Xyrichtys novacula’s PROTECTION IN THE PITYUSIC ISLANDS: DISTRIBUTION, FEEDING, MICROPLASTICS AND PARASITES

Abstract

[eng] Xyrichtys novacula is a sand burrowing wrasse found in the Mediterranean Sea. It is one of the main recreational fishing targets in the Balearic Islands, where it is commonly called raor and is one of the main targets of recreational fishing. This great fishing focus on raor led to a temporal ban during its reproductive season, to protect this species. The present study is aimed at surveying the actual state of this species in the islands of Ibiza and Formentera. To do so, various aspects of X. novacula’s life were assessed. The study focused on protection levels, and the various aspects were studied in and out of marine protected areas (MPA, Es Freus). Fishery data was studied to obtain the size distribution, captures per fishing effort and mortalities. Gastrointestinal microplastic (MP) content was assessed, as well as oxidative stress biomarkers associated with these microplastics and with the presence of ectoparasites, and stable isotopes were used to evaluate the diet and trophic position of X. novacula. The results showed that MPAs with open fishing areas have very high mortality rates and small sizes, due to overfishing as a result of a pull-effect. MP evaluation revealed a high count of MP (3,7±2,6 items/individual) for both MPA and non-protected area, whereas no oxidative stress was evidenced related to MP presence. Parasite presence did, however, generate certain oxidative stress levels. Individuals from the MPA were found to present a lower number of parasites with respect to the areas out of the MPA. In addition, the activities of antioxidant enzymes – catalase, glutathione peroxidase and glutathione s-transferase- were higher in the liver of fish captured in the areas with more parasites, whereas high SOD values for mucus were found, in the area with low parasite count. On the contrary, Lysozyme values were significantly higher for the high parasite count area. CAT values were also higher for the high parasite count area, although they were not significantly different. As for isotope values, X. novacula was found to have a high plasticity and adaptation when it comes to feeding, which permits its feeding in areas with different food source availability. In conclusion, restricted MPAs can be positive for this species, keeping mortality down and sizes up, as well as offering areas with a lower rate of parasitism, and more stable ecosystems. However, further studies are needed to increase our knowledge on this species in the Pityusic islands, providing tools for its management.