Centroscyllium Fabricii Research Articles

Monitoring data for a new large offshore marine protected area reveals infeasible management objectives

AbstractPredicting and measuring changes resulting from marine protected areas (MPAs) has posed a challenge for practitioners, partly because ecosystems are complex and can change in unanticipated ways, but also due to MPA characteristics such as design factors, conservation objectives (COs), and monitoring programs, that can leave little chance of meeting stated goals. We consider these design factors for the Laurentian Channel MPA, a large offshore Canadian protected area established to protect against fishing impacts. Specifically, in this study we evaluated (1) whether it is realistic to expect improvements in the MPA for four previously established taxa‐specific COs, and (2) whether existing scientific surveys are capable of detecting changes in these CO taxa even if they occurred. Three CO species were sampled in scientific multispecies research vessel trawl surveys (Black Dogfish, Smooth Skate, and Northern Wolffish) and a fourth CO, sea pen taxa, were enumerated using seafloor imagery. Simulations indicate that trawl surveys have very little chance of detecting change in the abundance of the three fish species examined, while seafloor imagery data had higher statistical power for sea pen taxa. Moreover, we show that expecting change related to the removal of fishing is unrealistic due to the fact that the MPA was established in an area of minimal fishing pressure. While positive change is unlikely to be induced by the MPA, or be detected if they occurred, this MPA could provide conservation benefits if COs and monitoring approaches were realigned to match the unique features of this area that represents largely unimpacted sensitive benthic habitats.

Whole genome sequence analysis enabled affirmation of the probiotic potential of marine sporulater Bacillus amyloliquefaciens BTSS3 isolated from Centroscyllium fabricii

Probiotics are microorganisms when administered in adequate amounts, confer health benefits on the host. Many probiotics find application in various industries however, probiotic bacteria linked to marine environments are less explored.Although Bifidobacteria, Lactobacilli, and Streptococcus thermophilus are the most frequently used probiotics, Bacillus spp. have acquired much acceptance in human functional foods due to their increased tolerance and enduring competence in harsh environments like the gastrointestinal (GI) tract. In this study, the 4 Mbp genome sequence of Bacillus amyloliquefaciens strain BTSS3, a marine spore former isolated from deep-sea shark Centroscyllium fabricii, with antimicrobial and probiotic properties was sequenced, assembled, and annotated. Analysis revealed the presence of numerous genes presenting probiotic traits like production of vitamins, secondary metabolites, amino acids, secretory proteins, enzymes and other proteins that allow survival in GI tract as well as adhesion to intestinal mucosa. Adhesion by colonization in the gut was studied in vivo in zebrafish (Danio rerio) using FITC labelled B.amyloliquefaciens BTSS3. Preliminary study revealed the ability of the marine Bacillus to attach to the intestinal mucosa of the fish gut. The genomic data and the in vivo experiment affirms that this marine spore former is a promising probiotic candidate with potential biotechnological applications.

Spatial ecology of black dogfish (

Context Shark pupping and nursery grounds are essential habitats, yet these areas are undocumented for deepwater species. Young juveniles of black dogfish (Centroscyllium fabricii) were found to be dominant in the Laurentian Channel, prompting an analysis of their distribution in Canadian waters of the Northwest Atlantic. Aims This study documents patterns of distribution by sex and life stage for black dogfish in shelf and slope waters of Canada. Methods Over 40 years of trawl survey data from the Canadian Department of Fisheries and Oceans (DFO) Newfoundland and Labrador Region was analysed to document patterns of distribution of black dogfish by sex and life stage. Key results Free-swimming neonates were found in the Laurentian Channel, along with adult females, including some with pups, indicating that the Laurentian Channel is the pupping grounds for this species. Small black dogfish, highly abundant in the Channel, is largely absent in slope waters, indicating that the Channel is the nursery ground for black dogfish in Canada. Conclusions As they grows, black dogfish individuals undergo a multi-year distributional shift extending over ∼4000 km, originating in the Laurentian Channel out to slope waters, with the largest fish being found furthest from the Channel. No other deep demersal chondrichthyans are known to undergo a progressive migration as they grow, more akin to pelagic sharks where separate pupping–nursery grounds and long-distance migrations are commonly documented. Implications The segregation by life stages shown in the present study differs from previously reported distribution patterns of black dogfish in Greenland and Iceland. Given warm and stable ambient temperatures in the Channel, similar to slope waters, black dogfish is stenothermal, maintaining a narrow thermal profile throughout its life. Identifying the essential habitats of pupping and nursery grounds is crucial to the management and conservation of this species.

Age of black dogfish (Centroscyllium fabricii) estimated from fin spines growth bands and eye lens bomb radiocarbon dating

Accurate age estimates are key life history parameters for understanding growth, reproduction and susceptibility to exploitation. Using a combination of fin spine growth increments and bomb radiocarbon dating, we provide minimum age estimates for the small Atlantic squaloid shark, black dogfish (Centroscyllium fabricii) sampled in Greenland waters. Age estimates based on growth increments in the fin spine, just distal to the end of the pulp cavity, were obtained from males (N = 64) and females (N = 70), and von Bertalanffy growth curves were fitted. The maximum growth increment count was 36 in males and 35 in females. Males and females had similar growth rates, but females grew larger (Linf, females = 68 cm, Linf, males = 61 cm). To evaluate the fin spine age estimates, bomb radiocarbon dating on eye lenses were done on a selection of females. All individuals larger than 65 cm (total length) were older than the bomb pulse corresponding to an age of at least 53 years, while those smaller than 55 cm were younger. Therefore, we observe a discrepancy between age estimates obtained from fin spines and bomb radiocarbon dating, indicating that fin spines are unsuitable for ageing black dogfish, at least for the oldest individuals.

Near-equal compressibility of liver oil and seawater minimises buoyancy changes in deep-sea sharks and chimaeras.

Whereas upper ocean pelagic sharks are negatively buoyant and must swim continuously to generate lift from their fins, deep-sea sharks float or swim slowly buoyed up by large volumes of low-density oils in their livers. Investigation of the pressure, volume, temperature (PVT) relationships for liver oils of 10 species of deep-sea Chondrichthyes shows that the density difference between oil and seawater, Δρ, remains almost constant with pressure down to full ocean depth (11 km, 1100 bar), theoretically providing buoyancy far beyond the maximum depth of occurrence (3700 m) of sharks. However, Δρ does change significantly with temperature and we show that the combined effects of pressure and temperature can decrease buoyancy of oil by up to 10% between the surface and 3500 m depth across interfaces between warm southern and cold polar waters in the Rockall Trough in the NE Atlantic. This increases drag more than 10-fold compared with neutral buoyancy during horizontal slow swimming (0.1 m s-1), but the effect becomes negligible at high speeds. Chondrichthyes generally experience positive buoyancy change during ascent and negative buoyancy change during descent, but contrary effects can occur at interfaces between waters of different densities. During normal vertical migrations buoyancy changes are small, increasing slow-speed drag no more than 2- to 3-fold. Equations and tables of density, pressure and temperature are provided for squalene and liver oils of Chimaeriformes (Harriotta raleighana, Chimaera monstrosa, Hydrolagus affinis), Squaliformes (Centrophorus squamosus, Deania calcea, Centroscymnus coelolepis, Centroscyllium fabricii, Etmopterus spinax) and Carcharhiniformes (Apristurus laurussonii, Galeus murinus).

Halogenated persistent organic pollutants in relation to trophic level in deep sea fish

The bioaccumulation of persistent organic pollutants (POPs) in deep sea fish from the Rockall fishing area was investigated. Predator and prey species were analysed for stable isotopes, fatty acids, polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs). δ15N indicated that black scabbard was at the highest trophic level and the prey the lowest. The fatty acid signatures indicated that black scabbard and black dogfish fed at a higher trophic level compared to the roundnose grenadier. PCBs and PBDEs were detected in the liver of all three predator species. PCB concentrations were significantly higher in the roundnose grenadier, possibly due to their longer life span. PCB concentrations were compared to OSPAR assessment criteria, concentrations were above background but below Environmental Assessment Criteria for all but one congener. PCB concentrations were below food safety levels in the flesh, but exceeded the limit for liver in the roundnose grenadier and black dogfish.

Persistence and Variation on the Groundfish Assemblages on the Southern Grand Banks (NAFO Divisions 3NO): 2002-2011

Data from EU-Spain (Instituto Espanol de Oceanografia) 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 (Anarichas minor), Arctic eelpout (Lycodes reticulatus), Northern wolfish (Anarichas 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 hyperborea) 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.

Cestodes from deep-water squaliform sharks in the Azores

The majority of our knowledge on marine tapeworms (cestodes) is limited to taxa that are relatively easy to obtain (i.e., those that parasitize shallower-water species). The invitation to participate in a deep-water research survey off the Condor seamount in the Azores offered the opportunity to gain information regarding parasites of the less often studied sharks of the mesopelagic and bathypelagic zone. All tapeworms (Platyhelminthes: Cestoda) found parasitizing the spiral intestine of squaliform shark species (Elasmobranchii: Squaliformes) encountered as part of this survey, as well as some additional Azorean sampling from previous years obtained from local fishermen are reported. In total, 112 shark specimens of 12 species of squaliform sharks representing 4 different families from depths ranging between 400 and 1290m were examined. Cestodes were found in the spiral intestines from 11 of the 12 squaliform species examined: Deania calcea, D. cf. profundorum, D. profundorum, Etmopterus princeps, E. pusillus, E. spinax, Centroscyllium fabricii, Centroscymnus coelolepis, C. cryptacanthus, C. crepidater, and Dalatias licha. No cestodes were found in the spiral intestines of Centrophorus squamosus. Light microscopy and scanning electron microscopy revealed several potentially novel trypanorhynch and biloculated tetraphyllidean species. Aporhynchid and gilquiniid trypanorhynchs dominated the adult cestode fauna of Etmopterus and Deania host species, respectively, while larval phyllobothriids were found across several host genera, including, Deania, Centroscyllium, and Centroscymnus. These results corroborate previous findings that deep-water cestode faunas are relatively depauperate and consist primarily of trypanorhynchs of the families Gilquiniidae and Aporhynchidae and larval tetraphyllideans. A subset of specimens of most cestode species was preserved in ethanol for future molecular analysis to allow more definitive determinations of the identification of the larval tetraphyllideans and trypanorhynchs lacking evaginated tentacles and other key diagnostic features.

Associations of demersal fish with sponge grounds on the continental slopes of the northwest Atlantic

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 477:217-230 (2013) - DOI: https://doi.org/10.3354/meps10127 Associations of demersal fish with sponge grounds on the continental slopes of the northwest Atlantic E. Kenchington1,*, D. Power2, M. Koen-Alonso2 1Fisheries and Oceans Canada, Bedford Institute of Oceanography, 1 Challenger Drive, Dartmouth, Nova Scotia B2Y 4A2, Canada 2Fisheries and Oceans Canada, Northwest Atlantic Fisheries Centre, PO Box 5667, St. John’s, Newfoundland A1C 5X1, Canada *Email: ellen.kenchington@dfo-mpo.gc.ca ABSTRACT: 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 continental 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 multidimensional 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 profundorum. 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, lanternfish (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. KEY WORDS: Demersal fish assemblages · Sponge grounds · Trawl catch Full text in pdf format Supplementary material PreviousNextCite this article as: Kenchington E, Power D, Koen-Alonso M (2013) Associations of demersal fish with sponge grounds on the continental slopes of the northwest Atlantic. Mar Ecol Prog Ser 477:217-230. https://doi.org/10.3354/meps10127 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 477. Online publication date: March 12, 2013 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2013 Inter-Research.

Demersal fish fauna of the continental slope off Nova Scotia, Canada, based on exploratory bottom trawl surveys in 1994�95

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.

Demersal fishes caught with bottom gillnets and baited gears at 500-2800m on the continental slope off Nova Scotia, Canada

Fishing trials with bottom fixed gears (primarily gillnets but also shrimp and crab traps and longlines) were conducted on the continental slope off Nova Scotia in August 1991. Fishing was conducted at several depths between 500 and 2800 m in two areas, one on the open slope south of Emerald Bank and the other at the mouth of The Gully, a large canyon. Catches by gillnets accounted for about 90% of the total and were predominated by deepwater chimaera (Hydrolagus affinis), black dogfish (Centroscyllium fabricii) and Portuguese shark (Centroscymnus coelolepis). The most frequently caught species in traps were snubnose eel (Simenchelys parasitica) and abyssal grenadier (Coryphaenoides armatus). Variations in catches by depth and area are described, and comparisons are made with catches from otter trawl surveys at similar depths with regard to the most prominent species caught and their size compositions.

Halogenated persistent organic pollutants in deep water fish from waters to the west of Scotland

Halogenated persistent organic pollutants [polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs)] along with total lipid, were measured in the liver and muscle of three species of deep water fish (black scabbard, black dogfish (liver only) and roundnose grenadier) collected from the Rockall fishing area, to the west of Scotland, between 2006 and 2008. Both contaminant groups were detected in the muscle and liver, with concentrations of PCBs being higher than PBDEs. There were no significant differences in the PCB or PBDE concentrations between the three species, or different sampling locations in the Rockall fishing area. PCB concentrations (ΣICES (International Council for the Exploration of the Sea)7 PCBs) greater than 500 μg kg −1 lipid weight were found in 26 of the 106 liver samples. PCB concentrations were compared to OSPAR assessment criteria, concentrations were above background but below Environmental Assessment Criteria. Estimated Toxic Equivalent (TEQ) concentrations, calculated using published models, in the fish muscle and liver indicated that consumption of deep water fish is unlikely to represent a risk to human health. The high squalene content in some of the black dogfish liver necessitated an additional clean-up step, involving gel permeation chromatography, when analyzing for PBDEs. Concentrations of PBDEs were low with many congeners being below detection limits, particularly in the muscle. There are currently no assessment criteria available for PBDEs. Furthermore, there is only very limited data on PBDEs in deep water fish. However, the concentrations observed in this study were similar to the concentrations recently reported in Mediterranean deep water fish.

Recent incidental catch of sharks in gillnet fisheries of Newfoundland and Labrador, Canada

ESR Endangered Species Research Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsSpecials ESR 11:133-146 (2010) - DOI: https://doi.org/10.3354/esr00268 Recent incidental catch of sharks in gillnet fisheries of Newfoundland and Labrador, Canada Steven Benjamins1,*, David W. Kulka2,3, Jack Lawson2 1Dept. of Zoology, University of Otago, PO Box 56, Dunedin, New Zealand 2Fisheries and Oceans Canada, PO Box 5667, St. John’s, Newfoundland and Labrador, A1C 5X1, Canada 3Present address: 50 Fernlilly Place, Waverley, Nova Scotia B2R 1X2, Canada *Email: stevenbenjamins@yahoo.com ABSTRACT: Waters of Newfoundland and Labrador, Canada, are home to a variety of shark species, many of which have been previously reported as incidental catch in several gillnet fisheries. However, defensible estimates of incidental catch rates are unavailable. This mortality is of concern, given reports of considerable declines in abundance of several large shark species in this area. On the basis of several data sources (incidental catch rates derived using different methods of reporting; fish landings and net days as measures of effort, with fishing trips as sampling units), the total numbers of incidentally caught sharks were estimated in 8 gillnet fisheries for 2001, 2002, and 2003. Confidence intervals were estimated using resampling techniques. Most fisheries reported incidental catch of some sharks, although there were distinct differences between different fisheries in diversity and abundance of species encountered. Spiny dogfish Squalus acanthias was the most commonly captured species, occurring in various fisheries along the south coast of the island of Newfoundland. Large sharks, including basking shark Cetorhinus maximus, shortfin mako Isurus oxyrinchus, porbeagle Lamna nasus, and blue shark Prionace glauca, were reported in small numbers in all fisheries. Deepwater fisheries targeting e.g. Greenland halibut Reinhardtius hippoglossoides caught mainly sharks of the continental slope, such as Greenland shark Somniosus microcephalus, black dogfish Centroscyllium fabricii, and several other deepwater species. Catch rates of several species appear high and may warrant conservation action. For the majority, however, there is insufficient information on abundance, and sometimes even basic biology, to accurately assess the impact of this incidental mortality. KEY WORDS: Sharks · Incidental catch · Bycatch · Canada · Northwest Atlantic · Mortality · Dogfish · Gillnets Full text in pdf format PreviousNextCite this article as: Benjamins S, Kulka DW, Lawson J (2010) Recent incidental catch of sharks in gillnet fisheries of Newfoundland and Labrador, Canada. Endang Species Res 11:133-146. https://doi.org/10.3354/esr00268 Export citation Mail this link - Contents Mailing Lists - RSS Facebook - Tweet - linkedIn Cited by Published in ESR Vol. 11, No. 2. Online publication date: April 07, 2010 Print ISSN: 1863-5407; Online ISSN: 1613-4796 Copyright © 2010 Inter-Research.

Halogenated persistent organic pollutants in Scottish deep water fish

Halogenated persistent organic pollutants (chlorobiphenyls (CBs), polybrominated diphenyl ethers (PBDEs), hexabromocyclododecane (HBCD) and tetrabromobisphenol-A (TBBP-A)) and total lipid content were measured in the liver and muscle of three species of deep water fish (black scabbard, roundnose grenadier and black dogfish) collected from the Rockall Trough, to the west of Scotland, in 2006. CB concentrations (SigmaICES (International Council for the Exploration of the Seas)7 CBs) >500 microg kg(-1) lipid weight) were found in 9 of the 31 deep water fish liver samples. Non-ortho CBs were measured in samples with the highest ortho CB concentrations. Non-ortho CBs (CB81, 77, 126 and 169) were not detected in any of the fish muscle samples. In liver, CB81 was not detected in any of the samples while CB169 was detected in all but one sample. The total 'dioxin-like' CB concentration was calculated based on the 5 mono-ortho and 4 non-ortho CBs measured. The non-ortho CB concentration made a very small contribution to the total 'dioxin-like' CB concentrations (<1%). Concentrations for the individual ICES7 CBs in fish liver were above OSPAR Background Assessment Concentrations (BACs) in all three species, except for CB28 and 101 in black dogfish. Toxic Equivalent (TEQs) concentrations calculated for the five mono-ortho and four non-ortho CBs measured, and estimated TEQs calculated using published models in the fish muscle indicated that consumption of deep water fish muscle is unlikely to represent a risk to human health. However, dioxins and furans were not measured and the contribution to the calculated TEQs from these compounds was not taken into account. Calculated and estimated TEQs for some roundnose grenadier liver samples exceeded the 25 pg g(-1) wet weight limit for fish liver and, therefore, there may be a health risk if consumed. PBDEs were detected in both the liver and muscle of the deep water fish, whilst HBCD and TBBP-A were not detected in any of the deep water fish.

Chemical characterization and properties of five deep-sea fish species

Some important flesh properties were determined for the deep-sea species Portuguese dogfish ( Centroscymnus coelolepis), leafscale gulper shark ( Centrophorus squamosus), black dogfish ( Centroscyllium fabricii), roughhead grenadier ( Macrourus berglax), and mora/deepsea cod ( Mora moro). Chemical composition, water holding capacity, cook loss and shelf-life, as indicated by bacterial counts, were determined. For some of the species investigated, variations could be observed between fish caught in spring and fish caught in summer. The fish used in this study were caught at Hatton Bank in the North Atlantic, where fishing takes place mainly from April to September.

Lipid content and fatty acid distribution in tissues from Portuguese dogfish, leafscale gulper shark and black dogfish

The lipid characterization in tissues from the three deep-sea sharks leafscale gulper shark ( Centrophorus squamosus), Portuguese dogfish ( Centroscymnus coelolepis) and black dogfish ( Centrocyllium fabricii) captured at Hatton Bank in the North Atlantic were examined. The objective was to determine the lipid content and the fatty acid composition in different tissues. In addition, the fatty acid composition in tissues and species was compared. The tissues examined were pancreas, heart, kidney, stomach, spleen and liver. The lipid content was high in liver (40–50%) and ranged from 1% to 5% in the other tissues. The dominant fatty acids were C16:0, C18:1 (n-9), C18:1 (n-7) and C22:6 (n-3) in all tissues. All tissues had a high content of unsaturated fatty acids.

Chemical characterisation of eggs from deep-sea sharks

The chemical characterisation and nutritional value of eggs from the five deep-sea sharks leafscale gulper shark ( Centrophorus squamosus), greater lantern shark ( Etmopterus princeps), longnose velvet dogfish ( Centroscymnus crepidater), Portuguese dogfish ( Centroscymnus coelolepis) and black dogfish ( Centrocyllium fabricii) captured at Hatton Bank in the North Atlantic were examined. The chemical composition was quite similar for all the eggs studied. The dominant fatty acid in all the eggs was the monounsaturated fatty acid C18:1, which varied from 27–39%. The eggs had a relatively high content of C16:0 (13.0–18.5%) and C22:6n-3 (10.3–15.1%). The two main lipid classes in the eggs were triacylglycerols (36–55%) and phospholipids (34–41%). The eggs had high amounts of vitamin A and E. The shark eggs were particularly rich in the amino acids aspartic acid, glutamic acid, leucine and arginine.

Proximate composition, fatty acid and lipid class composition of the muscle from deep-sea teleosts and elasmobranchs

Proximate composition of muscle was determined for the following deep-sea fish species: roughhead grenadier ( Macrourus berglax), mora/deep-sea cod ( Mora moro), Portuguese dogfish ( Centroscymnus coelolepis), black dogfish ( Centroscyllium fabricii), leafscale gulper shark ( Centrophorus squamosus), greater lantern shark ( Etmopterus princeps), smalleyed rabbitfish/ghostshark ( Hydrolagus affinis), birdbeak dogfish ( Deania calcea) and two species of smooth head ( Alepocephalus bairdii and Alepocephalus agassizii). The first eight species contained less than 1% fat in the muscle, while the last two contained 3.0% and 3.6% fat, respectively. Fatty acid and lipid class composition was determined for the first five fish species and showed that the dominant class of lipids was phospholipids. The lipids consisted mainly of polyunsaturated fatty acids (PUFA), and docosahexaenoic acid (DHA) was the dominant fatty acid. Roughhead grenadier and mora showed resemblance to cod ( Gadus morhua) regarding protein content, fat content and fatty acid composition. However, the muscle from the deep-sea fish species did contain a higher proportion of arachidonic acid (20:4n-6) than cod muscle.

Fatty acid and lipid class composition in eyes and brain from teleosts and elasmobranchs

The fatty acid and lipid class composition of the eyes and brain were determined for the following species: Atlantic cod ( Gadus morhua), saithe ( Pollachius virens), redfish ( Sebastes marinus), Atlantic salmon ( Salmo salar), rainbow trout ( Oncorhynchus mykiss), Portuguese dogfish ( Centroscymnus coelolepis), black dogfish ( Centroscyllium fabricii), and leafscale gulper shark ( Centrophorus squamosus). Fatty acid analyses of eyes from teleosts in the present study indicated that the lean species contained high ratios of docosahexaenoic acid (DHA) versus eicosapentaenoic acid (EPA), and high ratios of n−3 fatty acids versus n−6 fatty acids, while these ratios were significantly lower for the fatty fish species. The lipid class analyses revealed that among both elasmobranchs and teleosts, phospholipid was the dominant class of lipids in the eyes of lean species, while triacylglycerol was the dominant class of lipids in fatty species. Analyses of the fatty acid composition of brains revealed that the deep-sea elasmobranchs, Portuguese dogfish, black dogfish, and leafscale gulper shark, contained a level of arachidonic acid (AA) that was higher than their level of EPA and about fivefold higher than what was found in the brains of teleosts. Such high levels of AA are not normally observed in fish brains; rather, they are generally observed in brains of higher vertebrates.

Elevated levels of trimethylamine oxide in deep‐sea fish: evidence for synthesis and intertissue physiological importance

Tissue levels of trimethylamine oxide (TMAO) were compared for seven teleost and two elasmobranch species captured from three depth ranges: shallow (<150 m), moderate (500-700 m), and deep (1,000-1,500 m). Within the teleosts, the deep-caught species had significantly greater TMAO content than shallow- or moderate-caught species. In all teleosts, muscle had substantially more TMAO than all other tissues. Kidney or, in some cases, liver had elevated trimethylamine (TMA) content, 2.20-9.65 mmol/kg, along with appreciable trimethylamine oxidase (TMAoxi) activity, suggesting active TMAO synthesis. No correlation was found between TMAoxi activity and TMAO content. The elasmobranchs in this study, Squalus acanthias and Centroscyllium fabricii from shallow and deep water, respectively, were both squaliform sharks. The deep-caught species had significantly more TMAO in all tissues than the shallow species. Furthermore, urea was significantly less in the deep species in all tissues except liver, while the urea:TMAO ratio was significantly less in all tissues. As with teleosts, the TMAO content of muscle was substantially higher for both elasmobranchs than in all other tissues. TMAoxi was below levels of detection in both elasmobranch species, suggesting that TMAO is obtained solely from the diet. This study expands the trend of increased muscle TMAO in deep-sea fish to a variety of other tissues. The accumulation of TMAO in various tissues in deep-sea teleosts and the accumulation of TMAO and concurrent urea decrease in a deep-sea elasmobranch in comparison to a shallow water species strongly support the contention that TMAO is of physiological importance in deep-sea fish.