2 The Aerial Sightings Database

2.1 Data sources

The aer_sight database contains records of search effort and sightings of pelagic schooling species (mainly skipjack tuna, kahawai, blue mackerel, jack mackerel and trevally) from pilots spotting fish schools for purse-seiners around New Zealand. Aerial sightings data are not collected according to experimental design. They are captured opportunistically by pilots of light aircraft employed as fish spotters in purse-seining operations. The majority of effort is centred in the Bay of Plenty (BOP), Golden and Tasman Bays, the Kaikoura coast and to a lesser extent, the South Taranaki coast. The time series of these data begins in June 1976, and is ongoing.

2.2 Data validation

While the aer_sight database enforces data validation and integrity rules with the use of referential constraints and range checks, data go though rigorous data validation and error checking process before being entered.

This process includes instructions for data recording, simple data validation using the checkq2 validation program language and C programming language scripts. See Appendix 1 for a more detailed description of the processes involved.

2.3 Uses of the aerial sightings database

Aerial sightings data can be used for a range of outputs, from profiles of pelagic species distribution and purse-seine activity to providing background information on stock assessments of these species (Taylor in preparation). Probably the most important output is time series of relative abundance which can indicate fluctuations in their abundance from year to year (Bradford & Taylor 1995). Commercial and recreational interests request various types of data reports several times a year.