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Other deficiencies in the data collection are lack of complete reporting of total catch and lack of accurate information on species composition.
Dave Itano has attempted to make more accurate estimates of total catch by species from the offshore fishery. First, he identified every vessel that operated in this fishery during a single year (1995) and divided these vessels into three categories reflecting different production levels. The above estimate of total catch was produced by assigning estimates of mean catch and effort (# trips) per year to each group.
Until recently, all bigeye (Thunnus obesus) and yellowfin (T. albacares) catch was reported as “ahi” in the catch statistics for the Hawaii troll and handline fleets. Port sampling by the National Marine Fisheries Service, tagging surveys and interviews of fishermen and wholesale firms indicate that the “ahi” from the offshore fishery consists of closer to 75% bigeye and 25% yellowfin by weight.
According to the initial estimate by Itano, the offshore fishery landed about 1 million pounds of bigeye and 400,000 pounds of yellowfin by applying the 3:1 bigeye to yellowfin ratio. In contrast, reported catch of bigeye by all Hawaii handline and troll fisheries from the entire state was 113,000 pounds during 1995. An unknown amount of bigeye catch may have been included in the 2.4 million pounds of reported yellowfin catch for that year.