Estimated Total Boat Based Landings
Offshore Creel Survey Data Processing
The Estimated Total Boat Based Landings Graphs in this web site are based on expanded data from the Offshore Creel Survey System
Guam's Offshore Creel Survey data was originally expanded utilizing a spreadsheet format that does not include complemental statistics of confidence or biological data such as mean species lengths.
The establishment of an offshore Creel Survey at the Merizo Pier in 1991 and the Agat Marina in 1994, as well as the revision of expansion algorithms to expand the offshore survey data in 1995, has increased confidence in the expansion results using this spreadsheet format. However, species composition was still limited to BMUS and a few other species of major importance.
To rectify these data expansion deficiencies, WPACFin and DAWR have developed a computerized database program to collect and analyze the entire offshore fisheries data collected since FY97. The expansion program's algorithms were completed in FY01. The statistical basis for the expansion can be found in NOAA SWFC Admin.
Important changes in the data expansion process have been incorporated into the offshore survey since FY97. This includes the use of:
- Quarterly expansions to account for seasonal fisheries
- Boat log data to calculate participation in the expansion process
- Expansion data from the 3 surveyed ports
- Separating charter and non-charter fishing activity
- Separating bottomfishing into shallow and deepwater strata
- Collecting and analyzing bycatch data.
This improvement, combined with recent revisions of expansion algorithms, crosschecking features, and size distribution analysis have contributed to the increased efficiency in the production and reliability of the Guam annual reports.
The historical offshore data from FY82 to the present have been entered into the new database system. An expansion of the entire offshore time series was completed in 2001. The new offshore expansion program provided managers a standard expansion format, to give us a historic account of the boat-based fishery on Guam presented in this web site
A 365 day (366 days during leap years) expansion is run for each calendar year of survey data to produce catch and effort estimates for each fishing method surveyed. Percent species composition is calculated by weight for the sampled catch for each method to produce catch estimates for each species for the expanded period.
The annual catch for each species and species group are summed across all methods to obtain the numbers presented in this web site.