Quest for the Lanternfish
WHEN I FIRST STARTED to look for the glacier lanternfish (Benthosema glaciale), I still had an analogue camera. Some scientists had told me that lanternfish approached the surface at night to feed on northern krill and other small animals. But, they said, you must dive where it is at least 300m deep.
Finding fjords that deep in my area of Norway is not difficult, so we started doing pelagic night dives.
We would tie our boat to a huge buoy with 30-40m of white rope tied to a heavy weight. We would hang on the line for around an hour, looking for lanternfish and other pelagic creatures.
The most challenging task was to avoid losing the rope if a photo opportunity arose. It’s exciting to glide through the water like this, and we found quite a lot of lanternfish.
There was just one problem. Every time we pointed our light at them, they went straight down where no diver could follow them.
So we ended up with a heap of images of other creatures such as sea gooseberries and bristleworms, but no lanternfish.
This is a challenging and resource-hungry type of diving, so we went back to doing night dives from the shore inside the fjords during winter.
Glacier lanternfish are some 10cm long, with elongated, flattened bodies, and large heads and eyes. Existing mainly in the lightless depths (as deep as 800m in daytime and 12-200m at night) they have little need for bright pigmentation, so have dark brown backs and silvery sides.
Their fins also lack colour and are all soft-rayed, except for the fleshy adipose fin. Their large, heavy scales may offer some protection from predators.
Males have a small light organ above the caudal (tail) fin, while females have two small organs below it. These photophores emit flashes of light that may function to attract predators to the tail, allowing the fish to escape.
However, the differences between the sexes suggests that the light may also be used in mate location or courtship.
Lanternfish are found from western Greenland and the Davis Strait south to the Scotian Shelf.
In February 2009, my buddy Leif and I did a shore dive inside Hogsfjord, just 75 minutes’ drive from Stavanger.
We were looking for spiny dogfish, black-mouthed dogfish, velvet-belly sharks and the like, so I had the 35mm lens on my camera.
I had just captured some images of a hagfish when I spotted a small shiny fish swimming for the deep. Recognising it as a lanternfish, I swam after it, trying to capture an image.
At 50m I had to turn the dive – the fish was still going down like a flat-iron. However, I had managed to get one picture, and was very happy.
Over the next month we did four more dives at this spot, seeing lanternfish and Mueller’s pearlsides
on every dive, though we didn’t get any more images of the former, and only poor images of the latter.
When spring came we had to stop doing these dives, but Leif and I had a plan for the next winter.
Almost every Wednesday I would drive for an hour, take the ferry across the fjord and drive some more to meet Leif and photograph lanternfish.
But we saw none that winter, only a lot of black-mouthed dogfish. The most exciting experience was on a dive when the air temperature was -18°C, and we thought we would have to keep our drysuits and dive gear on until spring, because it all froze onto us. We could barely manage to get out of it.
I THOUGHT WE SHOULD PERHAPS change our strategy for the following winter, but I couldn’t figure out how.
So in November 2010 we were back in the fjord, looking for this strange and beautiful fish.
We did many dives without seeing anything. Even the hagfish seemed to have left the spot. Then, on 23 February this year, we prepared for a new dive.
A gale was blowing from the south-east and -4*C air gave us very cold fingers as we set up the gear.
The 1-1.5m waves were coming straight out of the fjord, but there was a little bay where we could enter the water without being battered too much.
The week before, I had flooded my main light, so I had only a small one with me. I wasn’t too optimistic about spotting any lanternfish.
We had decided to dive a bit deeper than usual. At 43m, we levelled out and followed the slope eastwards.
We quickly found a large starry skate and a hagfish. The latter are good swimmers, but when you point a light at them, they get confused and usually try to dig down or hide. Seeing this hagfish made me feel more optimistic.
We were going shallower as our computers got into decompression when, at 33m, I suddenly saw a lanternfish above Leif’s head. I signalled with my light, then swam to get between the fish and deeper water.
It isn’t easy to focus on a small, fast-moving, shiny fish in open water, but as I managed to get it in focus and fired the flash, it swam up the slope towards the surface.
Things became chaotic. Sometimes the fish swam into mud clouds we had made with our fins as it tried to get past us to deeper water. Leif had problems with his flashguns and managed only one shot, but he supported me in keeping the fish shallow and in sight.
When we reached 15m, the lanternfish took off towards the surface. Leif stayed at the bottom, pointing his light upwards as I followed the fish.
We both ended up among the big waves at the surface. I almost lost my camera, and as I was afraid of getting blown out into deep water, I decided to return to Leif and leave the fish alone.
The rest of the dive was uneventful, and soon we were wading through the breaking waves back onto dry land. We were very excited about the fish – at last I had a number of nice images, and Leif’s single shot had also turned out well. What a thrill the chase had been!