The reproductive biology of two aplacental viviparous deep sea sharks, Centroscymnus coelolepis and Centrophorus squamosus has been studied from 1735 and 675 specimens respectively, collected with bottom trawls between 600 and 1400 m depth off the west coast of the British Isles. A macroscopic maturity scale indicates that for both species, size at first maturity is greater in females than in males. In Centroscymnus coelolepis, genital maturity occurs at an average length of ∼86 cm for males and ∼102 cm for females. In Centrophorus squamosus, males are mature near 98 cm and females near 124 cm total length (TL). Smallest juveniles of both species are absent from catches: no specimens of Centroscymnus coelolepis shorter than 58 cm, nor specimens of Centrophorus squamosus shorter than 84 cm have been recorded. Ovarian fecundity is higher in Centroscymnus coelolepis than in Centrophorus squamosus. A maternal supply has been demonstrated for Centroscymnus coelolepis. Litter size has been estimated only in C. coelolepis because no pregnant females of Centrophorus squamosus were recovered. A dwarf embryo and a pair of twins have been observed. Segregation by sexual stage of development shows that immatures are generally found at greater depths than adults.

The records of tropical fishes and the warming of the European Atlantic waters. A recapitulation of the records of tropical fishes from European Atlantic waters shows that 67.6 % were fishes caught from the upper slope, between approximately 200 and 600 m; 19.8 % were fishes caught from the continental shelf; and 13.5 % were specimens caught from the middle slope, between 700 and 1 300 m. Since 1963, the upper slope species have made regular northward range extensions off of south Portugal to northwestern Ireland (about 55" 30' N), more and less rapidly, about 30 years for Cyttopsis roseus and only 6 years for Sphoeroides pachygaster. The continental shelf species, observed from 1969 but mostly from 198 1, have a northward range to southeastern Ireland (about 52" N), but 65.2 % of them have been caught off the south of the Bay of Biscay. The middle slope species, recorded only from 1991 according to the development of the deep fishery, were caught between 48" N and 60" N. The northward range extension of upper slope species and the higher frequency of records of continental shelf species from the southern part of the Bay of Biscay coincide with the investigations on the warming of the south-north current in the upper slope of northern Spain and of the south French Atlantic continental shelf. 0 Elsevier, Paris biodiversity I tropical fishes I warming I European Atlantic

No abstract

No abstract