Operation-Level Observer Data from the High-Seas Driftnet Fisheries of Japan, Korea and Taiwan in the North Pacific Ocean, 1990-1991

In the U.S., driftnet observer data were managed and archived by the Alaska Fisheries Science Center and disseminated to NMFS driftnet program scientists in the AKFSC and the Southwest Fisheries Science Center. Using the combined edited data from all 1990-1991 observer deployments on the squid and large-mesh vessels, Marian Yong of the SWFSC Honolulu Laboratory produced a text file of operation-level, species-specific summary statistics. For each observed operation, separate records of details were created for each species taken during the operation within each observed combination of retrieval type and net depth. In most operations there was just a single category - ordinary retrieval of gear set at the sea surface. All records included a set of header fields including information on vessel ID, flag state, observer nationality, date and location of gear deployment, environmental characteristics, and more. For fish and squid species, each record included additional fields of summary statistics pertaining to the totality of sections monitored: number of sections, mean mesh size, number of standardized (50-m) tans deployed, number of animals decked, number of dropouts, and number of animals of unknown status (this was always empty for squid and fish, as explained below). Other fields contained the same set of aggregate statistics for sections which were monitored for dropouts. In the case of mammals, birds and turtles, some of the fields just described for fish and squid were overloaded with different data pertinent to protected species. The field for decked animals represented the number of animals that were decked and discarded dead, the field for dropouts contained the number of decked animals released alive, and the field for unknown status referred to the number of animals released in unknown condition.

In addition to the species-specific records detailing primary monitoring information, data for each operation included a single "Null Species - Operation Marker" record. This was designated by species code 999 and included all the operation-level header data and operation-level summary statistics for average mesh size, total number of sections monitored, and total standardized tans deployed. These statistics were detailed for all the sections monitored and for the subset of sections where dropouts were assessed.

The Augmented Data

The original text files of observation-level data were prepared in 1992 (dn90obs, dn91obs, and a combined file DNALLOBS). They have been circulated and used in a few subsequent analyses and published papers. However, they have remained largely unavailable and undocumented. The purpose of this project was to create and describe an enhanced version of the original file of combined operation-level data that is easier to use for data analysis and visualization. The enhanced version includes several new fields. To augment the 'species code' field in the original file, new hierarchical taxonomic fields were added to provide species common name, scientific name, group and category. In addition, a new 'date' field was added based on the original fields of operation day, month and year. Finally, new decimal fields of operation 'latitude' and 'longitude' were added.

The new data set is provided in an accompanying Excel file: Driftnet Observer Data_12Aug24.xls

Send written request to PIFSC and requires approval by the PIFSC data owner.

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Oracle

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