When I first started fishing the Ningaloo Reef around 1990, both from boats and the shoreline, many quality species such as baldchin groper, red emperor, spangled emperor, rankin cod and spanish mackerel were targeted. Occasionally there would be a wahoo or sailfish landed in amongst this and then later on as we started venturing into deeper water to try and avoid the sharks, jobfish and rosey sea perch were targeted. Back then you would rarely lose a fish to a shark, but over the last ten years or more, fishos seemed to be increasingly complaining about the number of fish lost to sharks. Certainly when I taking school students to Exmouth on marine expeditions, 2000-2010, we had to ensure they had solid tackle to work with because it became harder and harder to sports fish with light gear. The attached photo shows a student, Jack West, who learnt this lesson the hard way when his mackerel was mauled right next to the boat. So either the sharks population was increasing, the sharks were getting smarter, there were more people fishing, or a combination of all of the above.
The smarter shark theory is more than plausible really. Let’s pretend you are a reef shark for just a moment. Your environment is teeming with fish species that are perhaps a little difficult to catch, you are immediately attracted to any vibrations in the water, especially a struggling fish and over time you work out that an outboard motor is intrinsically linked to this. More people fishing and less effort for the sharks, equals smorgasborg. But how do we really know if any of this is true and not just another fishing story blown out of all proportion, as fishers have been known to do. Well, I was intrigued to read an article in the Western Australian last week describing world-first research being conducted on this very topic by the University of WA, led by PhD student, Jonathan Mitchell. The study was indeed prompted by a growing number of complaints of sharks taking hooked fish and anyone who has fished the areas where the study was conducted, Ningaloo Marine Park and Exmouth Gulf, would likely have experienced this. The issue is not just that the recreational fishers are losing their catch, but that the mortality of fish is increasing, putting much more pressure on the species as a whole. Not surprising it was described in the study that, “We found that the areas that are fished more frequently have higher bite-off rates. Basically, it suggests a change in the behaviour of sharks in these areas where they’ve come to associate regular fishing and the presence of boats to the availability of food.” With a paper soon to be published, the statistics arising from interviews with fishers more than substantiated the long held view that sharks are getting it easy in this part of WA. Of over 400 fishers surveyed, 40 per cent reported losing a hooked fish to a shark in their most recent trip. “It amounted to 12 per cent of caught fish being taken by sharks.” Now we have the research evidence, it will be interesting to see how it can be used to reduce the impact, not just for the recreational fisher, but more importantly for the fish. In the meantime, fortunately, we do not have this issue down south and I have only ever lost one barramundi to a bull shark.