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Kelp Diving

Kelp 300One of the main features of the New Zealand coastline is our abundance of kelp. Like most temperate waters large, brown kelps dominate our shallows and provide the foundation of our reef eco-systems. The kelp provides food for all sorts of little critters that are predated on by larger fish and even some pretty good table fish like butterfish eat it as well. It provides shelter and protection for small fish and hunting grounds for larger ones. The fringes of the kelp beds where they terminate into the sand are the weedlines that provide some of the best spearfishing anywhere. Here virtually every fish on the list is concentrated.

The most abundant kelp species in the North Island is the common kelp Ecklonia radiata. It is a relatively small kelp only reaching about 1m in length. It holds tight onto the rocks and continues skyward with its thick stem before blossoming into a bunch of fronds at the top. Swimming along above the ecklonia and looking down you see a carpet of brown and it’s easy to be fooled into thinking you’re looking at what must be a flat featureless bottom but once you dive down through the canopy and into the stalks below a new 3d world of jumbled rocks and cracks and holes will open up for you. The best and thickest weed beds occur in shallow water where the kelp can get plenty of the sunlight it lives on but in relatively sheltered spots where the destructive forces of wind and swell can’t damage the kelp. When diving it’s common to come across large areas of bare rock holding nothing but kinas. For a long time it was thought that the kinas were to blame and that overfishing the large snapper that eat them had let the kina populations boom to a point where they were grazing whole areas of kelp right back to rock – these areas became known as kina barrens. This was a classic example of the dishonest scientific trickery used to promote marine reserves and the bald patches are really just the result of storms ripping the kelp from the rock. I was dismayed to find one of my favourite snapper rocks had been completely stripped bare following a storm one day. A month or so later the kelp had re-grown and the snapper were back but it is a tenuous existence and the rock is regularly stripped now during any times of big swell.

As we head south we enter the domain of the bull kelps Durvillaea sp. These amazing plants reach up to 10m long and their huge fronds float on the surface often completely covering it with gaps appearing only as the swell pushes them aorund. The bull kelps are far stronger than their northern relatives and can withstand the big seas common in the south and live for up to 10 years. The shade cast by thick bull kelp forests can encourage species usually only found in deep water like trumpeter up into the shallows where we can get them. Diving amongst the bull kelp is great fun but it does set traps for young players and struggling through it can be unsettling for even the most experienced divers.

The day after a South Island spearfishing competition I awoke to the gut wrenching news that there was a diver missing. He hadn’t been involved with the competition but was an inexperienced diver who had just swam off the shore for a feed of paua. His body was later recovered by the coastguard and he had drowned. It seemed most likely that he’d been wrapped or held under in the kelp and that had led to his tragic and what must have been a terrifying end. Diving in kelp and getting where you want to quickly and easily is a bit of an art particularly if there’s a bit of swell pushing it around a bit.

The real key to moving through the kelp is knowing that slower is really faster. You need to try and slide through the fronds on the surface or the stalks on the bottom. I will usually use my free hand to pull myself through the stalks on the bottom to minimize my leg movements. With kelp the harder you push or pull the harder it will grip onto you.

Streamlining is critical. Streamlining is always important in the water but moving through the thicker medium of the kelp it’s even more so. Keep your arms in tight by your sides or above your head and keep fin movements down to a minimum. Make sure that you don’t have any gear dangling off yourself that’s likely to get caught.

Time your dives with the swell. Good divers always use water movement to their advantage. We all know the way the sea can push and pull us around and it is critical to time our dives to make use of it – if you’re aiming to dive down and over a ledge it is pointless trying to dive just as the swell is pushing in as you’ll waste all your breath just trying to battle to the edge. Better to wait until the swell will help you glide over and down. Diving in bull kelp in particular this becomes even more critical as gaps in the blades on the surface will open and close as the water moves. Before you try and surface from a dive try and spot your gap before you leave the bottom rather than blindly swimming up and trying to force your way through the heavy, rubbery fronds. It is far better to pause on the bottom where you can relax and have something to hold on to for a few extra seconds and wait for your gap to reappear.

Weight is the enemy. Make sure you are buoyant on the surface. It’s far better to have to kick a bit harder to get down or to grab onto something to help you stay there than to struggle at the surface. This goes for your catch bag as well. A few pauas are heavy and you need to be prepared to drop them if necessary.

Most importantly relax and don’t panic! Movement through kelp is slow and struggling only makes it worse. If you feel caught simply pausing is usually enough for the kelp to lose its grip.

Learning to move effectively through the kelp is a crucial skill for any spearo. It will help you relax and be able to spend longer hunting rather than battling. As you get your eye in it can be surprising how far you can see through the kelp and just what is in there staying very still in the hope you don’t see them.

Matt Lind