This paper deals with the problem of estimating the parameters of the Rice distribution. The distribution has applications in sonar and radar signal processing and a proper estimation procedure with associated confidence intervals is important. Using the sample second moment as an estimate of the second moment of the distribution, two techniques, viz., methods of moments and maximum likelihood are applied to synthetic envelope data of known signal-to-noise ratios, in order to estimate the parameter from different sample sizes. It is concluded that the sample second moment is an unbiased estimate of the theoretical second moment and for the signal-to-noise ratio parameter both methods work without any significant bias and satisfy the criterion of maximum efficiency. However, the method of moments is simpler, easier to apply and therefore recommended as the method of choice.

Strategies and tactics are explored for increasing the usefulness of assessment information obtainable under manpower and budget restrictions. A concept of indirect rapid assessment is gradually emerging based on a collection of rapid methods of varying degrees of accuracy, sophistication, and data requirements. These tactics involve the use of statistics which are functionally related to parameters of interest. Stock composition, growth, mortality, population size, intrinsic rate of increase, and stock production may be efficiently estimated with these methods. Short-term forecasting is also possible. Tactics include group testing, correcting biased estimates, use of comparative studies, using length as a substitute for age, and remote sensing type assessments.

No abstract

No abstract

The impact of dredging on a biological community is assessed through the use of log-linear modelling. The experiment is designed as a nested design and the data is collected at several stations within each of natural and dredged areas. The log-linear modelling analysis indicates the dredging has an impact on the abundance of dominant species.