2 Longline Sampling Programme

The iki database was initially designed for the data collected by the longline sampling programme targeting snapper (Pagrus auratus) for the "iki jume" market. The measuring takes place on board vessels, and is representative of that portion of the catch that is caught. Initial data loaded into the iki database, were collected by technical staff engaged by NIWA Auckland, for the period from December 1997 to September 1998. This initial data loaded were collected on snapper caught by the iki longline fishery. However, the use of the iki database is not restricted to the iki snapper longline fishery.

Subsequent data loaded into this database have included catch sampling data from the snapper target fishery using longlines, trawls, and danish seines.

The nucleus of the iki database is a unit of effort and its associated catch, where a unit of effort is a longline set, one trawl, or one danish seine. Each unit of effort is allocated an effort number, commencing from one on the first unit of effort of the trip; each subsequent unit of effort follows sequentially.

From each unit of effort, the associated catch information is recorded for each fish caught as it is landed. For the initial sampling programme, these data are recorded on a page-by-page basis, with a maximum of 60 fish per page. Each page of a sets "LONGLINE FISH CHARACTERISATION

RECORD" data, acts as a sampling sub-unit, covering the time period taken to haul the section of the line on board and the sampling of the fish from that section of the line. This is to allow analysis of the fish characteristics, (a record of the status of the fish and various condition data), according to the time elapsed since set hauling commenced.

Biological data other than length were not collected for the initial data loaded. Due to the nature of the snapper iki fishery, cutting of fish is not possible; hence there is no requirement to collect sex data from that fishery. The form and database allow for sex to be recorded and is included to allow for the contingency of sexing fish should it be needed.

The highest economic value of snapper is obtained when fish are landed alive and killed by the "iki jume" method. Snapper boated dead suffer a rapid decrease in flesh quality, making them unsuitable for the export market. Reducing incidental mortality in larger size classes may therefore increase overall catch value. In longline fishing, lip-hooked snapper are generally landed alive, whereas fish ingest the hook ("gut-hook") are more likely to die as a result of damage to the gills or viscera. Trials have indicated that the incidence of gut-hooking in longline-caught snapper can be substantially reduced by using hooks modified by the addition of a wire appendage. Trials with modified hooks of varying sizes and with a variety of baits were conducted in the Hauraki Gulf in 1999, and there results of this experiment were stored into the iki database.