This dataset lists fishing effort targetting Southern Bluefin Tuna (SBT) from the Commission for the Conservation of Southern Bluefin Tuna (CCSBT) for the commercial surface (purse seine, pole and line only) fisheries from 1975 to 2015. Efforts are stratified by year, month, fishing gear, vessel flag reporting country, unit of effort, area (1° squares). It corresponds to the effort part of the CCSBT catch-and-effort (task2) dataset.

Efforts are expressed in number of hours searching.

This dataset was downloaded on the CCSBT website. It was then restructured to be in line with the Sardara database structure (columns normalization, names, etc.). However the content of data and the code lists were kept exactly as their are available in the source dataset.

The description below (caracteristics, specific issues and problems that need to be taken into account) is extracted from the CCSBT web page where the dataset has been downloaded.

Caracteristics, specific issues and problems that need to be taken into account :

It should be noted that the data for individual Flag States and fishing entities available here may differ to data that they provided to other organisations. This is in part due to the data manipulations conducted by the CCSBT in producing this dataset (a variety of data sources were used, requiring a range of correction and raising techniques) and in part due to differences in the data provided by individual Flag States and fishing entities to the CCSBT and to other organisations. In particular, the post 1994 SBT data provided by Japan to the CCSBT differs from the post 1994 SBT data that Japan provides to other regional fishery management organisations. The data that Japan provides to CCSBT takes advantage of a Real Time Monitoring Program for SBT to collect daily catch and effort reports from SBT targeting fishing vessels and this is considered to minimise the time lag in availability of the Japanese SBT log book data.

It should also be noted that the effort data provided here do not cover the full time-series of SBT fishing by each Flag State and fishing entity, nor do they contain the entire fishing effort targetting SBT for any year. The reason for incomplete time series is that the catch and effort data is compiled from vessel logbooks or similar detailed records that may not have been collected throughout a nations fishing history. Similarly, in some years, there may not be complete coverage of a particular fleet by catch and effort data collection systems.

It should be further noted that in cases where information on the number of vessels has been provided to the Secretariat, the subsets provided here are made up of observations with a minimum of three vessels per strata. This is due to the CCSBT confidentiality rules.

For some CCSBT Members, the data provided here are not restricted to fishing that targeted SBT. Instead, the data represents all purse seine and pole & line fishing in which catches of SBT were feasible. This includes fishing that targeted SBT, fishing that targeted other tuna or tuna like species, and/or fishing conducted in strata (year/month/area) where SBT were also taken. As a consequence, there are many fishing records with no SBT catch. Note: the extent to which fishing effort associated with past unreported catches has been reported is currently unknown. This causes difficulties for a meaningful interpretation of catch per unit effort trends from these data.