Introducing a Code of Fishing Practice aimed at avoiding seals appeared to halve the incidence of seal bycatch in this fishery. In SED trials, the problems of fish-loss via the SED escape hatch and net blockage via the SED grid were solved by changes in SED design. Although the effectiveness of most SED designs in reducing seal bycatch could not be quantified, the forward facing, ‘top-hatch’ SED design used in 2002 significantly lowered the incidence of seal bycatch in midwater trawl nets. Trials with this design are continuing. Some of the major factors that influence the probability of seal bycatch occurring in this fishery were delineated. Biological sampling of seal fatalities showed the dominant seal bycatch to be sub-adult male Australian fur seals habituated to foraging from trawl nets. Seal tracking studies developed a novel method of tagging seals at sea and indicated that a comparatively small and intransient sub-set of their population interacted with this fishery.

The following recommendations were made in the winter grenadier fishery: use open, forward-facing, ‘top-hatch’ SEDs (or a more effective design if one is developed) in all midwater net shots (or as directed for research purposes); continue the Code of Fishing Practice; continue the shot-by-shot recording of seal bycatch in the SEF1 logbook and maintain a level of scientific observer coverage and biological data collection; and, continue trials of the ‘top-hatch’ SED and gather more information by using underwater filming on the timing and depth–frequency of net entry by seals, and the circumstances of net entry that place seals at risk. 

The following recommendations were made in the rest of the SEF trawl fleet: Priority should be given to assessing the nature and extent of seal-fishery activities across the fishery; The Code of Fishing Practice should be followed where practicable; and, At this juncture, SED use should be confined to large midwater trawl nets in areas where seals are known to be common, as more assessment of SED effectiveness is needed before extending their usage.

Project results also assisted the goal of obtaining accreditation for the SEF under a Section 33 determination under this Act.

Keywords: Blue grenadier trawl fishery, seal bycatch mitigation, Seal Exclusion Devices, Australian fur seal biology.