Pond Boss Forums AQUATIC VEGETATION Controlling unwanted plants Oxygen stress

Read this article, and find the "clue" why Pond Boss magazine and Pond Boss "Ask the Boss" can be so valuable.

http://www.myfoxtwincities.com/story/24101170/lake-owasso-shoreview-fish-kill

Fall chemical application to kill aquatic vegetation? Hmmmm.

Just a side note:

Do you know that testing for VHS and others have killed countless many more fish than the affliction's ever have?

And, they never find them

Just some crap that needs to be fixed, but doubt it will be anytime soon.

Ouch!!
Those are some beautiful fish they killed.
I'm guessing Whitecap/Sonar....

Possibly. But at 300+ acres, I doubt that it was due to an overdose. More likely the decaying weeds used more O2 than normal and by the pictures, the clarity doesn't show a lot of phytoplankton. No snow cover, so there was enough sunlight during the day if there weren't heavy clouds.

In looking at the fish survey, it seems that the BOW was forage heavy and they were stocking predators to rectify the situation. No worries now, the lake isn't overpopulated anymore.......

Over carrying capacity with stress followed by an event. Even a minor one will add enough stress to push it over the edge. Studies indicate that waters that winter kill often do so repeatedly -- my guess is they cycle from few fish to past carrying capacity and it winter kills again. Anyone know this lakes history ?

Another possibility is very rapid cooling which will also do that even with enough O2. Rapid cooling causes a lipid imbalance at the cellular level and the fish muscles stiffen up causing them die.

Here is the info ;

Although it has been hypothesized that temperature
is closely linked to membrane composition,
relatively few studies have been conducted to determine
if a correlation exists between lipid composition
and cold tolerance. This study was designed
to determine the effect of a sudden temperature
change (a simulated cold front) …


Fish deaths due to cold temperatures have frequently
been reported. It is generally believed that
deaths arise from the rapidity of dropping temperatures
whereby the fish are unable to acclimate
to the lower temperature despite being within their
biokinetic range. In these fish, the fat
apparently hardens in the colder water, causing the
fat-impregnated muscles to stiffen and the fish to
become exhausted and lose movement.
The rate of increase in the ability of
fish to tolerate higher temperatures usually requires
less than 24 h at temperatures above 20C,
whereas the gain in resistance to lower temperatures
is a much slower process, requiring up to 20
d in some species (Doudoroff 1942; Brett 1944).
The rate of resistance to lower temperatures is governed
in part by the rate of metabolism, which is
depressed at lower environmental temperatures.
The simulated cold front in this study resulted in
higher mortalities

The rapid onset of cold temperatures
has been reported as the cause of death
in several species of fish (Verril 1901; Storey 1937;
Galloway 1941; Gunther 1941; Ash et al. 1974;
Coutant 1977; Mitchell 1990). It is believed that
the lipid composition in the fish muscle plays a
vital role in the ability of fish to adapt from one
temperature to another (Hazel 1984; Greene and
Selivonchick 1987; Henderson and Tocher 1987).
Phospholipids are the class of lipids in which the
most obvious changes occur.

the ability of a fish to alter its lipid composition when placed in
colder water is one factor that determines survival.

This study was designed
… determine the effect of a sudden temperature
change (a simulated cold front) on striped
bass, white bass, and their hybrids fed either a
natural or prepared diet, as well as to determine
their lower incipient lethal temperature. The association
of fatty acid composition and unsaturated:
saturated fatty acid ratios in these fish were
examined with respect to their tolerance to cold.

The dynamics of lipid composition of cells occurs
in order to maintain a constant fluid matrix for
enzymes associated with membranes (Greene and
Selivonchick 1990). Different species of fish differ
in their patterns of fat deposition and mobilization,
which in turn affects the temperature range in
which the species can grow and survive. For example,
the Nile tilapia Oreochromis niloticus does
not store excess lipids in the musculature but rather
relies on visceral deposits that it is incapable of
mobilizing at low temperatures, which results in
high mortalities between 8C and 6.5C (Satoh et
al. 1984).

Great infomation.

A strong lesson to learn from all fish kill events that often the situation is exacerbated by an accumulation of stressors. i.e. plant death/oxygen sag combined with sudden temperature drop, combined with possibly pH changes, etc.