A body that sinks beneath the waves of Francois Lake will almost certainly never come back up unless someone goes down to get it.
This was successfully done this past weekend, when authorities and volunteers worked together to retrieve an as-yet unnamed victim from that aquatic grave. The mysterious male was found by sonar at a depth of 170 metres (560 feet).
When a person dies in a watery environment, their body will almost often sink for a short period of time until the initial decomposition process causes gasification to occur within the soft tissue. Buoyancy and swelling is the result. If the body is not physically removed from the water, it will, as more time and decomposition goes on, sink permanently.
According to authorities involved in the search for missing Lakes District man Syd Neville on Francois Lake - it was Neville they were after when the anonymous male was discovered - this body of water is special. It is the 16th deepest lake in B.C. (244 metres or 800 feet, maximum depth) and the 12th largest lake in B.C. by surface area (25,400 hectares).
Only Quesnel Lake and Atlin Lake are both bigger and deeper.
Dead mammalian bodies of any kind will almost always sink to the very bottom, where the decomposition process then unfolds. If a body sinks deeper than about 100 feet, however, the factors change and the typical results don't apply. The body does not resurface, ever, without intervention.
"Francois is hundreds of feet deep almost everywhere," said BC Coroners Service spokeswoman Barb McLintock.
If the typical person does a typical dive off a typical dock, the pressure felt on their body at the bottom of their dunk is about two pounds of pressure per square inch. That's more than air, but easy for scads of organisms large and small to easily live their lives in and around a human body.
If that same diver kicks down to 10 feet deep, the pressure mounts to about four pounds per square inch - still a lively ecosystem.
At a depth of 500 or 600 feet where the mysterious body was found in Francois, the pressure ramps up to 215 to 260 respectively.
The temperature at that depth was measured, Tuesday, as being four degrees Celsius. That frigid level adds to the hundreds of pounds of pressure to create an environment almost devoid of decomposition factors.
"Some of the connective tissues may fall apart but the bones often retain their structural integrity," said McLintock. "Nothing is moving that body, like tides or river currents. Bodies that deep could be there forever."
Bacterial decomposition aside, an incalculable factor would be omnivorous fish. They do exist in northern B.C.
"The diversity and abundance of species dwindles quite quickly the deeper you go," said UNBC fish expert Dr. Mark Shrimpton. Francois has a population of lake trout and Arctic char, which can both survive at those depths, and the Upper Fraser region in general is known to have burbot, another species of fish capable of swimming that low, but none spends much time down that deep. The ecosystem is built on phytoplankton, zooplankton, on up into increasingly larger organisms. That, said Shrimpton, is richest along shorelines and in depths exposed to the sun's light.
Lead searcher on the Neville case, Gene Ralston, has the means to see fish as they trawl for clues.
"We've seen some fish down at lower depths, but not many," he said.
McLintock added another factor to the usual scenario of a deceased human in deep lake water. They do not move. Assumptions about subsurface currents, storms, etc. are almost always incorrect once that 100-foot threshold is broken.
"The weight of the descending body will overcome any force of movement within the lake water. It makes for a very stable scene," she said. "If you can pinpoint a general area they were last seen, you will almost certainly find them within a 500-foot radius of that, down on the bottom."
Complicating matters in the search for Neville is an inexact location of last sighting, and, as demonstrated by the mysterious body found along the way, several people have gone down in Francois Lake over the decades.
