Thursday 16 October 2014

October midnights

I've been in the field a lot this month, which at this latitude means the frequent juxtaposition of boats and snow. Most of this work's been in aid of a big project I've been putting together, getting at the problem of managing multiple stocks of lake trout that move among very large, interconnected lakes in the southern Yukon. In a nutshell, we're looking at lake trout subpopulation identity, movement patterns and harvest vulnerability using genetics, telemetry, netting surveys and angler submissions. What this means in early October, then, is that I'm out on lake trout spawning shoals at 2am, catching trout and surgically implanting acoustic transmitters. On a recent trip, with the aid of a calm night, clear water, good spotlights and a gopro on a stick, I managed to get a view of what lake trout spawning aggregations look like from a fish's perspective:




These fish were in ~3.5m of water, at around 3:30am, and were but a few of what might have been several hundred fish up on the spawning shoal. Most of these are male (distinguished by slightly hollow-looking flanks), whereas the few females are much more gravid-looking. A few round whitefish are skittering around the outskirts, looking for stray eggs that don't settle down between the cobbles. Pink floy tags below the right dorsal mean those fish were ones we implanted transmitters in last year. It's good to see them back, doing their thing.

2 comments:

  1. This is magical. Thanks for sharing!

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  2. I could have mistaken this for diving footage. Incredible. Freshwater sharks.

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