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The quality index method (QIM) is widely used for fish sensory assessment, but there are hardly any studies on quality changes in fish that have been previously frozen. A QIM scheme was developed for frozen Roundnose grenadier once thawed and stored at refrigerated temperatures (4 ± 1 °C). Next, this scheme was applied to determine the shelf life and evaluate the influence of frozen storage time on fish quality. The developed QIM scheme includes six descriptors. The quality index (QI) varies from 0 to 13 points. The maximum QI was reached 16 days after thawing. A strong linear correlation between QI and storage time was achieved (r = 0.9896), the least squares regression line being QI = 0.71 · (days after thawing) + 1.51. Using inverse prediction, the shelf life was estimated to be 5 days from the beginning of thawing. Statistical evidence of the negative effect of previous freezing time on the QI was found in a year-long study This research was supported by Xunta de Galicia (Spain), project 10TAL010CT SI

Nineteen species of the deep-water fish family Macrouridae inhabit the Mid-Atlantic Ridge (MAR) of the North Atlantic. Size and age structure, longevity and length at age were explored for seven of the more abundant species: Coryphaenoides armatus, Coryphaenoides brevibarbis, Coryphaenoides carapinus, Coryphaenoides guentheri, Coryphaenoides mediterraneus, Coryphaenoides rupestris and Macrourus berglax. The otoliths from these species had growth increments resembling those accepted as annuli in other deep-water species for which validation experiments have been conducted. Based on the counts of these growth increments, age estimates were derived as the basis for studies of age structure, growth and longevity. All the species appeared to have relatively low growth rates, but the interspecific variation in longevity illustrates that there is a considerable variation within the family and among species inhabiting the same deep-sea environment. Most of the species likely complete full life cycles on the MAR, but it is probable that both the youngest and the largest-oldest individuals of some of the species were not sampled adequately.

Intraspecific diversity promotes evolutionary change, and when partitioned among geographic regions or habitats can form the basis for speciation. Marine species live in an environment that can provide as much scope for diversification in the vertical as in the horizontal dimension. Understanding the relevant mechanisms will contribute significantly to our understanding of eco-evolutionary processes and effective biodiversity conservation. Here, we provide an annotated genome assembly for the deep-sea fish Coryphaenoides rupestris and re-sequencing data to show that differentiation at non-synonymous sites in functional loci distinguishes individuals living at different depths, independent of horizontal spatial distance. Our data indicate disruptive selection at these loci; however, we find no clear evidence for differentiation at neutral loci that may indicate assortative mating. We propose that individuals with distinct genotypes at relevant loci segregate by depth as they mature (supported by survey data), which may be associated with ecotype differentiation linked to distinct phenotypic requirements at different depths.

A dense aggregation of the roundnose grenadier Coryphaenoides rupestris was observed with a towed camera at a depth of 1500 m in the Rockall Trough during September. The density of fish was 100 times greater than other sites. Within the aggregation the fish showed directional alignment, rapid swimming actions, mid-water swimming and social interactions similar to those associated with spawning in other Gadiformes.

There are thousands of seamounts (underwater mountains) throughout the world's deep oceans, many of which support diverse faunal communities and valuable fish stocks. Although seamounts are often geographically and bathymetrically isolated from one another, it is not clear how biologically isolated they are from one another. We analysed the chemical signature of the otoliths of a deepwater fish, the roundnose grenadier (Coryphaenoides rupestris) to test the null hypothesis that there is random exchange between individuals from a seamount and other adjacent areas. The fish were sampled on the Scottish west coast, from the Rosemary Bank seamount and two adjacent locations of similar depth, in the same year at roughly the same time of year. We used flow-injection inductively coupled plasma mass spectrometry to measure trace element concentrations from micro-milled portions of the otolith corresponding to adult and juvenile life history stages. The elemental signatures of the fish from the seamount were distinguishable from the fish from the two other areas during both the juvenile and adult life-history phase. We infer that once juveniles settle on the seamount they remain there for the rest of their lives. Evidence for population structure should be factored into exploitation strategies to prevent local depletion and is an important consideration with respect to Rosemary bank being included in a network of Marine Protected Areas around Scotland.

In this paper, we revisit the state of deep-water fisheries to the west of the British Isles and aim to provide an overview on the key drivers behind community changes along continental margins. The deep-water fisheries to the west of the British Isles that extend from the shelf-slope break down to the lower slope and along banks and seamounts of the Rockall Basin, mainly target blue ling Molva dypterygia, roundnose grenadier Coryphaenoides rupestris, orange roughy Hoplostethus atlanticus, with by-catches of black scabbardfish Aphanopus carbo and tusk Brosme brosme. These fishing grounds experienced a long period of exhaustive exploitation until the early 2000s, but subsequently the implementation of management strategies has helped to relieve excessive fishing pressure. It is widely accepted that a better understanding of the long-term implications of disturbance is needed to understand patterns in deep-water communities and what sustainable use and exploitation of resources might look like in this context.

Understanding the trophic ecology of deep-sea communities provides valuable insight into deep-water ecosystem functioning, and can help inform fisheries management and conservation initiatives. However, few deep-sea food webs have been studied so far in the Northwest Atlantic. Here, stable isotope, gut content, and morphometric analyses were combined to explore trophic relationships in a deep-water fish assemblage off eastern Canada. While a weak depth effect was found on the isotopic composition of the species analyzed, isotopic and dietary records revealed the existence of two main, strongly coupled trophic pathways. The pelagic pathway either comprised pelagic fishes (e.g., meso- and bathypelagic species), primarily feeding on zooplankton and fish, or benthopelagic predators that showed a more pelagic-oriented diet. Such fishes displayed the lowest values of stable N and C isotope ratios. In contrast, demersal fishes representing the benthic trophic pathway had significantly higher values of δ15N and δ13C, and a taxonomically more benthic-oriented and diverse diet. Furthermore, smaller body sizes, larger mouths, and adaptations (e.g., bioluminescent structures and lures) prevailed in the pelagic species, consistent with living in a relatively food-poor environment. The largest average body sizes were found in the demersal fishes suggesting enhanced food intake and growth investment for the species. Only juvenile individuals of threatened species, such as Coryphaenoides rupestris and Rajella fyllae were caught, providing evidence of the vulnerability of such species to commercial fishing.

In the ocean, energy is transferred from the productive primary producers at the surface, down to the demersal fish fauna at the sea floor. When moving away from the surface layer, there is a decline in food availability, and demersal fish species has evolved different feeding strategies due to this (Merrett and Haedrich, 1997). Even though many studies have researched feeding ecology of demersal fish species in the ocean, little is known about the feeding ecology of demersal fish species in fjords. The aim of this thesis was to investigate the feeding ecology of roundnose grenadier (Coryphaenoides rupestris), a demersal fish species, in two Norwegian fjords. Three hypotheses were predicted; (1) that the diet would consist of mesopelagic fish and invertebrates, and benthic crustacean. (2) That diet and food composition would differ between the fjords. (3) Due to the importance of pelagic prey, a difference in prey composition and food amount would be found as a diurnal pattern, and there will be evidence that grenadiers migrate upwards during day or night to feed on pelagic prey. Stomach content of 303 roundnose grenadiers were analyzed to investigate importance of prey groups and differences between and within fjords. Pre-anal fin-length, weight, gonadosomatic index and hepatosomatic index were measured and calculated. In total, the diet consisted mostly of pelagic and benthic crustaceans, 19 % consisted of non-crustacean taxa. No major differences were found in prey composition between the fjords, with the exception of chaetognaths, which were only found as prey in Masfjord. Size of the grenadier influenced the foraging upon polychaetas and euphasids. Fish from Lustrafjord had more stomach content relative to body weight, while the Masfjord population had a higher distribution of sexually matured fish and more stored resources in the liver. There were no clear diurnal differences in consumed prey taxa or in food amount, but in general, pelagically caught fish contained more pelagic prey. Overall, diet analyses showed that roundnose grenadiers from two Norwegian fjords utilize food resources in both pelagic and demersal zone, and that size has an effect when specializing on specific prey groups such as krill and polychaetas. The feeding ecology of C. rupestris is similar to other populations in the Northwest-Atlantic, and they feed mostly on Amphipoda, Copepoda, Euphausiacea, Polychaetae and Mollusca, and are classified as 2nd or 3rd carnivorous consumer. Low amounts of fish found in the stomach content revealed that they rarely feed on fish. Diet consisted both of pelagic and benthic prey, no clear diurnal differences were found. Although the importance of pelagic prey was found, a diel vertical migration pattern could not be confirmed. Masteroppgave i biologi BIO399

Recent temporal variability in abundance, size and age structure, distribution, and recruitment of the Skagerrak population of the commercially exploited long-lived deep-water demersal macrourid roundnose grenadier (Coryphaenoides rupestris) appeared strongly influenced by a combined effect of a single pronounced recruitment incident in the early 1990s and a subsequent pulse in targeted exploitation a decade later. Fishery-independent annual survey data showed that probably only one strong year class occurred across an almost three-decade period, 1985–present. Recruitment studies in deep-water fish remain few, yet rarity of successful recruitment events may have to be added to life-history characteristics already recognized as limiting the potential for sustainable harvesting of deep-water demersal fish, i.e. extended lifespan, slow growth, high age at first maturity, and low fecundity.

We present a framework for evaluating fisheries management plans comprehensively, both rebuilding plans and others. The framework includes a first rapid appraisal of the likelihood that the plan will result in management meeting its objectives, and guides subsequent quantitative analyses of potential weaknesses in the proposed plan. The framework includes four steps: (i) evaluating if a set of management objectives, if achieved, would result in a sustainable fishery, (ii) using qualitative analysis of a bio-economic model to evaluate whether the set of stock management tactics might be capable of achieving the specified fisheries objectives, (iii) using empirical criteria derived from the literature to evaluate if other management measures in the plan related to the ecological, social or economic context of the fishery actually contribute to sustainability, and (iv) carrying out quantitative simulations to compare alternative implementation options. Generally, several management measures have to be combined to increase stock size without sacrificing the economic benefits to the fishers remaining in the fishery. We demonstrate application of the framework for evaluating the stock rebuilding plan for plaice (Pleuronectes platessa) and sole (Solea solea) in the North Sea and, the management measures currently in place for the roundnose grenadier (Coryphaenoides rupestris) stock exploited to the west of the British Isles.

This paper summarizes knowledge and knowledge gaps on benthic and benthopelagic deep-water fishes of the North Atlantic Ocean, i.e. species inhabiting deep continental shelf areas, continental and island slopes, seamounts and the Mid-Atlantic Ridge. While several studies demonstrate that distribution patterns are species specific, several also show that assemblages of species can be defined and such assemblages are associated with circulatory features and water mass distributions. In many subareas, sampling has, however, been scattered, restricted to shallow areas or soft substrata, and results from different studies tend to be difficult to compare quantitatively because of sampler differences. Particularly, few studies have been conducted on isolated deep oceanic seamounts and in Arctic deep-water areas. Time series of data are very few and most series are short. Recent studies of population structure of widely distributed demersal species show less than expected present connectivity and considerable spatial genetic heterogeneity and complexity for some species. In other species, genetic homogeneity across wide ranges was discovered. Mechanisms underlying the observed patterns have been proposed, but to test emerging hypotheses more species should be investigated across their entire distribution ranges. Studies of population biology reveal greater diversity in life-history strategies than often assumed, even between co-occurring species of the same family. Some slope and ridge-associated species are rather short-lived, others very long-lived, and growth patterns also show considerable variation. Recent comparative studies suggest variation in life-history strategies along a continuum correlated with depth, ranging from shelf waters to the deep sea where comparatively more species have extended lifetimes, and slow rates of growth and reproduction. Reproductive biology remains too poorly known for most deep-water species, and temporal variation in recruitment has only been studied for few deep-water species. A time series of roundnose grenadier Coryphaenoides rupestris recruitment spanning three decades of fisheries-independent data suggests that abundant year classes occur rarely and may influence size structure and abundance even for this long-lived species.

Association of demersal fish taxa with Geodia-dominated temperate sponge grounds was examined in 104 research vessel survey trawl sets from 500 to 1500 m depth along the conti- nental slopes of the Grand Banks and Flemish Cap, northwest Atlantic. The total number of fish taxa and their total biomass were negatively correlated with sponge biomass and catch depth, and sponge biomass increased with depth. ANOSIM identified significantly different fish communities (biomass and abundance composition) associated with 3 sponge catch weight classes, and multi- dimensional scaling plots showed separation of trawl sets labelled by this factor to be strongest for abundance. SIMPER analysis identified the fish assemblage associated with the sponge grounds (≥250 kg km �1 ): roughhead grenadier Macrourus berglax, roundnose grenadier Coryphaenoides rupestris, blue hake Antimora rostrata, longnose eel Synaphobranchus kaupii, turbot Reinhardtius hippoglossoides, black dogfish Centroscyllium fabricii and deep-sea cat shark Apristurus profun- dorum. These contributed to 92 and 81% of the similarity (~50%) among trawl set catches using biomass and abundance data, respectively. Four additional taxa contributed to 92% similarity in abundance: common grenadier Nezumia bairdii, shortnose snipe eel Serrivomer beanii, lantern- fish (Myctophidae) and goitre blacksmelts Bathylagus euryops. SIMPER dissimilarity identified 6 fish taxa with larger biomass in catches with high sponge catch weight: shortnose snipe eel, deep- sea cat shark, eelpout Lycodes spp., spinytail skate Bathyraja spinicauda, white skate Dipturus linteus and deepwater chimaeras Hydrolagus affinis. The first 3 species were also more abundant in those catches and are considered to be strongly associated with the sponge grounds. Future research focussing on these species identified as being associated with the sponge grounds may provide greater insight into the strength of the associations and the ecological linkages between these benthic and pelagic communities.

A time series from 1977–1989 and 2000–2002 of scientific trawl surveys in the Porcupine Seabight and adjacent abyssal plain of the NE Atlantic was analysed to assess changes in demersal fish biomass and length frequency. These two periods coincide with the onset of the commercial deep-water fishery in the late 1970s and the onset of the regulation of the fishery in the early 2000's, which allowed us to investigate changes in the relationship between total demersal fish biomass and depth between the pre- and post commercial fishing periods, as well as changes in the biomass (kg km−2) depth distribution and length frequency distribution of the most dominant fish species. Our results show a decline in total demersal fish biomass of 36% within the depth range of the commercial fishery (< 1500 m). Whilst there were significant declines in target (e.g. Coryphaenoides rupestris decreased by 57%) and non-target (e.g. C. guentheri and Antimora rostrata) species, not all species declined significantly. Changes in the overall length-frequency distribution were detected for 5 out of the 8 dominant species occupying depth ranges both within and outside the maximum depth for commercial trawling. This suggests that whilst there is evidence for likely fishery impacts on the biomass distribution of the demersal fish population as a whole, species-specific impacts are highly variable. It is clear that changes in population structure can extend beyond the depth at which fishing takes place, highlighting the importance for also considering the indirect effects on deep-sea fish populations.

There is a growing body of research examining the effects of corals on fish communities, species abundances, and biodiversity. Yet, few studies have quantitatively examined what factors are influencing the distribution of individual fish species. In general, many researchers believe they know what influences the distribution of grenadiers on large spatial scales, but numerous studies have shown the distributions of organisms are often determined by various factors that change in relative importance when viewed at differing scales. Our study used video collected from three deep canyons off Newfoundland, Canada (North west Atlantic) to examine how the factors apparently influencing the distribution of four grenadiers (Macrouridae: Coryphaenoides rupestris, Coryphaenoides carapinus, Nezumia bairdii, and Macrourus berglax) change when assessed at varying spatial scales. We paid special attention to the influence of deep-water corals found in the study area (large gorgonians/antipatharians, small gorgonians, sea pens, soft corals, and cup corals). The factors that influenced grenadier presence and/or abundance (and the magnitude of this effect) varied as different sampling resolutions were examined. We found C. rupestris abundance was positively related to cup coral abundance in transects longer than 10 m, likely as a result of similar habitat preferences between both taxa. When significant relationships between depth and C. rupestris presence and/or abundance were found, they were always negative. Depth was a significant predictor of C. carapinus abundance in transects longer than 10 m. Very few predictors of M. berglax abundance or presence could be found. Depth and the number of small gorgonians were consistent predictors of N. bairdii abundance.

The demersal fish fauna at 900–1800 m depths off Nova Scotia, Canada, is described using data from exploratory bottom trawl surveys conducted in November 1994 and March 1995 by a commercial fishing trawler. Approximately 25 metric tons (39 000 specimens) of demersal fish belonging to at least 82 species were caught, 30% of which had not previously been recorded from the area. However, more than half the catch consisted of the two species Centroscyllium fabricii (black dogfish) and Coryphaenoides rupestris (roundnose grenadier). Catches were higher in the shallower depth strata fished and cluster analysis showed that depth was the primary factor determining species composition of catches. It is suspected, however, that the vessel fished less effectively at depths greater than about 1500 m, contributing to the reduction in catch quantities at these depths. The importance in catches of large bodied species, particularly Chimaeriformes and sharks, contrasts with results from surveys in adjacent areas. This likely reflects the greater fishing power of the vessel/gear used in present surveys rather than real differences in faunal composition. Catches of mesopelagic species during these surveys, and during an earlier deepwater trawling survey in this area, are also described.

While deep-sea fish accumulate high levels of persistent organic pollutants (POPs), the toxicity associated with this contamination remains unknown. Indeed, the recurrent collection of moribund individuals precludes experimental studies to investigate POP effects in this fauna. We show that precision-cut liver slices (PCLS), an in vitro tool commonly used in human and rodent toxicology, can overcome such limitation. This technology was applied to individuals of the deep-sea grenadier Coryphaenoides rupestris directly upon retrieval from 530-m depth in Trond- heimsfjord (Norway). PCLS remained viable and functional for 15 h when maintained in an appropriate culture media at 4 °C. This allowed experimental exposure of liver slices to the model POP 3- methylcholanthrene (3-MC; 25 μM) at levels of hydrostatic pressure mimicking shallow (0.1 megapascal or MPa) and deep-sea (5−15 MPa; representative of 500−1500 m depth) environments. As in shallow water fish, 3-MC induced the transcription of the detoxification enzyme cytochrome P4501A (CYP1A; a biomarker of exposure to POPs). This induction was diminished at elevated pressure, suggesting a limited responsiveness of C. rupestris toward POPs in its native environment. This very first in vitro toxicological investigation on a deep-sea fish opens the route for understanding pollutants effects in this highly exposed fauna.

We observed significant genetic structure in a widely distributed North Atlantic demersal deepwater fish, the roundnose grenadier Coryphaenoides rupestris (Pisces: Macro - uridae). The overall estimate of genetic differentiation, based on 6 microsatellite loci (FST = 0.0152; p < 0.0001), was elevated by samples from the periphery of the species’ range, off Norway and Canada. Samples from the central area of distribution showed less pronounced genetic structure, indicating more extensive dispersal and gene flow. Simulations were run to assess expected patterns of genetic differentiation under 2 major hypotheses of gene flow: passive larval drift and demographic diffusion. In spite of the relatively long duration of the pelagic egg and juvenile phases, no correlation was found between observed pairwise FST values and those predicted under the hypothesis of drift of progeny by ocean currents. The observed pattern may instead arise from a combination of bathymetric barriers limiting deep pelagic mixing and advection, early life ontogenetic changes in vertical distribution, and limited migration once a benthopelagic life style has been established. 2017-07-24

12 pages, 10 figures, 6 tables, Macrourid fish are one of the most abundant marine species on continental margins worldwide. Although they play an important role in the ecosystem, little is known about their overall biology. We report here a large data set of the most abundant macrourid in Mediterranean waters, Trachyrincus scabrus, showing the main population and reproductive characteristics. The study was based on 3,239 specimens collected between 300 and 1,500 m depth on the northwestern Mediterranean in 2003–2004 and 2008–2009. The population showed a depth-related structure with the largest individuals at 1,100 m depth and the smallest (i.e., immature) at shallower depths. Macroscopic and microscopic analyses of the gonads showed that T. scabrus has a highly seasonal reproductive pattern. Spawning females were found during winter when the organic matter fluxes were highest on the continental slope. T. scabrus is a batch spawner with group-synchronous oocyte development and present low average fecundity of 14,191 oocytes, The authors would like to thank the Officers and crews of the R/V Garcia del Cid, F/V Montse III and Virgen del Vilar for helping to provide samples and the data necessary for our study. We also thank I Quagio-Grassiotto, M Metaksakis and C Cerviño for helping with the histological analyses and JA Garcia for developing the study area map. This study was conducted within the RECS, PROMETEO and DOS MARES projects by the Spanish Science and Innovation Ministry CICYT (REN02/04556/C02/MAR; CTM2007-66316-C02/MAR; CTM2010-21810-C03-03/MAR, respectively, to JBC) and European Community’s Seventh Framework Programme under the HERMIONE project (Grant Agreement 226354, to ERLL). UF-A is funded by a Spanish PhD doctoral fellowship FPI-2008. ERLL is funded by a Spanish JAE-CSIC postdoctoral grant. This paper is a contribution number 580 from AZTI Tecnalia (Marine Research Division)

The structures of inner ears were compared between six species of Macrouridae (grenadiers and rattails) that live at different ocean depths ranging from 200 to 5000 meters. The goal of this comparison is to find out if there are structural differences in their inner ears related to the depth of habitat. The size of the saccular otolith relative to fish head length varies considerably among the six species; with the largest otolith found in Nezumia aequalis and the smallest in N. parini, a mesopelagic species. N. aequalis is a species with potential sound production and auditory dominance by its drumming muscle on the swim bladder. Its saccular sensory area is four times larger than those from the two species live in shallower depths and have vision as their dominant sense (N. parini and Coryphaenoides rupestris). The differences found in the saccule and lagena of these species reflect the sensory advantages of habitats that are related to the benefits and constraints at different depths. It also reflects ...

Little is understood about connectivity of deep-sea fish populations. Analysis of the geo- chemical properties of fish otoliths is one way to draw inferences regarding their movements and habitat use in the marine environment. Trace element and stable isotope analyses of otoliths were undertaken to assess patterns of spatial and temporal population structure of a wide-ranging deep- water fish, the roundnose grenadier Coryphaenoides rupestris. Fish were sampled from 4 locations across the distribution range of the species in the northeast Atlantic. Multivariate analyses of elemen- tal ratios (Li/Ca, Mn/Ca, Ba/Ca, Zn/Ca, Cu/Ca) revealed strong geographic separation at each life stage, and an overall significant difference between life stages. Otolith oxygen (δ 18 O) and carbon (δ 13 C) stable isotope analysis indicated a depth migration (and reduction in metabolic activity) from relatively shallow in the juvenile phase to much deeper in the adult phase at all locations. The results suggest that roundnose grenadier are comprised of geographically distinct population units that persist throughout their life-history, migrating deeper as they get older.

Priede, I. G., Godbold, J. A., Niedzielski, T., Collins, M. A., Bailey, D. M., Gordon, J. D. M., and Zuur, A. F. 2011. A review of the spatial extent of fishery effects and species vulnerability of the deep-sea demersal fish assemblage of the Porcupine Seabight, Northeast Atlantic Ocean (ICES Subarea VII). – ICES Journal of Marine Science, 68: 281–289. We review information from scientific trawl surveys carried out between 1977 and 2002 in the Porcupine Seabight and Abyssal Plain area of the Northeast Atlantic (240–4865 m water depth). Since the late 1980s, commercial bottom-trawl fisheries targeting mainly roundnose grenadier (Coryphaenoides rupestris), black scabbardfish (Aphanopus carbo), and orange roughy (Hoplostethus atlanticus) have been operating at depths of 500–1500 m, intersecting the depth ranges of 77 demersal fish species that would therefore be vulnerable to fishery effects. Comparisons of trawls pre-1989 and post-1997 indicate a significant decrease in total abundance of demersal fish down to 2500 m. Detailed analyses of the 15 most-abundant species showed that nine species with depth ranges within the commercial fishing depth have decreased in abundance. Other species were either not affected (Bathypterois dubius) or only affected at the shallow end of their range (Coryphaenoides guentheri). Species with a minimum depth of occurrence >1500 m (Coryphaenoides armatus and Coryphaenoides leptolepis) increased in abundance over part of their depth range. Decreases in abundance are probably caused by commercial fishing activities, an effect that is transmitted downslope by removal of fish at the shallow end of their depth range, resulting in declines at the deeper end of the depth range. The estimated fishery area is ca. 52 000 km2, but the potential impact probably extends to ca. 142 000 km2 and to many non-target species.

Oceans function as a sink for organochlorine compounds (OCs) such as PCBs and DDTs. Deep-sea fish bioaccumulate OCs to levels 10 to 100 times higher than shallow-water species. OCs induce the cytochrome P450 (CYP) system, the activity of which may increase reactive oxygen species (ROS) production in liver cells. However,, the susceptibility of fish to the oxidative stress likely caused by OCs remains unclear. We analysed whether PCB and DDT contamination of roundnose grenadier Coryphaenoides rupestris was associated with higher ethoxyresorufin-O-deethylase (EROD) activity (CYP1A-related), and activities of antioxidant enzymes such as catalase (CAT), superoxide dismutases (SOD) and glutathione peroxidases (GPX). Biological parameters affecting EROD patterns (e.g. gender, ontogeny) were also investigated. Citrate synthase (CS) was used as a proxy for oxidative metabolism, responsible for basal ROS production and recruitment of antioxidant enzymes in liver cells. Hepatic OC levels were determined in individuals of different sizes (89 to 2016 g) from northern Atlantic slopes (depth range = 1000 to 1900 m). Median PCB and DDT values were 2.39 and 1.48 mu g g(-1) lipid weight, respectively, while median EROD activity was 15 pmol min(-1) mg(-1) protein. Gender greatly influenced OC levels (females were less contaminated), whilst weight (linked to ontogeny) positively affected DDT levels. EROD increased with PCB levels, and to some extent SOD and CAT were more influenced by EROD than CS, indicating that PCBs strengly affect the redox balance of roundnose grenadier liver cells through increased CYP1A activity. Therefore, 0C-related CYP1A induction may be a major source of cellular ROS in liver of roundnose grenadier.

Local populations within a species can become isolated by stochastic or adaptive processes, though it is most commonly the former that we quantify. Using presumably neutral markers we can assess the time-dependent process of genetic drift, and thereby quantify patterns of differentiation in support of the effective management of diversity. However, adaptive differences can be overlooked in these studies, and these are the very characteristics that we hope to conserve by managing neutral diversity. In this study, we used 16 hypothetically neutral microsatellite markers to investigate the genetic structure of the roundnose grenadier in the North Atlantic. We found that one locus was a clear outlier under directional selection, with F(ST) values much greater than at the remaining loci. Differentiation between populations at this locus was related to depth, suggesting directional selection, presumably acting on a linked locus. Considering only the loci identified as neutral, there remained significant population structure over the region of the North Atlantic studied. In addition to a weak pattern of isolation by distance, we identified a putative barrier to gene flow between sample sites either side of the Charlie-Gibbs Fracture Zone, which marks the location where the sub-polar front crosses the Mid-Atlantic Ridge. This may reflect a boundary across which larvae are differentially distributed in separate current systems to some extent, promoting differentiation by drift. Structure due to both drift and apparent selection should be considered in management policy.

In the Northeast Atlantic fishery for roundnose grenadier Coryphaenoides rupestris, discards account for about 30% of the catch in weight. Data on discards are scarce; however, length distributions and discard rates appear to be relatively stable from year to year. In contrast, landings data available since 1990 show that the average pre-anal fin length has decreased from 20.7 cm in 1990 to 15.2 cm in 2008, resulting in a 58% reduction of the mean individual weight (850 g in 2008) and an increasing occurrence of overlapping class sizes between landings and discards in recent years. For stock assessment, the method of separable virtual population analysis (SVPA) was used. However, because of the lack of discard data for many of the years covered by the study, the catch data used as input to the assessment model had to be reconstructed from the available information (landings, discards, fishing effort and bathymetric distribution of the stock) using two methods. The first method relied on the assumption that the recent length distributions of discards were applicable to the earlier years (1990-1997). It resulted in unrealistic bimodal length distributions, suggesting a change in discarding practices through time, with larger individuals being discarded in the early days. The second method, based on the fishing effort and length distribution by depth strata, produced unimodal distributions for the whole period and confirmed that the average length of discarded fish was higher in the early days of the fishery. In both cases, the estimates of biomass follow parallel trends, suggesting a strong decline in the population. The available information and methods are discussed.

We isolated nine new microsatellites for the deep-sea fish Coryphaenoides rupestris. These loci are highly polymorphic, with allele number ranging from 14 to 42 and heterozygosity ranging from 0.647 to 0.965. Four of these loci also amplified in C.brevibarbis.

The foremost temporal signal to the deep benthos, where temperature and light conditions are relatively constant, is a seasonal pulse of organic carbon sinking from the photic layer. In the Porcupine Seabight region of the NE Atlantic this flux begins during late spring and early summer, although the timing and intensity of the peak varies annually. A rapid response to this nutrient input is most apparent amongst bacteria and benthic meiofauna which can directly utilize the carbon. The question remains as to whether the seasonal influx of carbon to the deep Atlantic may affect, and possibly entrain, aspects of the life cycles of generalist scavengers near the top of the trophic hierarchy, such as macrourid fish. Biochemical analyses of the white muscle of three macrourid species indicate a slight seasonal effect. White muscle protein content in Coryphaenoides rupestris is twofold higher in autumn than spring, RNA content and RNA to protein ratio increased in C. guentheri in autumn, and protein, RNA, and RNA to protein ratio all are higher during autumn than spring in shallow living C. armatus (2,500 m). Changes in RNA to protein ratio in the white muscle of C. armatus, relative to depth of capture, appear to reflect expected patterns in specific growth rate. Significantly higher RNA to protein ratios are apparent in shallow than deep living C. armatus in both seasons. There is no significant decline in white muscle protein content with depth of capture in these three taxonomically related species. Data were collected over several successive years and the possibility of interannual variability complicates the interpretation of seasonal patterns. Despite these limitations this study does indicate a slight seasonal difference in the growth rate of C. rupestris, C. guentheri and C. armatus in the deep Northeast Atlantic.

Data on the distribution of juvenile rock-nosed grenadier Coryphaenoides rupestris in the northern Atlantic are provided. The results of studies of the size and age composition are presented, and specific features of vertical and horizontal distribution of juvenile individuals are analyzed. Directions of the subsequent study of the species in early ontogenesis are determined.

Much is known in very broad terms about the distribution of deep-sea fishes, but infor- mation on fine-scale habitat selection and behaviour in the largest living space on earth is still rare. Based on video sequences from 4 dives performed with the manned submersible 'Nautile' at depths between 400 and 2000 m in the Bay of Biscay, NE Atlantic, we studied the behaviour of co-occurring slope-dwelling deep-sea fishes. Five different habitats were identified according to depth range or topographical and hydrological characteristics. For each fish species or genus that could be identi- fied, estimates of absolute abundance were provided. The most frequently occurring species, round- nose grenadier Coryphaenoides rupestris, blackmouth catshark Galeus melastomus, bluemouth Helicolenus dactylopterus dactylopterus, orange roughy Hoplostethus atlanticus, North Atlantic codling Lepidion eques, greater forkbeard Phycis blennoides, and northern cutthroat eel Synapho- branchus kaupi were quantitatively compared with respect to the relative frequencies of disturbance responses to the submersible, locomotion behaviour, and vertical positioning above the bottom. Clear variations in behaviour and abundance among species and habitats were found, reflecting both species-specific and flexible adjustment to small-scale spatial and temporal variability on the Bay of Biscay continental slope. These results have important implications for the development of sustainable deep-water fisheries management.

French deepwater fish exploitation (500 m) began off the West coast of the British Isles in 1973. It further developed in the 1980s, and intensified in the 1990s. In 1997, the French fleet comprised 49 boats, and since 1995 has landed yearly about 19,500 t of deepwater fish species, of which, the grenadier Coryphaenoides rupestris (Macrouridae) has been the most abundant. Discard data were sampled on-board by observers on French high sea trawlers from 1995 to 1997. Eight species were identified as totally landed, 43 non-commercial species as totally discarded and only one, the grenadier, as both landed and discarded. The mean discarding rate by haul was 48.5% in weight, whereas the mean grenadier discarding rate was 21.2%; these rates increased with depth. Discard species composition and discard quantities varied with depth, and depended on the specific composition of the fish communities, species abundance and their length–frequency distribution. The latter, established for grenadier and Alepocephalus bairdii (Alepocephalidae), assumes a bathymetric ontogenic migration. Annual discards of the fishery accounted for about 17,500 t in 1996 and 1997, but the results are quite uncertain.

Coryphaenoides rupestris Gunnerus, 1765 – Roundnose grenadier; Lagartixa-da-rocha, ②③ The occurrence of the species C. rupestris is reported off Madeira, in the PECS area (Josephine Bank), BMNH, No. 1995.7.25.17, 14.3002º W, 36.7336º N; 11 Apr. 1972; SOC, Discovery No. 785705_210_FIS_119003, 14.5199º W, 36.7824º N, 12 Apr. 1972., Published as part of Carneiro, Miguel, Martins, Rogélia, Landi, Monica & Costa, Filipe O., 2014, Updated checklist of marine fishes (Chordata: Craniata) from Portugal and the proposed extension of the Portuguese continental shelf, pp. 1-73 in European Journal of Taxonomy 73 on page 35, DOI: 10.5852/ejt.2014.73, http://zenodo.org/record/3866515

The deep sea is often thought of as a cold, dark and uniform environment with a low-fish biomass, much of which is highly adapted for life in a food-poor environment. While this might be true of the pelagic fish living in the water column, it is certainly not true of the demersal fish which live on or close to the bottom on the continental slopes around the British Isles (the Atlantic Frontier). These fish are currently being commercially exploited. There is growing evidence to support the view that success of the demersal fish assemblages depends on the pelagic or benthopelagic food sources that impinge both vertically and horizontally onto the slope. There are several quite separate and distinct deep-water fisheries on the Atlantic Frontier. It is a physical barrier, the Wyville-Thomson Ridge, which results in the most significant division of the fisheries. The Ridge, which has a minimum depth of about 500 m, separates the warmer deep Atlantic waters from the much colder Norwegian Sea water and as a result, the deep-water fisheries to the west of the Hebrides and around the offshore banks are quite different from those of the Faroe-Shetland Channel (West of Shetland). The fisheries to the West of the Hebrides can be further divided by the fishing method used into bottom trawl, semipelagic trawl and longline. The bottom-trawl fisheries extend from the shelf-slope break down to about 1700 m and the target species varies with depth. The smallest vessels in the fleet fish on the upper slope, where an important target species is the anglerfish or monkfish ( Lophius spp.). On the mid-slope the main target species are blue ling ( Molva dypterygia ) and roundnose grenadier ( Coryphaenoides rupestris ), with bycatches of black scabbardfish ( Aphanopus carbo ) and deep-water sharks. On the lower slope orange roughy ( Hoplostethus atlanticus ) is an important target species. The major semipelagic trawl fishery is a seasonal fishery on spawning aggregations of blue whiting ( Micromesistius poutassou ). The other semipelagic fishery is on spawning aggregations of the greater silver smelt or argentine ( Argentina silus ). Spanish and UK vessels that target mainly hake ( Merluccius merluccius ) and a Norwegian fleet that targets ling ( Molva molva ), blue ling and tusk ( Brosme brosme ) dominate the upper slope longline fishery. West of Shetland, the fishery on the upper slope has some similarities with that of the Hebridean slope, with anglerfish and blue ling being important target species. A quite different fishery occurs in the transition zone between the Atlantic and Norwegian Sea waters. Here the main target species is Greenland halibut ( Reinhardtius hippoglossoides ). Below the transition zone biomass decreases rapidly and there is no fishery. It is generally agreed that many deep-water species have slow growth, a high age at first maturity and a low fecundity, which makes them vulnerable to over-exploitation. Other features of these fishes such as high mortality of discards and escapees will add to the problems. Despite this the only management procedures in place are general limitation of effort measures within the area of jurisdiction of the European Union.

The deepsea environment is generally regarded as being one of low energy and productivity. Species exploited at depths of over 600 m like orange roughy ( Hoplostethus atlanticus ), oreos (e.g. Allocyttus niger , Pseudocyttus maculatus ), and macrourid rattails (e.g. Coryphaenoides rupestris , Macrourus berglax ) have slow growth rates and high longevity compared to traditional commercial species from the continental shelf. They have low levels of sustainable yields, are vulnerable to overfishing, and have slow recovery rates. Yet, they are often high-value species, and this has maintained interest in developing new fisheries for deepwater species. In New Zealand waters orange roughy has been fished for 20 years. Familiar patterns of rapid fishery development with large catches, followed by contractions in stock distribution, and reductions in catch levels as the stocks become over-exploited, have occurred. Quotas in a number of New Zealand fisheries were reduced in the early 1990s, and this enables an insight into how stocks respond with reduced levels of exploitation, and how resilient and sustainable these fisheries may be in the long term. Examples are given for several New Zealand and Australian orange roughy fisheries. Changes in abundance, fishery performance, and biological characteristics are examined. In some cases fish stocks appear to be holding their own, and are supporting relatively stable catch rates, but in others stocks are still declining. There are few signs of biological compensation, and recruitment levels appear to be low. Lack of good data on levels and patterns of recruitment is a major source of uncertainty in current stock assessments, and a principal concern for long term sustainability of such fisheries

The reproductive strategies of three benthopelagic species of deep-water fish from the northeast Atlantic were studied: Helicolenus dactylopterus (245–800 m depth), Coryphaenoides rupestris (400–1500 m depth) and Alepocephalus bairdii (650–1700 m depth). The reproductive strategies and fecundity of the females of the three species were studied over a 2-year sampling period (December 1995–December 1997). H. dactylopterus reproduced from March to June and oocyte development within the population was synchronous. Annual fecundity was indeterminate, but batch fecundity ranged from 1212 to 20 504 oocytes per female. Reproduction in C. rupestris extended from February to November with a maximum from May to November. Oocyte development within the population was not synchronous. Annual fecundity was indeterminate, but batch fecundity was estimated to be between 4078 and 68 780 oocytes per female. The precise period of reproduction for A. bairdii could not be determined; however, mature fish were found throughout the year with a major spawning period from January to April. Oocyte development within the population was not synchronous. Annual fecundity was indeterminate, but batch fecundity was estimated at 458–7049 oocytes per female. There was a trend for an increase in the duration of the reproductive period and a decrease in synchronicity of maturation with increasing depth. A long spawning period and asynchrony in maturation may be partially explained by the lack of marked cyclic environmental factors in the deep sea.

The catch (landings and discards) at age of roundnose grenadier (Coryphaenoides rupestris) were used to assess the stock in the areas exploited by French trawlers. A pseudo-cohort analysis, corrected for changes in fishing effort in the period before the year which catch at age are analysed, was carried out for the years 1996 and 1997. Age distributions were derived from length measurements and an age length key (ALK) estimated from 1529 otoliths. Although, unvalidated in the size range of adult fish, this ALK looked consistent with validated length at age of juveniles and former age estimates of adult fish. It was also combined with length distributions data from surveys prior to exploitation and from landings in 1990 (early in the history of the fishery) to estimate the total mortality then equivalent to the natural mortality. This poorly converged pseudo-cohort suggested a low annual fishing mortality. However, the behaviour of the stock was further investigated from yield per recruit (Y/R) analysis. Because of a series of gaps in the knowledge of this species (stock(s) distribution, unvalidated ages, …), the estimates of fishing mortality must be considered with caution. The main interest of the analysis is probably to stress the impact of the discards on the potential yield of roundnose grenadier.

Three major fleets of high sea trawlers practising deep-water fishing are defined. Altogether, these fleets catch more than 90% of the French landings of deep-water species. A multiplicative model has been adjusted to monthly catch per unit effort (CPUE) weighted by effort to estimate annual abundance indices for the main deep-water species exploited since the late 1980s (Coryphaenoides rupestris, Hoplostethus atlanticus, Aphanopus carbo, Centroscymnus coelolepis and Centrophorus squamosus) and for the main other species caught by these fleets (Pollachius virens, Molva dipterygia and Molva molva). For the deep-water species, the CPUE trends are not consistent between fleets. The differences are interpreted to be due to technical changes and the indices from the fleet of larger specialised deep-water trawlers is considered to be the most representative of the actual fish abundance. For saithe and blue ling the declining trend in CPUE previously documented are observed again with slight differences in slopes probably due to method. The CPUE of deep-water species show strong declining trends suggesting severe impact of the fishery. However, declining CPUE is a normal feature of any new fishery. The possible effect of the fishing strategy on the amount of effort counted as species directed effort cannot be excluded because the catch and effort data available is detailed by statistical rectangles while the proper scale would be the trawl haul.

It was a long held belief that the constancy of the deep-water environment would result in continuous growth and all year round reproduction in deep-water fish. However, rings on scales and otoliths of deep-water fishes similar to those found in shallow-water fish species have been reported since the beginning of the 20th century. The development of a fishery for Coryphaenoides rupestris in the 1960s led to the use of scales and otoliths for age estimation without any attempt to validate the annual nature of the growth zones. This paper reviews the literature on age estimation in macrourid fishes. New data on the validation of age estimates of juvenile macrourids are presented. The species studied are all from the eastern North Atlantic and span a depth range from about 250 to 5000 m. A common feature is the apparent delay in the onset of the growing season until the autumn and winter months, which is possibly linked to food availability in the deep sea.

The diet of slope dwelling macrourid fishes in the eastern North Pacific is poorly known. We collected several hundred stomach samples to investigate the feeding habits of Coryphaenoides acrolepis and Albatrossia pectoralis , the two dominant slope dwelling macrourids off the continental United States. Coryphaenoides acrolepis exhibited a pronounced ontogenetic shift in diet. Specimens 15 cm with scavenged food constituting approximately 20% of the weight of total prey and occurring in approximately 20% of fish 21–29 cm. Albatrossia pectoralis consumed primarily midwater fish and squid, and we believe that it feeds in the water column. There were significant differences between the diets of A. pectoralis and C. acrolepis suggesting some degree of niche separation between macrourid species on the continental slope of the eastern North Pacific. Both species are at the top of the food web on the upper continental slope and, because of their abundance, may exert significant pressures on their prey populations.

Microsatellites represent an important tool for characterising population structure, for attributing individuals to stocks, and for revealing ecological processes taking place on population and meta-population levels. A sound knowledge of population structure is essential for sustainable management of exploited fish stocks, and helps to understand population connectivity and speciation. We developed for the first time primers for microsatellite loci in the carapine grenadier, Coryphaenoides carapinus, inhabiting the abyssal Atlantic. Eleven microsatellites were obtained from partial genomic DNA libraries enriched for tetranucleotide repeats. The loci were characterised in three unrelated individuals and nine loci were found to be polymorphic. Cross-amplification in two commercially exploited deep-sea macrourid species (Coryphaenoides rupestris and Macrourus berglax) resolved two polymorphic loci in each species.

Relative eye size, gross brain morphology and central localization of 2-[125I]iodomelatonin binding sites and melatonin receptor gene expression were compared in six gadiform fish living at different depths in the north-east Atlantic Ocean: Phycis blennoides (capture depth range 265 to 1260 m), Nezumia aequalis (445 to 1512 m), Coryphaenoides rupestris (706 to 1932 m), Trachyrincus murrayi (1010 to 1884 m), Coryphaenoides guentheri (1030 m) and Coryphaenoides (Nematonurus) armatus (2172 to 4787 m). Amongst these, the eye size range was 0.15 to 0.35 of head length with a value of 0.19 for C. (N.) armatus, the deepest species. Brain morphology reflected behavioural differences with well-developed olfactory regions in P. blennoides, T. murrayi and C. (N.) armatus and evidence of olfactory deficit in N. aequalis, C. rupestris and C. guentheri. All species had a clearly defined optic tectum with 2-[125I]iodomelatonin binding and melatonin receptor gene expression localized to specific brain regions in a similar pattern to that found in shallow-water fish. Melatonin receptors were found throughout the visual structures of the brains of all species. Despite living beyond the depth of penetration of solar light these fish have retained central features associated with the coupling of cycles of growth, behaviour and reproduction to the diel light–dark cycle. How this functions in the deep sea remains enigmatic.

Hepatic levels of OCs (Organochlorines) were analysed in deep-sea fish from the Nordfjord in Norway. Levels of PCBs in the present study exceed background levels in fish from Norwegian water by a factor of 1.5 to 50, and DDTs by one to two orders of magnitude. DDTs in fish from the Nordfjord have previously been attributed to DDT use in fruit orchards. The present levels of DDTs show that the decline usually found in biota in Scandinavia since the 1970s is not found in the deep-sea fish in Nordfjord. There is no known local PCB source that can explain the elevated levels in the present study. This indicates that the fjord efficiently accumulates atmospheric contaminants. Chlordanes and HCB were less important, and HCHs were not detected.

This paper summarizes the history of commercial exploitation of roundnose grenadier Coryphaenoides rupestris in the North Atlantic. Length frequencies of C. rupestris in 1993, from 400 to 1200 m on the slopes of the Rockall trough indicate a reduction since the 1970s in the modal length of fish found at 700–1000 m. Ages ranged from 2 to 50 years for males and 2 to 60 years for females, with most between 10–38 years. Females attained a greater asymptotic pre-anus length (L∞=19.5 cm) than males (L∞=15.5 cm) and had a greater weight for a given age (male W∞=761g, female W∞=1132g). This species may have a protracted spawning period. Using pre-anus lengths, 50% of male fish were mature at 10 cm (ages 8–10) while 50% of female fish were mature at 12 cm (ages 9–11). At the greatest depths sampled the length frequency of fish was bimodal with a hiatus between 9 and 11 cm (ages 8–12). Highest catch rates occurred on the Donegal slope in September at a depth of 800–1000 m.