Rare shark species found on the southwest coast of Portugal
There is much to learn and discover about the oceans, especially about the deep-sea ecosystems, inhabited by special creatures such as sharks and skates (elasmobranchs). During a field trip in March, our researchers from the DELASMOP project, found and identified on the southwest coast, 15 species of deep-sea elasmobranchs, including some quite rare ones: the goblin shark (Mitsukurina owstoni), the frilled shark (Chlamydoselachus anguineus) and the sailfin roughshark (Oxynotus paradoxus).
After collecting some important data for the researcher’s study, such as measurements and blood samples for diet analysis, the frilled shark was released back into the ocean.
The goblin shark and the sailfin roughshark were not as lucky and did not survive the capture. Thus, the researchers were also able to collect muscle and stomach content samples, which will provide important information about these rare species.
Even though the goblin and frilled shark are categorized as "least concern" on the IUCN Red List, there are still little information about these animals. With fishing vessels venturing into deeper waters due to the depletion of fish stocks close to shore, this may represent a threat to these animals, as they have low resilience to exploitation.
In the Algarve, discards from crustacean bottom-trawl fisheries represent about 70% of the total captured. A large part of the discarded animals in these fisheries are elasmobranchs since several species have no commercial interest or are under some protection through regulatory measures. According to data collected by our researchers in 2018 and 2020, between 80% and 90% of elasmobranchs caught, already arrive onboard dead or in poor condition.
The DELASMOP project aims to fill some knowledge gaps about deep-sea elasmobranchs, study the impacts that these animals undergo due to bottom trawl activities in Portugal, mainly in the Algarve, and try to find solutions to decrease their catches and mortalites in these fisheries. The project is funded by the "Save our Seas Foundation" award that was attributed to the PhD student from the University of Algarve and CCMAR Sofia Graça Aranha.