Swellsharks, belonging to the genus Cephaloscyllium, are a group of bottom-dwelling sharks characterized by their ability to “swell” their bodies when threatened, making them appear larger and deterring potential predators. Among them, eight species inhabit Australian waters, with four found in Western Australia alone.
One of the species is the whitefin swellshark (Cephaloscyllium albipinnum). The name ‘albipinnum’ originates from the Latin words “albi” meaning ‘white’ and “pinna” meaning ‘fin,’ referring to the distinctive white margins on its fins. A medium to large shark, typically grayish to brownish in color, its sturdy body features broad dark saddles along its back and large dark blotches on its sides, particularly noticeable in juveniles. Its gill slits are located within a large circular blotch. Despite its limited commercial value, it often ends up as bycatch in various fisheries, leading to declines in its population. Sometimes confused with the Northern draughtboard shark, the whitefin swellshark has long been documented along the southeastern coast of Australia. Yet recent discoveries have extended its range significantly westward into the waters off Western Australia.
Uncovering these sharks in their new location began with a chance encounter. A fisher operating in the deep waters off Albany stumbled upon a specimen ensnared in a commercial giant crab trap at a depth of 853 feet (260 meters) and took a photo of it. “The fisher stated that they are ‘not that rare’ and can get a couple a month in their traps,” the authors of a new paper detailing this discovery explained. “Following these image records, a request for specimens was made and soon after the authors were notifed by the Department of Primary Industries and Regional Development (DPIRD) in Western Australia that they had two frozen swellshark specimens provided by the fisher.” These specimens, meticulously examined and compared with existing descriptions, led the scientists to believe it to be the elusive whitefin swellshark. Genetic analysis using mitochondrial DNA markers provided additional confirmation of their suspicions.
The discovery of a thriving population off the coast of Western Australia holds crucial implications for the conservation status of this unique species. Characterized by its large size and deep-sea habitat, the whitefin swellshark faces significant threats from intensive trawling activities in the Southern and Eastern Scalefish and Shark Fishery. Such relentless fishing practices have led to a drastic decline in population, with a staggering reduction of over 80% in recent generations, as inferred from available data. Previously listed as Critically Endangered due to extensive trawling activities in its known habitat, the westward expansion of its range offers a glimmer of hope. By venturing into less exploited regions, C. albipinnum may find refuge from the pressures of human activity, possibly leading to a reassessment of its conservation status.
However, this newfound territory also presents challenges and uncertainties. Challenges remain on the horizon for these predators – despite their resilience, swellsharks face threats from habitat degradation, climate change, and incidental capture in fishing gear. It’s also unknown how the presence of swellsharks in these waters will impact existing ecosystems. And with them being here, what measures should be taken to ensure their continued survival? These sort of questions underscore the need for ongoing research and monitoring efforts. By incorporating this latest find into future conservation assessments, scientists can better inform policy decisions and management strategies aimed at protecting these vulnerable species.
