Estimating the Worldwide Extent of Illegal Fishing

Illegal and unreported fishing contributes to overexploitation of fish stocks and is a hindrance to the recovery of fish populations and ecosystems. This study is the first to undertake a world-wide analysis of illegal and unreported fishing. Reviewing the situation in 54 countries and on the high seas, we estimate that lower and upper estimates of the total value of current illegal and unreported fishing losses worldwide are between $10 bn and$23.5 bn annually, representing between 11 and 26 million tonnes. Our data are of sufficient resolution to detect regional differences in the level and trend of illegal fishing over the last 20 years, and we can report a significant correlation between governance and the level of illegal fishing. Developing countries are most at risk from illegal fishing, with total estimated catches in West Africa being 40% higher than reported catches. Such levels of exploitation severely hamper the sustainable management of marine ecosystems. Although there have been some successes in reducing the level of illegal fishing in some areas, these developments are relatively recent and follow growing international focus on the problem. This paper provides the baseline against which successful action to curb illegal fishing can be judged

Relative abundance of dolphins associated with tuna in the eastern Pacific Ocean:analysis of 1992 data

For most dolphin stocks, there is no evidence of trends in population size in recent years. The exception is the northern stock of the common dolphin Delphinus delphis which shows a significant decrease over recent years, although this may be due to a shift in the spatial distribution of the stock. -from Authors</p

Estimated trends in abundance of dolphins associated with tuna in the eastern tropical Pacific

Estimates trends in population levels in E tropical Pacific stocks of spotted (Stenella attenuata), spinner (S. longirostris) and common (Delphinus delphis) dolphins. -from Authors</p

Reducing bias in trends in dolphin relative abundance, estimated from tuna vessel data

Estimated the relative abundances of E tropical Pacific stocks of spotted Stenella attenuata, spinner S. longirostris and common Delphinus delphis dolphins. Estimates corresonding to each year from 1975-1987 are given for a new procedure. Conclusions are generally similar to those of Buckland and Anganuzzi (1988); the stocks for which we have most information (the E stock of spinner dolphin and the N offshore stock of spotted dolphin) both appear to have been relatively stable in size during the 1980s, with evidence of reductions in the latter stock in the late 1970s. -from Authors</p

Relative abundance of dolphins associated with tuna in the eastern Pacific Ocean:analysis of 1992 data

For most dolphin stocks, there is no evidence of trends in population size in recent years. The exception is the northern stock of the common dolphin Delphinus delphis which shows a significant decrease over recent years, although this may be due to a shift in the spatial distribution of the stock. -from Authors</p

Post-stratification as a bias reduction technique

Opportunistic, non-random surveys often provide information for management of wildlife resources, yet managers may be seriously misled due to biases in the data. Post-stratification may be used to reduce bias. For a given factor of interest, a variable is identified that correlates well with it. Observations on the variable are ordered, and strata are defined by determining appropriate cutpoints. The variable might be an estimator of the factor itself, or estimated from the same data as are used to estimate the factor, and evaluated for each of a number of small geographic units. Post-stratification can be applied to obtain an estimate of each component for a random point in the area occupied by the resource, and bootstrapping may be used to yield a robust variance of the composite estimate that does not require the assumption that the component estimates are uncorrelated. -from Authors</p

Relative abundance of dolphins associated with tuna in the eastern Pacific Ocean:analysis of 1991 data

For most dolphin stocks, there is no evidence of trends in population size in recent years. The exception is the northern stock of common dolphin Delphinus delphis which shows a significant decrease over the last ten years. Possible reasons for the decline are discussed. -from Authors</p

Relative abundance of dolphins associated with tuna in the eastern tropical Pacific, estimated from tuna vessel sightings data for 1988 and 1989

Incidental mortality of dolphins in the E tropical Pacific caused by the tuna fishery has probably been sufficient to affect abundance of stocks of spotted dolphin Stenella attenuata, spinner dolphin S. longirostris and common dolphin Delphinus delphis. There is little evidence of trends in population size in recent years, as determined by five-year tests for trend. -from Authors</p