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

Abstract

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.

Distribution, reproduction and population structure of three gulper sharks (Centrophorus, Centrophoridae) in south-east Australian waters

“…This contrasts with the non-continuous cycles of dogshark genera such as Centroscyllium, Centroscymnus, Deania and Etmopterus which are more commonly found in midslope depths (e.g. Clark and King 1989;Yano 1995;Wetherbee 1996;Daley et al 2002).…”

“…Maturity criteria were based on indices developed for deepwater sharks by Yano (1995), Girard and Du Buit (1999), Stehmann (2002) and Walker (2005). Outer clasper length (CLO; Compagno 1984) was the distance from the clasper tip to its insertion into the pelvic fin, measured with Vernier callipers to the nearest mm.…”

“…Biased sex ratios in dogshark catches are commonly reported and although segregation of the sexes by depth has been observed in several midslope dogsharks (e.g. Yano and Tanaka 1988;Yano 1995;Clarke et al 2001;Jakobsdóttir 2001), segregation by depth was unlikely for Centrophorus off NSW. Sampling during the 1976-77 survey encompassed most of the preferred depth range (300-650 m) of these species, and subsequent trawling in depths between 600 and 1000 m also caught predominantly males (Table 1).…”

“…Previous studies into the biology of deepwater squaloid sharks have mainly focussed on the essentially mid-slope species of Centroscyllium, Centroscymnus, Deania and Etmopterus from the North Atlantic Ocean (Yano 1995;Jakobsdóttir 2001;Clarke et al 2002), Japan (Yano andTanaka 1984, 1988) and New Zealand (Wetherbee 1996), while most studies into the biology of Centrophorus dealt with C. squamosus from the north-west Atlantic, for example Girard and Du Buit (1999), Girard et al (2000), Clarke et al (2001), Bañón et al (2008), Figueiredo et al (2008) and Severino et al (2009). Of the shallower upper-slope species, Bass et al (1976) gave brief details of size at maturity for 'C.…”

Body morphometrics, swimming diversity and niche in demersal sharks: a comparative case study from the Mediterranean Sea

“…al., 1969; clarke et. al., 2001), Centroscyllium fabricii (Yano, 1995), Scyliorhinus canicula (craik, 1978) and Squalus acanthias (bone and roberts, 1969). according to bone and roberts (1969), such an inter-tissue exchange of lipids maintains a fairly constant percentage weight in seawater for deepwater sharks.…”