Deep-water sharks exhibit species-specific reproductive strategies, which include segregation by sex, size and reproductive stage. However, due to the wide spatial distribution of most species, available information, usually collected at a regional scale, is usually not adequate to infer species reproductive spatial dynamics. This study draws together information on the distribution of reproductive stages of three species of squaliform sharks: Portuguese dogfish Centroscymnus coelolepis (Somniosidae), leafscale gulper shark Centrophorus squamosus (Centrophoridae) and birdbeak dogfish Deania calcea (Centrophoridae), gathering data from several geographical areas from the Atlantic, Indian and Pacific Oceans. For each species we analysed the sex ratio and the spatial patterns of reproductive stages within regions, considering the influence of geographical area, depth, season, temperature and Please note that this is an author-produced PDF of an article accepted for publication following peer review. The definitive publisher-authenticated version is available on the publisher Web site 2 salinity. The combination of statistical methods used in this study successfully identified a number of life history patterns which reflect different use of habitats by sex and life cycle stage. Pregnant females of the three species are spatially segregated, inhabiting shallower and/or warmer waters. In the case of the leafscale gulper shark this segregation might be associated with large scale migrations. In contrast, in Portuguese dogfish all adult maturity stages occur in the same geographical area. Pregnant female birdbeak dogfish were rare in all samples. Larger immature specimens of all the three species distribute deeper than the remaining maturity stages in most of the regions analysed. Mature males of leafscale gulper shark and birdbeak dogfish were more broadly distributed than mature females, supporting the possibility of sex-biased dispersal. Neonates and small sized specimens were scarce in the Northeast Atlantic potentially explained by their concentration in nurseries, and/or by gear selectivity. Management measures will benefit from considering the geographic scale of demographic variation between species. However, standardized collaborative approaches will be needed for comprehensive assessment.

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Age and growth of southern boarfish Pseudopentaceros richardsoni (Smith 1844) from south-west Indian Ocean seamounts were studied based on whole otolith readings using a non-linear back-calculation method and geometric mean regression to resolve the problem of the lack of young fish in the catches owing to age segregated habitat use by this species. Ages of the fish under study ranged from between 5 and 14 years (45.7–72.5 cm total length). Changes in relative growth of annuli were most probably related to aspects of the life history, such as migration to settle on seamounts. Age distribution was related to depth. The von Bertalanffy growth parameters for all individuals were L∞ = 65.1 cm; K = 0.27 year–1 and t0 = –0.34 years, obtained by mean length-age from back-calculated lengths. These data are needed to assist in the wise management of this potential fishery and the back-calculation approach shows promise for other species where juvenile fish are difficult to obtain. It is also clear that more information about the southern boarfish biology is needed to establish bases for a responsible fishery development off the seamounts of the Southern Indian Ocean and other deep-sea regions.