Friday, 14 September 2007

Lemon Entrees

So much shark behaviour seems to depend on whether we can see them or not, my main example of that being the time my step-son climbed upon a coral, and instantly the blackfin swimming with us went to him and sniffed his legs, quite aware, it seemed, that having his head above the water he could not see her. This came to mind again last night when I was drifting at dusk sketching the fin of an unknown juvenile blackfin who was roaming nearby. A movement off to the side caught my attention and I saw a good sized lemon shark approaching, already only a few feet away. They always look incongruous coming through the narrow coral canyons, seeming as big as a baby whale, though they are really smaller than that. Not wanting to startle him, I waited, perfectly still, for him to see me. He had a white spot on the tip of his nose, and that dazzling lemon shark smile.

Once my husband and I decided to celebrate Christmas by going to the end of Tahiti. The landscape resembled gently rolling hills covered with sage—the sage being the coral--always sloping downwards ever more steeply, into deepening gloom. Past 120 feet, huge dark purple roses bloomed around us, and the valleys deepened into gulches falling away. The light dimmed as we drifted downwards and finally we could see below that mysterious twilit place, the end of Tahiti. There the drop-off fell straight to the ocean floor, into the utter blackness of the abyss. We were at 200 feet and I was in a dream, more narcked than I had ever been, when a lemon shark came slowly, steadily, almost vertically, up out of the dark. So alien, the beauty; it might just as well have been another world. It saw us and turned towards us, the effect of its relentless oncoming heightened by the movement, back and forth, back and forth, of it's head with open mouth. The grotesque smile was hypnotic, and I saw with wonder that it had visited a joke shop and replaced its normal teeth with two inch spikes just to impress us. I waited for it to turn, actually physically preparing for a fight as I reflected on the reasons it might have for that open mouth. About eight feet away, the shark turned, and just as slowly disappeared into the gloom. My husband took my hand and we began swimming back up towards the light, me looking back often to the mystical place where the island ended.

So with dentition like that, it amazed me again that this lemon shark last night paused and turned away the moment he saw me, a small spindly creature under the surface. They're so shy! His path took him within inches of the little juvenile and neither shark reacted to the close proximity of the other. I went behind a dead coral formation out of the way, hoping he might come back. After a few minutes the slow moving behemoth appeared briefly just within visual range, then disappeared again. This was no accident; he came to look. I waited for awhile, occasionally checking behind me, because often the next thing they will do is come from behind to see. But it was getting dark fast, and I wanted to go. Becoming impatient, I went to my boat and was putting my camera and slate inside when I remembered that its just when my patience comes to its end that the animal often comes, their patience lasting just that little bit longer. So I swam back to my place at the coral, and as I did so, the lemon shark passed me coming from behind.

On another occasion, a lemon shark came with my sharks when I had brought them some food. I didn't feel very comfortable with him there, particularly since the current was so bad I could scarcely swim against it, which put me at a disadvantage, so instead of swimming around I stayed at my boat. Nevertheless, I threw in some tuna heads for him that I had brought for the nurse sharks, then wondered at my sanity when they landed so close to the boat that I felt to retreat up the anchor rope. The lemon shark came and went repeatedly, to my increasing irritation because some of my favourite sharks were just down-current and I wanted to go and see them. So, when he had not appeared for awhile, I let go of the boat and drifted down-current. The lemon shark came immediately, barely discernible through the cloudy light, and he went straight to my boat which he circled around for a time before disappearing again. He was very well aware of what I was doing, just as I had been keeping track of him. (Sharks usually keep watch over suspicious situations from beyond visual range, and that is why often they just appear in the distance for a moment to take a look, then disappear behind their curtain of blue). Later I saw this comparatively huge shark, nine or ten feet long and very stout, nosing slowly along the body of a tiny nurse shark, the size and colour of a human baby, who was munching on a bone. The lack of aggression towards the tiny creature that he could have inhaled whole had he wished, was striking.

Sharks often follow objects of their interest out of sight. To learn who is following you, stop and drift slowly backwards. And there they are, the sneaky things, caught in the act!

There was another occasion, again when it was nearly dark, that a lemon shark came sweeping into my fish party at high speed. There were several sharks over six feet there already, and a couple of about eight feet. I was feeding the fish, and a tiny brightly coloured eel kept waving the front half of his body out of his hole near my right hand. So now and again I tried to waft a bit of food to him. The multispecies cloud of fish agitating in front of me were so thick that I really couldn't see beyond them. I was running on instinct, trying to make sure that each fish got something: a bite for the butterfly fish looking into my mask, a scattering of crumbs for the needlefish at the surface, a bit for the rock cod waiting on my dead coral hold-fast, a handful for the squirrel fishes in the hole to my left, some bigger pieces for the groupers, and something for the five foot moray eel whose head was swaying just below my left elbow. And all the while, whenever I wasn't looking, the tiny eel would touch my hands with the softest, most delicate touches. Suddenly I felt that there was too much agitation in the site: two of the big sharks were moving too fast. So I dropped the tuna head I was using to feed the fish and drifted leftwards just as the lemon shark swept into the circle. Everyone present shot outwards from the centre, an effect called a flash expansion, used at times by fish as a protective measure. The visual effect was incredible—hundreds upon hundreds of jewel-coloured fish shooting outwards in a sunburst pattern along with sharks of all sizes moving at lightspeed. The lemon shark zoomed straight to the tuna head I had dropped and went nearly vertical, (as much as a three meter shark who is fatter than a horse can in two meters of water), with a great deal of tumult, as he tried to extricate it from under the coral. He failed, and came along behind the coral wall I had been using as a hold-fast. Horrified at this turn of events, since I had heard that lemon sharks can become irrationally angry, and this shark was already in a huff of some sort, (plus it was nearly dark), I remembered I had promised myself a photo of the next lemon shark, and readied my camera, an underwater throwaway, bought just for such unexpected opportunities since my usual one was being fixed.

Amazingly, the huge shark still had not seen me, and as he approached, I saw in awe that his head was covered with long, deep, criss crossing scars! He was just about underneath me when I took the picture, and he reacted so fast when I moved my finger to press the button, that the photo shows him already turned. How he got turned around in that narrow space is hard to picture, but he accelerated away and vanished. Shaking with terror, I threw my stuff into the boat and nearly drowned trying to get my anchor out from under the coral where it had become lodged, so frantic was I to get out of the water before he came back.

Once in the boat, I drifted, watching, over the glassy waters, rainbow colours melting together beneath the afterglow of the western sky. But I did not see the lemon shark, or any shark, reappear in those twilight waters.

Ila France Porcher

Thursday, 13 September 2007

Sharks: Wolves of the Sea

When I came to Polynesia, I was familiar with Canadian wild animals and had no idea what to expect when I began to meet sharks while exploring the lagoon. After a series of odd experiences with them I set out to find out what they were really like as animals and individuals. The species I concentrated on was Carcharhinus melanopterus, the reef blackfin shark.

To see what each one was doing from day to day, I had to be able to recognize them. So I drew their dorsal fins on each side, then copied them into a book, along with a description and any other details. I soon had so many that I had to give them names just to be able to remember them all. My notes grew to hundreds of pages and dozens of tables, and by now I have identified more than six hundred sharks, and could recognize half that many on sight before a large fraction of them were finned (starting on my study group in 2003—see 'In Memory of Madonna'). I spent as much time as I could with them, bringing them treats now and then as a gesture of benevolence.

Beneath the glimmering lagoon surface, in a thin skin of water just one and a half to two meters deep, exists an ecosystem of extraordinary complexity and vividness. Its always impressive: the sky above, the earth below, the sun slanting through the gently moving surface gilding the turquoise waters and the surreal landscape with golden light, and in just this tiny layer, so much life in all directions, it takes your breath away. Even the water seems alive. In that split second it takes to slip underwater, I go from being alone in the wind, to being surrounded by two or three dozen animals the same size as me, all approaching. There is always something surreal about it, the alien beauty, and the silence in which they move. One by one, those who know me well, swim up to my face, turning away at the last minute, if I just stay still, watching them.

For a long time this gesture was a mystery to me, and I finally decided it was an expression of excited recognition, like the way dogs will joyfully run to you when you arrive home.

That they always approach my face, indicates their recognition of the frontal view. On the other hand, strange sharks will come from behind to take a closer look without being seen, or pass close by when I'm looking the other way. Often sharks will immediately react when they become aware that a person cannot see them, for example when one looks above the surface. Sharks appear to use the limits of visibility to remain out of sight when it suits them, coming just close enough to have a look once in awhile, and keeping track of the object of their interest by using their other senses (hearing and detection of vibrations in the water-medium). Thus they appear to be aware of being present and viewable. Similar behaviour has been considered in bears as an indication of self awareness (Donald R. Griffin 'Beyond Cognition to Consciousness' 2001). A variety of behaviours indicating thinking in sharks are described in my accounts of specific individuals, soon to be put on line on my planned website, which constitute some of the first observations of cognition in sharks.

In time I became familiar with their daily life habits, social lives, and reproductive cycle—the article reproduced on this site 'On the gestation period of the blackfin reef shark, Carcharhinus melanopterus, in waters off French Polynesia' was published in the journal Marine Biology.

Most males, who are smaller than the females, live on the outer slope of the barrier reef; it is the males you mostly see on shark dives. The lagoon is the usual domain of the females and juveniles, and so it was those with whom I became most familiar. Each shark has a preferred area, called the home range, and these ranges overlap. Sharks living in the same region know each other as individuals, and have companions they often go with when they travel elsewhere. This indicates that sharks recognize each other as individuals, and because they appreciate a companion, it was easier, I think, for me to be accepted by them as a companion.

On the few occasions when I came with another person, they responded by vanishing behind their curtain of blue, sometimes after coming quickly over to verify my identity. They could tell the difference between me and another human; in other words, they recognized me as an individual too. Besides involving learning and memory, such behaviour showed their awareness of changes in the routine or their environment, and their ability to make quick decisions.

One of the very large and apparently quite old females I met was very dark, with a pure white marking symmetrically placed on each side of her head. It looked as if someone had stuck two large snowflakes on her. Arriving always at dusk, she was a dramatic sight with the twin white points glowing bright. I called her Kimberley. She remained in the area for nearly a month, and before she left, I saw another very similar visitor. Not only was the patterning of their colour lines and dorsal fins alike, but this shark, too, had pale markings placed precisely the same way on her head. She also arrived as night fell, and I called her Twilight. Since none of the other sharks had this type of white marking, I speculated that the two sharks were sisters. It was months before either of them returned to the area, but there came an evening when the twin snowflakes approached through the gloom. Kimberley glided in, and the following week, I saw Twilight.

For three years I watched the two come and go every few months, sometimes together. Was it chance? Or was there an association between them? Finally, when Kimberley appeared again after months of absence, at nightfall, I went looking for Twilight and actually found her, following about a minute behind Kimberley. She passed me, and just then Kimberley appeared equally distant on my other side. The two sharks were arcing towards each other, as though following the same circle. They met in front of me, passing so closely they may have brushed each other. But though I watched intently, I discerned no sign pass between them. Maybe just the close pass was the important thing, each shark reaffirming 'we are here.' Twilight languidly cruised back and forth in a figure eight pattern, strangely not minding me staying with her. Time after time she caught up to another female shark who was already present, apparently intercepting and pursuing her trail of scent. Then the two would swim together briefly, usually, before moving on and joining another shark.

Kimberley and Twilight arrived together at dusk each time I saw them for the following month, reinforcing my theory that they were associated, and maybe sisters. They continued their sporadic visits until shark finning began here, whereon Kimberley immediately disappeared, and Twilight held out for awhile, before she too vanished. Nearly all of my beloved females were slaughtered within a few months when the killers from Singapore arrived here, and the government pondered over whether or not to let them devastate the country's sharks.

Clementine and Odyssey were large, elderly females. They visited the study area together in the dark of the moon at the end of April four years in a row, and at no other time. Cheyenne, who was in about the same age-group, accompanied them the two last years, but after the initial visit she returned alone every few months. This is one of the more exceptional examples of sharks following a surprisingly precise schedule as well as traveling with favored companions.

Companions apparently move in loose contact, regularly meeting and moving on for awhile together, either side by side or nose to tail, but most of the time out of visual range of each other. They make wide circles forming enormous figure eights or cloverleafs, ideal for intercepting scent trails. Odours that interest them are from other sharks as well as possible food sources it seems, and thus, as well as through their sensitivity to underwater sounds and vibrations, they can remain in loose contact as they travel.

One morning when I went outside at 5:00 a. m., a single white feather fell from the empty sky to lie upon the surface of the lagoon, and as if in a spell, two shark pups appeared. Apparently just out of the nearby nursery, they were scouting the area, their circles and turns creating a mesmerizing ballet, full of grace. Sometimes they swam separately, sometimes they followed each other; sometimes they swam after each other in a perfect circle, each with its nose six inches from the tail of the other. The school of baby tangs that lived in the shallows formed a little yellow cloud, pointing towards them as they passed. A mynah bird swooped down to look. Sometimes they followed other fish, sometimes other fish followed them. The rhythmic side to side motion, like a heartbeat, that typifies this most graceful creature, felt like a beat in their music. Though I had formed a theory about being able to estimate the size of fish from the ripples generated on the surface, the passage of these little sharks showed not a sign upon the glassy surface. At 7:20 the neighbours started trying to shoot them, and bragged all weekend of their fruitless efforts, as though they had taken on visiting monsters.

Presumably the babies got to know each other in the nursery, where they were born alive in shallow, protected waters, and may even have been siblings. Such long term companionships as I witnessed in adults, could conceivably have begun just like this.

After years of watching sharks in different situations and interacting with them, I think that their type of mentality urges them to get one step ahead of the object of their attention, clearly an advantage to predators who run down fish for a living.

No matter what happened, I was never bitten by any shark, though in intimate contact with most species, one is usually eventually bitten, whether it is accidentally by one's dog, or intentionally by an irritated parrot, mouse, or skunk. Sharks were the only type of animal I had intimate contact with who never bit me, and I came to believe that this species, at least, has a built in inhibition against biting companions.

It was one reason they became the favoured ones, of all the wild animals I have known. Never did they betray my trust and hurt me. No matter what happened or went wrong, time after time.

I hope my accounts will contribute to appreciation of sharks as the intelligent animals they are, counter shark attack mania, and encourage their conservation.

Ila France Porcher © 2006