses in sharks, highlighting the types of diseases, their causes, and the implications for shark populations.

Types of Terminal Illnesses in Sharks

Bacterial Infections

Sharks can suffer from severe bacterial infections that can lead to terminal illnesses. For instance, a wild sandbar shark (Carcharhinus plumbeus) was found to have a fatal infection caused by Streptococcus agalactiae, a bacterium known for causing epizootic mortalities in both wild and farmed fish species3. This infection was confirmed through post-mortem examination, histopathology, and advanced molecular techniques.

Fungal Infections

Fungal infections are another significant cause of terminal illnesses in sharks. A study reported fatal fusariosis in baby bonnethead sharks (Sphyrna tiburo) due to an atypical strain of Fusarium solani, which showed a predilection for hyaline cartilage5. Additionally, systemic mycosis caused by Paecilomyces lilacinus and dual fungal infection by Exophiala pisciphila and Mucor circinelloides were documented in captive sharks, leading to severe tissue destruction and terminal disease7.

Parasitic Infections

Parasitic infections can also be debilitating for sharks. Research on spiny dogfish (Squalus acanthias) and smooth dogfish (Mustelus canis) revealed various parasitic lesions, including pancreatic nematodiasis and biliary myxosporeosis, which could potentially contribute to natural mortality and morbidity4.

Impact of Human Activities

Fishing Gear-Related Injuries

Human activities, particularly fishing, can indirectly cause terminal illnesses in sharks. A longfin mako shark (Isurus paucus) was found with systemic lesions associated with a retained fishing hook, leading to chronic proliferative and pyogranulomatous pericarditis and myocarditis, ultimately causing the shark’s death1. This highlights the significant impact of delayed post-release mortality on shark populations due to fishing gear.

Environmental Contaminants

Sharks are also susceptible to environmental contaminants that can lead to terminal illnesses. The presence of various bacteria, such as Vibrio spp., in the teeth of a great white shark (Carcharodon carcharias) suggests that these pathogens could cause infections in both sharks and humans, particularly following shark bites6.

Do sharks get terminal illnesses?

Douglas Fenner has answered Likely

An expert from National Oceanic and Atmospheric Administration in Marine Biology

Sharks can get cancer. Cancers aren’t reported often from sharks, perhaps because this isn’t studied very much.

https://www.amnh.org/learn/pd/sharks_rays/rfl_myth/myth_page6.html

Other types of terminal illness probably haven’t been studied much in sharks. Probably, all organisms have diseases, but some organisms are studied much more than others. Humans are the most studied organism.