Centroscyllium Fabricii Research Articles

Biological aspects of two deep-water squalid sharks: Centroscyllium fabricii (Reinhardt, 1825) and Etmopterus princeps (Collett, 1904) in Icelandic waters

This paper describes some aspects of the biology of the black dogfish ( Centroscyllium fabricii) and the greater lantern shark ( Etmopterus princeps) based on material collected during surveys of Marine Research Institute, Iceland. C. fabricii was most abundant at depths between 800 and 1200 m (range 436–1653 m). The overall sex ratio was 1.00:1.19 in favour of females. Males were more numerous in shallower waters but in depths >1000 m, the sex ratio was significantly in favour of females. E. princeps was most abundant between 800 and 1000 m (range 436–1653 m). The overall sex ratio was 1.00:1.59 in favour of females, females being significantly more numerous in depths >1000 m. For both species there was a trend for a decrease in mean length with increasing depth. Both species were sexually dimorphic with females growing to a larger size than males and being larger at first maturity. Maturity stages were observed during two seasons and indicated that neither of these two species have a defined breeding season. A study of the diets showed that larger specimens of C. fabricii fed mainly on teleosts but smaller specimens seemed to feed more opportunistically on teleosts, cephalopods and crustaceans. E. princeps fed mainly on three prey categories: teleosts, cephalopods and crustaceans. A considerable amount of these two species, and especially of C. fabricii, are likely to be discarded by the commercial fishery for Reinhardtius hippoglossoides off the West of Iceland.

The Effect of the Mesoparasitic Barnacle Anelasma on the Development of Reproductive Organs of Deep-sea Squaloid Sharks, Centroscyllium and Etmopterus

Specimens of the mesoparasitic barnacle, Anelasma, were found attached to several host deep-sea squaloid sharks, Centroscyllium fabricii from off Greenland, Etmopterus princeps from the Canary Islands, and Etmopterus unicolor and Etmopterus granulosus from Three Kings Ridge and Louisville Ridge near New Zealand. One to three parasites were partially embedded in each host shark in the head, mouth, bases of 1st and 2nd dorsal fins, pectoral and pelvic fins, caudal fin, abdomen or claspers. Testes and claspers of parasitized mature-sized males were less developed than those of non-parasitized mature males. The ova of parasitized females of mature size were small and whitish-yellow compared to the large yellow ova of non-parasitized mature females. The number of mature ova in a parasitized specimen was lower than expected in relation to a non-parasitized individual of the same size. Attachment of parasitic barnacles appeared to retard the development of reproductive organs of host sharks.

Feeding of Centroscyllium fabricii and the influence of discards on its diet in Flemish Pass (north-west Atlantic)

One hundred and fifty-one Centroscyllium fabricii stomachs containing food were analysed on board freezer vessels in north-west Atlantic in 1992. Three length groups were established to study variations in diet with length. The most important prey group was waste products from fish processing by the fleet and fish. Diet varied with length, smaller specimens feeding on crustaceans and molluscs, offal and fish forming the main prey in larger predators.

Preparation of polyunsaturated fatty acid concentrates from the liver oil of dogfish (<i>Squalus acanthias</i>) from the Black Sea.

The fatty acid composition of the liver oil from the Black Sea dogfish Squalus acanthias , as well as its seasonal variations were determined. A scheme for concentration of polyunsaturated fatty acids from the dogfish liver oil by urea complexation was proposed. From 360g of free fatty acids a 48g concentrate was obtained, containing 7,8% C 20:4 , 16,4% C 20:5 . 9,2% C 22:5 and 49,7% C 22:6 .

Reproductive Biology of the Black Dogfish,Centroscyllium Fabricii, Collected From Waters off Western Greenland

The reproductive biology of 1124 male (165–760 mm TL) and 1476 female (175–898 mm TL) black dogfish,Centroscyllium fabricii, was examined. The sharks were caught off western Greenland with bottom otter trawls. Size at maturity was about 550 mm TL in males and 650 mm TL in females. Ovarian ova did not continue to develop during gestation. The sex ratio of embryos was 1:1. Litter size ranged from 4 to 40, with a mean of 16–4. The total number of mature ova, fertilized ova, or embryos tended to increase with size of the females. Development of black dogfish embryos is dependent solely on yolk reserves. Near-term embryos (152–192 mm TL) had completely absorbed their external yolk sacs. The smallest free-living specimens collected in this study were 165 mm TL for males and 175 mm TL for females. The black dogfish does not seem to have a well-defined breeding season. This species displayed a well-defined pattern of depth segregation by size. The sex ratios in five shallow depth strata (500–599, 600–699, 700–799,800–899, and 900–999 m) were 1:1, but those of three deeper depth strata (1000–1099,1100–1199, and 1200–1299 m) contained a significantly greater number of females than males. Four abnormal hermaphrodites possessed gonads containing both testicular and ovarian tis-sues. Two specimens had normal female reproductive organs (e.g. ovaries, oviducts, nidamental glands, and uteri) as well as claspers.

A preliminary investigation of the feeding ecology of squaloid sharks off the west coast of southern Africa

The diets of 15 species of squaloid sharks caught between Walvis Bay and Cape Agulhas over a depth range of 50–1 016 m are analysed. The most common prey items were fish and cephalopods. Hake Merluccius spp. were common in the diets of Centrophorus squamosus, Squalus acanthias, and S. cf. mitsukurii. Myctophids were extensively preyed on by Centroscyllium fabricii, Deania calcea, D. profundorum, Etmopterus cf. brachyurus, E. compagnoi, S. acanthias and S. megalops, among others. The most common cephalopods in shark stomachs were Histioteuthis miranda, Lycoteuthis ?diadema, Octopus vulgaris and Todarodes angolensis. Crustaceans were uncommon prey of most species, except for Centroscyllium fabricii and Etmopterus cf. granulosus. Centroscymnus coelolepis was the only squaloid with cetacean remains in the stomach. That species appears to parasitize its cetacean victims.

Differences in Force-Frequency Relationships and Calcium Dependency between Elasmobranch and Teleost Hearts

ABSTRACT Ventricle strips from little skate (Raja erinacea), spiny dogfish (Squalus acanthias), black dogfish (Etmopterus spinax), sea raven (Hemitripterus americanas), cod (Gadus morhua), hagfish (Myxine glutinosa) and white sturgeon (Acipenser transmontanus) were mounted for isometric force recording. Force development was assessed as a function of external calcium concentration and frequency of contraction. Post-rest potentiation was determined in skate and the teleost species to assess indirectly calcium storage capacities. Sea raven and cod preparations were also treated with ryanodine to assess the importance of calcium release from the sarcoplasmic reticulum. Ventricle strips from skate and black dogfish showed a five-fold increase in force development when external calcium was raised from a physiological to a saturating level. Force development by ventricle strips from other species tested increased by only about 50% over the same range of calcium concentration. For all elasmobranchs tested, an elevation in frequency of contraction of ventricle strips resulted first in an increase and subsequently in a decrease in force development. The apices of the curves were well within the physiological range of heart rates exhibited by these species. Preparations from teleosts showed only a decrease in force development when contraction frequency was elevated. Skate ventricle strips exhibited a very marked post-rest potentiation at 3 mmol 1−1 external calcium. This protocol is considered to reflect the importance of intracellular calcium stores in the beat-to-beat maintenance of contractility. Sea raven and cod ventricle strips did not show any major post-rest potentiation, suggesting that calcium storage in hearts of these species is minimal. Ryanodine treatment had no effect upon sea raven and cod heart preparations. This approach further implies that calcium release from sarcoplasmic reticulum is not critical in these species.

Albionella fabricii n. sp. (Copepoda: Lernaeopodidae) from the gills of Centroscyllium fabricii from the Northwest Atlantic

Albionella fabricii n. sp. is described from the gills of the black dogfish Centroscyllium fabricii caught off the west coast of Newfoundland. Morphological differences are found in all the female and male appendages between Albionella fabricii n. sp. and A. centroscyllii, another species occurring concurrently on the same host. Female A. fabricii n. sp. can easily be distinguished from its four congeners by the length and structure of the second maxillae and the length of the uropods. A comparison between Albionella fabricii n. sp. and identifiable females of the genus Lernaeopoda is necessary, since both genera differ mainly in the morphology of the male. Two specific characteristics, the number of secondary denticles on the claw of the maxilliped and the number of setae on the exopod of the first maxilla, distinguish females of Albionella from those of Lernaeopoda.

Diets of the sharks and chimaeroids of the Rockall Trough, northeastern Atlantic Ocean

The sharks and chimaeroids are important members of the deep-water associations of fish of the continental slopes, but little is known about their trophic interactions. The diets of these fish were studied through the deployment of demersal trawls at successive 250 m depth intervals, within a total range of depth of 500 to 2 900 m, in the Rockall Trough to the west of Scotland and Ireland during the period 1975 to 1981. The sharks and chimaeroids, however, only occurred between 500 and 2000 m but principally in the 500 to 1 250 m bathymetric zones. These are the zones of maximum biomass of prey species of fish and probably also of prey species of epibenthos. The sharks divide into 3 trophic groups. Apristurus spp., Centroscymnus crepidater, Ttmopterus spinax and E. princeps exploit micronekton in the vicinity of the sea bed. Centroscyllium fabricii, Centroscymnus coelolepis, Deania calceus and Lepidorhinus squamosus are principally fish eaters. A third group may consist of 2 rarer species in the Rockall Trough, Galeus melastomus and G. murinus that exploit the epibenthos but also, to some extent, the micronekton. The 3 species of chimaeroids (Chimaera monstrosa, Hydrolagus mirabilis and Harriotta raleighana) prey on the epibenthos and the last species may also utilize, to some extent, infaunal species.

Occurrence of dimethyl-ß-propiothetin in marine phytoplankton : Ackman R. G., C. S. Tocher and J. McLachlan, 1966. J. Fish Res. Bd Can., 23 (3): 357–364.

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.

Redescription of Lernaeopoda centroscyllii Hansen, 1923 (Copepoda: Lernaeopodidae)

Lernaeopoda centroscyllii, a lernaeopodid copepod parasitic on Centroscyllium fabricii, and briefly described by Hansen on the basis of one damaged female specimen in 1923, has not been recorded since that date. This paper gives a detailed account of both the male and the female of the species, recently taken in Newfoundland waters.