Henry's Diary
Friday 29 February 2008
I set out on my sixth fishing trip around the Pages at 6.30 this morning. I headed straight for the bountiful fishing grounds near Deep Creek, arriving there at 9:13 this morning. I plan on spending the day here, working over some tried and true fishing hot spots that I’ve come to know like the back of my hand.
Heading out, I swam through an enormous school of sardines - it was a hive of activity. Of course, the fast and furious fur seals were taking their share of the ocean bounty. But the most incredible sight was a flock of Australasian gannets spearing into the school of sardines. The gannets hit the water at an incredible speed, with their wings folded back, they reminded me of archers’ arrows being shot into the water. I can’t catch sardines, because I’m simply too big and slow and the school always seems to move around me and away from my mouth as I barge through them. So I always end up chomping at nothing but the cold water. It’s pretty frustrating really so, instead of trying to catch them, like I used to when I was young and naïve, I now sometimes just float around and watch the trembling schools of sardines as they are attacked from all angles.
The fur seals slip in and out of the silvery school, which glimmers in the rising sun. And from above, the gannets plunge into the middle of the school and crank their necks around like swans in fast motion, picking off one sardine at a time before they float to the surface and clumsily take off. Underwater or in the air, the gannets are so graceful and quick, and but when they are taking off from the surface they seem so gangly and awkward. Like me, they are hungry critters and, once they mange to take off they quickly circle up and up, before diving again at break-neck speed into the water. They don’t seem to get head aches and I have never seen one injure itself using this rather weird hunting technique. They rarely miss catching one sardine on each dive.
As the sun rises, the gannets can see the sardines better – and the sardines seem to know it. So, soon after dawn, the nervous sardine school heads for the relative safety of the deep waters, to escape the sunshine and gannets - but the fur seals calmly follow and continue their hunting expedition.
About three hundred gannets are born in South Australia each year. They are all born in the same place - an abandoned light house platform near Cape Jaffa. There's no lighthouse there anymore - it was moved in 1975. There are other breeding colonies of gannets in Victoria, but here in South Australia gannets only breed on this one, slim platform above a wild reef in the middle of the ocean. You can see more information on this platform at:
http://www.lighthouse.net.au/LIGHTS/Bulletin/0511/cape_jaffa_platform.htm
I guess the constant wind helps to clear their aching heads, after all that diving!
Must close now and leave the sardines, gannets and fur seals to fend for themselves, I’ve got some serious fishing of my own to do!
Thursday 28 February 2008
Got the fright of my life this morning! I was only half awake when I thought I saw the biggest shark on the planet…it broke the water surface and breathed out time and time again, circling around the island and surfacing every 5-6 minutes. It had nostrils large enough to fit a small child. Although today was a sunny day, which is very unusual for North Page Island, I was regretting leaving the relative safety of the Holdfast Shores marina and the boat ramps of Adelaide. I stayed ashore for most of the day because I was simply too scared to get into the water with that thing out there!
So I sat on top the island, which is only 30 metres above sea level, and I could see right around the barren rock. The young sea lions were mucking around near the water’s edge like they always do. Eventually, curiosity got the better of a couple of them and they went to investigate this gasping sea monster. I thought they were going to be killed but it ignored them completely, which I thought was odd because sharks love to eat sea lions. It just continued diving and surfacing, finally exploding through a ball of krill at the surface. It was only then that it dawned on me - this monster was a blue whale - the largest animal on the planet – and blue whales only eat krill, which are like minute prawns. As I mentioned in my diary yesterday, blue whales gather in quite large numbers to feed along the south coast of Australia between November and May. In Australia, blue whales sometimes come close to land, and in relatively shallow water considering how huge they really are. Sometimes they are in water less than thirty metres deep – considering that the adults are 33 metres long, and weigh over 150 tons (which is roughly the weight of 2000 adult humans) that’s pretty shallow. Blue whales eat more than 5 tons of krill in a single day.
They are rarely seen by humans, and people don’t know much about them but they are quite common around here in summer. They don’t leap out of the water like humpback whales so sailors and fishers go about their business not realising that such incredible animals are in the sea below them. Nobody knows where these guys go when they leave here and they are not about to tell anyone.
Being a bit of a city slicker, who normally lives on the Adelaide coastline I love to visit the Pages Islands. It is cold, barren, full of sharks, noisy, smelly and remote – which probably does not sound terribly appealing to humans but it does remind me of what most sea lions do and how they live. If you would like to learn about the Pages, check out this website: http://www.parks.sa.gov.au/parks/sanpr/the_pages/index.htm?ParkID=ThePagesCP
Speaking of Adelaide, I am starting to miss the place. I might think about going home soon.
Wednesday 27 February 2008
I spent all morning sleeping on North Page Island after ducking out yesterday afternoon to spend the night fishing in the waters between the Pages Islands and the Deep Creek Conservation Park.
The sea is that area is about 10-20 metres deep, which is pretty shallow, so I didn’t have to have to hold my breath for very long to find a decent feed. Like all sea lions, I am perfectly capable of diving to more than 300 metres, but, hey, if the fishing is good in the shallows why venture into the cold dark waters of the Bonney Upwelling?
The Bonney Upwelling is a seasonal thing which happens on the continental shelf between north-west Tasmania and Kangaroo Island. Between November and April, strong south-east winds drive the sea current north-westwards along the coast. This pushes the surface water offshore…something to do with the Coriolis effect, I’m told. The displaced water has to be replaced with something, so cold, nutrient-rich bottom water is drawn up onto the continental shelf. When the nutrients reach the sunlit surface zone, there is an explosion of minute plant life called ‘phytoplankton’. This stuff is the basis of the marine food web, and is a primary food of krill – which are a bit like miniature prawns. There are very few areas in the world where there are swarms of millions of krill just swimming on the top of the ocean, so the Bonney Upwelling is one of the few places on Earth where blue whales can be seen – even feeding on the surface.
If you understand temperature maps, have a look at: http://www.marine.csiro.au/remotesensing/oceancurrents/Adelaide/latest.html
The Bonney Upwelling creates a marine smorgasbord because the phytoplankton and krill provide the basics for lots of other creatures to survive. For example, the New Zealand fur seals are here in a huge numbers frantically munching the arrow squid and redbait (a small fish, like a sardine) that are in turn eating the krill and other plankton that thrive in the Upwelling – so everything in this ecosystem is linked to everything else. The New Zealand fur seals have just finished their breeding season so the new mothers are hurriedly gulping fish and squid, and turning it into milk for their growing pups.
I don’t mind the fur seals, because they don’t get in my way. They are much faster than I, and somehow manage to catch their fast moving prey in mid water. We sea lions do eat some arrow squid, but we are slower than fur seals so most of the time we catch slower prey from the seafloor, such as octopus, flatheads, cuttlefish and leatherjackets and the occasional, super yummy, rocklobster.
Its pretty neat really, even though sea lions and fur seals feed and live in the same area, we don’t compete for food but we often pass each other while hunting (well, more accurately they pass us – they are really, really fast underwater!).
Tuesday 26 February 2008
Today was a really lazy day. I spent most of it sleeping on North Page Island – well, trying to anyway.
The crested terns squawked incessantly, making it virtually impossible to sleep. Crested terns bring a single small fish back to their chicks every few hours. There are more than 2000 chicks on North Page Island, so the noise of parents trying to find and feed their chicks is deafening at times. When night falls the terns roost on the island and a cold peacefulness descends.
The Pages Islands are an amazing place. It is strange to think that this rocky outcrop was central to Australia’s first export industry. It was once home to some of the roughest humans to grace the earth - the sealers. Soon after Australia was settled, sealers were dropped onto the Pages with scant supplies and had to shelter in caves that were too small to shield them from the rain. The rain and wind here can be incredible. And they would have had to tolerate the noise and smells of the birds and the sea lion colony as well. By day the sealers harvested sea lions for their pelts and for meat. By night, they would have shivered and felt totally isolated from everything that reminded them of home.
The pelts were sent overseas, where they were used to make hats, coats, and boots. It was Australia's first export industry. Together with the pelts of New Zealand fur seals, which also occur in this area, at least 300,000 skins were exported from southern Australia. The pelts of big males, like me, were not the preferred pelts because they are scarred from battles with other sea lions and white sharks.
I know that DEH officers will be coming to the Pages soon to count the new born sea lion pups. Fortunately, modern day sealers work for the conservation of sea lions and the places we fish and live.
Monday 25 February 2008
I am still hunting off to the North of the Pages. Having swum here, I intend to eat as much as I can before the younger males give me my marching orders. When that happens, I will probably head back to Adelaide, but I will see what I feel like doing at the time.
Something interesting happened today. A leatherback turtle was entangled in a fishing long line off Kangaroo Island and ended up tangled against a boat mooring at Island Beach. He was quite large, about two metres across the carapace. Fortunately, someone saw him and let the Fisheries and National Parks officers know he was there. They untangled him and let him go so he will live to see another day.
Unfortunately for you guys, the officers couldn’t attach a satellite tracking device to him – but at least he’s free again, and he will head back around Tasmania and up the east coast of Australia to his breeding grounds off Queensland.
Australian sea lions have one of the highest rates of entanglement of any seal species in the world. Fortunately I have not been entangled yet – although I choose to live around people and the debris they leave in the ocean. I guess that between surviving seven shark attacks and somehow avoiding entanglement I was born lucky. I think I just have lucky genes. I hope my luck holds!
Over the past week I have swum 160 km, most of it over the weekend. People think sea lions are lazy when they see them lying around on the beaches. If they swum those distances, they would probably want to veg out on the beach for a while too. As I told you, when we are hunting, our circulation system changes to maximise the oxygen available to our brains and muscles. The flip side of this is that we do not digest our food very effectively while we are at sea. So the time spent lying on the shore is absolutely essential to recovering from a hard day’s fishing and digesting our catch – which is another reason why we don’t like being disturbed by people and dogs. On average, we tend to spend four or five days at a time in the ocean and then about the same period of time digesting our catch on shore somewhere.
Sunday 24 February 2008
I spent today this morning hunting off to the North of the Pages then took a break and hauled out on the North Page in the middle of the afternoon. The colony is still abuzz, noisy, smelly and crowded – but hey, it’s home and the food is great.
Saturday 23 February 2008
Today I continued heading south – towards the Pages. This is where I grew up so, although Glenelg is really home now, it is nice to go back to where it all started occasionally.
The Pages Islands lie at the tip of the Bonney Upwelling - a seasonal upwelling that injects huge pulses of nutrients into the water. This comes from the cold, dark, deep waters well to the south of Australia. All these nutrients mean that there are plenty of fish in the water so it is a perfect spot for sea lions. The region is also a hotspot for school and gummy sharks, which make quite reasonable eating. The high level of nutrients also means lots of arrow squid, one of the favourite foods of sea lions, so it is a pretty good spot for us.
The Pages are home to the largest colony of Australian sea lions anywhere. They are a rough, inhospitable pair of islands with almost no vegetation. There’s an automated lighthouse on South Page Island – no humans live there. About 200 pups are born on North Page and 200 on South Page Island each season (18 months). Scientists from DEH on Kangaroo Island fly to the Pages by chopper each breeding season to count them.
Sea lion colonies are smelly, crowded, very noisy places. There are always a million crested terns in the air squawking and seagulls carry on over every scrap of fish any sea lion leaves on the rocks and there are just so many sea lions around! Leading up to breeding season, the males get very territorial and puff themselves up and act aggressively to every other male – just to impress the females and makes sure they get the best breeding partner available. There is just too much testosterone around for one small rocky outcrop.
The breeding season is about to commence on The Pages Islands, so in my relatively skinny condition, I have no doubt that I will be booted out of there fairly quickly by the big contenders. There are always large numbers of big sharks around breeding colonies so the risks are always there too.
It was about a hundred kilometres from O’Sullivan’s Beach to the Pages so it was a pretty reasonable swim by any standard.
Friday 22 February 2008
Today I have done some real hunting and swimming. First of all, I went diving for fish. Most of the dives are about 13 metres down but the deepest was 29 metres. Pinnipeds are designed to go deep and stay underwater for a long time. We have what is known as a “dive reflex”. That means that as soon as we go underwater our entire blood circulation system changes. The blood vessels to our internal organs reduce in size so our brains and muscle get more blood – thus conserving oxygen. Which is why we can dive longer and deeper than any human ever could. I stayed around the southern metropolitan area for the day. This section of coastline is renowned for three things, namely fantastic surf, really nasty rips and very big sharks. But the fishing is good.
Thursday 21 February 2008
I decided that it was time I went and found some real food so headed out to sea. Sea lions often stay in the open ocean for up to five days at a time and hardly sleep at all while we are out there. For one thing, sleeping can be pretty dangerous. Over the past seven years, I have been bitten by sharks seven times. I guess I was just born lucky – and quick! Sharks, especially great whites, are the main predators of seals and sea lions but they are not our only threat. I will tell you more about that another day. In any case, I ended up at the O’Sullivan’s Beach boat ramp and stayed there for the night. That is about thirty kilometres from Glenelg, so isn’t that far really. And yes, I do like boat ramps. They are just like rocky haul outs and there are often people around. Most people like me and take photos of me but some get a bit fed up – especially people who want to use a boat ramp for launching boats! They just don’t understand the real reason for having boat ramps, namely to give me convenient haul outs all along the metropolitan coast!
Wednesday 20 February 2008
I was feeling better this morning and was not vomiting anymore so I cruised down to Glenelg, my favourite haunt to check things out. It is only a couple of kilometres from West Beach to Glenelg. It was a lovely sunny day and Glenelg is a really nice place to be. I was sitting on the Promenade and a guy approached me carrying a large bag. He opened it and fed me some cooked crabs. I see this man quite often and he feeds me quite regularly. Nobody refuses a free lunch so, of course I ate it. The team say that maybe this is part of the reason I have been off colour lately. In any case, this time another person rang one of my team and he came down and told the man to stop it. That was okay - cooked crabs are not part of my natural diet and I am probably better off without them anyway. I spent the rest of the day lying on the sand or cooling off in the shallows.
Tuesday 19th February 2008
I was feeling a bit seedy so was just hanging around the Adelaide Shores boat ramp at West Beach this morning. I vomited again which was not very pleasant. Then my Team arrived. They are the people from the Department for Environment and Heritage, South Australian Research and Development, the South Australian Museum, Zoos SA and Project Dolphin Safe. They anaesthetised me and took a whole series of tests and applied a tracking device to follow where I was going and what I was doing. That took an hour or so. I didn’t feel any of it – just a prick like a sea louse bite in my rump when the tranquiliser dart hit, then I slept through the whole thing. For the rest of the day, I just stayed on the boat ramp where they had found me and watched the world go by. A couple of the team hung around to make sure I was okay but they need not have worried. I was fine.