Abstract

A two year experimental trap fishery commenced in April 1998 to assess the feasibility of re-establisbing a commercial fishery for the spotted spiny lobster Panulirus guttatus following the fish pot ban of 1990. Historically, this species was caught using fish pots and reported annual landings ranged from 13,000 to almost 42,000 lobsters for the period 1975 - 1989. As no measures of directed effort for P. guttatus are available in the database, it is not possible to generate catch per unit effort (CPUE) data to assess changes in the fishery during this period.\The current experimental fishery tested two basic trap types, a commercially manufactured plastic crustacean trap (Fatboms Plus) and a wire mesh trap (A1) produced by the Division of Fisheries. In the first year, four commercial fishers were provided with approximately equal numbers of thetwo trap types to fish commercially with the provision that detailed information on trap catches was provided. In the second year, the same number of traps were used but were divided equally between three pairs of fishers. In addition, biological sampling was conducted by the authors and fishers to collect data on size structure, sex ratio and reproductive condition.\A total of 10,592 spotted spiny lobsters were caught in the first year with 64.8% taken in the Fathoms Plus traps. The CPUE values (lobsters per haul) were 1.87 (±0.06 SE) and 1.43 (±0.06 SE) for the Fathoms Plus and wire traps respectively. In the second year, the total catch was 9,206 lobsters with CPUE values higher in wire traps than in the Fatboms Plus, although statistical analyses showed no significant difference between the means. In addition, the fish by-catch in the Fathoms Plus traps was much less than the level in the wire traps in both years.\The highest catch rates of spotted spiny lobster were recorded in the summer months (June - August). The biological sampling revealed a male-biased sex ratio in the trap samples of approximately 10:1 (M:F) in the first year and 12.8:1 in the second year. The mean size of males (66.7 mm carapace length (CL) (±0.06 SE)) was larger than females (60.0 mm CL (± 0.39 SE)). The presence of ovigerous females in the catches indicated that the reproductive period was from May to September with a probable peak in June-July.

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