The release of artificially reared pheasants is a widespread practice in Great Britain, used to increase the number of birds available for hunting. We examined the spatial and temporal patterns of release and shooting between 1960 and 2014 using data from a self-selected sample of 1195 sites. We examined changes in the efficiency of release, the contribution of birds that were not released that year to the numbers shot, and the form of these relationships through time. An annual estimate of the efficiency by which releasing increased the numbers shot was 50% over the period 1960-1990 declining rapidly to 35% by 2005 and reducing more slowly thereafter. There was no obvious regional pattern to this relationship. It has been hypothesised that the efficiency of releasing is lower on sites that release higher densities of pheasants; this study does not support this hypothesis. Annual variation in the density of birds shot in the absence of releasing was closely correlated with a measure of annual gamebird chick survival. After this date, the relationship was no longer significant, consistent with a decline in wild pheasant stocks and coinciding with the declines in other farmland birds. We highlight increased fox abundance, genetic and behavioural changes arising from the rearing process, and increased shooting in late winter as possible causes for the observed decline in releasing efficiency. We consider the general increase in rearing, habitat changes, increased disease or losses to protected predators as unlikely to have been important causes of the changes in releasing efficiency. Pheasant releasing results in increased numbers for shooting, but has not prevented the wide-scale decline of wild pheasant numbers.
Despite the commercial and ecological importance of the European lobster Homarus gammarus, estimates of the population dynamics within socio-economically important fishing areas remain understudied. We implemented a mark-recapture approach to estimate population density, rates of loss and catchability of H. gammarus off the coast of northeast England, an important area for lobster fishers, and one of high exploitation. The short-term study used continuous trapping data from a commercial parlour trap array, fished over 6 wk. Over 9 haul occasions, 562 lobsters were marked using persistent external T-bar tags with unique ID numbers; 13.7% of these lobsters were subsequently recaptured. Catch data were used to determine the relationship between trap soak time and the effective fishing effort over time. Capture histories and effort data were analysed using a modified Cormack-Jolly-Seber (CJS) model, adapted for the short-term and continuous nature of the study. Model estimates of male lobster density varied depending on capture occasion between 732 (95% CI = 423, 1267) and 2730 (95% CI = 1585, 4701) lobsters per km2. Similarly, female density was estimated at between 2410 (95% CI = 476, 12176) and 8060 (95% CI = 1592, 40810) lobsters per km2. Low rates of loss of individuals from the area and large differences in catchability between sexes led to a female-skewed density estimate. If these findings are corroborated, the effects of sex-specific catchability and the potential for biased sex composition in populations and catches should be addressed in stock assessments and when interpreting sex ratio data in commercial catches.
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