A silky shark (Carcharhinus falciformis) was seen during a freediving expedition by the dive crew of the M/V White Holly along with CONANP Park Ranger, in the pelagic waters of the Revillagigedo Archipelago. As our freedivers remained calm and still, the shark gently approached us with curiosity. But something was dangling from its mouth – a fishing hook from a longline. The shark had escaped a life-threatening situation but we can’t say where exactly the incident had occurred – silky sharks are a highly migratory species. Fortunately for our shark-friend here, hooks like these rust and dissolve within just a couple of months.
This swift and shiny-looking shark is one of the most commonly caught sharks in pelagic longline and purse seine fishing. Even though purse seiners usually target tuna species and longline fisheries usually target tuna and swordfish, bycatch still results from it. Silky sharks are the most commonly caught shark as bycatch in the eastern Pacific and Gulf of Mexico tuna fisheries, and overall the second-most commonly caught shark as bycatch after the blue shark, worldwide.
Bycatch is an inevitable consequence of commercial fishing.
Bycatch is often left discarded – live, injured or dead.
Bycatch is often unregulated, commonly under-reported, and therefore, illegal in most cases.
Silky sharks are also a targeted species for their valuable fins as the main ingredient in the Chinese celebratory dish, shark fin soup.
Silky sharks get their name from their skin – it has a smooth, “silky” texture. Their extremely good sense of hearing makes them perfect and effective hunters. They dive together with large groups of fish and attack at fast speed with open mouths. Unfortunately, they chase fish at such fast speed that they don’t notice the longlines. The diet of a silky shark usually includes bony fish, such as mullet, mackerel, yellowfin tuna, albacore and porcupine fish, but also squid and pelagic crabs. Longline fishing hooks are NOT part of their diet. Silky sharks can survive up to 23 years. The most vulnerable silky sharks to longline fishing are the immature. They rarely reach the age of 3 years old. Unfortunately, like many other shark species, silky sharks are a very low-producing species – only giving birth to litters of up to 16 pups annually or biennially after a lengthy 1-year gestation period.
The International Union for Conservation of Nature (IUCN) includes silky sharks in the Red List of Threatened Species. Silky sharks are classified as a vulnerable species as they are suffering from a population decline. For this reason, it’s extremely important to understand their behavioral patterns and take the necessary action to protect and conserve their species.
The waters of the Revillagigedo Archipelago are a safe-haven for these beautiful sharks as the area is now a Marine Park with a zero-tolerance policy regarding fishing across its 14-million hectares. It’s important that more nations around the world follow the same efforts in order to better protect their waters from exploitation.
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📸: Melissa Romao / Sea Shepherd