The Big Little Migration

Sometimes the most incredible marine life encoutners aren’t in the ocean, they’re hiding under lily pads in remote Canadian lakes

Words by Russell Clark / Photography by Maxwel Hohn

You may well remember seeing a couple of images we’ve previously published of tadpoles. They are always crowd pleasers, and have sparked an interest that we decided to dive into…well, snorkel at least. So this summer we spent some time with DIVER columnist Maxwel Hohn as he spent his fourth season documenting the western toad tadpoles on their daily migration.  

How did you discover this incredible marine life event?

Maxwel: Each summer I explore many different lakes and rivers on Vancouver Island, BC. One of these times I was looking for lily pads to shoot from underwater. I was after that unique perspective being underneath the lilies looking up, with the sun above. When I jumped in this particular lake (which will remain undisclosed to help preserve their environment – Ed.) I came across the tadpoles and my mind was completely blown away. I saw millions of them swimming through the lily pads and I was just stunned. 

I’ve been returning here four years now, photographing and videoing the amazing journey of the western toad, from eggs to tadpole.

Why has this experience resonated with you so much?

Being able to capture the entire life cycle of an animal is rare, challenging, and lots of fun. From the toad’s breeding during spring time, to their laying their eggs in the water, hatching in a matter of days, then their incredible metamorphosis over the next 6-8 weeks until they literally jump out of the lake and take their first bites on land. 

Trying to figure out what their routine is, figuring out where they start each morning, what time, and why. For me as a photographer I really want to document each of those moments. 

Tell us about the “migration”…

They swim an incredible gauntlet every day, starting in the deeper part of the lake in the morning, working their way towards the shallows. They use the lily pads as cover from predators during their journey. They congregate into a ‘cloud of tadpoles’ and weave in and out of the lily pads. It looks like an underwater river of black. Once they arrive in the shallow area of the lake, they can bathe in the oxygen-rich waters and feast on the micro plants and algae. A few hours later, they turn around and do the same route in reverse, swimming the same gauntlet lined with predators, this time so they can spend the night in the deeper parts of the lake. They repeat this daily migration every day throughout their metamorphosis.  

How tough is it to capture stills and video of the action?

One of the biggest challenges is not stirring up the bottom. As with most lakes, the bottom substrate is very fine and very loose, so with any kind of movement you lose visibility. Even the tadpoles stir up silt. So I try to move as slowly as possible; patience is key. They’re not scared of you, in fact they’re quite fearless little guys. They swim towards you, even landing on my camera, and they move a lot faster than you think! They’re very rarely resting still, so it’s all about spending hours in the water each day.

I choose to snorkel and freedive as it’s the least invasive method, scuba gear gets you tangled in the lily pads. A simple wetsuit, mask, snorkel and fins makes it easier to get close. It’s a fragile environment. I also take advantage of some natural trails made from beavers. They like to eat the lily pads roots —leaving a natural trail through the lilies. I make use of these trails where possible, slowing snorkelling on the surface. Besides, the tadpoles are usually in about three feet (1m) of water, so it makes more sense than using scuba. 

How do they develop over time?

During the 6 to 8 weeks the tadpoles will evolve dramatically. First their back legs will begin to appear, they will develop patterns and colours, and their front legs will grow internally before breaking out of their thin skin. The tadpoles slowly start to use their new legs, learning how to hop underwater. As other respiratory systems begin to develop, they will gradually stop extracting oxygen from the water using their gills. Finally their tails will be reabsorbed and the tadpoles will take their first steps on land, becoming toadlets.

On of my final night camping at the lake there was a heavy rain downpour, and I started to see the tadpoles actually come out of the lake and becoming toadlets. As I followed them along into the forest I noticed one was stationary for a while, so I took some shots and could actually see the little one take its very first bites of tiny little land-dwelling bugs. It was quite a moment. 

They now begin a new journey on land, before eventually heading back to their aquatic birthplace to find a mate, and start the cycle once more, introducing a new generation of tadpoles.

People don’t think of tadpoles being photogenic…

When you just take the time to look at their features they are really cute. They have this permanent smile. I find when they’re in their cloud, they’re confident little ones, they have the strength in numbers and just ignore me, continuing with their day. They have such a personality, you see it in their eyes. 

What predators do they have?

Water bugs will strike on an unsuspecting, lone tadpole, forcing it towards the surface and feasting on its eyeballs, it’s pretty gross! 

Loons and trout will also go for the occasional tadpole dinner, but the most striking of predators is the leech. They detect their prey with a range of different sophisticated sensors, they also move very quickly, before striking and swallowing their prey hole. It’s an impressive albeit sad sight when the tadpoles meet such a grizzly end, but it’s all an important part of the lake’s fragile ecosystem.  

Their biggest predator though, is us. This ecosystem is thriving, but our quest for urban development has made the western toad a threatened species. At some point we have to put these animals first if we want to see them rebound and recover.  

We know when the tadpoles begin to come out of the lake (late July this year), we know they cross a busy logging road used by recreational campers, and ATVers, so this year signs have been installed to help people become better aware. Next we’ll be trying to get the road closed to better protect them. We have to let these little guys come first at some point, they are an integral part of a vital marine eco system.

How does it feel to whiteness such a massive, tiny event most people wouldn’t even consider jumping in the water for?

I was born in BC and have always seen tadpoles as a young kid, so to be in the water now as a photographer and capture their journey has been a lifetime in the making for me. 

When they’re in the big thick, carpet-like black mass, it was just mind-blowing. We estimate three million tadpoles in this one location. A friend compares it to the migration of wildebeest moving across the Serengeti, but on a tiny scale! It was humbling and heartwarming. 

To see these aquatic tadpoles evolve into terrestrial animals before my own eyes left me feeling like a proud parent, and is proof that even the smallest of animals can have the biggest of impacts. 

For more visit: www.maxwelhohn.com