A demographic technique is used to compare the intrinsic rates of population increase of 26 shark species hypothetically exposed to fishing mortality. These rates (r2M) are used as a measure of the relative ability of different sharks to recover from fishing pressure. The method incorporates concepts of density dependence from standard population modelling and uses female age at maturity, maximum reproductive age, and average fecundity. A compensatory response to population reduction is assumed in pre-adult survival to the extent possible given the constraints of the life-history parameters. ‘Rebound’ productivity was strongly affected by age at maturity and little affected by maximum age. Species with lowest values (r2M < 0.04) tended to be late-maturing medium- to large-sized coastal sharks, whereas those with the highest (> 0.08) were small coastal, early-maturing species. Sharks with mid-range values (r2M = 0.04–0.07) were mostly large (> 250 cm maximum size) pelagic species, relatively fast growing and early maturing. Possible selection pressures for these three shark groups, management implications, practical applications for the derived parameter r2M, and recommended areas of research are discussed.

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Aims: The Environmental Determinants of Diabetes in the Young (TEDDY) planned biomarker discovery studies on longitudinal samples for persistent confirmed islet cell autoantibodies and type 1 diabetes (T1D) using dietary biomarkers, metabolomics, microbiome/viral metagenomics and gene expression. Methods: This paper describes the details of planning the TEDDY biomarker discovery studies using a nested case-control design that was chosen as an alternative to the full cohort analysis. In the frame of a nested case-control design, it guides the choice of matching factors, selection of controls, preparation of external quality control samples, and reduction of batch effects along with proper sample allocation. Results and Conclusion: Our design is to reduce potential bias and retain study power while reduce the costs by limiting the numbers of samples requiring laboratory analyses. It also covers two primary end points (the occurrence of diabetes-related autoantibodies and the diagnosis of T1D). The resulting list of case-control matched samples for each laboratory was augmented with external quality control (QC) samples.

SynopsisThe age, growth, and sexual maturation of the leopard shark, Triakis semifasciata, from central California were studied. Growth band counts in vertebral centra of 162 leopard sharks produced von Bertalanffy growth curves with L,, K. and t, parameters of 1536mm. 0.082, and -2.31, respectively, for both sexes combined. The L, value for females (1602mm TL) was slightly but insignificantly higher than for males (1499 mm TL), but the K and t, values were almost identical. Seasonal changes in size modes of young-of-theyear leopard sharks, centrum edge characteristics, and growth and tetracycline mark-recapture from the field were used to validate annual deposition of vertebral centrum band pairs. Sexual maturity was evaluated by the gonads and presence of sperm and eggs; males mature at 7 yr and at about 63% of asymptotic length, and females mature at 10 yr, and at about 72% of asymptotic length. This slow growth, late maturity, and relatively low fecundity may increase their susceptibility to over-exploitation.