If you're wondering why I'm having a go at fish farms at the moment it's cos there's an EIA that's in the process of getting approved that will allocate a large area just 2k's off the beach at Pipe for up to 9 commercial fish farms. Which I think is a pretty kak idea. The first in this series of posts looked at the pollution that fish farms can cause, and how it'd be a really uncool (and unhealthy) idea to be swimming and surfing in fish poo. But what's also really pertinent to us as surfers is the potential for it to change the shark behaviour in this part of the bay. Not good.
Fish farms can act like a big McDonalds drive-through for our toothy locals. Nothing like 35 cages (100m wide by 20m deep) packed with yellowtail to draw interest from any passing shark. They'll pull in to check out the fish farm, not only if they're hungry, but just cos they sense all the agitation in the water of thousands of tons of fish swimming about. The hiccup with all this is that it's happening just 2k's off our beach.
For sure we have sharks cruising along our part of the bay - the stats from the Algoa Bay White Shark project have had 9 whites pinging at the receivers that are 500m offshore at Something Good, Humewood and Kings (between May '12 and Jan '13). But currently that's what they're mainly doing....cruising by. En route to their usual chill spots north of the harbour or out at the islands.
The problem with plonking a fish farm right off the beach is that it could change their behaviour patterns - in that they are now specifically drawn to this area. Whether it's cos they're hungry and smell the fish, or that they're just attracted by the electrical signals form thousands of tons of agitated yellowtail. Quizzy or hungry, it doesn't matter - they've gone from passing through to hanging about. And not just hanging about, maybe hanging about hungry cos they can't get at the fish in the cages.
None of this is ideal if it happening pretty close to where we're surfing. Cos logic says that statistically if you have more sharks in an area you stand the chance of an increase in shark/human encounters. Sure, we aren't on the sharks menu, but they're inquisitive creatures, and so if he wants to suss out what we are he picks us up. The problem is it's with his mouth. This generally doesn't turn out so well for the peep being "picked up"
The Marine Specialist report within the EIA even acknowledges that "Potential changes in large shark distribution patterns and behavior caused by fish cages have been documented and the potential change in risk to personal water sport participants (particularly should Algoa 1 be developed for fin fish cage culture) is not quantified"
One of the issues I have with the shark section of the Specialist Report, is well, it didn't consult our resident specialist! Matt Dicken runs the current Algoa Bay White Shark project. Surely if you're wanting an opinion on white shark behaviour in our bay, and how the fish farm might effect it, then you ask the guy studying them? Matt was just asked for comment via email, and at no stage asked to submit a formal opinion. When I spoke to him about it he felt that not only could the numbers of sharks increase, but there could also be a behaviour change with them staying for longer periods instead of being transient.
If we're looking for evidence of a correlation between fish farms and an increase in shark attacks, Reunion Island might be an example. There has been a sharp spike in attacks in recent years (many of them fatal). Many of the locals point the finger at the fish farm in St Paul Bay which was built in 2007 (consists of 7 cages). Reunion had experienced shark attacks before, but generally only 1 or 2 a year, with many years of no attacks. However since 2010 there has been 14 attacks, of which 6 have been fatal. The majority of attacks have occurred on the NW and west side of the island - right where the fish farm is located.
It's not as simple as going 1+1 = 2, and blaming the fish farm for the increase in attacks, but yoh, it's an unnerving coincidence if nothing else.
A 2010 study on the association of sharks with fish farms in Hawaii found that sharks occur at fish farms more frequently and at higher densities than is typical for coastal Hawaiian waters.
Here's a disconcerting lil statement from the Marine Impact Assessment of the EIA "Fish will be bled on the workboat and placed in ice, no blood or offal should enter the water."(pg 2). I don't have an enormous amount of faith in that word "should". How do you bleed tons of fish for transport to the harbour and keep all that blood and guts on the boat? Cos where are they going to put that waste on the boat....and once it's back in the harbour what are they going to do with it anyhow. The dodgy (and easy) option would be to just chuck it overboard. Who's gonna be checking?
So there's a few reasons as to why a fish farm just off our main beaches could result in an increase in local shark activity. Something I don't think any of the bathers or surfers are too stoked about.
Why fish farms suck - part 1 (marine pollution)