Search

Batoid fishes are among the most endangered marine vertebrates, yet conservation efforts have been confounded by incomplete taxonomy. Evidence suggest that the critically endangered ‘common skate’ actually represents two species: the flapper skate (Dipturus intermedius) and the blue skate (Dipturus batis). However, knowledge of the geographic range of these two nominal species is limited. Here, DNA sequencing is used to distinguish these species, allowing their spatial distributions to be clarified. These records were also used as the basis for species distribution modelling, providing the first broad scale models for each species across the Northeast Atlantic. Samples were obtained from Iceland, the UK (specifically Shetland), the North Sea and the Azores. Results suggest that D. batis was commonly distributed in the Western Approaches and Celtic Sea, extending out to Rockall and Iceland. D. intermedius generally appears to be less abundant, but was most frequent around northern Scotland and Ireland, including the northern North Sea, and was also present in Portugal. Two individuals were also identified from seamounts in remote areas of the Atlantic around the Azores, the furthest south and west the species has been found. This supports reports that the flapper skate historically had a much wider distribution (which was also highlighted in the distribution model), emphasising the large scale over which fisheries may have led to extirpations. Furthermore, these Azorean samples shared a unique control region haplotype, highlighting the importance of seamounts in preserving genetic diversity.

The complexity and spatio–temporal scale of populations’ dynamics influence how populations respond to large‐scale ecological pressures. Detecting and attributing synchrony (i.e. temporally coincident fluctuations in populations’ parameters) is key as synchronous populations can become more vulnerable to stochastic events that can affect the viability of harvest and have profound consequences to community structure. Here, we aimed to estimate the level of synchrony in fish growth within and among species across 1 million km2 and identify the environmental drivers contributing to synchronous population fluctuations. We developed otolith increment‐based growth chronologies for two deep‐sea scorpaenid fishes (Helicolenus dactylopterus and Pontinus kuhlii) from geographically and bathymetrically disjunct populations in the northeast Atlantic (one species in three locations; two species with different depth preferences). We used hierarchical models to partition variation in growth within and between populations attributing it to intrinsic (age, species, population) and extrinsic (environmental variables) drivers. We assessed synchrony in growth variation within and among species and identified common change points in population specific growth patterns. We documented time‐variant synchrony in growth variation of geographically and bathymetrically segregated deep‐sea fish populations, lasting 25 and 18 years, respectively. The observed synchrony was likely driven by shared environmental forcing (Moran effect) as large‐scale climate indices (East Atlantic pattern and North Atlantic Oscillation) were important environmental drivers of overall growth variation while the onset of synchrony in growth variation was likely related to marine regime shifts occurring in a wide area of the northeast Atlantic that affected the entire ecosystem. However, our capacity to extrapolate growth information across species and locations was dependent on the timing and magnitude of environmental change. Developing a better understanding of the mechanisms driving growth synchrony is key to ensure sustainable management of populations in habitats that are fragile and highly sensible to environmental change, such as the deep‐sea.

The presence of the opal chimaera, Chimaera opalescens, is reported for the first time in the deep waters of the Azores, with the capture of four specimens by fishermen and the video recording of an additional five individuals. Species identification was supported by the 646 bp sequenced fragment of the mitochondrial gene cytochrome oxidase subunit I. Because C. opalescens is a recently recognised species that had been recurrently misidentified as rabbitfish, Chimaera monstrosa, the historical data of C. monstrosa in the Azores were reviewed to assess the possible presence of both Chimaera species in the region. Although several authors have reported the occurrence of C. monstrosa in the Azorean waters since the 1800s, the majority of these are based on only three specimens caught during the late 1800s. The investigation performed using literature and examination of the museum specimens still available concluded that the most likely scenario is that C. monstrosa is absent from the Azores and past records of that species in the region are most likely misidentifications of C. opalescens.

According to the most recent taxonomical revision, the deep-sea dogfish genus Deania encompasses four species. Three of them, D. calcea, D. profundorum, and D. hystricosa, occur in the North Atlantic. Whilst D. profundorum can be identified by the presence of a subcaudal keel, the other two species are not easily visually distinguished. Uncertainties over identification raises concerns over stock units and whether management plans are adequate. In this study we compared onboard visual identification of Deania specimens, with morphological inspection of skin denticles under stereo microscope and with independent molecular taxonomical assignment using two molecular markers. Particular emphasis was paid to specimens identified as D. calcea and D. hystricosa in the NE Atlantic where these species potentially occur sympatrically and may be easily confused. In the past the species have been discriminated on the basis of the size of skin denticles (skin roughness), but our study showed that the crown length of skin denticles covaries with size (and sex), irrespective of species, and therefore this is not a reliable morphological character and should not be used to discriminate between the two species. Phylogenetic analyses did not indicate that D. hystricosa to be a distinct lineage from D. calcea. Interestingly, however four individuals (specimens from: UK, Azores Is., Madeira Is. and Seine seamount) formed a well-defined sub-clade nested within the D. calcea clade, possibly a signature of a past vicariance event or a result of coalescent stochasticity.

The deep ocean ecosystem hosts high biodiversity and plays a critical role for humans through the ecosystem services it provides, such as fisheries and climate regulation. However, high longevity, late reproduction, and low fecundity of many organisms living in the deep ocean make them particularly vulnerable to fishing and climate change. A better understanding of how exploitation and changing environmental conditions affect life-history parameters (e.g., growth) of commercially important fish species is crucial for their long-term sustainable management. To this end, we used otolith increment widths and a mixed-effects modeling approach to develop a 42-year growth chronology (1975–2016) of the commercially important deep-sea fish species blackspot seabream (Pagellus bogaraveo) among the three island groups of the Azores archipelago (Northeast Atlantic). Growth was related to intrinsic (age and age-at-capture) and extrinsic factors (capture location, temperature-at-depth, North Atlantic Oscillation (NAO), Eastern Atlantic Pattern (EAP), and proxy for exploitation (landings)). Over the four decades analyzed, annual growth patterns varied among the three island groups. Overall, temperature-at-depth was the best predictor of growth, with warmer water associated with slower growth, likely reflecting physiological conditions and food availability. Average population growth response to temperature was separated into among-individual variation and within-individual variation. The significant among-individual growth response to temperature was likely related to different individual-specific past experiences. Our results suggested that rising ocean temperature may have important repercussions on growth, and consequently on blackspot seabream fishery production. Identifying drivers of blackspot seabream growth variation can improve our understanding of past and present condition of the populations toward the sustainable management of the fishery.

Background: Orthotospovirus has a wide range of hosts, widely distributed in southwestern China and have serious harm to crop production. Tomato spotted wilt orthotospovirus (TSWV) and Hippeastrum chlorotic ringspot orthotospovirus (HCRV) are seriously harms the quality of pepper (Capsicum annuum L.). However, the detailed molecular mechanism of pepper disease caused by TSWV and HCRV remains obscure.Method: Transcriptome analysis (RNA-seq) based on high-throughput sequencing, with TSVV, HCRV and mock-inoculated plants as controls, to investigate and compare the gene expression changes in pepper leaves, and analyze the plants invaded by orthotospoviruses defensive response.Results: The RNA-Seq results of pepper 1 day after inoculation (1 dpi) showed that the number of differentially expressed genes(DEG) after HCRV infection was greater than that after TSWV infection. Gene Ontology enrichment and KEGG pathway analyses were performed on the two viruses, and the KEGG results showed that DEG were mainly enriched in plant-pathogen interactions, plant hormone signal transduction, and defence processes.Conclusion: The conclusion of this study is that after orthotospovirus infects pepper, the DEG changes in the processes of plant-pathogen interaction, plant hormone and phenylpropanoid synthesis. In addition, transcription factors such as WRKY and MYB changed significantly. These factors comprehensively affect the plant's defence response and ultimately enhance the plant's resistance to viruses. Findings of present study will significantly help enhance our understanding of the complicated defense process of plant responses to orthotospoviruses infection.

It has been emphasized that seafood consumers may have a higher risk of mercury (Hg) exposure. Nevertheless, the co-occurrence of selenium (Se) in organisms may affect the toxicity and bioavailability of Hg. In this work, we aim to demonstrate the possible role of Se as a potential protective element against Hg in muscle and liver tissues of three demersal deep-sea fish species: common mora Mora moro, birdbeak dogfish Deania calcea, and smooth lanternshark Etmopterus pusillus. Comparing species, the birdbeak dogfish D. calcea showed the highest Hg concentrations, the lowest Se levels, the lowest mean Se:Hg molar ratio, a negative HBV-Se index, and no correlation between total length. On the other hand, smooth lanternshark E. pusillus showed the lowest Hg concentrations, the highest Se concentrations, the highest mean Se:Hg molar ratio, a positive HBV-Se index, and a significant positive correlation between total length and Se concentrations in muscle. Comparing tissues, the common mora Mora moro seems to accumulate more Hg and Se in liver than shark species D. calcea and E. pusillus that showed to accumulate Hg and Se preferentially in muscle. Our results indicate that these three species for having Hg concentrations near and above the EU regulatory thresholds and for presenting low Se:Hg ratios, and negative (or low positive) HBV-Se index may pose a real risk of Hg toxicity for the consumer.

The Generic Knowledge Indicator (GKI) was developed to classify the state of knowledge for worldwide fisheries regarding three main components: biological/ecological information, fishery data, and stock assessment. The data quality outcomes (data deficient, low quality, medium quality, high quality) for each of the components results from evaluating sub-criteria for precision, age, spatial scale, and accuracy, which are then combined to obtain the GKI. This framework was tested by studying of the current state of knowledge for snapper and grouper fisheries. Snapper and grouper are important fisheries resources with high commercial value, and they play an important role in the livelihoods and food security of many local communities worldwide. However, the status of many snapper and grouper stocks is unknown, particularly in the small-scale fisheries in developing countries where the reporting system is absent or insufficient. Therefore, to assess the state of knowledge for snapper and grouper, several sources of data were used: fisheries statistical data, stock assessment reports, and a review of a wide range of published studies. Results of the application of the GKI indicate that 70% of the snapper and grouper fisheries included in this study present a low knowledge outcome and only 2% of the cases presented a high outcome. Through the application of the GKI, this work presents an overview of the state of knowledge for the snapper and grouper fisheries worldwide, identifies the main gaps of knowledge, and highlights areas where research improvements are critical to ensure long-term sustainability of these resources.

Small-scale fisheries, demersal, in particular, are a main fishery component in the Azores archipelago, catching a high diversity of species, including “groupers” (Serranidae family) that have high commercial value and demand in the market. Blacktail comber (Serranus atricauda) and Dusky grouper (Epinephelus marginatus) dominate grouper landings, but their fishery status in the Azores is generally unknown. This study applied a length-based approach (Length-Structured Growth-Type-Group Model) to assess the status of grouper fisheries in the Azores, using length-composition data from the commercial fishery and covering distinct gear selectivity and spatial (islands) patterns. Blacktail comber is in worse condition than dusky grouper, with spawning potential ratio (SPR) estimates below 30%, which indicates that this species is fished currently at unsustainable levels in the Azores; SPR for dusky grouper, well above 30%, suggests that this species is fished at sustainable levels. Given the low SPR estimates for Sao Miguel Island, we propose to, urgently, develop, and implement management measures to ensure the recovery and sustainability of blacktail comber. Our findings support the development of management measures that take into account different selectivity by fleet (gear) and the distinct fishing strategies by island (spatial patterns). This study, the first attempt to assess the sustainability status of serranids in the Azores, highlighted limitations of the sampling coverage that deserve urgent fix, as well as other areas where improvements are critical to ensure the sustainability of these resources in the Azores.

Many fish species are well-known obligatory inhabitants of shallow-water tropical coral reefs but such associations are difficult to study in deep-water environments. We address the association between two deep-sea fish with low mobility and large sessile invertebrates using a compilation of 20 years of unpublished in situ observations. Data were collected on Northeast Atlantic (NEA) island slopes and seamounts, from the Azores to the Canary Islands, comprising 127 new records of the circalittoral Labridae Lappanella fasciata and 15 of the upper bathyal Ophiididae Benthocometes robustus. Observations by divers, remote operated vehicles (ROV SP, Luso, Victor, Falcon Seaeye), towed vehicles (Greenpeace) and manned submersibles (LULA, Nautile) validated the species association to cold water corals (CWC) and large hydrozoans. L. fasciata occurred from lower infralittoral (41 m) throughout the circalittoral, down to the upper bathyal at 398 m depth. Smaller fishes ( 10 cm) occurring at

A comparison of the genetic structure of Chimaera monstrosa populations from the Atlantic Ocean and the Mediterranean Sea was carried out using mitochondrial DNA analysis. Results indicate high and significant pairwise ΦST values with no shared haplotypes between the two areas. Furthermore, migration rate estimates suggested absence of gene flow between the two basins. These findings, coupled with the species vertical distribution, suggest that the shallow depth of the Strait of Gibraltar may act as a barrier limiting the dispersal capabilities of these populations, which likely became separated at the end of the middle Pleistocene.

Snapper and grouper are important fisheries resources, with high commercial value and an important role in the livelihoods and food security of many local communities worldwide. However, the status of many snapper and grouper fisheries is unknown, particularly in the cases of small-scale fisheries in developing countries. The main goals of this work are to provide an overview of the current status and trends of these resources and to find alternative sources of information that could be used to determine the status of snapper and grouper fisheries, as well as other data-limited fisheries. Several complementary approaches were explored, including determination of the status of snapper and grouper fisheries based on FAO assessment criteria, analysis of landings time-series trends, and investigation of whether other variables could be used as proxies for fishery status. About half of these fisheries were classified as overexploited, 30% as non-fully exploited and 19% as fully exploited. The FAO landings data indicated that the number of overexploited fisheries has been increasing over the years and that the majority of these fisheries are in transition between the fully exploited and overexploited statuses. The Human Development Index emerged as a potential proxy for the status of the biomass. The multinomial modeling approach explained about 44% of the variability observed in the biomass stock status classification data and indicated a high level of correspondence between original and estimated status, which makes this approach very attractive for application to other data-limited fisheries.

Mapping biodiversity is the marathon of the 21st Century as an answer to the present extinction crisis. A century in which science is also characterised by large scientific datasets collected through new technologies aiming to fill gaps in our knowledge of species distributions. However, most species records rely on observations that are not linked to specimens, which does not allow verification of species hypotheses by other scientists. Natural history museums form a verifiable source of biodiversity records which were made by taxonomists. Nonetheless, these museums seem to be forgotten by biologists in scientific fields other than taxonomy or systematics. Naturalis Biodiversity Center (NBC) in Leiden is care keeper of large collections of marine organisms, which were sampled in the Northeast Atlantic during the CANCAP and Tyro Mauritania II expeditions (1976–1988). Many octocorals were sampled and deposited in the NBC collection, where they became available for study and were partially identified by the senior author (M.G.) in the 1980s. Nonetheless, no checklist or taxonomic revision was published so far with the complete results. In 2016 the first author visited NBC to examine NE Atlantic Plexauridae octocorals. Plexauridae octocoral-vouchered records were listed and mapped to reveal high standard primary biodiversity records unreported so far for the NE Atlantic Ocean. Twenty-four Plexauridae species with ~ six putative new species to science were discovered and eleven new biogeographical records were made from distinct Macaronesian archipelagos. Finally, new depth range records were found for three species at sea basin level and for eight species at a regional scale.

The velvet belly lanternshark, Etmopterus spinax, is a deep-sea bioluminescent squaloid shark, found predominantly in the Northeast Atlantic and Mediterranean Sea. It has been exposed to relatively high levels of mortality associated with by-catch in some regions. Its late maturity and low fecundity potentially renders it vulnerable to over-exploitation, although little remains known about processes of connectivity between key habitats/regions. This study utilised DNA sequencing of partial regions of the mitochondrial control region and nuclear ribosomal internal transcribed spacer 2 to investigate population structure and phylogeography of this species across the Northeast Atlantic and Mediterranean Basin. Despite the inclusion of samples from the range edges or remote locations, no evidence of significant population structure was detected. An important exception was identified using the control region sequence, with much greater (and statistically significant) levels of genetic differentiation between the Mediterranean and Atlantic. This suggests that the Strait of Gibraltar may represent an important bathymetric barrier, separating regions with very low levels of female dispersal. Bayesian estimation of divergence time also places the separation between the Mediterranean and Atlantic lineages within the last 100,000 years, presumably connected with perturbations during the last Glacial Period. These results demonstrate population subdivision at a much smaller geographic distance than has generally been identified in previous work on deep-sea sharks. This highlights a very significant role for shallow bathymetry in promoting genetic differentiation in deepwater taxa. It acts as an important exception to a general paradigm of marine species being connected by high levels of gene-flow, representing single stocks over large scales. It may also have significant implications for the fisheries management of this species.

Indonesia is the most important producer country of snapper and grouper species worldwide, with a notable increase in landings over the past decades. The Java Sea is one of the most frequently fished areas for these species in Indonesia, but in 2016 a decrease in landings was observed. This study applied two approaches (Length-based Indicators and Length-Structured Growth-Type-Group Model) to assess the status of snapper and grouper fisheries in the Java Sea, using length-composition data from the commercial fishery and covering multiple gears with different selectivity. The work focused on the dominant species in the catches: Malabar blood snapper (Lutjanus malabaricus), Areolate grouper (Epinephelus areolatus), Crimson snapper (Lutjanus erythropterus), and Goldbanded jobfish (Pristipomoides multidens). Considerable differences were observed, related to the type of gear used. Catch data obtained from the longline fishery presented good stock status indicators for all species studied. The spawning potential ratio (SPR) estimates calculated for Malabar blood snapper and crimson snapper indicated that these species are currently fished in the Java Sea at unsustainable levels (below 30 % SPR) by the dropline and mixed-gear fleets, while areolate grouper and goldbanded jobfish are not overfished (above 30 % SPR). For both methods, bias in Linf and, secondarily, bias in M/K have a stronger influence on the indicators values, in particular for the proportion of individuals above the length of optimal yield + 10 % (Pmega) estimates and SPR, than bias in Lmat values. This study highlighted other areas where improvements are critical to ensure the sustainability of the snapper and grouper fisheries in the Java Sea.

Small-scale artisanal fisheries can have a significant negative impact in cetacean populations. Cetacean bycatch has been documented in the pole-and-line tuna fishery in the Azores with common dolphins being the species more frequently taken. Based on data collected by observers on ∼50% of vessels operating from 1998 to 2012, we investigate the influence of various environmental and fisheries-related factors in common dolphin bycatch and calculate fleet-wide estimates of total bycatch using design-based and model-based methods. Over the 15-year study dolphin bycatch occurred in less than 0.4% of the observed fishing events. Generalized additive modelling results suggest a significant relationship between common dolphin bycatch and duration of fishing events, sea surface temperature and location. Total bycatch calculated from the traditional stratified ratio estimation approach was 196 (95% CI: 186–205), while the negative binomial GAM estimated 262 (95% CI: 249–274) dolphins. Bycatch estimates of common dolphin were similar using statistical approaches suggesting that either of these methods may be used in future bycatch assessments for this fishery. Our work shows that rates of common dolphin bycatch in the pole-and-line tuna fishery in the Azores are low, despite considerable variations between years. Dolphins caught were released alive although the fate of these individuals is unknown. Continued monitoring will provide a better understanding of dolphin bycatch and more accurate estimates essential in the development of potential mitigation measures.

Cold-water corals and sponges aggregations are important features of the deep sea, recently classified as vulnerable marine ecosystems (VMEs). VMEs increase habitat complexity, believed to act as feeding, reproductive, nursery and refuge areas for a high number of invertebrates and fish species. In the Azores archipelago (NE Atlantic), VMEs are prevalent but their ecological role has not received much attention. The objective of this study was to investigate the importance of VMEs in influencing the distribution of demersal fish in the Azores. With data collected during experimental longline surveys , we modeled the catch of six demersal fish species of commercial value (Helicolenus dactylopterus, Pagellus bogaraveo, Mora moro, Conger conger, Phycis phycis, Pontinus kuhlii) in relation to the presence of VMEs and other environmental factors using General Additive Models (GAMs). Our study demonstrated that total fish catch was higher inside VMEs but the relationship between fish and VMEs varied among fish species. Species specific models showed that catch was strongly influenced by environmental factors, mainly depth, whilst the presence of VMEs was only important for two rockfish species; juvenile and adult P. kuhlii and juvenile H. dactylopterus. Although the association between deep-sea demersal fish and VMEs may be an exception to the rule, we suggest that VMEs act as an important habitat for two commercially important species in the Azores.

Comprehensive trophic studies in the vast mid-oceanic regions are rare compared to coastal and fisheries-oriented investigations. Field sampling conducted by the multidisciplinary, international Census of Marine Life project MAR-ECO, namely the 2004 G.O. Sars cruise, has generated one of the largest open ocean deep-pelagic sample collections ever obtained. With the overall goal of understanding carbon flow processes within and through the deep-pelagic nekton associated with the northern Mid-Atlantic Ridge system (N MAR), quantitative trophic analyses were conducted in order to identify the major intraspecific patterns in diet of characteristic members of the midwater fish community. Diets of five abundant species of zooplanktivorous fishes were examined in detail in terms of prey taxonomy and variability in space, ontogeny and diel cycle. Two major patterns of feeding were identified. Pattern 1 included three species preying primarily on copepods, Argyropelecus hemigymnus, Maurolicus muelleri and Vinciguerria attenuata, the former two of which revealed spatial differences in diet with latitude, mostly likely related to latitudinal prey distributions and densities. Maurolicus demonstrated ecological differences in diet that mirrored phenotypic variation North and South of the Subpolar Front, an “oceanic species concept” question that warrants further research. Pattern 2 included two species feeding primarily on amphipods, Argyropelecus aculeatus and Sternoptyx diaphana, both of which showed ontogenetic variability in feeding primarily related to specific amphipod taxon sizes, rather than prey switching to other major prey taxa. This is the first study that highlights the importance of amphipods in the diets of these species. All fish species showed selectivity in prey choice, possibly related to competition with the other major nekton components along the N MAR, namely the Myctophidae and other zooplanktivorous Stomiiformes. Daily ration fell within the expected values for midwater fishes (1–4% of body weight) with the exception of S. diaphana, suggesting that this species is unique among the zooplanktivores – either its ration is three times higher than the other species, or it eats one-third as often (i.e., every 3 days). Given the high percent stomach fullness observed throughout the diel cycle, we believe the former to be the case, which is the first estimate of its kind for a midwater fish. In order to facilitate further quantitative research on mesopelagic carbon cycling, detailed prey length/weight regressions are presented here.

The variability of phytoplankton biomass (chlorophyll a as a proxy of biomass) and community structure was evaluated over and around the Condor seamount SW of Faial Island in the Azores Archipelago using data provided from five cruises (July and November 2009, and March, July and October 2010). Phytoplankton cell abundance, taxonomy and chlorophyll a concentration were related to both the physical–chemical conditions and to the main circulation patterns observed, bringing new insights into the temporal and spatial variability of phytoplankton. Only microphytoplankton and large nanophytoplankton were identified. Higher phytoplankton abundances were observed during 2010 with a maximum in October (1.3×105 cells.L−1), and higher biomasses were reported at sub-surface in March (0.43 mg Chl-a.m−3). Diatoms were the dominant group (e.g., Pseudo-nitzschia spp. and Chaetoceros spp.) except in November 2009 when coccolithophores dominated (e.g., Ophiaster spp.). Significant differences were found between seasons but not in space, and salinity appears to be an important factor contributing for this seasonal variation. The present study also provides, for the first time, a list of phytoplankton species for this seamount.

The offshore rockfish ( Pontinus kuhlii ) is a widespread demersal fish in the temperate eastern Atlantic. This species inhabits hard bottoms at depths between 100 and 600 m and it is an important resource for the Azorean commercial fishing fleet. During several research fishing surveys in the Azores, Madeira and Cape Verde archipelagos diverse biological data on this species were collected. The degree of geographical population differentiation across the three Atlantic archipelagos was examined using two mitochondrial markers, control region (CR) and cytochrome b (cyt b). A total of 44 specimens were sequenced for each marker revealing high haplotypic diversity (CR: H d =0.9736; cyt b: H d =0.8520) and low nucleotide diversity (CR: π =0.0171; cyt b: π =0.0059). The sample size from the different subareas was limited but sufficient to reveal that no genetic structure was evident ( Φ ST =−0.0465 to −0.0224), suggesting the existence of one panmictic population. Despite very different exploitation rates between archipelagos, the size structure of P. kuhlii was very similar and inter-annual variation was also low. Exploitation rates are probably too low to significantly affect the size structure, even in the Azores where the species is a secondary target of the commercial fishery. In the Azores region this species is more abundant on seamounts, however bigger fishes tend to occur on island slope than on seamounts.

Commercial fishing data were analyzed in order to reconstruct the history of the demersal fishery on Condor seamount, a temporarily protected area in the Northeast Atlantic (Azores). Considering the eight commercially most important demersal fish species, estimates for the period 1993–2009 revealed that on average landings from this area represented 2% of the annual landings by weight of these species in the Azores. Over this period the average estimated volume of the Condor landings was 71 t/year, with the blackspot seabream (Pagellus bogaraveo) and the wreckfish (Polyprion americanus) representing about 54% of the landings, and the average value was €346 thousand per year. Annual trends of landings and of landings per unit effort suggest species-specific abundance responses to fishing, but most of the exploited species may have been significantly reduced at the Condor seamount. The proportion of large specimens may have declined in some of the studied species. Results suggest that artisanal fisheries are capable of causing important reductions in abundance levels of demersal species living on seamounts. Species life history characteristics, their degree of residency, and dependence on outside source areas may be important determinants for the status and the time scales required for recovery to previous abundances of the species. With the current Condor seamount fishing moratorium, exploitation rate has been reduced to zero and this is a unique opportunity to study the responses of the different previously exploited species to the reduced fishing mortality. New understanding may benefit seamount fisheries management in the region.

Seamounts, in general, are thought to support high biodiversity and special biological communities. They have been targeted by commercial fishing for demersal and pelagic fish species due to the occurrence of large aggregations in mid- and deep-water. Specimens of Phycis phycis, Helicolenus dactylopterus, Pontinus kuhlii, Beryx splendens, Beryx decadactylus, Etmopterus pusillus, Mora moro, Pagellus bogaraveo, Deania profundorum, Scomber colias and Trachurus picturatus were collected at the Condor seamount and on the slopes of Faial and Pico islands of Azores archipelago. Concentrations of V, Cr, Mn, Co, Ni, Cu, Zn, As, Se, Cd and Pb were determined in muscle and liver of each individual. Values of the 11 trace elements in the two tissues of the benthopelagic and benthic specimens, from the two surveyed areas, presented a significant inter-specific variation. In general, levels were lower in muscle than in liver, and negative relations between weight and Co, Mn, Zn, As, Cd and Pb concentrations in muscle and liver of three species were found. Pagellus bogaraveo, S. colias and T. picturatus presented enhanced elemental concentrations in liver, particularly of Cd. The extremely high storage of this potentially toxic element suggests a response to high uptake of Cd and the existence of an additional natural source of Cd to the environment.

Age and growth of Mora moro and Epigonus telescopus were studied using 634 and 232 otoliths, respectively, from specimens caught in the Azores between 1999 and 2009. Otoliths of both species were sectioned through the nucleus, a preparation method that improved the age assignment. Marginal increment analysis showed that, for both species, growth increments (consisting of as single set of translucent and opaque growth increments) were formed annually. M. moro specimens ranged from 22 to 76 cm fork length, were aged from 8 to 59 years, and showed a sexual dimorphism in growth. E. telescopus specimens ranged from 32 to 70 cm fork length which corresponds to ages between 12 and 39 years. No differences in growth between sexes were observed. Growth behaviour of M. moro was better explained by the three parameter von Bertalanffy model. The five parameter model provided a better fit to the E. telescopus data. Under this model a change in growth at 26 years for females and 25 years for males may be related to the onset of sexual reproduction.

Deep sea rockfish, Helicolenus dactylopterus and Pontinus kuhlii from the Azores archipelago were used to study population structuring using the trace element composition of the otolith. Through solution-based inductively coupled plasma mass spectrometry we identified elemental profiles that adequately identified fish from different island groups in the region (East, West and Central). Mg:Ca, Pb:Ca and Li:Ca ratios combined to distinguish H. dactylopterus with 67% overall success. Sr:Ca, Ba:Ca, Li:Ca and Cu:Ca provided adequate distinction in P. kuhlii with a mean jack-knifed classification success of 75%. This was a first attempt at determining the distinguishability of fish aggregations from this oceanic island setting, where suitable habitat for these species is limited and fragmented. Results of our study corroborate with previous research pointing to constrained home ranges for these species. Implications for fisheries management are important since these commercial resources should be managed locally rather than regionally.

Basin-scale spatial and depth-related distribution patterns of deepwater demersal fishes were analysed using bottom trawl datasets from the North Atlantic continental margin, slopes of oceanic islands and seamounts, and the mid-Atlantic Ridge. Depth-stratified presence-absence data for 593 species were compiled from fisheries-independent trawl studies with full species lists. The datasets comprised trawls conducted on the upper continental slope (200 m) to abyssal depths, and 750 m wide depth strata were used. Number of species and families declined with depth in all areas. Species number was highest in the western North Atlantic, significantly lower on the mid-Atlantic Ridge and eastern North Atlantic. Observed species numbers are also low in southern areas (Bahamas, NW Africa, southerly seamounts), but the sampling effort in these waters has been much less than in northern sites. Fish assemblages vary by depth, latitude and longitude, and the study corroborates earlier suggestions that assemblages are broadly distributed in relation to regional circulation and watermass features. The mid-Atlantic Ridge assemblages between Iceland and the Azores are most similar to those on eastern North Atlantic slopes and rises, rather dissimilar to all others, including western Atlantic, Greenland, northwest Africa and Azorean seamount and island assemblages. Across the North Atlantic differences between subareas are strongest at slope depths, much less pronounced at the less speciose rise and abyssal depths. Demersal fish biomass estimates suggest that the American slope (New England) has low biomass compared with Newfoundland and European areas, and that the supposedly oligotrophic mid-Atlantic Ridge has a level of biomass similar to or higher than the European margin.

Summary Weight–length relationships were estimated for 27 demersal fish species of the Cape Verde archipelago. Samples were collected in October and November 2000 using longline gear in depths up to 600 m, and occasionally to 1200 m. The b values were within expected ranges, varying between 2.406 and 3.761, except for Syacium micrurum (1.574) and Paraconger notialis (4.476), which presented strong allometries instigated through further analysis. This work revises previous literature in the archipelago and provides the first reference on weight–length parameters for 10 fish species worldwide and for 21 species of the Cape Verde archipelago.

Deep-sea fishes have been poorly sampled globally, and overall knowledge of demersal fish distributions and the drivers of community composition and diversity remain limited. Here, we used nine comparable datasets with species-level identification of fishes from research surveys around the world to test the hypothesis that deep-sea demersal fish assemblage composition on seamounts is consistent between major oceans. Two levels of analysis were undertaken: the first combined all presence-absence data from a seamount, while a second more detailed analysis included catch weight data based on a smaller number of seamounts. Overall, there was a consistent separation of seamounts by region based on the compositions of their fish assemblages. New Zealand and SE Australian seamounts have a very similar ichthyofauna, which differs substantially from seamounts in the eastern South Pacific Ocean off Chile. In the North Atlantic, Bear Seamount appears to be distinct from all others, while seamount fish assemblages off Ireland, the Azores, and Faraday Seamount have some affinities. The Tasman Sea and New Caledonian seamounts show strong intra-regional variation. On an ocean basin scale we therefore reject the hypothesis that the composition of deep-sea demersal fish fauna is homogeneous globally. However, regional patterns of both species composition and relative abundance show some similarities between widely separated geographical locations, especially where orange roughy is a dominant species. Salinity was the main environmental factor identified in a multivariate analysis of environmental covariate data. This is likely to be a result of salinity being a key characteristic defining both Antarctic Intermediate Water and North Atlantic Deep Water, the water masses found over most seamounts examined in this study, and which may explain similarities between deep-sea fish assemblages.

Machete, M., Morato, T., and Menezes, G. 2011. Experimental fisheries for black scabbardfish (Aphanopus carbo) in the Azores, Northeast Atlantic – ICES Journal of Marine Science, 68: 302–308. In this study, we used fisheries observers' data to analyse and describe the experimental fishing of black scabbardfish in the Azores in terms of type of gear, fishing operation, catch per unit effort (cpue), and fish size compositions. Standardized catch in numbers per 1000 hooks varied from 103 to 210 fish with an overall average of 132 fish per 1000 hooks. Recorded cpue values were similar to those recorded for Madeira and mainland Portugal in early 2000 but were higher than those observed in mainland Portugal for recent years. Bycatch was similar to that observed for other longline fisheries but much lower than in the North Atlantic deep-water trawl fishery. Fish size composition showed differences between locations in the Azores. Fish in Pico and São Jorge/Graciosa were consistently smaller than in other areas sampled and this may reflect the occurrence of an additional species, Aphanopus intermedius, in this area as proposed by gene analyses. Black scabbardfish (of possibly two species) may be considered an alternative resource for Azorean fisheries. Based on experience from other scabbardfish fisheries, however, it is suggested that fishing mortality should be maintained at a low level, traditional fishing methods should be encouraged, and bycatch should be closely monitored. Future studies of biology and distribution, stock assessments, and fisheries management advice should take into account the probable occurrence of two very similar species in the area. This study also highlights the importance of maintaining the fishery monitoring programme for the black scabbardfish fisheries in the Azores.

Seamounts are thought to support special biological communities, and often maintain high standing stocks of demersal and benthopelagic fishes. Seamount fish fauna have been described in several studies but few works have included species taken below 600 m. The demersal fish assemblages of the Seine and Sedlo seamounts (northeast Atlantic) from the summits to 2000 m depth were investigated based on longline survey catch data, conducted as part of the OASIS project. A total of 41 fish species from 24 families were caught at Seine near Madeira, and 30 species from 19 families were caught at Sedlo north of the Azores. Both fish faunas have high affinities with the neighbouring areas of the Azores, Madeira and with the eastern North Atlantic and the Mediterranean Sea. Overall abundances and mean body weights were slightly higher at Sedlo seamount, appearing in conformity with the latitudinal effect of increasing species abundance and productivity from south to north. The differential influence of the Mediterranean Water at each seamount may contribute to explain (a) the differences found in vertical distribution of common species, which tend to distribute deeper at Seine, and (b) the observed changes in the species composition and dominance in deeper waters. Multivariate analysis revealed a vertical structure that is approximately coincident with the expected zonation of water masses at each seamount. Physiological tolerance to the prevailing vertical hydrological conditions may explain the species distribution and the large-scale vertical assemblage structure found. However, further ecological factors like productivity patterns affecting the amount and quality of the available food appear to shape the abundance, diversity or dominance patterns of functional groups within those main assemblages. At Seine, the species Trachurus picturatus dominated the catches, mainly at the shallower edge of the plateau, appearing consistent with the sound-scattering layer interception hypothesis [Isaacs, J.D., Schwartzlose, R.A., 1965. Migrant sound scatterers: interaction with the sea floor. Science 150, 1810–1813]. At both seamounts mesopelagic feeders (e.g., Beryx splendens) dominate the upper-slope assemblages ( 1300 m) were dominated by squaliform species (e.g., Centrophorus squamosus, Centroscymnus coelolepis, Etmopterus princeps) along with Mora moro or the Antimora rostrata. The lower abundance of C. squamosus observed at Seine may be a result of the fishing activities in the area, since the species is an important by-catch of the black-scabbard fish fishery in the Madeira archipelago. The slightly higher predominance of scavenger species at Seine in deeper assemblages may be the result of an ecological response favouring this functional group in lower productivity regimes. Especially relevant was the record of large reproductive aggregations of B. splendens and Epigonus telescopus found at the edge of the Sedlo plateau.

The velvet belly lantern shark (Etmopterus spinax) forms a large component of the by-catch of the longline fishery off the Azores, but is discarded due to the lack of commercial value. The distribution and some biological aspects of Etmopterus spinax were investigated from longline surveys between 1995 and 2005 off the Azores. The highest catch rates were at depths between 500 and 650m (range 250–1200 m). The overall sex ratio was 1:2.26 (M:F), with the predominance of females in all depth strata. The total length range was 17.5–48.0 cm for females and 18.5–45.0 cm for males. This species is sexually dimorphic, with females growing to a larger size than males and attaining greater size at first maturity. During the sampled months all the maturity stages were observed. The immature females predominated but the increase proportion of expecting and post-natal females between April and July could indicate a breeding season. The variations of hepatosomatic index indicate that this species maintains a ...

A 10-year bottom longline survey and a smaller scale hook-and-line survey were used to study how habitat and fishing might affect the population structure of red porgy ( Pagrus pagrus ) at various scales in the archipelago of the Azores, central north Atlantic. The size and sex of fish caught responded to local factors rather than fishing or larger scale (geographic) factors. Young-of-the-year red porgy recruit to shallow, sandy habitats located inshore, and apparently migrate toward deeper and progressively rockier bottoms. This pattern seems to explain why red porgy are only found around the islands’ shores, being absent from shallow seamounts where suitable adult habitat exists but juvenile habitat is absent. The probability of sex-change was higher in sites whenever abundance was low. Significant large-scale differences among islands may well be attributable to exploitation, as the lowest abundances were consistently found off islands subject to higher fishing efforts. We also found some evidence of positive effects on porgy abundance and biomass from a 4-year ban on inshore longline fishing, but such benefits lack further (temporal) evidence. Recruitment to the fishery varied twice by an order of magnitude during the 10-year longline monitoring period, reflecting also high natural variability. These findings highlight the need to explicitly include the habitat essential for growth and, eventually, the presence of adequate ontogenic migration corridors when devising schemes of spatial management of red porgy populations, including marine reserves.

Mid-ocean ridges offer diverse habitats to benthic and benthopelagic fish, and the species-specific patterns of abundance and distribution as well as community patterns have not been extensively studied. Analyses were conducted of the demersal fish on the Mid-Atlantic Ridge using bottom trawl data from the 2004 R.V. G.O. Sars expedition to the ridge segment north of the Azores (42°N) to south of Iceland (54°N). Overall fish biomass and abundance declined with depth from the summit of the ridge to the middle rises on either side. Sixty-nine species were recorded in the 17 trawls used in the analyses, but several specimens could only be determined to genus level, and the real species number is probably around 80. Multivariate analyses revealed that the species composition primarily changed with depth, and that variation by latitude was secondary. The latitudinal variation was greater in shallow than in deep areas. Cross-ridge differences were apparently minor, but pairwise comparisons of stations at the same depth and latitude on either side of the central rift valley indicated that such differences may occur. The number of species was inversely related to latitude, but declined with depth below the slope depths. Evenness was higher in deep slope and rise areas than on the slopes. Assemblages of species could be defined for different depth zones and sub-areas, but there was no clear zonation by depth. Individual depth and latitudinal ranges of the different species produced the patterns. Temperature, salinity, and oxygen concentration were similar at all trawling locations, and other factors varying more strongly with depth and latitude appear to influence the distribution patterns of individual species and assemblage structure. A general decline in food availability with depth may explain the decrease in abundance and biomass with depth. A difference in pelagic productivity and species composition of zooplankton and pelagic nekton between the areas north and south of the Sub-polar Front may underlie the latitudinal change in abundance and species composition.

SUMMARY: This work describes and identifies the macroscopic and corresponding microscopic changes of the gonads of an important commercial fish species, Helicolenus dactylopterus dactylopterus, from Azores Archipelago. The new contribution relates the macroscopic scale with the histological stages. The annual changes in the gonad, together with the analysis of the monthly gonadosomatic indices, and complementary observations with scanning electron microscopy, allow us to conclude that the females are internally inseminated between July and November and spawn between January and March. There is a separation between female and male reproductive cycles. The overall sex-ratio observed was 1:1, but seasonal and length related differences were observed. This suggests differences and changes in availability, probably related to the annual reproductive cycle and changes in feeding behaviour

Weight–length relationships are presented for 33 fish species of Azores archipelago. This work is the first reference on weight–length parameters of 16 species. Samples were collected between the years of 1999 and 2003 using longline at depths ranging from a few meters to 1200 m. The parameters of a and b of the equation W = aL b were estimated. The b values of the species caught ranged from 2.701 for Lepidopus caudatus to 3.677 for Centroscymnus crepidater . Whenever possible, the b values for the species obtained both in this study and some of the previously reported in the Portuguese waters were compared.

Catarino, Diana ... et. al.-- 19 pages, 5 figures, 4 tables, data accessibility http://dx.doi.org/10.5061/dryad.ss368, supporting information http://dx.doi.org/10.1111/mec.13453, Knowledge of the mechanisms limiting connectivity and gene flow in deep-sea ecosystems is scarce, especially for deep-sea sharks. The Portuguese dogfish (Centroscymnus coelolepis) is a globally distributed and near threatened deep-sea shark. C. coelolepis population structure was studied using 11 nuclear microsatellite markers and a 497-bp fragment from the mtDNA control region. High levels of genetic homogeneity across the Atlantic (Φ = -0.0091, F = 0.0024, P > 0.05) were found suggesting one large population unit at this basin. The low levels of genetic divergence between Atlantic and Australia (Φ = 0.0744, P < 0.01; F = 0.0015, P > 0.05) further suggested that this species may be able to maintain some degree of genetic connectivity even across ocean basins. In contrast, sharks from the Mediterranean Sea exhibited marked genetic differentiation from all other localities studied (Φ = 0.3808, F = 0.1149, P < 0.001). This finding suggests that the shallow depth of the Strait of Gibraltar acts as a barrier to dispersal and that isolation and genetic drift may have had an important role shaping the Mediterranean shark population over time. Analyses of life history traits allowed the direct comparison among regions providing a complete characterization of this shark's populations. Sharks from the Mediterranean had markedly smaller adult body size and size at maturity compared to Atlantic and Pacific individuals. Together, these results suggest the existence of an isolated and unique population of C. coelolepis inhabiting the Mediterranean that most likely became separated from the Atlantic in the late Pleistocene, This study was performed under the framework of ReDEco (FP6 ERA-NET, MARIN-ERA/MAR/0003/2008) and Hermione (FP7-ENV-2008-1, nr 226354) projects. Samples were collected under other scientific projects: DEECON (ESF, 06-EuroDEEP-FP-008 & SFRH-EuroDEEP/0002/2007); CONDOR (EEA Grants, PT0040/2008); SMaRT (M.2.1.2/029/2011) and DEMERSAIS (Azorean Government); OASIS (FP5, EVK3-CT-2002-00073-OASIS); PescProf I (INTERREG III B, MAC/4.2/M12); BIOFUN (ESF, CTM2007-28739-E); DOS MARES (CTM2010-21810-C03-03); ADIOS (EVK3-CT-2000-00035). DC is a PhD student funded by FCT (SFRH/BD/65730/2009); HK is cofunded by the University of Agder and the University of Oslo (CEES); AV is a postdoctoral fellow funded by FCT (POPH/FSE; SFRH/BPD/77487/2011); DS is a postdoctoral fellow funded by the DIANET programme (FP1527385002); and SS is a research fellow supported by the Marie Curie grant cofunded by the EU under the FP7-People-2012-COFUND; Cofunding of Regional, National and International Programmes, GA n.600407 and the Bandiera Project RITMARE. MARE is funded by FCT through the strategic project UID/MAR/04292/2013

During 1997, quarterly exploratory cruises of the R/V “Archipelago” were carried out in order to study the deep water crab Chaceon affinis [Res. Camp. Sci. Monaco Fasc. VII (1894) 1], South of Pico island (Azores) and at the Menez Gwen hydrothermal vent area (SW of the Azores, within the Azorean Economic Exclusive Zone). The crabs were caught with bottom traps according to a specified survey design. Different areas between 300 and 1200 m depth were surveyed. Information from previous collections was also compiled and analysed. A total of 1153 crabs (726 males and 427 females) were caught at depths ranging from 600 to 1100 m on rocky and/or muddy bottoms. Size ranged from 39 to 177 mm carapace length (CL), the males being larger than females. Males were relatively more abundant at depths 800 m. The greatest abundance occurred at depths from 700 to 800 m. Ovigerous females, which were consistently >70 mm CL, were found only from October to March. An annual reproductive cycle is suggested. Size at first maturity for the females, was estimated to be within the size range of 83–97 mm CL. Other ecological and biological information such as distribution, morphometric aspects related to reproduction, occurrence of parasites and epibionts, are discussed, as well as by-catch species.

The present investigation provides an efficient diagnostic method based on polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis to discriminate between two cryptic species of scabbardfish, Aphanopus carbo and A. intermedius, with commercial relevance in several European fish markets. Two DNA fragments from the mtDNA, including control region and partial cytochrome oxidase subunit I genes of about 1100 bp and 700 bp, respectively, were isolated by PCR amplification. Digestion of the amplicon including the control region with HaeII and the amplicon including the COI gene with Sau3AI restriction enzymes allowed an unequivocal discrimination between the two scabbardfish species. This PCR-RFLP method allowed a clear and rapid discrimination of the trichiurid species studied.

Several fish surveys were carried out in recent years at Sedlo Seamount, Azores, north-eastern central Atlantic Ocean. An objective of the surveys was to determine the species composition of the demersal fish species living in the area. Four types of sampling gears (bottom trawl and three types of longline) were used at Sedlo Seamount resulting in very different species composition by gear and a very complete coverage of the fish fauna of the area. A list of fishes caught with these sampling methods is presented, along with other specific auxiliary information. Altogether 78 species from 43 families were listed for Sedlo Seamount, and as far as is known, 15 species were recorded for the first time for Azorean waters.

Six microsatellite loci were identified for the demersal deep-sea fish Helicolenus dactylopterus. All loci were highly polymorphic (5-21 alleles per locus). Observed heterozygosities were from 0.378 to 0.868, while the expected heterozygosities ranged from 0.529 to 0.925. Multiplex PCR reactions were optimized. Microsatellite markers were developed for analysis of genetic structure including identification of stocks and migration patterns. The resulting data will be used to help in the establishment of scientifically based fisheries management for this species. Departures from the expected Hardy-Weinberg equilibrium were observed in three loci, and are likely to be a consequence of population structuring across the Azorean islands.

We relate fish biological and ecological characteristics to total and organic mercury concentrations to determine whether accumulation is influenced by trophic level, Hg concentration in the diet, and vertical distribution. Levels of total mercury and methylmercury were determined in the muscle tissue of eight species of fish: Pagellus acarne, Trachurus picturatus, Phycis phycis, P. blennoides, Polyprion americanus, Conger conger, Lepidopus caudatus and Mora moro, caught in the Azores. All such fishes are commercially valuable and were selected to include species from a wide range of vertical distributions from epipelagic (200 m) to mesopelagic (300 m) environments. Methylmercury was the major form accumulated in all species, comprising an average of 88.1% of total mercury. Concentrations of mercury (total and methylmercury) increased with age, length and weight. Based on data from other studies, mercury concentrations in fish diet were estimated. Mercury levels in food ranged from 0.08 to 0.32 ppm, dry weight. Hg concentrations in the food and in muscle tissue from different species were positively correlated. Total Hg levels in the muscles were approximately nine times those estimated in food. Total mercury concentrations in muscle were positively correlated with both trophic level and median depth. Such enhanced mercury bioaccumulation in relation to depth appears to be determined primarily by concentrations in food and ultimately by water chemistry, which controls mercury speciation and uptake at the base of the food chain.

Helicolenus dactylopterus is an Atlantic benthopelagic fish species inhabiting high-energy habitats on continental slopes, seamounts and islands. Partial sequences of the mitochondrial control region (D-loop) and cytochrome b (cyt b) were used to test the hypothesis that H. dactylopterus disperses between continental margin, island and seamount habitats on intraregional, regional and oceanic scales in the North Atlantic. Individuals were collected from five different geographical areas: Azores, Madeira, Portugal (Peniche), Cape Verde and the northwest Atlantic. D-loop (415 bp) and cyt b (423 bp) regions were partially sequenced for 208 and 212 individuals, respectively. Analysis of variation among mitochondrial DNA sequences based on pairwise F-statistics and AMOVA demonstrated marked genetic differentiation between populations in different geographical regions specifically the Mid-Atlantic Ridge (Azores)/northeast Atlantic (Portugal, Madeira) compared to populations around the Cape Verde Islands and in the northwest Atlantic. Some evidence of intraregional genetic differentiation between populations was found. Minimum-spanning network analysis revealed star-shaped patterns suggesting that populations had undergone expansion following bottlenecks and/or they have been colonized by jump dispersal events across large geographical distances along pathways of major ocean currents. Mismatch distribution analysis indicated that Azores and northwest Atlantic populations fitted a model of historical population expansion following a bottleneck/founder event estimated to be between 0.64 and 1.2 million years ago (Ma).

It has been speculated that some deep-sea fishes can display large vertical migrations and likely doing so to explore the full suite of benthopelagic food resources, especially the pelagic organisms of the deep scattering layer (DSL). This would help explain the success of fishes residing at seamounts and the increased biodiversity found in these features of the open ocean. We combined active plus passive acoustic telemetry of blackspot seabream with in situ environmental and biological (backscattering) data collection at a seamount to verify if its behaviour is dominated by vertical movements as a response to temporal changes in environmental conditions and pelagic prey availability. We found that seabream extensively migrate up and down the water column, that these patterns are cyclic both in short-term (tidal, diel) as well as long-term (seasonal) scales, and that they partially match the availability of potential DSL prey components. Furthermore, the emerging pattern points to a more complex spatial behaviour than previously anticipated, suggesting a seasonal switch in the diel behaviour mode (benthic vs. pelagic) of seabream, which may reflect an adaptation to differences in prey availability. This study is the first to document the fine scale three-dimensional behaviour of a deep-sea fish residing at seamounts.