Migrating Salmon Video

Ran into this video made of individual Chinook and Steelhead Salmon smolt migration in British Columbia. These individuals are tagged before they are released as stocked salmon in the Snake and Thompson Rivers. Their movements are monitored by an impressive system called the POST array. I don't really know much about the details, however, the punch line is there is an impressive monitoring system in place for these salmon and it makes a great video. Also if you are more interested here is the paper where they have some interesting survival data like survival /100km migrated and on places with and without hydroelectric dams.

RFF: red fluorescent fish

On the upcoming podcast we explain amongst other things why the sea is blue and what happens to red light in water (subscribe to the rss to listen!). For depths over 10m red light is pretty much irrelevant to fish. There is no purpose to see it since it is largely absent, and therefore no value in displaying it. Or is there? Here is a paper in BMC ecology with some stunning pictures and an account of how actually not only are some fish red-fluorescent, but it is also a really good private communication solution:

"We here report that at least 32 reef fishes from 16 genera and 5 families show pronounced red fluorescence under natural, daytime conditions at depths where downwelling red light is virtually absent. Fluorescence was confirmed by extensive spectrometry in the laboratory. In most cases peak emission was around 600 nm and fluorescence was associated with guanine crystals, which thus far were known for their light reflecting properties only. Our data indicate that red fluorescence may function in a context of intraspecific communication. Fluorescence patterns were typically associated with the eyes or the head, varying substantially even between species of the same genus. Moreover red fluorescence was particularly strong in fins that are involved in intraspecific signalling. Finally, microspectrometry in one fluorescent goby, Eviota pellucida, showed a long-wave sensitivity that overlapped with its own red fluorescence, indicating that this species is capable of seeing its own fluorescence."

Not only is this cool in itself but it may be useful for us lab rats to use in imaging and microscopy as it would have different properties than RFP and current dyes.

Fishy post

I'm big on fish science I guess as I have done a few bayblab posts on fish before. Here's a couple of 'good news' fish science stories:
1. Apparently Ontario has done a large study showing that mercury is eliminated from an aquatic ecosystem relatively quickly.
2. It is possible to derive trout from salmon. Apparently this could be used in various conservation approaches. The method involves injecting trout spermatogonia into salmon embryos. Some of the adult salmon then produce trout gametes.

Do fish get 'the bends'?

One of the dangers of SCUBA diving is the bends, or decompression sickness, which results from gases (usually nitrogen, but potentially helium or hydrogen) come out of solution and form bubbles upon rapid shift from high to low pressure. These bubbles can cause excruciating pain in the joints (this is where the name 'the bends' comes from) as well as itchiness, shortness of breath and neurological problems.

But what about that delicious PEI lobster stolen from the depths and put on a plane to get to your dinner plate? While most tales of exploding seafood are anecdotal, a small number of studies have shown that fish and other marine life can also suffer from the bends. Biological specimens from the deep ocean have to be brought up slowly (like a diver) or kept pressurized or the drastic change could cause internal bleeding or burst swim bladder. Even catch and release fishermen should be warned. In small-mouth bass, removal from a depth as shallow as 5 metres has caused gas bubble formation and signs of tissue damage, and the survivability of these fish after 'the bends' isn't known. (Dr. Tufts of Queens University and author of the study predicts they'll swim back to the right depth and be fine). And if you're not releasing, but eating instead the stress may affect the taste.

Drinking the Rideau

I live in a city that, like many cities, has a river running through it. A quick informal poll I conducted suggested that no one would drink water from the Rideau River in Ottawa Ontario. This is disturbing to me especially since I think of Canada as having great fresh water resources. It also just pisses me off that it is acceptable and expected that the water is unsuitable to drink. What exactly is wrong with Rideau water? It is the drinking water to the community of Smith Falls, but they are quite a bit more upstream. All municipalities along the Rideau dispose of treated waste water into the Rideau. However the health of the river must not be that bad because I fish there and catch many bass and I've heard that there are walleye. Also I have seen two large snapping turtles in the Rideau suggesting that even long lived animals aren't dying of toxic pollutants. The Rideau Valley Conservation Authority has a great website explaining water quality and legal aspects about the river. They also have available their sampling data that you can check out with the Watershed Information System. It is a pretty amazing source of information and it gives you water quality data for specific sampling spots along the river. Unfortunately they don't sample within the city of Ottawa and the data is just that, data with no explanation of significance. Fortunately the Rideau Roundtable, a non-profit group of enviromentalists, provides some great data about the river that is more easily digested. Basically the only thing that might be a problem is periodic high levels of E.coli, probably a consequence of waste water but that is not addressed. Low metals, lower phosphorus than ever before since data has been recorded. There are some invasive species but nothing that harmful. Also nitrates are rising slightly but apparently still at acceptable levels.Next time I'm fishing I'm going to drink a cup of it. I'll report back with any symptoms.

Red hair was sexually selected

We recently had a debate as to which animals have colour vision. Being avid fly fishermen, we debated wether the colour of the fly really does anything. Can fish see colour? Obviously tropical fish are very colourful but can they appreciate it? Well it turns out, that fish may in fact see more colours than we do. Some of them can see ultraviolet as well as infrared. In fact if you look at reef fish with a UV filter, all kinds of new interesting patterns emerge. The goldfish for example has 4 different cones sensitive to different wavelengths. This brings up the question as to why evolution drives the selection for colour vision. Our ability to see red, green and blue is actually a recent event in our common ancestors with primates. The proposed hypothesis for the evolution of red vision is that it enabled the foraging of ripe fruits in the green background of the vegetation. From then on, red hair, and red appendages were positively selected for in primates by sexual selection. Red hair effectively became sexually desirable, and a red bottom for example, would be a very good cue of the receptivity of the female monkey.