Another Black Marlin Breeding Ground Off Queensland

The northern reaches of Queensland’s Hervey Bay, and the even more remote waters east of Fraser Island’s northern tip seldom see much fishing pressure. Although these grounds are revered as fish rich hotspots for a multitude of pelagic and reef species, their remoteness keeps their full potential still somewhat undiscovered.

For many years the northern end of Hervey Bay has been renowned for producing an extraordinary run of baby black marlin over the shallow inside grounds during late winter and spring. In recent years, the offshore waters have also gained a reputation for their exceptional numbers of blue and striped marlin during spring and early summer. This heavy-tackle fishery has lured Gold Coast gameboat Mistress to spend several months running liveaboard charters to these remote grounds. This year they were there in June and discovered a surprising number of tiny black marlin in the bay, catching some as small as 2kg and seeing others so small they proved difficult to hook.

The discovery of these baby black marlin at that time of year is remarkable because it does not match with the timing of the species’ currently—known spawning off Cairns. Considering the phenomenally fast growth rate of black marlin, the marlin caught by Mistress in Hervey Bay during June would have been only two to three months old, whereas fish spawned off Cairns in October/November would be far larger. This has led Dr Julian Pepperell to suspect that another black marlin breeding ground must be located much closer to Fraser Island than Cairns, with a separate spawning event occurring in perhaps February or March.

Dr Pepperell has requested anglers catching these tiny black marlin to keep and freeze the heads of a couple of specimens so that their otoliths (ear bones) can be extracted and examined to more precisely determine their age. This will help lead to the discovery of their other breeding ground, and that will have huge ramifications for anglers wanting to find the giant parents.