MOST SHARK SPECIES are fussy eaters of a surprisingly narrow range of smallish fishes or squids. The raggies, however, eat both larger prey and a much wider variety than most sharks. They don’t seem to often, if ever, try to attack the sweepers that shoal here at Broughton Island off the New South Wales coast, partly because they are too small or too agile, and partly because the sharks seem to eat less and rest more when we see them in these shallow sites during the day.
Raggies generally forage a little more at night, heading offshore and a little deeper to do so. The few divers visiting these sharks at night describe them as very different animals by day.
They also become perhaps a little less docile during breeding season, when males get a bit more aggressive and almost territorial around females.
And there have been instances when spearfishermen with struggling prey have earned themselves a nibble. But in most circumstances, these sharks seem to be the most inoffensive of just about any 100kg shark.
Jamie Watts’ picture of the classic nurse shark fly-by.
We see many sharks trailing hooks and line, not always from the mouth – they frequently seem to get foul-hooked by passing gear. Observations from local divers and researchers suggest that it might take only a small hook lodged in their throat for at least some sharks to get septicaemia, stop eating and eventually starve to death.
Raggies will take static bait throughout the day and night, although they seem far less keen on trolled bait and lures, which makes sense – they’re not really built to chase moving prey for much more than a quick lunge.
Whether intentionally or by accident, fishing has had a big impact on numbers in Australian and US colonies in recent years. We don’t really have a good idea of what the natural populations were, but based on their feeding reasonably high in the food web, and their habitat, global populations may have naturally once been in the hundreds of thousands.
Today on Australia’s east coast they are listed as critically endangered, down to perhaps a couple of hundred animals, and on the west coast they’re as vulnerable.
Worldwide, the order of magnitude may be a few thousand to a couple of tens of thousands.
Evolutionarily, these are odd beasts. They are lamniform sharks, which means they’re closely related to only a handful of unusual large sharks, including the basking shark, megamouth shark and the warm-blooded predatory makos and great whites.
Not really built like any of their cousins, if anything raggies are most similar in body shape to the unrelated lemon sharks. They’re rather sedentary compared to their closer cousins, and the flat tailstock and long upper tail hint at animals that aren’t built to travel either particularly far or particularly fast.
They are also more sociable than most large sharks, and whether off South Africa or Australia are usually encountered in groups, spending time at a handful of sites in each area in which they occur, apparently at least partly segregated by gender.