2 Kina Population Surveys

2.1 Data sources

This database results from the experimental fishing of kina (Evechinus chloroticus) off Fiordland.

Recent surveys of kina in Dusky Sound revealed abundant stocks, but insufficient information to predict sustainable yields from any fishery (McShane & Naylor 1991). To gain a detailed stock assessment of kina, a small number of fishers (participants) have been granted permits to harvest 1000 tonnes per annum of kina between them, commencing in the 1992-93 fishing year in Dusky Sound.

Fishing is restricted to free dive harvesting within the fishdown area, with permanent non-fish (control areas) established within the Sound. Each participant can have several divers fishing for them. Small-scale records of catch and effort are collected from the participants, which can be verified by scientific observers. Observers also record morphometric data from random samples of the catch.

During the survey, Marine Research divers from the Kina Research Group regularly survey sites within the fishdown and control areas.

Stratified random surveys of kina in Dusky Sound (McShane et al. 1993) were conducted prior to the commencement of fishing. These surveys allow changes in kina stock structure and disturbances to the marine community caused by fishing to be accurately assessed.

As at September 1993, these surveys may be repeated at other sites within New Zealand, such as the Marlborough Sounds.

Data therefore come from three sources: (a) commercial catch and effort, (b) the Scientific Observer Programme (SOP) catch sampling, and (c) research dive surveys.

2.1.1 Commercial Catch and Effort

Each participant in the Kina Development Programme must complete daily catch log sheets at the end of each fishing day. This log is over and above the catch and effort landing returns that must also be completed. On this daily log sheet the participant records the landed catch weight, total time spent diving, and position for each catch site used that day by a diver; i.e., there is one daily log sheet for each diver. Hence, differences in catch and effort between individual divers can be estimated. Catch and effort for kina landed from a single dive site, but from multiple divers, are divided equally between the divers concerned.

2.1.2 SOP Catch Sampling

Scientific observers present on fishing boats during the Kina Development Programme collect biological data from the daily catches.

Each observer takes representative samples from a participant's daily catch. Samples are taken only from catches that can be traced back to a single dive site, and preferably from a single diver.

Samples from a single dive site and diver can be linked back to the catch details as listed in the daily log sheet. Samples from a single dive site but multiple divers cannot be linked back to any catch details, but are still very useful in determining stock structure.

From a sample, an observer collects two sets of information:

1. The observer collects length frequencies of the commercial catch sample. This is achieved by measuring the test (shell) diameter (to the nearest millimetre) of about 200 individual kina. Each length frequency sample contains header information including, the participant's name, fishing date, grid reference, diver's names (there may be more than one diver), etc.

2. The observers are also required to provide information on kina morphometrics and biology (length/total weight/roe volume). Observers are instructed to take a random sample of 25 individual kina from the original sample of 200. For each kina, observers measure the test diameter to the nearest millimetre, weigh the whole animal to the nearest gram, record roe volume to the nearest millilitre, and record the colour, hence quality, of roe on a scale of 1 to 5 (with 5 representing top quality).

Observers also complete a daily catch log sheet, which is very similar to the participant's log sheets.

Therefore, on most fishing days there are two sets of catch information. The compulsory filling of the logs by the participants ensures catch data for every fishing day, and the observer filled catch logs allow verification of the participant's logs. The kina database contains mostly observer collected catch data. Participant catch data are substituted only when there is no observer coverage.

2.1.3 Marine Research Dive Surveys

At randomly selected sites within a defined area, currently within Dusky Sound, two divers each descend to a randomly chosen depth (0-10 metres). Beginning in a randomly chosen direction, each diver turns a 1 metre square quadrat over 25 times. Each quadrat is thoroughly searched and all kina are counted and collected. The collected kina form the length frequency sample for that site.

For some sites, a sub sample of 20 kina are randomly selected from the mature sized fish in the sample for a morphometric and biological examination. Data are collected and recorded as for the SOP sampling.

2.2 Data Validation

While the kina database structure enforces data validation and integrity with the use of referential constraints and range checks, the data also goes through a rigorous data validation and error checking process before being inserted.

The punched data are reformated using the checkq [See the local Unix manual page on checkq] program, which performs range checks, and the data are checked for invalid entries. The data are then loaded into temporary tables in the database where cross checks are made including checking that the grid references are valid, i.e., not on land or in too deep water, nor outside the valid area. Strata are allocated based on the grid references.

Each SOP sample is also checked to ensure it has an accompanying catch record, and each biological record has a corresponding length frequency record.