2 Rock lobster Catch Sampling Programs

2.1 Nomenclature

2.2 Sources of data

The rlcs database predominantly contains catch sampling data related to rock lobster catch samples, for both rock lobster species. Additionally, there are morphological measurement data (including some market sampling data) within rlcs. It has been created in response to a need to maintain a time series on biological and CPUE data independent from the industry daily landing logs.

The basis for these data is a sample. A sample is defined as one fishing day per vessel and information relating to the day’s fishing is recorded on a cover sheet.

A unique sample number, up to 10 characters long, identifies each sample: the first character denotes a geographic area; the next two characters are a sequential sample number for a calendar year, the next two characters are the year. The last five are available for identifying the data source: data collected by Rock Lobster Industry Council (RLIC) or by NIWA. The use of five characters to identify data source has been used for samples since 1 January 1998. The characters “NIWA” indicates the sample was collected by NIWA stock monitoring staff, and “RLIC” indicates RLIC staff collected the sample.

Prior to 1 January 1998, the first character of the sample number had been based on the FMA (Fisheries Management Area) codes in use when the pilot catch sampling program began in 1987. As these FMA codes subsequently changed, and as more codes were added to cover special cases, this first character identifying the area soon became irrelevant.

Guidelines for interpreting the first character of the sample number are shown in the table below:

For example, there were three codes to identify Chatham Island samples depending on the type of sample and who collected them. Samples beginning with the character “A” or “B” were market samples of an entire landed catch from individual vessels collected by workers contracted to NIWA. A prefix of “7” indicates NIWA staff collected the data as part of a catch or tagging sample.

Prior to August 1993, all catch sampling in the CRA3 red rock lobster management area had the sample number prefix as “1” (Central Region). However, from August 1993, NIWA (formerly MAF Fisheries) was contracted by NZFIB to collect a specific number of samples within CRA3. To keep the NZFIB data easily identifiable from the rest of the Central Region data, which also included the Napier area, they were given a prefix of “8”.

Some samples collected by industry in the Northland area in the latter part of 1997 were given a prefix of “N”, as their sample numbers were duplicates of NIWA’s sample numbers.

Because of the changes with the sample number prefix, the table below should be used as a guide for pre-1998 data and selection of the required data based on the attribute area in the table t_sample.

As of 1 January 1998, the first character now represents the CRA management area. These changes are shown in the table below. The attribute area, from t_sample, can still be used to select a particular statistical area within a CRA management area.

Two sets of information can be gained from a sample.

The first is data on the pot lift, which is the unit effort for the rock lobster industry. Data are recorded on the Pot Catch Form and include the number of lobsters caught (both dead and alive) pot type, depth, soak time, bait and an escape gap code. The latter was used to identify pots with closed escape gaps during a red rock lobster tagging program. This was done under special permit during a closed season.

The second is biological data for individual rock lobsters recorded on the Length Frequency Form. It includes sex, carapace length, and tail width (across the spines on the second abdominal segment), tail length, weight, injuries, moult and run states, and the red rock lobsters status as to whether it was landed to a Licensed Fish Receiver (LFR).

Two catch sampling programs have been run. There is the primary program for the red rock lobster, and an exploration program for packhorse rock lobster

While the red and packhorse rock lobster catch sampling programs each catch both rock lobster species as a bycatch of each other’s target fish ery, only the packhorse rock lobster are measured in the packhorse rock lobster program. Both species are measured in the more extensive red rock lobster catch sampling program.

2.3 Data validation

This process includes instructions for data recording, simple data validation using the checkq⁴ validation program language, PERL and C programming language scripts, followed by inserting data into a database. See Appendix 1 for a more detailed description of the processes involved.

While the rlcs database enforces data validation and integrity with use of referential constraints and range checks, the data go through a rigorous data validation and error checking process before being entered. The various codes used in this database are documented in Appendix 2.