Comparison of data from voluntary logbook and research catch-sampling programmes in the New Zealand lobster fishery

Abstract

Since 1993, the New Zealand Fishing Industry Board has run an extensive voluntary programme to collect biological information from rock lobster (Jasus edwardsii) pot fisheries using logbooks maintained by commercial fishers. The New Zealand Ministry of Fisheries has run since 1989 an intensive research sampling programme of the rock lobster commercial fishery which measures nearly every lobster caught in a selected trip. A comparison of these two programmes was made for the southern South Island fishery over a period from August 1993 to January 1996. Length frequency distributions stratified by month and statistical area showed similar distributions from both sampling programmes in most strata, with a tendency for higher frequency modes to be estimated by the voluntary logbook data and larger frequency modes estimated by the research sampling data. These differences were slight except for five instances (of 40 strata compared) where the research sampling programme estimated flat frequency distributions which were not typical of the distributions estimated in other strata. Catch per potlift from the voluntary logbook programme and the compulsory catch per effort landing returns were similar for the same fishers. This indicated that the voluntary fishers were successful in designating ‘representative’ sampling units for their programme.