The scientific name of this species is Astrospartus mediterraneus, in reference to its shape as a shrubby star (aster) (spartos) of the Mediterranean. Depending on the area, it is known as gorgoncephalus (in this case, in relation to the Gorgon, a Greek mythological figure) or brittle star (by the class or taxonomic category of ophiuroids).
It is a relatively common species in various areas of the Mediterranean, as indicated, but little is known and studied, partly because it is a relative of starfish with no commercial fishing value that inhabits -under normal conditions- more than 30 meters deep.
In other words, until now the Astrospartus mediterraneus was one of the many weirdos that survive in relative tranquility in a sea increasingly affected by pollution, overfishing, warming and acidification of the waters, and invasive species.
In recent years, however, fishermen working in the waters of Cap de Creus have observed an increase in the presence of these tree stars in their nets; an involuntary capture that “would be causing havoc in the fishing sector of the area”, according to the Institute of Marine Sciences (ICM-CSIC) in an informative note in which the results of the first scientific study on this problem are presented.
“In 2018, fishermen reported an ‘unusual’ abundance of this starfish, which they caught more and more by accident. This interfered with their activity, as the nets filled with these stars to the point of making work significantly difficult of the fishermen”, explains the ICM-CSIC.
Given this scenario, and taking advantage of the collaboration framework established with the ICM-CSIC thanks to the RESCAP and MITICAP projects, the species was monitored between the months of April and August 2018, with more than 140 trips to sea with the fishermen. In these outings, underwater robots were used to determine the ecology and state of the populations of the species.
“The collaboration with the fishermen has allowed us to become aware of this phenomenon and investigate it. Without this exchange of information, the scientific community would probably have overlooked it”, explains Janire Salazar, biologist, oceanographer and co-author of this study, whose results have also been published in the scientific journal Continental Shelf Research (February 15, 2023).
The results of the study show a preference of the species A. mediterraneus for rocky substrates with the presence of gorgonians -a type of coral- and a steep slope. Likewise, they reveal that the majority are relatively young organisms, which fits with the perceptions of the fishermen and could indicate the beginning of a massive outbreak of the species, which would also seem to be expanding in other parts of the Catalan coast such as the Gulf of León, where significant increases have been detected by the brotherhoods of Llançà, Roses and Palamós.
“If that were the case, it is possible that the population densities that have been observed continue to increase and this could become a chronic situation, so exhaustive monitoring of the population is necessary in order not to endanger the fishing activity” , points out in this sense Andreu Santín, another of the authors of the study.
In fact, following its publication, several guilds on the Catalan coast associated with the Life ECOREST project (which continues the scientific-fisheries collaboration established in the RESCAP and MITICAP projects) have expressed their willingness to monitor the evolution of the species given the interference that causes them in their activity. And it is that, there are many hours that fishermen dedicate to removing brittlestars from the nets, which on many occasions have to end up renewing because they have been damaged due to the capture of this species.
