Small brook trout appeared to prefer areas 65–85 cm deep and 25–45 cm deep. Large brook trout appeared to prefer water 45–65 cm deep, and avoided water <35 cm deep.
Its interesting to me that the large trout were in the middle water column and the small trout are both below and above. With varying water temperatures with depth I tend to wonder why the small trout avoid the middle water column.
Brook trout were grouped as 8–30 cm TL, considered to be juvenile and river resident (“small trout”), and TL >35 cm representing the anadromous adults (“large trout”),
I believe the researchers should consider adding a few more groupings in order to obtain more accurate information. A fish that is 8cm compared to a 30cm fish is in a completely different part of its life cycle yet they are grouped together.
Snorkelling surveys were conducted at each site to observe fish locations
Another method with questionable accuracy. A big question that arises is how can you tell different fish apart from one another without a tag and release system?
The flight altitude was selected to optimize resolution (pixel resolution = 0.44 mm) while providing an image wide enough to capture the active channel (129 m). The TIR sensor was set to acquire images at a rate of 1 image per second resulting in 40–70% forward overlap between images.
How do methods like these compare to something like using a thermometer floating down the river? This method seems much quicker and thorough but it seems very expensive compared to the alternatives.
Concurrent with global scale climate change, local and regional scale human activities such as forestry can increase summer, surface water temperatures and shallow groundwater temperatures
With an added unnatural increase to water temperatures in the summer we may find that salmon and trout will adjust the time of the year in which they lay eggs. In order to find a suitable temperature for egg aggregation.
Salmon parr appeared to aggregate at 27°C, and after several events over 27°C variability in aggregation behaviour was observed – some fish aggregated at 25°C, others did not.
This change in Salmon parr aggregation where some fish aggregate at 25C and others at 27C means that in the future with warmer waters the salmon may be able to adjust the temperature at which their eggs aggregate.