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Marchal, P., and Vermard, Y. 2013. Evaluating deepwater fisheries management strategies using a mixed-fisheries and spatially explicit modelling framework. – ICES Journal of Marine Science, 70: 768–781. We have used in this study a spatially explicit bioeconomic modelling framework to evaluate management strategies, building in both data-rich and data-limited harvest control rules (HCRs), for a mix of deepwater fleets and species, on which information is variable. The main focus was on blue ling (Molva dypterygia). For that species, both data-rich and data-limited HCRs were tested, while catch per unit effort (CPUE) was used either to tune stock assessments, or to directly trigger management action. There were only limited differences between the performances of both HCRs when blue ling biomass was initialized at the current level, but blue ling recovered more quickly with the data-rich HCR when its initial biomass was severely depleted. Both types of HCR lead, on average, to a long-term recovery of both blue ling and saithe (Pollachius virens) stocks, and some increase in overall profit. However, that improvement is not sufficient to guarantee sustainable exploitation with a high probability. Blue ling CPUE did not always adequately reflect trends in biomass, which mainly resulted from fleet dynamics, possibly in combination with density-dependence. The stock dynamics of roundnose grenadier (Coryphaenoides rupestris), black scabbardfish (Aphanopus carbo) and deepwater sharks (Centrophorus squamosus and Centroscymnus coelolepis) were little affected by the type of HCR chosen to manage blue ling.

In contrast to generally sparse biological communities in open-ocean settings, seamounts and ridges are perceived as areas of elevated productivity and biodiversity capable of supporting commercial fisheries. We investigated the origin of this apparent biological enhancement over a segment of the North Mid-Atlantic Ridge (MAR) using sonar, corers, trawls, traps, and a remotely operated vehicle to survey habitat, biomass, and biodiversity. Satellite remote sensing provided information on flow patterns, thermal fronts, and primary production, while sediment traps measured export flux during 2007-2010. The MAR, 3,704,404 km 2 in area, accounts for 44.7% lower bathyal habitat (800-3500 m depth) in the North Atlantic and is dominated by fine soft sediment substrate (95% of area) on a series of flat terraces with intervening slopes either side of the ridge axis contributing to habitat heterogeneity. The MAR fauna comprises mainly species known from continental margins with no evidence of greater biodiversity. Primary production and export flux over the MAR were not enhanced compared with a nearby reference station over the Porcupine Abyssal Plain. Biomasses of benthic macrofauna and megafauna were similar to global averages at the same depths totalling an estimated 258.9 kt C over the entire lower bathyal north MAR. A hypothetical flat plain at 3500 m depth in place of the MAR would contain 85.6 kt C, implying an increase of 173.3 kt C attributable to the presence of the Ridge. This is approximately equal to 167 kt C of estimated pelagic biomass displaced by the volume of the MAR. There is no enhancement of biological productivity over the MAR; oceanic bathypelagic species are replaced by benthic fauna otherwise unable to survive in the mid ocean. We propose that globally sea floor elevation has no effect on deep sea biomass; pelagic plus benthic biomass is constant within a given surface productivity regime. Publisher PDF

Data from EU-Spain (Instituto Español de Oceanografía) bottom trawl surveys in the NAFO Regulatory Area (2002–2011) were analyzed to examine patterns on the South of Grand Banks (NAFO Div. 3NO) of groundfish assemblage structure and diversity in relation to depth. The 1160 hauls from the slope surveys spanned between 38 and 1460 m in depth. We focused on the 28 most abundant species, which made up 92.6% of the catch in terms of biomass. Assemblage structure was strongly correlated with depth. For the most part, changes in assemblages seem to be fairly continuous, although there were more abrupt changes at 300 m. Five assemblages were identified. Two shallow assemblages were found in the shelf. Assemblage I (Shallow) comprises the strata with depths lesser than 150 and include yellowtail flounder (Limanda ferruginea), American plaice (Hippoglossoides platessoides), Northern sand lance (Ammodytes dubius), moustache sculpin (Triglops murrayi), capelin (Mallotus villosus) and web sculpin (Hemitripterus americanus). Assemblage II (Shallow) includes the strata with depths between 151 and 300 m and comprises Atlantic cod (Gadus morhua), American angler (Lophius americanus), wolfish (Anarichas lupus) and thorny skate (Amblyraja radiata). Assemblage III (Intermediate) contains the depth strata between 301 and 600 m. Redfish (Sebastes spp.), spotted wolfish (Anarhichas minor), Arctic eelpout (Lycodes reticulatus), Northern wolfish (Anarhichas denticulatus), white hake (Urophycis tenuis), witch flounder (Glyptocephalus cynoglossus) and longfin hake (Phycis chesteri) were included in the intermediate assemblage. Finally, we found two deep clusters: Assemblage IV (Deep) contains the depths between 601 and 1000 m, and Assemblage V (Deep) the depth strata greater than 1001 m. Greenland halibut (Reinhardtius hippoglossoides), marlin-spike (Nezumia bairdii), roughhead grenadier (Macrourus berglax) and spinytail skate (Bathyraja spinicauda) formed Assemblage IV. Snubnosed spiny eel (Notacanthus chemnitzii), blue antimora (Antimora rostrata), Northern cutthroat eel (Syphanobranchus kaupii), roundnose grenadier (Coryphaenoides rupestris), black dogfish (Centroscyllium fabricii), Arctic skate (Amblyraja hyperborean) and longnose chimera (Harriotta raleighana) made up the deepest assemblage. Despite dramatic changes in biomass and abundance of the species in the area, the boundaries and composition of the assemblages seem to be similar to the period before the collapse. Although some changes were evident, the main ones were replacements of the dominant species in several assemblages and bathymetric range extension of distribution of some species. Yellowtail flounder appears to be the dominant species in the shallowest assemblage instead of Atlantic cod and American plaice that were dominant in the period before the collapse in the area; redfish is the dominant species in the second shallow and intermediate assemblages. Diversity appears inversely related to biomass in the different assemblages. Despite the fishing effort in the deep waters of the Grand Banks, the overall pattern of demersal fish assemblages remains similar over time. This pattern is similar in other Atlantic areas; it indicates that changes in the fish populations in Northwest Atlantic have been produced on a large scale and are not limited to specific areas.

The reproductive biology of roundnose grenadier Coryphaenoides rupestris was investigated against a background of increasing commercial exploitation. Samples were taken from surveys carried out in Rockall Trough between 1993 and 1995. An eight-point maturity scale was developed based on both visual inspection of the ovaries and histological screening. The various stages of development of roundnose grenadier oocytes were described and the relative proportion of oocyte types and their respective size range in each maturity stage were investigated. The dynamic organization of the ovary indicated a determinate maturation cycle in this species. Population spawning appears to be prolonged, extending from July to at least November. However, data were insufficient to clarify individual spawning duration. The potential fecundity of 29 mature fish ranged from 11 083-55 175 (63-95 cm total length). The results were very similar to previous values from the North Atlantic. The reproductive strategy of the roundnose grenadier is discussed in the light of the current commercial exploitation of the Species.

Comparative bottom trawl and longline surveys were carried out on two chartered commercial fishing vessels in the deep waters (350-1300 m) of the Rockall Trough, an area subjected to heavy commercial exploitation. The species composition, catch rates and length distributions from each survey were very different and reflected the fundamental difference in the two types of fishing operations. Bottom-trawled catches produced greater species diversity and higher discard rates. Longline catches produced larger specimens of teleost fish and were dominated by squalid shark. Trawl discards, expressed as kgs of discards per tonne of roundnose grenadier Coryphaenoides rupestris landed, were calculated for a broad range of the most abundant species taken in the catch. First estimates of total international discarding from deep-water trawling operations in the Rockall Trough area (7530 tonnes; 26.5 million individuals) were made by raising the discard rates using international grenadier landings for 1995. The outlook for the continued exploitation of the deep-water fish resource in the Rockall Trough and possible management options are discussed.

Validation of the ageing of deep-water fish is difficult and there are only a few instances where the rings on the otoliths have been shown to be laid down annually. Roundnose grenadier have been fished commercially in the North Atlantic since the 1960s and the adult fish have frequently been aged by counting the rings in otoliths or scales. All the ageing was done on the assumption that the rings in the otoliths or scales were annual. Between 1975 and 1992, the Scottish Association for Marine Science carried out seasonal trawling surveys in the Rockall Trough using a fine-meshed trawl, and collected otoliths from a wide size range of roundnose grenadier. An examination of the growing edge of otoliths from juvenile fish from these collections suggests that the rings in the otoliths are laid down annually. The broader, opaque zones which represent the growth phase were dominant between September and March. The thinner, hyaline zones were dominant between April and July. The apparent delay in the growth phase compared with most shallow-water species is discussed in relation to the availability of mesopelagic prey.

The abundance of the macrourid Coryphaenoides (Nematonurus) armatus was investigated using a single warp trawl and baited camera at soundings from 2500 to 5000 m in the north-east Atlantic Ocean. There was no significant relationship between abundance (n km−2) as determined from swept area of the trawl and numbers of fish photographed at standard baits. However, timing of the first arrival (tarr s) of the first fish at bait correlated well with the trawl data through the relationship: It is concluded that by measurement of arrival times, the baited camera provides a cost-effective complement to trawl sampling for estimating abundance of deep-water fish including Synaphobranchus kaupi, Anlimora rostratu and C. (N). armatus. However, some abundant species such as the roundnose grenadier Coryphaenoides rupestris were not attracted to baited long-lines or baited cameras and therefore could be sampled only by trawl.

In situ biomonitoring of roundnose grenadier (Coryphaenoides rupestris) and Norway lobster (Nephrops norvegicus) and measurements of pollutants levels in caged common mussel (Mytilus edulis) were used to assess the environmental impact of contaminants in the Skagerrak and Kattegat and near the Faroe Islands. By comparing the responses of a suite of established and potential biomarkers, i.e. different liver detoxification enzymes and histopathology in roundnose grenadier in the Skagerrak, and at a reference site off the Faroe Islands, evidence was found that the deeper parts of the Skagerrak are affected by anthropogenic contaminants. Levels of polycyclic aromatic hydrocarbons (PAH) and organochlorines in caged mussels were compared with those sediment. The Skagerrak/Kattegat area was found to be more polluted than the Faroe area and the caged mussels bioaccumulated the PAHs to a higher degree than the organochlorines. This seems to indicate that the PAHs in the sediments are more bioavailable than the organochlorines and that the induced ethoxyresorufin-O-deethylase activities observed in Skagerrak roundnouse grenadier may be due to PAH exposure. The Norway lobster accumulated manganese to various degrees in the different parts of the organism. The excretion rate of manganese could not cope with the uptake rate at higher exposure concentrations. Enhanced manganese concentrations, especially in the gills and haemolymph, seem to be a useful indication of increased manganese levels in the water. Hypoxia makes a sediment-bound manganese much more bioavailable. The elevated levels of manganese in Norway lobster from the Skagerrak/Kattegat area therefore seem to reflect the increasing occurrence of hypoxic conditions in the Kattegat and coastal areas of the Skagerrak. Accumulated manganese in Norway lobster may thus serve as a biomarker of hypoxia. In conclusion, the use of a suite of different biomarkers in ecotoxicological and ecophysiological studies and analyses of contaminant levels have provided evidence of a large-scale environmental impact of pollutants and nutrients in the Skagerrak/Kattegat area. This should lead to further efforts to decrease transport into and deposition of waste compounds in the sea.

The eggs of only 13 macrourid species have been reported hitherto, eight identified from free buoyant eggs and five from ripening oocytes. Eggs of 11 species had raised, hexagonally patterned ornamentation on the envelope, while two species bore only partial ornamentation. Ripening oocytes of a further eight species showed that, overall, the eggs of 13 species had characteristic hexagonal ornamentation and three partial ornamentation, but four were smooth. Fertilized eggs of Coryphaenoides (Coryphaenoides) rupestris were found with smooth envelopes, while ornamented eggs have been reported for this species also. Little taxonomic significance could be attached to these results. Some correlation was found between the three categories of egg envelope ornamentation and species' bathymetric distributions. A recent model of egg development in a slope dwelling trachichthyid species suggested analagous potential ecological advantage for ornamentational variation in macrourids.

Demersal fishes on the continental rise and slope were sampled by trawl, baited trap and a baited camera. Seventy-one different species were trawled, but only 18 species approached baits. At rise soundings (4100 m to 2250 m) Coryphaenoides (Nematonurus) armatus was dominant at baits and comprised 41·5% of the trawl catch. On the slope (Synaphobranchus kaupi was dominant at baits and comprised 32·7% of the trawl catch. At 1500–2501 m Antimora rostrata competed at baits and comprised 5–10% of trawl catches. At 1500–1650 m Centroscymnus coelolepis also consumed baits but was not captured by trawl. For C. (N.) armatus abundance was proportional to tarr2 (where tarr= arrival time), demonstrating that arrival time of the first fish at baits provides an estimate of population density. Maximum estimated abundance at 2897 m was 877 km-2, more than five times the abundance on the abyssal plain. Halosauropsis macrochir, Lepidion eques, Coryphaenoides guentheri, Gadiculus argenteus and Coryphaenoides rupestris were important in trawl samples but absent or rare at baits.

Two species, Coryphaenoides rupestris and Argentina silus, were abundant in the ichthyoplankton of the 150–550 m depth zone of the Skagerrak in 1992. Eggs of C. rupestris occurred only in October and December and a single yolk sac larva was caught in December. Postlarvae and juveniles occurred in all months (Feb, Apr, Jun, Oct, Dec) and showed a continuous increase in length through the year. This confirms earlier indications of a single late autumn spawning period. By October the juveniles had attained a demersal mode of life. Argentina silus eggs and larvae occurred year-round, but eggs were most abundant in the spring. Most of the other fish eggs and larvae were probably caught incidentally in surface layers. Exceptions may be four postlarval Atlantic halibut Hippoglossus hippoglossus L.

We developed polymerase chain reaction primers for eight dinucleotide microsatellite loci in the marine deep sea fish, roundnose grenadier (Coryphaenoides rupestris). All markers were obtained from a partial genomic DNA library, and characterized in 90 unrelated individuals from one putative population sampled on the Mid-Atlantic Ridge. The number of alleles ranged from two to 61 with an average of 21 per locus. The observed heterozygosity levels ranged from 0.301 to 0.987 with an average of 0.672. Several of the markers amplified multiple alleles from either the Atlantic cod (Gadus morhua) or the deep-sea fish roughhead grenadier (Macrourus berglax).

The Macrourid fish roundnose grenadier, Coryphaenoides rupestris, is one of the most common benthopelagic fishes on the northern mid-Atlantic Ridge. The ecology of the species is comparatively well studied in continental slope waters of the North Atlantic, but not on the mid-Atlantic Ridge, which is a central mid-ocean area of its distribution. In total, 166 specimens from the RV G.O. Sars cruise in July 2004 were examined. The diet mainly comprised cephalopods, pelagic shrimps and fish. Pelagic and benthopelagic copepods were the most numerous prey, but did not contribute much on a weight basis. Cephalopods were by far the most important prey of the small grenadiers, while shrimps and fish became increasingly significant with increasing size. Previous studies from other areas have also found pelagic prey to be important, but in contrast to this study, cephalopods were generally of less importance. The study was an element of more wide-ranging food-web studies of the mid-Atlantic Ridge macro- and megafauna communities within the international MAR-ECO project. Accepted version

The variation in species composition of continental slope fishes as determined by the catches of different trawls towed either on single or paired warps was analysed by Detrended Correspondence Analysis (DCA). The catches of two trawls, a semi-balloon trawl (OTSB) and a Granton trawl (GT) were very similar when towed on paired warps. Significant differences were found between the catches of the OTSB trawl towed on single and paired warps. The DCA effectively provided information on the important gradients, e.g. depth, trawl type, and indicated which species were most abundant in the different depth zones and trawl types. Detailed accounts of the abundance and biomass of different species by trawl type and depth zone are given and the observed pattern of distribution discussed.

To investigate the trophic ecology of two of the dominant families of deep-sea fish (Macrouridae and Moridae) fatty acid and stable isotope analyses were applied to liver and muscle samples of five abundant species from the NE Atlantic. In conjunction with stomach content data these methods made it possible to identify differences in feeding strategies between the five study species as well as variation in feeding in relation to increasing depth and body size. Biomarkers identified strong similarities between Coryphaenoides armatus and Antimora rostrata though differences were found associating C. armatus more with the benthic food web whereas A. rostrata showed stronger links to the pelagic food web. While Lepidion eques was classified as a species linking benthic and benthopelagic food webs, both fatty acid and stable isotope data suggested that Coryphaenoides guentheri fed on an exclusively benthic diet. Coryphaenoides rupestris on the other hand were largely dependent on a copepod-based food web. Ontogenetic changes in feeding were found for both A. rostrata and C. armatus with the indication of a switch from active predation to scavenging occurring with increasing body size. Biomarkers also reflected the seasonal influx from the photic zone though changes were species-specific and probably reflected the variation in prey availability and abundance in response to these inputs. Our findings have thus demonstrated that the combined use of these biomarkers can elucidate trophic specialisations in situations where conventional methods alone previously provided insufficient data.

The dynamics of clearance, segregation and elimination of a marine bacterium, Moraxella sp., by the shore crab, Carcinus maenas (L.) has been studied utilizing fluorescent and radiolabelling techniques. In addition to the gills, the hepatopancreas was a major site of bacterial accumulation with sequestration occurring within haemocyte clumps and groups of stationary cells in this organ. The heart, excretory organ and subcuticular tissues also incorporated bacteria, but to a lesser extent. By the first day post-injection, many of the segregated micro-organisms had been removed from the organs. This latter process was not due to the exodus of laden haemocytes or of intact cell clumps from the host but seemed to result from lytic action by the host blood cells. Little material arising from such bacterial/haemocytic interaction was, however, immediately excreted, and much was relocated in the general body tissues as well as the gill nephrocytes.

An account based on hydroacoustic data and trawl surveys of the distributional patterns and species assemblages of the fishes inhabiting the Norwegian Deep and adjacent slopes is presented. The Norwegian Deep is the moderately deep (275 to 700 m) shelf channel extending from the Norwegian Sea into the North Sea and Skagerrak. The Norwegian Deep has a pelagic and demersal fish fauna which is rather different from the fauna in adjacent shallow areas. Blue whiting (Micromesistius poutassou) and Maurolicu muelleri form a widely distributed and normally two-layered pelagic association. There appears to exist a rather sharp boundary at about the 200 m isobath between species assemblages of the Norwegian Deep and those of the shallow plateaus of the North Sea and Skagerrak. The fish fauna of deeper zones of the Skagerrak differs from the areas off western and southwestern Norway. The more conspicuous feature in the Skagerrak is the rather high abundance of greater argentine (Argentina silus) and roundnose grenadier (Coryphaenoides rupestris) at depths greater than 300 m. The species assemblages of the Norwegian Deep resemble those found in the areas along the outer shelf of the Northeast Atlantic and the deep fjords of Norway. The western and southern slopes appear to be feeding and overwintering areas for some fish species from adjacent shallow areas, particularly populations of saithe (Pollachius virens) and Norway pout (Trisopterus esmarki). It is suggested that the Norwegian Deep, due to its characteristic bathymetry and the strong influence of Atlantic inflow, is colonized by mesopelagic and benthic species from the other shelf areas of the Northeast Atlantic. The shelf channel appears to be deep enough to allow outer shelf species temporary or permanent access to the inner shelf environment.

The roundnose grenadierCoryphaenoides rupestris Gunnerus, 1765 occurs benthopelagically in the deepest parts of the Norwegian Deep, i.e., at depths >300 m in the Skagerrak. Based on studies of distribution carried out in the years 1984 to 1987, it appears that the concentrations contitute a largely self-sustaining population. From age-readings using transverse otolith sections, the population appears to consist of at least 50 to 60 age-groups and to include a very high proportion of old fish. Population growth-curves in terms of length and weight revealed that females grow comparatively fast for a longer time and attain greater asymptotic sizes than males. Maximum lengths appear however to be lower in the Skagerrak than in waters to the west of Scotland, and the length/weight data indicate that the weight at a given length (weight at length) of large individuals is less than reported from other areas. The major spawning season is in late autumn, probably extending into early winter. Fifty per-cent of females and males become mature for the first time at Age 10 and 8 yr, respectively. Corresponding pre-anal lengths are 11 and 8.5 cm.

The behaviour of eight large benthopelagic fish taxa was analysed using video records collected with an ROV on the mid-slope of the Bay of Biscay. The studied species were roundnose grenadier (Coryphaenoides rupestris), orange roughy (Hoplostethus atlanticus), deep-sea scorpionfish (Trachyscorpia cristulata echinata), and black scabbardfish (Aphanopus carbo), as well as individuals belonging to the families Alepocephalidae, Chimaeridae, and Scyliorhinidae, and to the order Squaliformes. Some of the observed fish were grouped at the family taxonomical level due to visual identification to species being unreliable. Assumed natural (undisturbed) behaviour was categorised in terms of (i) body position with respect to the bottom sea floor, (ii) locomotion and (iii) activity type. Reaction (disturbed) behaviour to the approaching ROV was categorised in terms of reaction type and distance. Environmental conditions (depth, temperature, current speed and direction) and observation conditions (ROV speed and altitude) were recorded simultaneously with fish observations in order to explain the variability in the observed reaction behaviour. A multivariate analysis identified three groups corresponding to a behaviour pattern of a sit and wait strategist (one species), an active bottom hunter (three taxa), and a group of species displaying little activity in their bottom habitat (three taxa). At species level the environmental and observation conditions had some explanatory power for individual behaviour variability. It is hypothesised that the varied behaviour of mid-slope benthopelagic fish contributes to maintain a high species diversity of large predators in an energy poor environment.

Sagittal otoliths of Coryphaenoides rupestris (roundnose grenadier), Helicolenus dactylopterus (bluemouth) and Merluccius merluccius (European hake) were collected using a variety of handling and storage treatments and their elemental composition was examined using inductively coupled plasma mass spectrometry. Some differences between element concentrations were identified between the control and treatment groups, most notably for the element Li. For H. dactylopterus and M. merluccius, Li concentrations were significantly higher in the otoliths extracted with metal forceps and stored in paper envelopes (treatment), compared to those from the same fishes that had been extracted using plastic forceps and stored in polyethylene vials (control). Lower concentrations of Ba and Cr were found in M. merluccius otoliths extracted from fish that had been stored frozen. The presence or absence of elemental concentrations above the instrumental limits of detection was noted, but no significant differences were identified between otolith pairs for any of the treatments. The differences between otolith pairs attributable to storage and handling effects are small compared to between-area differences. © 2006 The Fisheries Society of the British Isles.

Polychlorobiphenyls (PCBs) and pesticides are persistent, semivolatile contaminants whose global circulation is now well established. One of their ultimate sink is the bio- and geo-phases in the deep-sea. We have investigated the distribution of selected PCBs and pesticides with depth and longitude in various deep-sea fish, namely black scabbardfish (Aphanopus carbo), orange roughy (Hoplostethus atlanticus), roundnose grenadier (Coryphaenoides rupestris) and Bathysaurus ferox from Madeira, Sesimbra, the Meriadzec Terrace and Rockall Trough in the North Eastern Atlantic at 1000 m depth, and at 2000 m depth where available. In most species, males presented higher levels of contamination than females. This pattern was probably due to the females eliminating contaminants through egg production. Roundnose grenadier presented higher levels of contamination (mainly p,p'-DDE, CB 153, 138, 180, sigmaCB(24) and p,p'-DDT) in fish caught at 2000 m than at 1000 m depth. Similarly, B. ferox, which is found deeper than the other species studied, showed much higher levels of most CBs and pesticides (lipid normalised) than the other species. Concentrations were up to 10 times higher, and showed differences between water masses.

Description de Fellicola longispiculus n. g., n. sp., parasite de la vesicule biliaire du Poisson Coryphaenoides rupestris recolte au large des iles Feroe (Atlantique Nord). Le nouveau genre appartient a la famille des Rhabdochonidae. Il est proche des genres Johnstonmawsonia, Vasorhabdochona et Pancreatonema, mais en differe par la presence d'epaississements longitudinaux sur la paroi interne de la partie anterieure dilatee du pharynx

This document describes the Spanish deep-sea fishery performed in international waters on the Hatton Bank and proximities (NE Atlantic) during the period 1996-2000. This is a multi-species fishery, carried out by stern bottom trawlers, mainly between June and September, in depths mainly between 800 m to 1600 m. The importance of the fishing activity in this area is increasing notably. This fishery has been monitored since the beginning in 1996, with the collaboration of the fishing industry, by means of a scientific observer programme. The observers on board provide data on catches, discards, location and depth, haul by haul. Length samples of the main species and biological material are also collected. The species composition of the catches is presented. In terms of weight, the roundnose grenadier (Coryphaenoides rupestris) and the bairdii smoothhead (Alepocephalus bairdii) are the most important species in the catches. Other less important species are the Portuguese dogfish (Centroscymnus coelolepis) and the blue ling (Molva dypterygia). In addition to the total catch, the composition of the retained catch and the discard are studied. For the main retained species, the dressing types are described and the conversion coefficients are presented. The length distribution of the catches and the discards, length-weight relationships and other biological aspects of some of the main species are analysed.

In the early-1960s a deepwater form of redfish (Sebastes mentella Travin) was found at depths more than 500 m on the continental slopes of Labrador and North Newfoundland. This group differed from the beaked redfish commonly distributed in these areas by the biological peculiarities of non-developed reproductive organs and lack of sexual dimorphism. The results of nearly 30-year observations showed that the form of non-maturing redfish had not changed. They were distributed along the continental slope northward of Div. 3K and the fish size increased from north to south. The distribution of this form of redfish was similar to that of non-maturing roundnose grenadier (Coryphaenoides rupestris). The origin and causes which led to inhibition of gonadal development of both groups were considered to be analogous. The non-maturing group of redfish was thought to originate from partial eggs and larval drifts from the Irminger Sea to form a pseudo-population in the area studied. The need for studies of the population and its exploitation of this potentially commercially valuable group is emphasized.

Catch Per Unit Effort (CPUE) trends of the main target species of the deep-sea fishery were recorded for one sample trawler in two areas to the west of the British Isles, from 1993 to 1997. Considered species were the orange roughy (Hoplostethus atlanticus), the roundnose grenadier (Coryphaenoides rupestris), the black scabbard fish (Aphanopus carbo) and two squalid sharks: the Portuguese dogfish (Centroscymnus coelolepis) and the leafscale gulper shark (Centrophorus squamosus). Two sources of data have been used: the catch and effort database of IFREMER and the personal logbooks of the skipper from the sample trawler. The personal logbooks indicate the catch per haul, whereas the IFREMER database provides the catch and effort per day and statistical rectangle. From the personal logbooks, the time spent on deep-sea species can be known and CPUE corrected for the depth. These corrected CPUE allow to take into account the changes of the fishing strategy and the variations of the fish abundance according to depth. Both, the life strategies of the exploited species and the fishing strategy of the trawler are very important to consider the CPUE as abundance indices., Les Captures Par Unité d’Effort (CPUE) des principales espèces cibles de la pêcherie récente de l’étage moyen du talus continental ont été suivies dans deux secteurs géographiques à l’ouest des Iles britanniques, de 1993 à 1997, pour un bateau témoin. Les espèces choisies sont l’empereur (Hoplostethus atlanticus), le grenadier de roche (Coryphaenoides rupestris), le sabre noir (Aphanopus carbo) et deux requins de la famille des Squalidae: le pailona commun (Centroscymnus coelolepis) et le squale chagrin de l’Atlantique (Centrophorus squamosus). Deux sources de données ont permis de réaliser ce suivi: la base statistique IFREMER et les cahiers de bords personnels du patron de pêche du bateau témoin. Cette dernière source d’information indique la capture par trait contrairement à la base statistique qui donne la capture par rectangle statistique. Elle permet de connaître précisément le temps de pêche alloué à la capture de ces espèces mais aussi d’estimer des CPUE corrigées de l’effet profondeur, c’est-à-dire de tenir compte de la stratégie de pêche du navire et des variations d’abondance en fonction de la profondeur. Ces deux aspects sont importants pour interpréter de façon pertinente les CPUE en tant qu’indice d’abondance.

Age is a necessary parameter used in population dynamics to assess the state of exploited resources. This parameter is poorly known for most deep-sea species (depth > 400 m). This work focused on age estimation from otoliths of Alepocephalus bairdii (Alepocephalidae), Coryphaenoides rupestris (Macrouridae), Helicolenus dactylopterus (Sebastidae) and Hoplostethus atlanticus (Trachichthyidae), which French fishery exploitation, off the west coasts of the British Isles, began the late 1980's. Considering otolith growth zones as annual, the four species all show high longevity: 38, 54, 43 and 130 years, respectively, together with slow growth. The differences in growth between sex were estimated and difficulties in accurately estimating the age were highlighted and showed the need to standardise and validate age estimation. The ages currently estimated for deep-sea fish must be used with caution.

Russian investigations of the deep-water species of the Atlantic commenced in 1963 and have continued to 1993. The first investigations were carried out by fishing vessels and research vessels on Greenland halibut (Reinhardtius hippoglossoides) in the Barents Sea, and then on witch flounder (Glyptocephalus cynoglossus), in the western Atlantic. In 1967–68 a commercial fishery for roundnose grenadier (Coryphaenoides rupestris) and Greenland halibut started on the slope in the north west Atlantic. At this time there was also a fishery at Iceland for Greenland halibut. Since 1973 Russian vessels have been fishing on the ridges and underwater rises in the open areas of the North Atlantic for a variety of deep-water species.

A review is presented of the literature on aging of deep water fishes and of experiences from studies of Coryphaenoides rupestris, Argentina silus, Molva molva, Molva dipterygia, Brosme brosme, and Glyptocephalus cynoglossus of the Skagerrak.

The structure of a deep water fish assemblage on the upper continental slope of Canada’s Labrador Sea was studied using a survey time series dataset from the years 1978 to 1991. Greenland halibut (Reinhardtius hippoglossoides) and roundnose grenadier (Coryphaenoides rupestris) were the dominant regular members of the assemblage, and both were commercially exploited. Less abundant but regular members of the upper slope assemblage (Antimora, Centroscyllium, Macrourus, and Nezumia) were not the subject of a fishery, although all occurred as by-catch. Overall biomass of the commercial species declined significantly during the period, and the mean size of Greenland halibut was reduced by half. The biomass of non-target species was less affected, and the mean sizes of less abundant species changed very little, except for broadhead wolffish (Anarhichas denticulatus) which almost doubled in size. There were no consistent temperature changes in the geographic area occupied by the assemblage. Population shifts, mostly from north to south and including dominant species such as Greenland halibut and witch flounder (Glyptocephalus cynoglossus), took place on the shallower adjacent continental shelf but did not occur within the region. The structure of the assemblage on Labrador’s upper continental slope is similar to other upper slope assemblages. Focus on faunal regions and overall species ranges seems preferable to arbitrary management zones. Scientific and socio-economic matters relating to fisheries on the upper slope must be addressed in the same time and space frameworks.

French commercial fishermen have been engaged in a deep-water fishery for blue ling (Molva dypterygia) since 1973, and in the early days the roundnose grenadier (Coryphaenoides rupestris) was considered a by-catch species. As a consequence of the decline in catches of the more traditional gadoid species on the continental shelf, increased effort from 1989 onwards, has been directed at the slope fisheries in the north east Atlantic . Today there are commercial catches of blue ling, roundnose grenadier, orange roughy (Hoplostethus atlanticus), black scabbard fish (Aphanopus carbo) and Portuguese sharks (mainly Centroscymnus coelolepis). The fishing vessels engaged in this fishery range from 24 m. to 60 m. in length and 500 kw. to 2000 kw. in power.

Preface. Introduction. 1: Scientific papers. Environmental and biological aspects of slope dwelling fishes of the North Atlantic J.D.M. Gordon, et al. Structure over time of an exploited deep-water fish assemblage R.L. Haedrich. The biology and fishery of roundnose grenadier (Coryphaenoides rupestris, Gunnerus, 1765) in the North West Atlantic D.B. Atkinson. Greenland halibut (Reinhardtius hippoglossoides): A review of the dynamics of its distribution and fisheries off eastern Canada and Greenland W.R. Bowering, W.B. Brodie. The distribution, relative abundance and the biology of the deep-sea fishes of the icelandic slope and Reykjanes ridge J.V. Magnusson, J. Magnusson. Deep-water resources in Faroese waters to the south, southwest and west of the Faroes - a preliminary account J. Reinert. Comparisons between longlining and trawling for deep-water species - selectivity, quality and catchability - a review N.R. Hareide. A comparison of deep-water trawl and longline research fishing in the Davis Straits G.A. Jorgensen. Experience with management of orange roughy (Hoplostethus atlanticus) in New Zealand, and the effects of commercial fishing on stocks over the period 1980-1993 M. Clark. Age determination of deep-water fishes experiences, status and challenges for the future O.A. Bergstad. 2: Review papers. Spanish North Atlantic deep-water fisheries S. Iglesias, J. Paz. The Irish experience of deep-water fishing in the North East Atlantic R. McCormick. Fisheries policy and the survival of fishing communities in eastern Canada R.E. Ommer. Line fishing for black scabbard fish (Aphanopus carbo, Lowe, 1839) and other deep-water species in the eastern mid-Atlantic to the north of Madeira R.Martins, C. Ferreira. French exploration of the deep-water fisheries of the North Atlantic A. Charuau, et al. Russian (USSR) fisheries research in deep waters (below 500 m) in the North Atlantic F.M. Troyanovsky, S.F. Losovsky. Norwegian experience of deep-water fishing with longlines H.E. Olsen. 3: Technical papers. Experimental utilisation and marketing of by-catches and deep-water species in Ireland H.P. Thorsteinsson, G. Valdimarsson. Deep-water trawling techniques used by Icelandic fishermen G. Gunnarsson. Canadian experience: deep-water fishing gill netting in the Northwest Atlantic Ocean A. Duthie, A. Marsden. 4: Summary of workshop sessions. Appendix: List of delegates and the steering committee.

Deepwater species fishing trials commenced in Ireland in 1988 assisted by the European Union Commission’s Exploratory Fishing Voyage scheme. The objective was to develop a fishery for unexploited non-quota species and divert fishing effort from existing quota species which were under severe pressure. The first species targeted was blue whiting (Micromistius poutassou) quickly followed by argentines, also known as silver smelt (Argentina silus), and progressing to a wider range of species in even deeper water such as grenadiers (Coryphaenoides rupestris), black scabbard fish (Aphanopus carbo), Portuguese shark (Centroscymnus coelolepis) etc. This involved pelagic and demersal fishing techniques at a cost of considerable material damage as a result of working on unknown fishing grounds. Over the 3 year period 1988 to 1990 the catches of argentines suffered a rapid and alarming decline. The reasons for this are not known, although various possibilities are considered.

Exploratory fishing by the Soviet Union in the north west Atlantic during the early 1960s revealed substantial concentrations of roundnose grenadier (Coryphaenoides rupestris Gunnerus 1765) inhabiting slope areas in depths greater than about 500 m. Because of this, a commercial fishery began in 1967, and has continued to the present, albeit at relatively low levels in recent years. The biology and population dynamics of this species have been difficult to study because of their deep distribution. As a result, although many hypotheses have been put forward, much of the research has been generally inconclusive. Their relative unimportance as a commercial species in the north west Atlantic has also contributed to our general lack of understanding of the species. Nonetheless, over the years considerable information has been gathered, and this report summarises the biological investigations to date, as well as describing the history of the fishery and its management.

The reproduction of deep-sea fishes is still poorly known, when it is not a total mystery. This is true in the case of those belonging to one of the most important bathybenthic families, the Macrouridae. During several research expeditions conducted by the Institut scientifique et technique des peches maritimes aboard the oceanographic vessels Thalassa and Cryos, the stages of sexual maturity of two important species, Macrourus berglaxand Coryphaenoides rupestris, were studied. The individuals examined came from trawl catches made on the Iceland-Faroe Ridge and the Rockall and Hatton Banks in spring 1975 and 1976 and on the continental slope off the Labrador and Newfoundland coasts in summer 1975 and winter 1976. In the light of the observations made, it was possible to determine the time of spawning, especially for Coryphaenoides rupestris in the North-East Atlantic. Both males and females of this species were at the spawning stage in mid-April 1975, while a month later, they had all reached the...

1. 1. The intestinal diamine oxidase of some teleostean fishes was assayed using 14C-putrescine as substrate. 2. 2. Diamine oxidase could easily be detected in all species investigated. The most active preparation (Coryphaenoides rupestris) was about thirty times as active as the least active one (Gadus poutassou). 3. 3. When cadarevine or histamine was included in the assay medium the deamination of putrescine was inhibited. In all species, at pH 7·8, histamine was the most powerful inhibitor. 4. 4. The pH dependence of the histamine inhibition was also determined. Histamine was most powerful as an inhibitor at a pH where the histamine monocation dominates.

The weight-length relationships of roundnose grenadier ( Coryphaenoides rupestris Gunn.) caught in different parts of the northwest Atlantic were determined and compared with relationships reported previously for various areas of the North Atlantic. The results indicate that this species is lighter at length in NAFO Subareas 0 + 1 and the north Mid-Atlantic Ridge area than in either the northwest or northeast Atlantic. Roundnose grenadier in the northwest and northeast Atlantic have approximately the same weight-length relationships.

Chitinase, exo-N-acetyl-β-D-glycosaminidase (NAGase) and lysozyme activities were assayed in the digestive tract of 6 species of marine fishes: Myxine glutinosa (cyclostome), Chimaera monstrosa (holocephalan), Squalus acanthias, Etmopterus spinax, Raja radiata (elasmobranchs) and Coryphaenoides rupestris (teleost). Strong chitinase activity was found in the gastric mucosa of the elasmobranchs (S. acanthias, E. spinax and R. radiata) and the teleost (Coryphaenoides rupestris). A remarkably high chitinase activity occurred in the pancreas of the stomachless holocephalan fish Chimaera monstrosa. NAGase activity was strong in the digestive tract of all species. It could be concluded that marine fishes with diets consisting largely of chitinous invertebrates may display high chitinase and NAGase activities in their digestive system; however, only low chitinase activity was found in the intestine of the cyclostome Myxine glutinosa. Coryphaenoides rupestris gastric mucosa chitinase had one optimum activity at pH 1.25, whereas S. acanthias chitinase had two optima, at pH 1.6 and 3.6. The NAGase pH-activity curves from S. acanthias and R. radiata gastric mucosa displayed similar optima, at pH 4.5 and 4.25 respectively. Chimaera monstrosa pancreatic chitinase had a very strong optimum around pH 8 to 10, and one less strong at pH 3. These enzyme activities could not be separated by gel filtration or isoelectric focusing. The pI (isoelectric point) was approximately 4.9 for both enzymes. The molecular weight of the C. monstrosa pancreatic chitinase was estimated to be approximately 43 000. Lysozyme activity was absent or extremely weak in the material studied.

The Macrouridae are the most common fish caught in demersal trawls on the continental slope and rise of the Rockall Trough. They represented 41% of all fish caught, with Coryphaenoides rupestris amounting to 28% of the catch. No previous study of the trophic interaction of these fish has been made over a wide bathymetric range. Samples were obtained at 250-m intervals of depth between 400 and 2 900 m in the period 1975 to 1981. The stomachs of 5 326 fish belonging to 12 species were examined to define their diets. Eight species are primarily benthopelagic feeders while four are primarily epibenthic feeders. The bathymetric centres of distribution of the populations of the benthopelagic feeding Trachyrhynchus murrayi, Malacocephalus laevis, Coryphaenoides rupestis, C. guentheri, Nematonurus armatus, Chalinura brevibarbis, C. leptolepis and C. mediterranea are different from each other. Similar differences in bathymetric distribution occurred among the epibenthic feeding Nezumia aequalis, Coelorhynchus coelorhynchus, C. occa and Lionurus carapinus. These differences decrease competition among species that exploit similar resources.

Roundnose grenadier (Coryphaenoides rupestris) was stored in ice in order to investigate changes in chemical and sensory characteristics. Analyses indicated that the keeping time of at least 18 days was better than that of most species of whitefish. Total lipid and free fatty acid concentration did not significantly change during iced storage. Inosine monophosphate, inosine, hypoxanthine, iodine number, peroxide value, thiobarbituric acid value, trimethylamine content determined by the Tozawa method, trimethylamine content determined by the Dyer method, moisture content, and pH all significantly (P ≤ 0.05) changed during iced storage. Both peroxide and iodine values appeared to have potential as indicators of sensory quality. Trimethylamine concentrations, determined by both methods, were similar throughout the iced storage study.

Marine fishes caught in the Skagerrak, 27 different species representing various groups of fishes (Cyclostomi, Holocephali, Elasmobranchii and Teleostei), were examined for the following haematological and biochemical blood parameters: haematocrit, haemoglobin, mean corpuscle haemoglobin concentration, total plasma protein, blood glucose and blood lactate. Interspecies variations as well as variations within some species were observed. The haemoglobin values for all species showed a positive correlation to the corresponding haematocrit values. Relatively low values for haematocrit and haemoglobin were found in cyclostomes, holocephaleans and elasmobranchii compared to the majority of teleosts. Within the teleost group, the haematocrit and haemoglobin levels were positively correlated with the activity of the fish species. The cyclostome Myxine glutimsa L. had a total plasma protein content in the same range as most teleosts, whereas holocephaleans, elasmobranchii and the deep-water teleost Coryphaenoides rupestris Gunnerus showed comparatively low values. Among teleosts some relationship seemed to exist between the total plasma protein level and the activity of the fish species. In addition, a correlation between plasma protein content and levels of blood lipids were noted. Values for blood glucose and blood lactate were found to be lower in cyclostomes, holocephaleans and elasmobranchii than in most teleosts. Higher blood glucose levels were observed in the more active teleost species.

A total of over 28,000 benthic and benthopelagic fish belonging to 34 families and comprising at least 85 species were collected from the Hebridean Terrace in the Rockall Trough between soundings of 500 and 2000 m. Commercial type trawls (20.6 m Granton or 140 foot German bottom trawls) fished on paired warps at 33 stations accounted for 89% of all individual caught, the remainder being caught by a 16.4 m prawn trawl fished on a single warp (22 stations) and a 3 m Agassiz trawl (12 stations). The stations sampled, with a few exceptions, fell into discrete bathymetric zones separated by increments of approximately 250 m and different combinations of nets were used at each of these zones. The catch composition of the commercial trawls differed from those of the other nets. The most obvious difference was that squalid sharks, the alepocephalid Alepocephalus bairdii and the black scabbard fish Aphanopus carbo were important in the commercial type trawls but were absent or poorly represented in the other nets. Net size and towing speed were considered to be important factors influencing the catch composition. Net selectivity was most apparent on the upper and mid slopes but less apparent on the lower slopes. Relatively few families contribute to the total biomass at a given bathymetric zone and because the families Squalidae and Alepocephalidae contribute significantly to the biomass on the upper and mid slope it is therefore concluded that small nets must grossly underestimate the biomass at these depths. The greatest biomass occurred at mid slope depths (750–1000 m).

Data from 9 major trawling surveys made around the North Atlantic Basin at slope, rise and abyssal depths provide directly comparable information on deep demersal fish distribution and faunal composition. 338 species in 57 families and 189 genera are recorded, and semi-diagrammatic maps showing relative abundance both horizontally and vertically for 67 of these are presented. Alepocephalidae, Gadidae, Macrouridae, Moridae and Ophidiidae comprise nearly 2/3 of all species taken. 296 species were taken at slope depths (200–2250 m), 99 at rise depths (2250–4500 m), and 32 at abyssal depths (>4500 m). Diversity and the rate of endemism were highest on the slope. The Norwegian, Caribbean and Mediterranean Basins appear to harbor impoverished versions of the adjacent Atlantic Basin fauna. Each species distribution appeared to be rather exceptional and no repeatable pattern could be found amongst the maps.

The problem of tail breakage and regeneration in grenadiers instigated the initiation of studies to find a suitable partial length measurement as a replacement for the traditional total length measurement. Studies undertaken in 1978 and 1979 on roundnose grenadier, Coryphaenoides rupestris, indicated that the partial length mesurements, pre-anus length and anal-fin length, were highly correlated with total length. The anal-fin length was considered to be more practical than pre-anus length, as the latter is sometimes affected by distortion of the anus due to air-bladder expansion and extrusion of intestines when the fish are brought to the surface from deep water. Consequently, the Scientific Council of NAFO at its meeting in June 1980 adopted anal-fin length (tip of snout to base of first anal fin ray) as the standard for measuring roundnose and roughhead grenadiers.

Examination of the retinae of 13 species from waters off Labrador shows that the retinal layers are closely related with one another in their development and that the general retinal features vary with habitat depth. The retinae of Aspidophoroides monopterygius, Triglops ommatistius, and Gadus callarias with as yet well-developed pigment epithelium, many cones, and conducting elements appear to be capable of functioning fairly normally even in a brighter environment. The retinae of Lycodes lavalaei, L. vahlii maculatus, Sebastes marinus marinus, and S. m. mentella with degenerating pigment epithelium, numerous rods, and poor conducting elements are presumably not any longer suitable for bright light vision. The pure rod retinae of Notoscopelus kröyeri, Ceratoscopelus maderensis, and Argentina situs are different from those of Macrourus bairdii, Coryphaenoides rupestris, and Antimora rostrata in having much better developed layers of conducting elements. This may mean that, in the former three species, form perception plays a significant role, while it is of little importance in the latter three species which are adapted completely to a habitat with only very meager light. In the cone-bearing species, with the exception of A. monopterygius and G. callarias, the cones are mostly of the twin type. This contradicts the generally held opinion that twin cones seem to be associated with vision in bright light.

The marine deep-water fish Coryphaenoides rupestris has a lymph-like fluid in its large cranial lateral-line canals. A similar canal endolymph is also found in a few other fishes possessing closed lateral-line canals. We have analysed, chemically, the canal endolymph from 3 species of teleosts. In C. rupestris, the ionic composition resembles that of blood plasma, but the content of potassium is slightly lower. In Lota lota, the canal endolymph has a high potassium concentration, as does the inner-ear endolymph. In Glyptocephalus cynoglossus, the ionic composition of the canal endolymph resembles sea water. In all species, the concentrations of glucose and protein are much lower than in the blood plasma. Analyses were further made on endolymph and perilymph of the inner ear, on jelly-like material from the acusticolateralis system, and on body fluids from a small number of fish species, even elasmobranchs and a holocephalan. The water phase of the cupulae of the lateral-line system of C. rupestris had an ionic composition similar to that of the endolymph surrounding the cupulae. High potassium and low values for glucose and protein were found in the inner-ear endolymph of all species investigated. No carbonic anhydrase activity was found in the lateral-line system of C. rupestris, whereas a low activity of this enzyme was found in the inner ear of Gadus morrhua. The investigation shows that the composition of the fluids in contact with the mechano-receptors of the lateral-line system differs between different species of fishes. A few observations were made on the structural organization of the cranial lateral-line system in C. rupestris.

Johann Heinrich von Thunen-Institute, Federal Research Institute for Rural Areas, Forestry and Fisheries began publishing the Informationen aus der Fischereiforschung – Information on Fishery research in 2010