NOAA Logo click for NOAA website 6th International Fisheries Observer and Monitoring Conference  
Data Extrapolation Workshop

MONDAY, 20 JULY · 8:30 AM UNTIL ~6:00 PM



Lisa Borges, European Commission, Belgium, Email:
Vicki Cornish, Ocean Conservancy, USA

Data from fisheries observer programs around the world are used as a basis for management decisions, as they collect vital information on fisherman behaviour and operational activities. While most countries collect data at-sea, few programs have the resources or the management requirement to sample a fishery at 100% observer coverage. This results in the need for robust methodologies to be used in data extrapolation. Currently, a variety of methods are used, but there has been little discussion as to the advantages and disadvantages of each methods, or comparisons between methods.

Therefore, the IFOMC Steering Committee is proposing a pre-conference workshop on data extrapolation for the 2009 Conference. The objective of the workshop is to establish a set of common best practices in data extrapolation. The specific objectives of the workshop are to:

  • Review extrapolation methods used around the world.
  • Compare the results from extrapolation methods used in different fisheries, identifying the advantages and limitations of each procedure.
  • Identify and summarize the concerns different programs have with respect to extrapolation procedures
  • Suggest guidelines for achieving a common approach in the application of data extrapolation methodologies.

By taking part in the workshop, participants will have a chance to discuss specific extrapolation issues related to their programs, and also to learn about traditional as well as new methods to provide and/or improve global estimates of catch through data extrapolation.

The precise content of the workshop will be determined with input from the participants. Which of these issues are of the most interest to you?

  • Voluntary vs. compulsory/mandatory sampling. What are the effects of different types of sampling programs on the data and its statistical implications?
  • Random samples and the representativeness of the sampled vessel/trip/haul. How to check if samples are representative of the fishery? What are the impacts of biased sampling in terms of data extrapolation?
  • Extrapolation to haul, to trip and to fishery level. What errors may be introduced at each level of extrapolation? What are the best estimators?
  • Modelling discards. Under what circumstances should models be used to extrapolate data? What kinds of models are best (generalized linear models, generalized additive models, mixed-models, spatial, etc)?
  • Rare events/occurrences. Can rare events be extrapolated? If so, what methods can be used and what kinds of biases may be introduced?

If you plan to attend this free workshop, please indicate your interest on the conference registration form. If you would like to learn more about the workshop, please contact the workshop coordinator, Lisa Borges, email:

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