Over 50 species of chondrichthyan fishes are known from waters around the British Isles, of which 26 have been recorded in The Centre for Environment, Fisheries and Aquaculture Science (CEFAS) trawl surveys. The distribution and relative abundance of dogfishes, skates and rays are described from groundfish surveys in the North Sea, English Channel, Irish Sea and Celtic Sea. The contemporary distribution of species in relation to their biogeography and major changes in the distribution are discussed. Nursery areas of elasmobranchs were typically in shallower water than adult habitats, a pattern evident for blonde (Raja brachyura), thornback (R. clavata), small-eyed (R. microocellata) and spotted ray (R. montagui). In contrast, juvenile cuckoo ray Leucoraja naevus occurred further offshore and were most abundant in the western Irish Sea and northern St George's Channel. Oviparous species require a suitable substratum for the deposition of eggs, and the distribution of egg-cases is illustrated and important egg-laying substrates identified.

Age and growth of bull shark, Carcharhinus leucas, was investigated in the southern Gulf of Mexico (Veracruz and Campeche, Mexico) from December 1993 through June 1997. Ninety-five specimens were obtained from commercial fishery catches, and vertebrae were examined from 20 males, 61 females and 14 individuals unidentified to sex. Vertebrae were examined using five different techniques to enhance the visibility of growth rings: i) alizarin red stain, ii) crystal violet stain, iii) X-ray, iv) silver nitrate stain, and v) without staining. Verification of temporal growth ring formation was done by the indirect method of marginal increment analysis. An isometric relationship was found between growth and length of centrum, is described by a linear equation. Age-at-maturity was 10 years (204 cm total length, TL) for females and 9-10 years (190-200 cm TL) for males. The oldest female was 28 (256.0 cm TL), and the oldest male was 23 (243.0 cm TL). The von Bertalanffy growth parameters were estimated for the species (L ∞ = 256.4 cm TL, k = 0.1397 per year and t o =-1.935), for males (L ∞ = 248.4 cm TL, k = 0.1692 per year and t o =-1.03), and for females (L ∞ = 262.1 cm TL, k = 0.1235 per year and t o =-2.44). Sexual differences for each particular growth curve were found, L ∞ being the parameter that showed the greatest difference between males and females; females attain a larger size.

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Weight-length relationships (WLR) were estimated for six batoids, namely: Urotrygon chilensis, Narcine entemedor, Rhinobatos leucorhynchus, Rhinobatos planiceps, Rhinobatos prahli and Urobatis tumbesensis captured in the Ecuadorian Pacific. Data were collected between

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