64. In this presentation, the progress of the Bureau of Rural Sciences (BRS) in predicting the distribution of deepwater demersal resources based on past catch, sea surface temperature (SST) and depth was described. Two modelling techniques had been used - GAMs and GLMs together with Expert Modelling. Presence of orange roughy was regressed as a logistic function of fishing history, year, SST and depth. The catch-per-unit-effort (CPUE) was modelled as a function of individual boat identify, month, SST. Plans for future work were described.
65. It was noted that orange roughy were believed to spawn near the bottom in depths of 600 - 1200 m; the eggs then rise to 200 m where they hatch, develop and subsequently sink. It was thought that bottom temperature at 200 m in July could determine hatching success. Further, more data would permit better model results.
66. It was noted that orange roughy fisheries often overlap with those for southern bluefin tuna. As the Japanese longline fishermen record temperature, this temperature might be useful to modelling efforts.
