In the last 25 years, nematode parasites of the genus Anisakis have attracted international attention from various socio-economic sectors, with serious concern about the impact of these parasites on seafood quality and safety, and public health (related to both zoonoses and allergy). A knowledge-based understanding of the population structure of Anisakis spp. is useful to provide valuable data about the infection dynamics, host specificity and its ability to adapt to local environments and to climate change by adapting to the food-web structure. This study first aimed to investigate the taxonomic biodiversity of Anisakis spp. collected from commercial fish and cetacean species from the most significant Northeast Atlantic fishing grounds and evaluate the ecological connections of A. simplex and A. pegreffii (L3 and adults) in cetaceans and fish from NW Spain, through the analysis of their genetic diversity and population structure. A total of 1399 Anisakis spp. L3 larvae from six fish species and 475 adults from six cetacean species were identified using the ITS rDNA region as a molecular marker. Molecular identification allowed for the first detection of A. berlandi in European waters parasitizing the long-finned pilot whales Globicephala melas and the first report of A. nascettii and A. zhiphidarum infecting the striped dolphin Stenella coeruleoalba, as well as the identification of A. simplex, A. pegreffii and the hybrid genotype between both species. The analysis of the mitochondrial cytochrome oxidase 2 gene of A. simplex and A. pegreffii, the most prevalent species in FAO area 27, revealed panmictic populations for both species with high haplotype diversity. The predatory–prey relationship involving two major fish species (European hake and blue whiting) and the common dolphin appears to provide an important mechanism for maintaining genetic diversity and structure in major Anisakis species in the NE Atlantic.

Aim: Oviparous elasmobranchs lay benthic eggs with long incubation periods, many of which also require habitat‐forming sessile organisms for their development. However, they are threatened by bottom‐trawling fishing impacts. Here, we aimed to identify the suitable habitat distribution of small‐spotted catshark (Scyliorhinus canicula) egg nursery areas, assess their current protection extent by an existing no‐take MPA network and their coverage by other delimited spatial‐based conservation areas.Location: Balearic Sea, northwestern Mediterranean.Methods: Egg cases were collected over 5 years (2018–2022) by a bottom‐trawling monitoring programme along the eastern coast of the Iberian Peninsula. We used these occurrences and various environmental variables (bathymetry, slope, sea bottom temperature, sea bottom dissolved oxygen and seabed type) to model the habitat suitability of egg nurseries for the species using maximum entropy modelling.Results: Sea bottom temperature was the most important variable explaining habitat suitability of egg nurseries. Small‐spotted catshark eggs were found either attached to or in the same samples as various species of habitat‐forming sessile organisms. We found only 3.6% (381 km²) of the modelled suitable egg nursery habitat in the Balearic Sea to be currently covered by an implemented no‐take MPA network. At the same time, 52% of said MPAs are inadvertently protecting suitable egg nursery habitats (and their associated benthic community), as they were not initially planned with elasmobranchs as conservation targets. Important shark and ray areas (ISRA‐IUCN) were also observed to cover egg nursery habitat (4502 km² or 15.52%) within their boundaries.Main Conclusions: While half of the current MPA surface is providing protection to this elasmobranch species' egg nursery areas and their associated benthic communities, they are not sufficient for their conservation. However, mapping the distributions of these essential fish habitats can help towards the 2030 European conservation target of ‘strictly protecting’ 10% of marine environments.

Marine conservation and spatial planning are seeing increasing interest by stakeholders at the local, regional and international levels to balance biodiversity protection, sustaining fisheries and accommodating new uses of the marine environment. Marine protected areas (MPAs) are one of the most common conservation tools being implemented worldwide to reach conservation targets. However, their implementation does not usually take the heterogeneous distribution of bentho‐demersal communities into account. This has led to uneven conservation of existing communities, resulting in the misinterpretation of current protection coverage levels. Here, we mapped the distribution of the bentho‐demersal community of the Balearic Sea, in the northwestern Mediterranean Sea, using a joint species distribution model of 129 species of fish, crustaceans and cephalopods. We identified three distinct bioregions, and found that only 3.13% of the Shelf, 2.96% of the Upper slope and 0.89% of the Middle slope bioregions are covered by the 1089 km ² of demersal no‐take MPAs included in our analyses. Bentho‐demersal communities were distributed mostly as a factor of bathymetry, but were also clearly delimited by bottom temperature, and had lower species‐rich communities in deeper bioregions. Furthermore, we found a negative effect of bottom trawl fishing on species richness in more heavily fished locations. Our results allow for the evaluation of an already implemented MPA network in the Balearic Sea, and suggest that more coverage is needed to fulfill current conservation set at the European and international levels. In order to achieve meaningful biodiversity conservation and help future marine conservation efforts, increases in MPA coverage will need to be supported by studies such as this one to ensure even representation of all marine bioregions and their communities.

The ocean is increasingly being used by new human activities, fueled by an expansion of the “blue-economy” adding new pressures to the marine environment. These changes are happening fast, and balancing biodiversity conservation and present and future uses of the marine space needs to be done in an equitable way for human and ecological communities. Here, we used a systematic conservation planning approach to generate five different scenarios to inform the extension of marine protected areas using the Balearic Sea as a case study of a region with conflicting high fishing activity and new human uses. These scenarios were designed to (1) maximize biodiversity protection, (2) balance biodiversity and socio-economic costs, and (3-5) ensure fishing fleet equity for 10%, 20% and 30% of area extent. Our results show protecting 30% of the Balearic Sea in line with European commitments of 30x30 (i.e., 10% of fully no-take MPAs and 20% demersal no-take MPAs) through our ‘Equitable’ scenario would require an overall cost of 13% of annual fishing revenue in the area. However, scenarios differ in the final areas selected and the total costs of protection; supporting flexibility in the marine spatial planning process. These differences underscore the importance of evaluating multiple scenarios and objectives to reach biodiversity conservation targets while limiting socio-economic and inequitable costs. Regionally informed systematic conservation planning is key to accommodate human uses and biodiversity conservation in the marine environment. We show a transferable and equitable approach that could be implemented to achieve 30x30 throughout European marine waters.

The location of shark egg nursery areas in the Mediterranean Sea is not well known. Moreover, decades of trawling have depleted flat muddy bottoms of both organic (sessile colonial organisms) and inorganic (rocks) three‐dimensional structures in the western Mediterranean Sea. Here, we present observations of 263 egg cases of small‐spotted catshark ( Scyliorhinus canicula ) that were found attached to artificial mooring structures located within a demersal no‐take MPA at 300‐ to 400‐m depth. The area is located within a previously identified suitable habitat for small‐spotted catshark egg nurseries, and where conservation measures, such as a no‐take MPAs, have been implemented to recover the heavily‐impacted ecosystem. However, the slow growth of habitat‐forming sessile organisms combined with previous extraction of rocks and other objects from the seabed is hampering the recovery of these areas and the reproduction of oviparous sharks such as the small‐spotted catshark. Our findings reveal that three‐dimensional artificial structures with ropes and other attachments placed within suitable egg nursery habitat are effectively used by small‐spotted catsharks to complete their reproductive cycle. Passive conservation tools such as no‐take MPA may be coupled with active restoration activities such as the deployment of artificial structures in order to improve the conservation and recovery of oviparous elasmobranchs and other marine fauna.