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Several life history traits of sharks result in juveniles being particularly vulnerable to exploitation. However, population level impacts of harvests on juvenile sharks have not been well quantified. This paper examines a range of harvest strategies, including those targeting juveniles. Reproductive value and yield per recruit are used to compare the harvests, which are represented by Leslie matrix models with a harvest matrix. Two species are used as examples: the short-lived Rhizoprionodon taylori and the long-lived Squalus acanthias. Harvests that maintain a stationary population size cause reproductive values to change in opposing ways, but they remove equal fractions of the population's reproductive potential. A new theorem gives population growth as a function of the fraction of reproductive potential removed by a harvest, a relationship useful for comparing harvests on juveniles and adults. Stochastic projections indicate that the risk of depletion is associated with the fraction of reproductive potential removed annually, a measure which encompasses the information in both the selectivity and the rate of fishing mortality. These results indicate the value of focusing conservation efforts on preserving reproductive potential.

Many endemic plant species belong to taxonomically complex groups. These endemics have often arisen as a consequence of recent and rapid evolutionary divergence facilitated by processes such as hybridization, polyploidy and/or breeding system transitions. The rapid and dynamic nature of divergence in taxonomically complex groups leads to problems in the implementation of traditional species-based approaches for the conservation of the biodiversity that they contain. Firstly, the taxa of interest can be difficult to define and identify, leading to practical difficulties in implementing conservation measures. Secondly, a species-based approach often fails to capture the complexity of diversity present in the taxonomically complex group. To accommodate these challenges, we have developed a Process-Based Species Action Plan approach. This is designed to conserve the processes leading to the generation of biodiversity, rather than focusing on the preservation of individual named taxa. We illustrate the approach using a group of endemic tree species (Sorbus) on the Scottish island of Arran that have originated via a combination of multiple recent hybridization events and apomixis. The plan focuses on the optimization of habitat management to ensure the reproduction and regeneration of Sorbus in the zone in which these evolutionary processes operate, and to facilitate hybridization that will ensure the continued generation of diversity in this groupPeer reviewe

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The confounded effects of changes in climate and density on a population’s demography are hard to separate for long-lived species because demographic traits are usually the aggregated result of conditions faced over years. Demographic parameters are compared for spiny dogfish ( Squalus acanthias ) in the Northeast Pacific, the longest lived and latest maturing of all sharks, using samples from the 1940s and 2000s. This 60-year interval has seen ocean temperatures rise by almost 1 °C and dogfish harvests peak above 50 000 tonnes (t)·annum–1 and then drop below 50 t·annum–1. Over this period, the age at 50% maturity for dogfish declined from 43 to 32 years, while the estimated average number of embryos per litter for a 100 cm dogfish increased from 5.9 to 6.7. Growth parameters changed significantly, with faster growth to a smaller size. Leslie matrix analysis showed that these changes could lead to an increase in population growth rate of about 1%. Comparison with published demographic parameters from the 1970s and 1980s indicated that the greatest change in demographic parameters occurred between the 1940s and 1970s, prior to the largest changes in ocean temperatures. The implications for fishing on long-lived populations during times of rapid environmental change are explored.

SUMMARY Hearing, speech, and language were studied in 26 children who survived severe perinatal asphyxia. The results of hearing tests showed that most children had a favourable outcome. Only 1 child had sensorineural deafness. Hearing loss in 6 others was due to middle-ear disease which resolved after treatment, and on retesting was found to be normal. The study also showed that neither gentamicin treatment nor incubator noise seemed to affect hearing. The results of speech and language assessment were less encouraging and about one-third of the children without serious mental or physical handicap had deficits in speech and language. It is suggested that the quality of life in such children could be improved if these deficits were detected early and adequately treated.