Underwater Rainbow Trout Feeding Behaviour on Aquatic Insects

[FishDoc]

No fish were caught in the making of this film, but plenty of trout were analyzed during the video.

Understanding Rainbow Trout and other fish behaviour is sometimes best done by entering their underwater environment and observing their actual movements with an underwater camera or while snorkeling. That is exactly what I did in this video. I suited up this spring with the wetsuit, snorkel, fins and brought along the GoPro to see what I could catch on camera. To tell you the truth half way around the lake I had pretty low expectations as I wasn't seeing many fish at all. Then I get to the area with some mid day shade and deeper water. I dive down in the center and all of a sudden I am surrounded by rainbow trout. They are everywhere. From the bottom up the water column. It was like I was swimming in a Bass Pro Shop Giant Acquarium full of trout. They could be seen actively feeding on something. Was this the spot... the 90% of the fish in 10% of the lake. It really is cool when you see sayings like this proving to be true. It keeps you searching on these slow days to try to find some actively feeding fish. After a while and a few dives the fish went elsewhere or I drifted off the spot. Most of the rest was uneventful until I was almost back at the dock. Then a rainbow trout showed up out of nowhere and let me follow her for several minutes in close proximity while she just went on her way feeding and relating to structure. Fascinating to see them in the environment and what a fish does in a span of several minutes. Brings light to what is happening under the float. Well I hope you enjoy this underwater footage even a fraction as much as I enjoyed swimming with them. My commentary is my rambling thoughts from what I thought about what I saw. People seemed to really like my thougths on an underwater walleye video. Lets see if this on gains some interest.

Thanks for checking it out.

 

[agentaqua]

nice video, FishDoc. One of the more informative ways to begin to understand the distribution of fish in a lake is do take DO/temps @ depth. Forgive me for telling you what you may already know - but I'll state the obvious for everyone else's benefit. Typically, the top layer warms-up; while there is a colder-water layer underneath that is separated by what is termed the thermocline. Often that top layer ranges from a few cm (in the spring) to maybe 10-60ft later in the summer - dependent upon where the lake is, and what rainfall, snow melt & temps the lake is exposed to. Most larger fish hang-out where the best temps/DO are - and come out to grab food and smaller fish when/where it exists - which changes seasonally. Higher gradient tribs with cooler water and higher DO are another good place to look @ where fish end-up - where they empty into the lake. A camera is helpful, as you've shown - but so is a tethered DO/temp meter. You'll notice some interesting seasonal patterns as the year progresses...

 

[FishDoc]

nice video, FishDoc. One of the more informative ways to begin to understand the distribution of fish in a lake is do take DO/temps @ depth. Forgive me for telling you what you may already know - but I'll state the obvious for everyone else's benefit. Typically, the top layer warms-up; while there is a colder-water layer underneath that is separated by what is termed the thermocline. Often that top layer ranges from a few cm (in the spring) to maybe 10-60ft later in the summer - dependent upon where the lake is, and what rainfall, snow melt & temps the lake is exposed to. Most larger fish hang-out where the best temps/DO are - and come out to grab food and smaller fish when/where it exists - which changes seasonally. Higher gradient tribs with cooler water and higher DO are another good place to look @ where fish end-up - where they empty into the lake. A camera is helpful, as you've shown - but so is a tethered DO/temp meter. You'll notice some interesting seasonal patterns as the year progresses...

Yeah I was looking into buying one of those to use during ice fishing season for curiousity sake when the fish are not as active in the late ice season. Usually the thermocline is pretty easy to locate in open water situations and the newer color fish finders. The fish stack up along it really well and makes controlled depth angling much easier once the water warms up a bit. Spring time it is a bit of a free for all as fish are top to as low as they want to go and oxygen levels are at their peak. So usually forage is the attractor early in the year. But as summer wheres on the temp and DO are for sure majoy drivers as you say. But this really is more limitted to trout and salmonids. When I fish for cold water fish like pike, walleye, perch, bass they don't usually suspend related to thermoclines. Sometimes they do but more than not they still relate to bottom structure.

 

[FishDoc]

It has been a long COVID-19 season of Social Distancing and Isolation. So when Rodney Hsu from "Fishing with Rod" invited me to drive up to the Interior of BC this spring and join him on the water for some stillwater Fly Fishing I was super excited! To tell you the truth I'm a beginner in the realm of fly fishing, but always love trying new things. I have never fished much on the interior stillwaters in the open water season, so I didn't know what to expect. It was a stunningly beautiful spring day and when I pulled up to the lake Rod and his buddy could be seen on the water pulling in fish. So I loaded up the canoe and headed over to them to join in on the action. Before the camera was even on I tossed a jig and hooked three small ones. Then the action slowed and the fish went straight to a chironomid diet. Once I had some chironomids in the right depth range with the help of the Deeper Chirp+ I started getting a bunch of slight bobber downs. Most I was too slow to even set the hook. I got the hang of it thought and started catching a few. With the Deeper Chirp+ I could cast it out and see what depth line to place my floats for the highest traffic. Then I would watch to see where the majority of the fish were swimming on the sounder and place my fly at that depth. It worked perfectly, some say it is cheating. I say it beats a skunk. There much have been 10 boats on the lake and most of the guys were having a very slow day besides the three of us. Shows that it pays to go with someone who knows what they are doing and make sure you have sonar to help you locate the fish.

 

[agentaqua]

Another excellent post, FishDoc.

Ya agreed on the trout verses the so-termed "coarse" fish lake positions. Seeing this is a BC sportsfishing forum - I was focused on the trout & salmonids. The exception to that broad-scale observation you mentioned would be spawning time/habitat (typically spring) & pelagic lake inhabitants (e.g lake whitefish).

As far as the tethered DO/temp meters - one could spend upwards of $1400 for a YSI w a 30m tether. No need to tho. Even the low-priced (~$200) DO/temp meters (that usually come w 12' tether) are adequate enough for most stuff - and one can easily get a van dorn water sampler or equivalent for under $200 that allows sampling @ deeper depths that you can use in conjunction w the meter. Getting temp readings is almost immediate while DO has to stabilize for 10-15 min. In waterbodies w elevated (high) summer temps (above 17-19C) - DO is way more informative than temps - esp for the tribs. In cooler waterbodies, DO is less of an issue and just looking @ temps is more than adequate for most things - possibly w the exception of iced over lakes, as you mentioned. Dynamic aqua supply is a great place to shop w reasonable prices: http://www.dynamicaqua.com/watersamplers.html#lamotte

 

[WoollyBugger]

Can you do the same in a big oligotrophic lake for us? lol. Maybe trade in the snorkel for a scuba!

 

[agentaqua]

takes more time on a larger lake, WB - but can be done. Kinda fun doing this stuff, IMHO

 

[FishDoc]

Another excellent post, FishDoc.

Ya agreed on the trout verses the so-termed "coarse" fish lake positions. Seeing this is a BC sportsfishing forum - I was focused on the trout & salmonids. The exception to that broad-scale observation you mentioned would be spawning time/habitat (typically spring) & pelagic lake inhabitants (e.g lake whitefish).

As far as the tethered DO/temp meters - one could spend upwards of $1400 for a YSI w a 30m tether. No need to tho. Even the low-priced (~$200) DO/temp meters (that usually come w 12' tether) are adequate enough for most stuff - and one can easily get a van dorn water sampler or equivalent for under $200 that allows sampling @ deeper depths that you can use in conjunction w the meter. Getting temp readings is almost immediate while DO has to stabilize for 10-15 min. In waterbodies w elevated (high) summer temps (above 17-19C) - DO is way more informative than temps - esp for the tribs. In cooler waterbodies, DO is less of an issue and just looking @ temps is more than adequate for most things - possibly w the exception of iced over lakes, as you mentioned. Dynamic aqua supply is a great place to shop w reasonable prices: http://www.dynamicaqua.com/watersamplers.html#lamotte

Thanks for all the info... i will have to consider one of those devices. Would really be interesting to add to the information for figuring the fish out.

 

[FishDoc]

Can you do the same in a big oligotrophic lake for us? lol. Maybe trade in the snorkel for a scuba!

Yeah that would be very interesting. I do how a bunch of underwater videos from trolling in Kalamalka lake. I do have Scuba certification but no personal gear. It would be interesting. Im not sure that rainbows actually school up as heavy in those big lakes unless its around and inflow or outlet or pinch point. Otherwise seems less dense populations. What do you find in your experience?

 

[FishDoc]

takes more time on a larger lake, WB - but can be done. Kinda fun doing this stuff, IMHO

For sure, finding fish on larger lakes can be quite challenging. There usually are starting points though and depending on sonar helps to narrow search before dropping the lines. Usually seeing lots of smaller fish or bait is a good bet even if not marking bigger fish. Seems the whole food web is usually in the same place. I always look for the diving fish eating birds. Sometime my grandparents used in Alberta before we had sonar. Loons and Red Necked grebes were our fish finders. They find the minnows that the other fish also eat. Sometimes these simple pieces of information make finding the fish much easier. Old knowledge still works.

 

[WoollyBugger]

Yeah that would be very interesting. I do how a bunch of underwater videos from trolling in Kalamalka lake. I do have Scuba certification but no personal gear. It would be interesting. Im not sure that rainbows actually school up as heavy in those big lakes unless its around and inflow or outlet or pinch point. Otherwise seems less dense populations. What do you find in your experience?

From my experience rainbow don't school up in med/large lakes but are opportunistic. Kamloops Trout also seem more pelagic than some other strains. I believe they start eating Kokanee when they are 12" and eventually makes up 70% of their diet. Like you said if you can mark bait fish you're likely in a good spot for the predators. I find I can distinguish kokanee from other fish on the finder due to large air bladders, but have a hard time determining what else is a pikeminnow vs rainbow vs laker vs burbot etc. so I typically don't chase the deep readings.