Author: Bee Smith
The megamouth is a large shark, reaching up to 5.5m or possibly even 6m, and it is named after its proportionally large mouth. It is only one of three filter-feeding sharks, along with the whale and basking shark, feeding on zooplankton such as krill. It is a deep sea species but inhabits deep water during the daytime and comes up to shallower waters at night in order to follow its food.
It was only discovered in 1976 when one became tangled in the anchor of a US Navy ship in Hawaii. Since then, it has been seen less than 300 times, with most sightings involving dead specimens, either washed on shore or caught by fisheries. The locations of these specimens suggest a global range, but a hotpot occurs in East Asian waters along the Kuroshio current between April and August.
The majority of global sightings, around two-thirds, are from fisheries caught in Taiwan. When megamouths come to shallower waters at night, they are caught by large mesh drift net fisheries that target other large pelagic species, which also migrate to surface waters at night, such as sunfish, sailfish, and thresher sharks.
The first public record of a megamouth caught in Taiwan was in 2003, and in 2013 reporting of megamouth became mandatory in Taiwan, which led to a dramatic increase in records. Megamouths had to be reported to the fisheries agency and to the National Taiwan Ocean University (NTOU) shark lab, which enabled scientists to collect tissue samples for genetic analysis and stomach samples to understand their feeding ecology.
After a large number of megamouth catches in Taiwan in 2018, 2019, and 2020, the Environment and Animal Society of Taiwan (EAST) campaigned for a ban of megamouth catching. In late 2020, following this successful campaign, the fisheries agency introduced a ban meaning that if a megamouth is caught it must be returned to the ocean immediately, whether it is dead or alive.
In July and August 2023 I was in Taiwan investigating this policy for a documentary. To explore all sides, I interviewed EAST, megamouth scientists from NTOU and other institutions, and a megamouth fisher and his wife. These interview revealed that there are a number of issues with the catch and release policy, and that a lot of the public information about the megamouth situation in Taiwan is incorrect.
Megamouht after being tagged and released Credit: Zola Chen
In May and June 2024, I went back to film the catch and release, for footage for the documentary, but principally to gain an understanding of whether the sharks likely survived this catch and release. A megamouth scientist from NTOU, Dr. Chi-Ju Yu (Debbie), joined in order to collect tissue samples and place acoustic tags on the megamouths. Zola Chen, an underwater photographer, joined in recording additional in-water footage. Three megamouths were found, which were all alive when removed from the nets and swam away steadily, suggesting they likely survived to release, and hopefully, the tags will provide confirmation.
Bee with a megamouth Image: Zola Chen
I will reveal the true story about megamouth catches in Taiwan in a publicly available documentary soon. But for now, I would like to highlight that megamouth fishers are not evil, they simply see megamouths as any other fish: a source of income that they depend on to make a living. When catch bans are put in place for sharks, they must consider the livelihoods of fishers and give compensation or alternatives, in order to be fair and to be effective. As shark lovers we wish that no sharks were being killed and so catch bans seem an obvious solution, but in reality shark conservation is complex and we have to work with fishers not against them in order to actually protect sharks.
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