A t - (n, k, lambda) covering design consists of a collection of k-element subsets (blocks) of an n-element set X such that each t-element subset of X occurs in at least lambda blocks. We use probabilistic techniques to obtain a general upper bound for the minimum size of such designs, extending a result of Erdos and Spencer [4].

We report the results of two investigations requested by the Scientific Committee regardingalternative methods for Bayesian synthesis assessment of the Bering-Beaufort-ChukchiSeas stock of bowhead whales (Balaena mysticetus).The first series of studies examines the effect of assuming that the historic pelagic catchrecord is known without error. We propose a model for variability in the historic catchrecord and we investigate the potential influence of catch record uncertainty on...