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S. luridus, S. rivulatus , P. miles, and E. golanii are four Lessepsians among the approximately 90 alien fish and have already demonstrated detectable negative impacts on local fish stocks and ecosystems in the Mediterranean Sea. The purpose of this review is to evaluate the feasibility and sustainability of their eradication through depletion fishing based on available knowledge and practices because there is positive mutual reinforcement between the altered state of a marine ecosystem due to changes in biogeochemical cycling and fishing and aliens' establishment. Mediterranean artisanal and recreational fisheries already use efficient fishing gear, namely gill and trammel nets for S. luridus and S. rivulatus , spearguns for P. miles, and pelagic trawls for E. golanii. Removal of the aliens of concern restores local fish populations in field and modeling studies but the effects appear not to be long-lasting due to hydrodynamic connectivity with source populations and insufficient local natural mortality and predation either at the early (egg, larva) or later (juvenile, adult) stages of the aliens' growth. Τo transcend the goal of management from local control toward resolution for these four Lessepsians' entry and establishment in the Mediterranean Sea, the re-active intervention of their depletion fishing needs to be aligned with pro-active interventions at their sources of entry and means of transport upstream and with inter-active interventions of their monitoring by the multiple active users of marine resources. Sustainability of the resolution goal will be ensured provided it is designed in the large Mediterranean marine ecosystem jurisdiction, which includes both sources and sinks of aliens; planned locally, which caters for differential effects of aliens on local ecologies, societies, and economies; and considers mediators and moderators of the whole context of multiple-source, multiple-sector, nascent alien trophic web, and altered state of local ecosystems. • most efficient gear is gill and trammel nets (S. luridus and S. rivulatus), speargun (P. miles) , pelagic trawl (E. golanii). • restoration of local fish stocks depends on fishing effort, population densities of aliens, and ecosystem state. • depletion of aliens requires system-level design and regional implementation jurisdiction. [ABSTRACT FROM AUTHOR]

The Mediterranean region is, by far, a prime travel destination, having hosted more than 330 million tourists in 2016, mostly for seaside holidays. A greatly increased influx of thermophilic Red Sea species, introduced through the Suez Canal in a process referred to as Lessepsian invasion (in honor of Ferdinand de Lesseps who instigated the building of the Suez Canal), have raised awareness among scientists, medical personnel, and the public, of health risks caused by some venomous and poisonous marine species. The main species of concern are the poisonous Lagocephalus sceleratus, and the venomous Plotosus lineatus , Siganus luridus , Siganus rivulatus , Pterois miles , Synancea verrucosa, Rhopilema nomadica, Macrorhynchia philippina and Diadema setosum. Recognizing that the main factors that drive the introduction and dispersal of Red Sea biota in the Mediterranean, i.e., Suez Canal enlargements and warming seawater, are set to increase, and international tourist arrivals are forecasted to increase as well, to 500 million in 2030, an increase in intoxications and envenomations by alien marine species is to be expected and prepared for. • Non-indigenous marine species (NIS) have been introduced from the Red Sea into the Mediterranean Sea through the Suez Canal. • A surge of in the number of venomous and poisonous NIS over the past 40 years was noted in the Mediterranean Sea. • Some of them present highly toxic properties and cause human intoxications and deaths. • Several factors (as climate change and modifications of the canal) converge to increase the phenomenon. • As population around the Mediterranean Sea will increase a rise of human intoxications is to be expected and prepared for. [ABSTRACT FROM AUTHOR]

Abstract A lionfish invasion in the Western Atlantic has been one of the most ecologically harmful fish invasions to date. Experience there has shown that its management is most effective when the public and stakeholders are involved. The lionfish (Pterois miles) has recently invaded the Mediterranean, spreading at an alarming rate. To understand lionfish knowledge and perceptions, questionnaire surveys were conducted with a representative cross section of the adult general public (via telephone) and stakeholders (via organised meetings) in Cyprus. Results from 300 public surveys revealed limited awareness about the lionfish but strong support for its local management. Men and older respondents showed stronger support compared to women and younger respondents, respectively. Results from 108 stakeholder revealed high level of awareness and almost unanimous support for management measures. The majority had not experienced any effects from the recent lionfish invasion, but some reported negative impacts such as limited access to dive sites, ecosystem damage and fishing gear destruction. Few stakeholders perceived benefits of this invasive species, e.g. to dive tourism or as a food source. Almost all stakeholders expressed a willingness to get involved in lionfish management, but only around half would consider personal consumption, or sports incentives as good incentives for their participation. Encouragement from scientists through coordination, training and support was suggested as an essential part of effective management strategy. The results of this study can inform an efficient adaptive management process across the Mediterranean region and assist future engagement of citizen scientists in lionfish control and mitigation. [ABSTRACT FROM AUTHOR]

Abstract Mitigating the negative impacts of invasive lionfish (Pterois volitans/miles complex) is a top priority for marine reef fisheries management, with human removals considered the most viable approach to population control. Control efforts via diver spearfishing removals have annually removed tens of thousands of lionfish throughout their invasive range, but the effectiveness of removal efforts to remove 100% or achieve target lionfish densities in a given reef system has not been fully evaluated. Accounting for detection and removal efficacy is necessary for developing and evaluating lionfish management targets, as population- and community-level effects of lionfish removals may be diminished by undetected lionfish remaining in the system. This study quantified lionfish detection, catchability, and removal efficiency to evaluate the effectiveness of lionfish surveys and removal efforts on northern Gulf of Mexico (nGOM) artificial and natural reefs. Detection was assessed during crepuscular and midday time periods via diver and remotely operated vehicle (ROV) video surveys, with covariates for time of day and survey methodology assessed using generalized linear mixed models. Catchability and removal efficiency were estimated via depletion models based on serial removals via spearfishing on 6 artificial reefs and 9 natural reefs. A priori , we had expected lionfish detection to be higher during crepuscular periods given lionfish in the Caribbean and in their native range have been shown to forage more actively away from reefs then. However, we found lionfish detection was not significantly different between midday and crepuscular periods. Survey methodology affected detection, with 24% fewer lionfish being detected via ROV surveys versus diver surveys at artificial reefs and 72% fewer lionfish detected via ROV surveys at natural reefs. Therefore, density estimates on nGOM natural reefs, which constitute of >99% of the region's habitat, may be higher than previously reported and problematic for lionfish management. Mean catchability for spearfishing lionfish was 0.88 on artificial reefs and 0.69 on natural reefs standardized for area. Mean removal efficiency for the first removal event was 87% on artificial reefs and 67% on natural reefs, higher than removal efficiency computed for Caribbean reefs (47%). Incomplete detection and <100% removal efficiency, in concert with density-dependent processes, may explain recent findings that sustained lionfish removal efforts had no discernible positive impacts on native reef fish communities. [ABSTRACT FROM AUTHOR]

This study aims at quantifying and characterising microplastics (MP) distribution in the water column of the NW Mediterranean Sea as well as MP ingestion by the 2 main planktivorous fish of the area, sardine and anchovy. Debris of similar sizes were found in all water column samples and in all but 2 fish guts (out of 169). MP were found in 93% of water column samples with an average concentration of 0.23 ± 0.20 MP·m−3, but in only 12% of sardines (0.20 ± 0.69 MP·ind−1) and 11% of anchovies (0.11 ± 0.31 MP·ind−1). Fibres were the only shape of MP encountered and polyethylene terephthalate was the main polymer identified in water columns (61%), sardines (71%) and anchovies (89%). This study confirms the ubiquity of MP in the Mediterranean Sea and imparts low occurrence in fish digestive tracts. • Microplastics were studied in the NW Mediterranean Sea using 17 stations in 2015. • Microplastic concentration averaged 0.23 ± 0.20 MP·m−3 in the water column. • Microplastic ingestion occurred in only 11–12% of anchovies and sardines. • The main polymer type recovered in each sample was polyethylene terephtalate. • Fibres were the only microplastic shape encountered. [ABSTRACT FROM AUTHOR]

Discarding is major issue globally in terms of conservation, fisheries management and economics. To date, studies on fisheries discards have been primarily focused on large-scale fisheries and little attention was given to small-scale fisheries (SSF) discards. The multi-species and multi-gear nature of SSF in the Mediterranean makes any scientific effort to study discards and management action to regulate discards challenging. The study attempted, for the first time in Levantine Sea, to quantify discards, identify discarded species, and comprehend the causes and drivers of SSF discarding in Cyprus through 208 fishing trips by observing the fishers' regular fishing operations using trammel nets, gillnets, monofilament nets and bottom set longline. Out of the total catch, 1408.385 kg were landed and 956.581 kg were discarded. The majority of discarded individuals were non-indigenous species (73.7 %). Results exhibited a discard rate of 9.92 individuals (4.6 Kg) and a mortality rate of 0.86 per sampled fishing trip, indicating that almost all individuals discarded were released dead. The proportional discards rate (%) out of the total catch was calculated at about 41 % and the average landings/discards ratio in terms of weight was 1.5:1. The five most common discarded species in terms of numbers belonged to osteichthyes and were Sargocentron rubrum followed by Lagocephalus sceleratus , Torquigener flavimaculosus , Scorpaena scrofa and Pterois miles representing 27.8 %, 25.2 %, 13.9 %, 4.7 % and 2.4 %, respectively, of all discarded species. 'Poisonous fish', 'undersized fish' and 'low' and 'no commercial value' fish were the main reasons for discarding. Other reasons included 'prohibited' to land species, 'poor condition' and 'depredated' fish. Elasmobranchs were the second most abundant class accounting for 4.3 % of the total discarded taxa, including threatened, endangered and critically endangered species. Net length, soak time, gear type, and seasonality are the main factors driving discards. The findings of the current work could support the development of national fishery-specific management action plans to mitigate discards and impact on marine ecosystems. • On average, for every 1.5 Kg of landings there was 1 Kg of discards. • Non-indigenous species accounted for a large be part of the discard fraction. • Mortality rate of discarded individuals is relatively high. • Net length, soak time, gear type and seasonality were the main drivers of discards. • Specific management measures are needed to increase fishing gear selectively. [ABSTRACT FROM AUTHOR]

A wide range of ecological and environmental factors influence metal bioaccumulation in fish. Studies of mercury and other metal contaminants in invasive Indo-Pacific lionfish are limited, yet consumption of the invasive predator is increasingly utilized as a management strategy. In this study, we examined the effects of body size, body condition, sex, trophic level, carbon source, diet, depth and capture location on mercury concentrations in lionfish collected from Curaçao. In addition, we examined whether or not a local petroleum refinery is the source of metal contamination in lionfish. Mercury concentrations ranged from 0.008 to 0.106 mg/kg and we found no effect of the petroleum refinery on metal bioaccumulation in lionfish. Low concentrations of metal contaminants indicate lionfish from Curaçao are safe for human consumption. [ABSTRACT FROM AUTHOR]

The management of invasive species can be facilitated by public participation. The drivers of public involvement and success at invasive removal in tournaments (derbies) to catch Indo-Pacific lionfish ( Pterois volitans / miles ) in the Western Atlantic were examined. Information on 69 lionfish derbies held in the wider Caribbean region from 2010 to 2015 was compiled. Derbies attended mainly by artisanal fishers reported lower catches but higher participation than derbies dominated by recreational divers or attended by a mixed public. As predicted, the number of lionfish caught increased with effort and with time since lionfish were established in an area. In contrast, participation was best predicted by national wealth (GDP per capita) and number of local dive shops. From the point of view of public engagement, derbies should therefore be held in areas where lionfish are well established, and where the pool of potential participants is large. However, if the management goal is instead to slow the invasion, early detection is critical. The focus should then shift to areas where no or very few lionfish have been detected, and the derby approach modified to a more frequent or continuous, monitoring-like incentive scheme. [ABSTRACT FROM AUTHOR]

Understanding the drivers and barriers to participation in citizen science initiatives for conservation is important if long-term involvement from volunteers is expected. This study investigates the motivations of individuals from five marine protected areas (MPAs) in the Dutch Caribbean to (not) participate in different initiatives around lionfish. Following an interpretive approach, semi-structured interviews with seventy-eight informants were conducted and analyzed using thematic network analysis. Approximately 60% (n = 48) of informants indicated that they had participated in citizen science initiatives at the outset of the invasion. From this group, almost half said that they still participated in some type of data collection, but only a few did so within a citizen science context. Many informants were initially motivated to participate in lionfish detection and response initiatives due to concern for the environment. Personal meanings attached to both the data collection experiences and to the data influenced informants’ motivations to sustain or cease data collection and/or sharing. In time, the view of lionfish as a threat changed for many informants as this species’ recreational and/or commercial value increased. Enabling and constraining factors for data collection and sharing were identified at the personal, interpersonal, organizational and technical levels. Our findings have implications for the design of future citizen science initiatives focused on invasive species. [ABSTRACT FROM AUTHOR]

Lionfish ( Pterois spp.) are invasive species that have recently spread throughout the Caribbean. Lionfish are available for purchase in local markets for human consumption in several islands of the region. We examined the prevalence of ciguatoxins (CTXs) in lionfish from the French Antilles, a ciguatera-endemic region. The neuroblastoma-2a (N2a) cell assay was used to assess composite cytotoxicity in 120 fish samples collected from the surrounding waters of Guadeloupe (n = 60), Saint Barthélemy Islands (n = 55) and Saint Martin (n = 5). Twenty-seven of these samples exhibited CTX-like activity by the N2a assay. Ciguatoxin (CTX) was confirmed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) in multiple samples that presented highest composite toxicity levels by N2a. Those fish found to contain CTXs were all from Saint Barthélemy. Lionfish from Guadeloupe and Saint Martin did not exhibit toxin activity, although the sample size from Saint Martin was insufficient to draw any conclusions as to the incidence of CTXs. In this study, we provide information about the potential hazard of ciguatera associated with the consumption of lionfish from known endemic areas. We also demonstrate the utility of the cell-based assay combined with LC-MS/MS to assess activity and to provide structural confirmation of CTXs respectively. [ABSTRACT FROM AUTHOR]

The Atlantic invasion of Indo-Pacific lionfish ( Pterois volitans / P. miles ) has been as swift as it has been disastrous. Lionfish are non-native to the Mediterranean, but an invasion is perhaps even more likely than for the Atlantic. First, as for the Atlantic, there are many major cities on the coast of the Mediterranean (where aquarium-keeping is a common practice and chances of accidental and deliberate releases are high), and second, lionfish are native to the Red Sea, to which the Mediterranean is connected via the Suez Canal. Furthermore, there have already been four records of lionfish in the Mediterranean and so the pretext for an invasion is already in place. Up until now, however, it has been difficult to gauge the likelihood of an infestation of lionfish in the Mediterranean as, unlike the Atlantic, this sea has not been examined in terms of its hydrodynamics, ocean climate, and bathymetry, all factors known to be relevant to assessing the possibility of invasion. Motivated by this knowledge-gap, this study used remote sensing and computer modeling to investigate the connectivity between areas along the Mediterranean coastline that fulfill the necessary physical criteria to serve as potential lionfish habitat. Model results from the Mediterranean were compared and contrasted to those from the Atlantic and eastern Pacific. The Atlantic was considered because the lionfish invasion there has been voracious. Meanwhile, the eastern Pacific is interesting as a site without native lionfish, but with plenty of opportunity for their introduction, but no invasion yet recorded. Results indicated that, unlike in the Atlantic, connectivity among potential lionfish habitats in the Mediterranean was low in the study and comparable to that in the eastern Pacific. Although oceanographic conditions in the Mediterranean were found unfavorable for wide dispersion of lionfish larvae, hotspots where numerous lionfish sightings would forewarn an impending invasion were identified. This paper can therefore serve as a guide to the most efficient monitoring of lionfish in the Mediterranean and to where removal efforts should be concentrated, should the species become established. [ABSTRACT FROM AUTHOR]

Highlights: [•] Mercury concentrations in muscle from 107 lionfish were below consumption guidelines. [•] No significant relationship between mercury concentrations and the size of lionfish. [•] No significant difference in concentrations from 2 sampling events in 3 locations. [Copyright &y& Elsevier]

Abstract: Understanding how individuals within a population of invasive organisms disperse during various life history stages has obvious implications for long term population dynamics in the invaded range. With the rapid expansion of the invasive Indo-Pacific lionfish (Pterois volitans and Pterois miles) in the western Atlantic and Caribbean, it has become increasingly important to understand how individuals move following initial recruitment, as this may have critical implications for population control and management. We conducted a 10-month mark–recapture study in the lower Loxahatchee River estuary (Florida, USA) to identify movement patterns and site fidelity in juvenile and young adult lionfish. We tagged 55 lionfish, ranging in size from 45 to 185mm standard length (66–256mm total length). Eighty percent of the tagged fish were recaptured at least one time during the course of the study. Lionfish in this system exhibited extremely high site fidelity over extended periods of time and across multiple size classes. Maximum range occupied by individuals along the shoreline of the estuary was small (mean=28m, asymmetrical 95% CI: 10 to 51m), and did not vary with lionfish size. The majority of lionfish recaptures (74%) occurred at or near (0–10m) the previous capture site, even after weeks or months at liberty. In systems where lionfish exhibit extremely high site fidelity and small maximum ranges, localized population control may be feasible, since lionfish removed from a given habitat would be replaced largely through larval recruitment rather than migration of older individuals. However, since lionfish grow extremely rapidly (averaging 0.46mm/day, but reaching as high as 0.78mm/day in one individual), localized control efforts would need to be carried out frequently in order to maintain a younger, smaller population. Localized control may be less effective if lionfish exhibit greater movement and lower site fidelity in other invaded systems. [Copyright &y& Elsevier]

Abstract: Lionfish, members of the genera Pterois, Parapterois and Dendrochirus, are well known to be venomous, having venomous glandular tissues in dorsal, pelvic and anal spines. The lionfish toxins have been shown to cross-react with the stonefish toxins by neutralization tests using the commercial stonefish antivenom, although their chemical properties including structures have been little characterized. In this study, an antiserum against neoverrucotoxin, the stonefish Synanceia verrucosa toxin, was first raised in a guinea pig and used in immunoblotting and inhibition immunoblotting to confirm that two species of Pterois lionfish (P. antennata and P. volitans) contain a 75kDa protein (corresponding to the toxin subunit) cross-reacting with neoverrucotoxin. Then, the amino acid sequences of the P. antennata and P. volitans toxins were successfully determined by cDNA cloning using primers designed from the highly conserved sequences of the stonefish toxins. Notably, either α-subunits (699 amino acid residues) or β-subunits (698 amino acid residues) of the P. antennata and P. volitans toxins share as high as 99% sequence identity with each other. Furthermore, both α- and β-subunits of the lionfish toxins exhibit high sequence identity (70–80% identity) with each other and also with the β-subunits of the stonefish toxins. As reported for the stonefish toxins, the lionfish toxins also contain a B30.2/SPRY domain (comprising nearly 200 amino acid residues) in the C-terminal region of each subunit. [Copyright &y& Elsevier]

Abstract: Pterois volitans and Pterois miles, two sub-species of lionfish, have become the first non-native, invasive marine fish established along the United States Atlantic coast and Caribbean. The route and timing of the invasion is poorly understood, however historical sightings and captures have been robustly documented since their introduction. Herein we analyze these records based on spatial location, dates of arrival, and prevailing physical factors at the capture sights. Using a cellular automata model, we examine the relationship between depth, salinity, temperature, and current, finding the latter as the most influential parameter for transport of lionfish to new areas. The model output is a synthetic validated reproduction of the lionfish invasion, upon which predictive simulations in other locations can be based. This predictive model is simple, highly adaptable, relies entirely on publicly available data, and is applicable to other species. [Copyright &y& Elsevier]

The common lionfish Pterois miles has rapidly spread across the eastern Mediterranean Sea. We compiled occurrence data from both native and invaded range under the framework of Species Distribution Modelling (SDM). Through a construction of an environmental suitability model and estimation of spread rates we investigated the lionfish climate niche in both its native and invaded domains, this latter represented by the Mediterranean region. Model projections allowed to identify suitable areas for lionfish establishment in the Mediterranean. Spread analysis suggested that a further geographical expansion in this basin could be completed within the next years. Our results did not provide evidence for niche expansion but highlighted a high degree of niche unfilling thus prospecting a likely spread of Mediterranean lionfish invasion beyond the predictions of current SDMs. These findings provide novel inputs to forecast the future geographical evolution of the lionfish in the Mediterranean Sea and asses the related risk of invasion. • The lionfish has an ongoing invasion and can reach until Gibraltar in the next 5 years. • The incomplete invasion makes SDM to fail predicting the full potential of spread. • Invasive SDM has to include data from both the native range and invasive area. [ABSTRACT FROM AUTHOR]

Risk screening tools are being increasingly used to identify the potential invasiveness and associated risks of non-native species. In this study, the Aquatic Species Invasiveness Screening Kit was used to evaluate the invasiveness risks of extant and horizon non-native marine fish species for the coastal waters of South Korea. In total, 57 marine fish species were screened and the threshold scores for the Basic Risk Assessment (BRA) and the BRA + Climate Change Assessment (BRA+CCA) (5.5 and 1.5, respectively) reliably distinguished those species carrying a high risk of invasiveness from those carrying a low to medium risk. For both the BRA and BRA+CCA, common lionfish Pterois miles was the highest-scoring species, followed by white perch Morone americana , red drum Sciaenops ocellatus , marbled spinefoot Siganus rivulatus and redcoat Sargocentron rubrum. The outcomes of this study will contribute to the management of non-native marine fish species for the conservation of the native ecosystems in the coastal waters of South Korea. • Out of 57 marine fish species assessed, 18 were classified as high risk. • 45 species increased invasiveness risk by climate change assessment. • Climate change assessment resulted an increase in all very high risk species. • Standard errors indicated overall similarity in confidence levels and factors. [ABSTRACT FROM AUTHOR]