Effectiveness of shore‐based remote camera monitoring for quantifying recreational fisher compliance in marine conservation areas

1. Marine conservation areas require high levels of compliance to meet conservation objectives, yet little research has assessed compliance quantitatively, especially for recreational fishers. Recreational fishers take 12% of global annual fish catches. With millions of people fishing from small boats, this fishing sector is hard to monitor, making accurate quantification of non‐compliance an urgent research priority.
2. Shore‐based remote camera monitoring was tested for quantifying recreational non‐compliance in near‐shore, coastal rockfish conservation areas (RCAs) in the Salish Sea, Canada.
3. Six high definition trail cameras were used to monitor 42 locations between July and August 2014.
4. Seventy‐nine percent of monitored conservation area sites showed confirmed or probable fishing activity, with no significant difference in fishing effort inside and outside RCAs.
5. Mixed effects generalized linear models were used to test environmental and geographic factors influencing compliance. Sites with greater depth had significantly higher fishing effort, which may imply high, barotrauma‐induced, rockfish mortality in RCA sites.
6. Non‐compliance estimates were similar to aerial fly‐over compliance data from 2011, suggesting that trail camera monitoring may be an accurate and affordable alternative method of assessing non‐compliance in coastal conservation areas, especially for community‐based organizations wishing to monitor local waters.
7. Widespread non‐compliance could compromise the ability of RCAs to protect and rebuild rockfish populations. Increased education, signage, and enforcement is likely to improve compliance.

     

Reconstructing the history of the sand tiger shark (Carcharias taurus) in the Mediterranean Sea

1. Sharks are globally exposed to several anthropogenic threats, which, in many cases, have severely reduced their distribution and have impacted populations. In the Mediterranean Sea, because of its long history of exploitation and the relatively short span of scientific monitoring, reconstructing shark baselines is challenging. Many vulnerable species declined in population abundance and geographic distribution before it was possible to adequately track these changes. Consequently, for many of these species, current conservation assessments are now suffering from a severe case of shifting baseline syndrome, whereby their historical occurrence in the area is questioned.
2. The sand tiger shark (Carcharias taurus) is one of these cases. Characterized by high philopatry, restricted home range, and low interchange between populations, its Mediterranean population may have been severely impacted by the high historical fishing pressure in the region before scientific monitoring began.
3. In this study, the history of the abundance and distribution of C. taurus in the Mediterranean Sea was reconstructed through a comprehensive search of occurrence records in the literature and in museum collections. Between 1810 and 2008, 31 occurrence records and 54 publications provided information on the presence of the species in the area. These records were sparse but systematic over time and indicated occurrence hot spots in the south‐western Mediterranean Sea and in the eastern Adriatic Sea.
4. The presence of ten sightings of juveniles from a total of 18 sightings with length information suggested local parturition. Habitat and extinction models indicate that the area has suitable oceanographic conditions for the occurrence of the species and that the species cannot be considered extinct in the Mediterranean Sea. Our study suggests that there is still hope for the recovery of the species and underlines the crucial role of historical investigations to reconstruct the history of large elasmobranchs in the Mediterranean Sea.

     

Cold‐water coral Madrepora oculata in the eastern Ligurian Sea (NW Mediterranean): Historical and recent findings

1. Cold‐water coral (CWC) ecosystems are long‐lived, slow‐growing and fragile, which makes them especially vulnerable to physical damage. In recent decades, CWCs have been severely threatened by fisheries, hydrocarbon extraction, pollution and other human activities.
2. In the Mediterranean Sea, some investigations have been carried out on CWC ecosystems, mostly focused on their distributions within the central and eastern basins.
3. Historical reports and fishermen's maps for the eastern Ligurian Sea (NW Mediterranean) from the 1960s document the occurrence of extensive banks of living CWC, mostly Madrepora oculata, between depths of 200 and 500 m.
4. In 2013/2014, multibeam, side scan sonar (SSS) and remotely operated vehicle (ROV) surveys were carried out in that area, specifically in the Levante Canyon, to assess the occurrence, distribution and conservation status of CWC.
5. The SSS and ROV showed numerous trawl tracks and small (10 cm high), dead, buried colonies at 300–500 m. Deeper, between 525 and 575 m, dense populations of living, 1 m high colonies of Madrepora oculata were found on the flanks of Levante Canyon. The deep sites showed colonies overturned or entangled by long‐line fishing activities.
6. The discovery of new CWC banks not yet heavily damaged by fishing activities, suggests that urgent measures for conservation should be taken in the Mediterranean and worldwide. The present limitation of trawl‐fishing to above 1000 m depth, established by the General Fisheries Commission for the Mediterranean (GFCM) in 2005, seems to be ineffective, since CWCs are mostly located at less than 1000 m depth in the Ligurian Sea. A network of high‐seas/deep‐sea marine protected areas (MPAs) would favour a better strategy for protecting substantial areas of CWCs.

     

An interview‐based approach assessing interactions between seals and small‐scale fisheries informs the conservation strategy of the endangered Mediterranean monk seal

1. Small‐scale fisheries may pose a serious threat to the conservation of marine mammals. At the same time various factors have led to the decline of small‐scale fisheries, often making them unsustainable. Current rates of biodiversity loss and the reduction of fish stocks and fisheries dictate a thorough understanding of fisheries‐related issues and the implementation of effective management actions.
2. The Mediterranean monk seal is one of the most endangered marine mammals on Earth; its survival in the eastern Mediterranean Sea is threatened by negative interactions with fisheries. A nationwide questionnaire survey among fishers and port police authorities was carried out in Greece to describe the main characteristics of small‐scale fisheries, and to understand the nature and assess the magnitude of negative interactions between the monk seal and these fisheries. Questionnaire information was verified by a second round of interviews during landings.
3. The main attributes of the fishers, their fishing boats, and their practices were characteristic of the small‐scale fisheries sector. Overfishing was considered the main reason for fish‐stock reduction, and negative interactions with marine mammals was considered the main issue for the fishing sector.
4. Monk seals were present, caused damage, and got accidentally entangled in fishing gear throughout Greece. Damage to fishing gear was recorded mainly during spring and summer, and on average affected 21% of all fishing trips and 1% of nets deployed during a fishing trip.
5. Based on these results, the implementation of general and specific nationwide fishery management and conservation actions are proposed. These actions are mainly aimed at improving fish stock status, changing the behaviour of the fishers, and mitigating seal–fishery interactions in Greece, while promoting the recovery of the Mediterranean monk seal in the eastern Mediterranean Sea.

     

Biological implications of recreational shore angling and harvest in a marine reserve: the case of Cape Creus

• 1. Recreational shore fishing along the coast of the marine reserve of Cap de Creus (NW Mediterranean) was studied in 2007 and 2009 based on roving creel surveys (on‐site angler surveys during which anglers' harvests are examined by the survey clerk). The study aimed to assess the biological impacts of this leisure activity on coastal fish stocks and the potential risks arising from the use of exotic baits.
• 2. Recreational shore fishers employ seven different fishing techniques, of which the bottom fishing rod (a fishing rod whose hooks, together with the bait, lie on the bottom or near it by means of a heavy weight) is by far the most widely used method (nearly 90% of observations). In total, 25 fish species were identified in the catch from the bottom fishing rod.
• 3. The estimated annual shore fishing catches (c.3 tons) are much lower than those obtained by recreational boat and spear fishing (c.20 tons each), and those from commercial (artisanal) fishing (c.50 tons). The weighted mean vulnerability index and trophic level values in the catch from the bottom fishing rod are 52.2 and 4.03, respectively.
• 4. A minimum of 43% of the baits used by the shore anglers were live, non‐native species (mostly polychaetes).
• 5. Overall, results highlight the impact of shore angling on coastal fish communities of a protected area and the increasing environmental risks arising from the use of exotic marine baits, which constitute a potential and unregulated vector of introduction of non‐native species in the Mediterranean. Copyright © 2011 John Wiley & Sons, Ltd.

     

The vulnerability of fish and macroinvertebrate species with bioactive potential in a Mediterranean marine protected area

1. A high percentage of marine animals produce bioactive compounds that may play a leading role in the discovery of future compounds and drugs of marine origin. However, commercial fishing and other human activities leading to sea warming and pollution may affect these marine animals, even putting them in danger of extinction.
2. To date, no comprehensive studies have evaluated the conservation status of Mediterranean species with bioactive potential, which is crucial to better understanding of how these species cope with the impacts of human activity.
3. The study reviewed the bioactive potential and vulnerability of 833 fish and macro-invertebrate species inhabiting the marine protected area of Cap de Creus and surrounding areas. The most active taxa found were Porifera (49 out of 59 species; 83.0%) and Tunicata (17 out of 27 species; 63.0%). The most vulnerable species were Chondrichthyes (eight out of nine species) and Porifera (nine out of 12 species), which together account for over 75% of species classified as such.
4. Results emphasize the need to introduce specific management measures that protect vulnerable species with bioactive potential as this is a valuable component of marine ecosystems, as well as a potential source of molecules with pharmacological properties beneficial for human health.
5. Marine protected areas can contribute to preserving marine species of medical interest and achieving their sustainable use in the marine biotechnology industry.

     

Coastal breeding aggregations of threatened stingrays and guitarfish in the Levant

1. Stingrays and guitarfish are globally threatened by overexploitation, particularly so in the Mediterranean Sea. Nevertheless, very little information is known about their ecology, behaviour, and taxonomy in the Mediterranean, and especially in the Levant, where water temperature, salinity, and the impact of invasive species are relatively high.
2. Although it has been suggested that some species may aggregate in the Levant, this has not been formally documented and the scale of this phenomenon, the taxonomic composition, and the temporal dynamics are unknown.
3. Visual surveys were conducted, which allowed the documentation of stingrays and guitarfish behaviour, and which was not available from data based on fishery catches. The census took place within a marine protected area over a period of 3 years.
4. Altogether, we documented 675 batoid observations. One of the observed species is Endangered (Glaucostegus cemiculus) and one is Vulnerable (Dasyatis pastinaca), whereas the others are classed as Least Concern (Torpedo torpedo and Torpedo marmorata), Data Deficient (Taeniurops grabatus), non‐assessed within the Mediterranean (Dasyatis chrysonota), and Not Evaluated (Himantura uarnak). Results show clear seasonal patterns, with dense aggregations recorded during spring and early summer, when densities reached 85 observations per kilometre. In addition, there were clear indications of breeding behaviour in D. pastinaca and D. chrysonota, including the first recorded documentation of D. pastinaca courtship in the Mediterranean.
5. Large seasonal stingrays and guitarfish aggregations in shallow waters have not, to our knowledge, been documented in the Mediterranean Sea previously. This highlights the importance of conserving shallow habitats as potential breeding grounds. As these sites are easily reached while both snorkelling and diving, the aggregation of these charismatic species can serve as potential ecotourism sites. Finally, this study shows the benefits of using simple visual census, as opposed to catch‐based methods, to record both the diversity and the behaviour of batoids.

     

Sea turtles bycatch in the Adriatic Sea set net fisheries and possible hot‐spot identification

1. Bycatch resulting from fishing activities is the main threat for the conservation of sea turtles in the Mediterranean Sea. Fixed nets are a matter of concern for sea turtles mainly in coastal areas during the neritic stage when both juvenile and adult life stages are affected. Mortality caused by entanglement in set nets is related to forced apnoea due to the high soak time of the nets and consequent drowning.
2. This study investigated the loggerhead turtle bycatch in set net coastal fisheries in the northern Adriatic Sea (General Fisheries Commission for the Mediterranean Geographical Sub‐Area 17, [GSA 17]) through an interview‐based approach, to understand the potential contribution of these fisheries to the general decline of the sea turtle population. A second goal was to identify a possible hot‐spot turtle bycatch area through on‐board observations.
3. The study estimates that more than 5400 turtles are caught in the west GSA 17 each year with the largest number in the summer. A hot‐spot for entanglement was also identified in an area located south of the River Po delta (41.5–69 m depth) during the summer. Sixty‐four turtles were caught over a period of 30 fishing days by either trammel nets and gillnets (0.7 and 0.5 turtle per km of net respectively) and was the greatest number that has been observed anywhere in the Mediterranean.
4. Possible management strategies to reduce bycatch include technical modification to gear setting (such as reducing netting slack and using small meshes), bycatch reducer devices (such as LED UV), and area and seasonal gear restrictions to small‐scale fisheries in areas of greatest concern in the northern Adriatic Sea.

     

Using historical fisheries data to predict tuna distribution within the British Indian Ocean Territory Marine Protected Area,and implications for its management

1. Recently, several large marine protected areas (MPAs) have been established globally, and it is hoped that they will aid the recovery of populations of highly mobile, large pelagic species. Understanding the distribution of these species within MPAs is key to delivering effective management, but monitoring can be challenging over such vast areas of open ocean.
2. Historical fisheries data, collected prior to MPA establishment, can provide an insight into the past distributions of target species. We investigated the spatial and temporal distribution of yellowfin (Thunnus albacares) and skipjack (Katsuwonus pelamis) tuna catch using logbook data from the purse seine fishery in the British Indian Ocean Territory from 1996 to 2010, before it was established as an MPA in April 2010.
3. Generalized additive models were used to predict tuna presence and relative abundance from fishing records in relation to temporal and environmental variables. Significant variables included sea salinity, temperature, and water velocity.
4. Predictions from the models identified a distinct hotspot for large yellowfin tuna within the MPA, and areas of high predicted relative abundance of skipjack tuna. We recommend that these areas are used as focal points from which populations can be monitored and investigations into tuna residency time can occur, so that the effectiveness of the MPA in conserving highly mobile pelagic fish can be determined.

     

Citizen science helps assessing spatio‐temporal distribution of sea turtles in foraging areas

1. Spatio‐temporal distribution is fundamental information for species of conservation concern, like sea turtles, that are threatened by anthropogenic activities at sea such as fishing. While coarse‐scale distribution information is available for several sea turtle populations, fine‐scale distribution informing on hot‐spot areas for spatial management is more difficult to obtain.
2. Here a citizen science approach involving tourism boats was undertaken to investigate the spatio‐temporal distribution of the loggerhead sea turtle (Caretta caretta) in the Pelagie Archipelago, located in a major foraging area for this species in the Mediterranean and where high fishing‐induced mortality occurs. The study was designed to provide data of absence and total sampling effort, commonly under‐reported in citizen science studies, allowing comparison among zones and periods. This was complemented by reports from fishing vessels.
3. Tourism boats reported 584 loggerhead turtle sightings during 1718 daily trips and fishing vessels reported 280 loggerhead turtles captured during 1040 fishing days. The results indicate a strong heterogeneous distribution in the Archipelago, with a low turtle occurrence around the main island, Lampedusa, where the highest human presence and activity occur. This may represent rare evidence of displacement behaviour of turtles that is worth further investigation. This also suggests that the current small marine protected area around Lampedusa has a low conservation impact. Zones with higher loggerhead turtle occurrence appear to be in the south and the west parts of the Archipelago, suggesting that spatial management would be possible when relatively small hot‐spots have been identified through specific surveys.
4. This study shows the potential of citizen science for providing preliminary information to guide more demanding and specific investigations. Such an approach may tremendously and rapidly improve the current knowledge on fine‐scale sea turtle distribution in regions with a great extension of coastlines and intensive tourist activities, such as the Mediterranean.

     

Bottlenose dolphins (Tursiops truncatus) in the north-western Adriatic Sea: Spatial distribution and effects of trawling

1. Many species and populations of odontocetes have modified their behaviour to take advantage of feeding opportunities provided by fishing activities, with depredation of fishing gear being the most common type of adaptation.
2. The northern Adriatic Sea has been identified as an important marine mammal area because of a regular occurrence of common bottlenose dolphins. Boat surveys were conducted within a 3,000 km² sector of the Adriatic Sea off the coast of Veneto, Italy, between April and October 2018–2019. Based on 76 days at sea, 10,711 km of navigation, and 81 h 26 min of dolphin tracking, this study contributes novel quantitative information on dolphin spatial distribution, and on their occurrence in the wake of beam trawlers, otter trawlers, and midwater pair trawlers.
3. A combined generalized additive model and generalized estimation equation framework indicated that trawling—along with other physiographic, biological and anthropogenic variables—influenced dolphin distribution. In days of trawling, the chance of encountering dolphins increased by ~4.5 times (95% confidence interval 1.8–11.0) near active beam trawlers, by ~16.0 times (7.1–36.0) near otter trawlers, and by ~28.9 times (12.0–69.6) near midwater pair trawlers.
4. Spatial modelling was used to create maps of predicted distribution, suggesting differences in habitat use between trawling and no-trawling days. Spatial modelling for all days identified a dolphin distribution hotspot of 832 km², situated off the Po river delta.
5. Evidence contributed by this study can be used to inform management action within one of the world's areas most heavily impacted by fishing and other human encroachment. Such management action would help enforce the European Union's Habitats Directive and Marine Strategy Framework Directive, while also informing EU's Maritime Spatial Planning.

     

First attempts towards the restoration of gorgonian populations on the Mediterranean continental shelf

1. In the Mediterranean Sea, gorgonians are among the main habitat‐forming species of benthic communities on the continental shelf and slope, playing an important ecological role in coral gardens.
2. In areas where bottom trawling is restricted, gorgonians represent one of the main components of trammel net bycatch. Since gorgonians are long‐lived and slow‐growing species, impacts derived from fishing activities can have far‐reaching and long‐lasting effects, jeopardizing their long‐term viability. Thus, mitigation and ecological restoration initiatives focusing on gorgonian populations on the continental shelf are necessary to enhance and speed up their natural recovery.
3. Bycatch gorgonians from artisanal fishermen were transplanted into artificial structures, which were then deployed at 85 m depth on the outer continental shelf of the marine protected area of Cap de Creus (north‐west Mediterranean Sea, Spain). After 1 year, high survival rates of transplanted colonies (87.5%) were recorded with a hybrid remotely operated vehicle.
4. This pilot study shows, for the first time, the survival potential of bycatch gorgonians once returned to their habitat on the continental shelf, and suggests the potential success of future scaled‐up restoration activities.

     

Comparative analysis of artisanal and recreational fisheries for Dentex dentex in a Marine Protected Area

The common dentex, Dentex dentex (L.), is an iconic marine coastal fish in the Mediterranean Sea. This study was performed in the Bonifacio Strait Natural Reserve (BSNR), (NW Mediterranean Sea). The aims were to: (1) evaluate temporal variation of the artisanal fishing of common dentex (2000–2012); (2) compare and quantify catch rates, fishing techniques and catch composition for artisanal and recreational fisheries, and determine the influence of management measures by both activities; and (3) estimate the production of both artisanal and recreational fisheries. Fishery data were collected from different artisanal fishing surveys (onboard fishing vessels and landings) and recreational fishing surveys (roving). The gears with the highest rates of exploitation were longline (3554 g per 100 hooks) and Trolling (351 g boat^?1 h^?1 ±SE), respectively, for artisanal and recreational fishing. This study showed that catches by both activities were quantitatively higher in partially protected areas than outside them. Production estimations suggest that the recreational fishery contributes significantly to fishing mortality and that it can magnify the negative effects of artisanal fisheries. Specific measures are needed for the sustainable fishery management of common dentex.     

Historical DNA as a tool to genetically characterize the Mediterranean sand tiger shark (Carcharias taurus,Lamniformes: Odontaspididae): A species probably disappeared from this basin

1. The sand tiger shark (Carcharias taurus) is a coastal species distributed in temperate and sub‐tropical waters, classified as ‘Vulnerable’ at global level and ‘Critically endangered’ in eastern Australia, south‐western Atlantic Ocean, and Mediterranean Sea. Six populations (north‐western Atlantic, Brazil, South Africa, Japan, eastern Australia, and western Australia) with low genetic diversity and limited gene flow were identified worldwide, but genetic information for many other geographic areas are still missing. Specifically, this species is listed in several reports as part of the Mediterranean fauna, even if there has been a lack of catches and sightings in recent years in this basin. To clarify the origin of C. taurus individuals caught in the past in the Mediterranean Sea, historical samples were genetically analysed.
2. Nine samples with certain Mediterranean origin were collected from different European museums. DNA was extracted and ~600 bp of the mitochondrial DNA control region were amplified using eight overlapping species‐specific primer pairs. Sequences obtained were aligned with all the haplotypes globally known so far.
3. Genetic analysis revealed the misidentification of one museum specimen. Among the remaining Mediterranean historical samples, three different haplotypes were recovered. Two of them previously observed only in South Africa and one described in both South African and Brazilian populations.
4. Results suggest a genetic relationship between Mediterranean sand tiger sharks and those from the western Indian Ocean. According to previous studies, we hypothesized that, during the Pleistocene, the cold Benguela upwelling barrier was temporarily reduced allowing the passage of C. taurus individuals from the Indian to Atlantic Ocean. After the restoration of this phylogeographic barrier some individuals were trapped in the Atlantic Ocean and probably migrated northward colonizing the western African coasts and the Mediterranean Sea.

     

Linking small pelagic fish and cetacean distribution to model suitable habitat for coastal dolphin species,Delphinus delphis and Tursiops truncatus,in the Greek Seas (Eastern Mediterranean)

1. A large‐scale assessment of the summertime suitable habitat for Delphinus delphis (short‐beaked common dolphin) and Tursiops truncatus (common bottlenose dolphin) in Greek Seas (Eastern Mediterranean) was conducted using data from dedicated and opportunistic cetacean surveys and published data records.
2. Using a presence/absence approach, generalized additive models were applied to define a suite of environmental, bathymetric and biotic factors that best describe common and bottlenose dolphin spatial distribution, during early (May, June, July) and late (August, September) summer.
3. A geographic information system (GIS) was used to integrate sightings data with environmental characteristics, distance from the coast and sardine probability of presence. These variables were considered as good proxies for defining species‐suitable habitat within the study area's coastal environment.
4. The final selected models were used to produce annual probability maps of the presence of the species in the entire Greek Seas, as a measure of habitat suitability. Based on the mean probability and standard deviation maps for the study period GIS techniques were subsequently used to determine the persistent (areas with high mean and low variation) and occasional (high mean and high variation) habitat of each species.
5. Results showed that there was a high probability of common dolphin presence in areas with a high probability of sardine presence. For bottlenose dolphin, higher probability of the presence of species occurred in areas closer to the shore, with a high probability of sardine presence and with high concentrations of chlorophyll‐a.
6. In both seasons, the North Aegean Sea and the Inner Ionian Sea Archipelago were indicated as the most suitable areas for common dolphin distribution. Persistent habitat areas of the bottlenose dolphin included enclosed seas, continental shelf waters, and waters surrounding islands. The indicated suitable areas are discussed along with deficiencies of the models and future implications for conservation.

Copyright © 2016 John Wiley & Sons, Ltd.     

You cannot conserve a species that has not been found: The case of the marine sponge Axinella polypoides in Liguria,Italy

1. Detailed knowledge about the distribution of species in need of protection is required for the management of Marine Protected Areas, a major tool to reduce marine biodiversity loss. Such knowledge is deficient for most marine invertebrates.
2. Axinella polypoides is a marine sponge included on the list of protected species by the Barcelona Convention (1976) and the Bern Convention (1987). This large and erect species has an important ecological role in habitat forming and benthic–pelagic coupling.
3. Bathymetrical, geographical and ecological data over the last 60 years were collated from publications and reports, together with new surveys to assess the distribution and protection status in Liguria of A. polypoides. It identified a more widespread distribution than previously thought, which points at a general need for dedicated investigations on the occurrence of species that require protection.
4. Bathymetrical distribution was trimodal, with peaks corresponding to different geomorphological settings: coastal cliff bases (around 38 m depth), inner shelf shoals (52 m) and rocks amidst coarse sediment on the outer shelf (79 m). Density was significantly greater at the shallowest depths. The species was mostly found in the coralligenous biocoenosis, in association with other characteristic species or forming a monospecific facies.
5. On (sub)vertical cliffs, A. polypoides often exhibited an unusual cane shape, rather than the typical bushy morphology, thus causing confusion with the congeneric A. cannabina, a more southern species. Records of the latter in the Ligurian Sea therefore need confirmation.
6. Only a minority (22.6%) of A. polypoides records were in Marine Protected Areas, the remainder being located in areas with no current environmental protection plans in place. While the occurrence of this species in MPAs remained stable over the decades, the only quantitative historical data available indicated that populations in non-protected areas were declining owing to anthropogenic impacts (fishing and anchoring).

     

Estimating fishery effects in a marine protected area: Lamlash Bay

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Insights into population genetics,connectivity and demographic history of the longnosed skate Dipturus oxyrinchus (Linnaeus, 1758) in the western Mediterranean Sea

1. Genetic information is crucial for the conservation of Dipturus oxyrinchus (Linnaeus, 1758), a threatened large skate with declining populations over most of its geographical range. The main aim of the present study was to investigate the genetic structure, connectivity and demographic history of the longnosed skate in Sardinia (western Mediterranean Sea).
2. Patterns of population structure were assessed in 175 specimens from six sampling sites. Variation in two mitochondrial genes (cytochrome c oxidase subunit I (COI) and control region) highlighted high genetic diversity and low but significant genetic differentiation among sites, which clustered into three groups corresponding to the north‐west, north‐east and south Sardinian coasts.
3. The observed genetic structuring could presumably depend on a combination of past geological events, contemporary restrictions to dispersal and biological characteristics of the species (e.g. site‐fidelity, no pelagic larval stage, limited dispersal of juveniles and/or adults).
4. Demographic analyses showed signs of past population expansion, but substantial current stability of Sardinian populations. From a conservation perspective, these results are encouraging, and indicate that Sardinian populations are still large and stable, and seem not to have suffered negative side‐effects from the ever‐growing fishing pressure in the region.
5. The occurrence of genetic structuring strongly supported the close monitoring of populations to identify any erosion of their gene pool, and high genetic variability of the Sardinian D. oxyrinchus populations could thus represent priority populations for conservation purposes, providing potential sources for recolonization in cases of local extinctions in other areas of the distribution range of the species.
6. When the sequences from Sardinia were compared with those available from other areas, the data seem to exclude the possibility that the Atlantic and Mediterranean host totally isolated populations or even different species, as recently suggested. However, additional markers and a larger sampling sites are needed to confirm these findings.