M
Mike
Well-known member
- Joined
- Nov 10, 2006
- Messages
- 5,567
What is the typical "Stockie Depletion Rate", or "Stockie Removal Rate" on stocked streams?
Suppose 1000 trout are stocked. At the end of Opening Weekend, how many have been removed, and how many are left?
At the end of 1 week?
2 weeks?
3 weeks?
Surely this has been studied.
And how does this compare to the situation on DH areas?
The removal rate from ATW's varies considerably. The older numbers from the early 1990's when there was less C&R generally ranged from thirty to ninety percent in the first nine days of the season, but I believe there were some lower numbers too on small, rural streams.The range, of course, was at least in part related to human population densities...urban, suburban, and rural, as well as public vs private waters, and a host of other variables, and the results influence today's stocking rates in various human population density, width, and recreational use potential classifications of streams. Angler use drives this and that is part of the reason why we continue to do opening day angler use counts in various classes of stocked waters (and we will be out again this year). You may be able to find more up to date numbers in the 2004 or 2005 statewide stocked trout angler use and harvest studies. Inseason stockings were generally harvested at lower rates, which makes perfect sense.
As for DH Areas, the loss during the C&R period in SE Pa (at least 6) was measured by us to be about 6.5 percent per week across a number of waters with various characteristics. That means that there was about a 40 percent loss in the avg 6.5 weeks between the preseason and inseason stocking with no legal harvest. Now a number of DH areas are stocked even earlier in the year than they used to be....up to two weeks earlier so losses between the pre and inseason stocking can be expected to be perhaps fifty percent on average, which makes the frequent blame aimed at poaching being the primary culprit a scape goat if there ever was one. To have that kind of harvest would make harvest obvious to everyone, including conservation officers. And remember, these losses are without the stressful water temps seen later in the C&R season. Once the water temp is consistently over 68 degrees, which is above the thermal optimum, rainbows, for instance, will be lost at up to a 75 to 80 percent rate in a month based on important peer reviewed scientific research published in 2008. When the water warms up, blaming such losses on perceived high harvest, even when some harvest is witnessed, ignores reality.
Suppose 1000 trout are stocked. At the end of Opening Weekend, how many have been removed, and how many are left?
At the end of 1 week?
2 weeks?
3 weeks?
Surely this has been studied.
And how does this compare to the situation on DH areas?
The removal rate from ATW's varies considerably. The older numbers from the early 1990's when there was less C&R generally ranged from thirty to ninety percent in the first nine days of the season, but I believe there were some lower numbers too on small, rural streams.The range, of course, was at least in part related to human population densities...urban, suburban, and rural, as well as public vs private waters, and a host of other variables, and the results influence today's stocking rates in various human population density, width, and recreational use potential classifications of streams. Angler use drives this and that is part of the reason why we continue to do opening day angler use counts in various classes of stocked waters (and we will be out again this year). You may be able to find more up to date numbers in the 2004 or 2005 statewide stocked trout angler use and harvest studies. Inseason stockings were generally harvested at lower rates, which makes perfect sense.
As for DH Areas, the loss during the C&R period in SE Pa (at least 6) was measured by us to be about 6.5 percent per week across a number of waters with various characteristics. That means that there was about a 40 percent loss in the avg 6.5 weeks between the preseason and inseason stocking with no legal harvest. Now a number of DH areas are stocked even earlier in the year than they used to be....up to two weeks earlier so losses between the pre and inseason stocking can be expected to be perhaps fifty percent on average, which makes the frequent blame aimed at poaching being the primary culprit a scape goat if there ever was one. To have that kind of harvest would make harvest obvious to everyone, including conservation officers. And remember, these losses are without the stressful water temps seen later in the C&R season. Once the water temp is consistently over 68 degrees, which is above the thermal optimum, rainbows, for instance, will be lost at up to a 75 to 80 percent rate in a month based on important peer reviewed scientific research published in 2008. When the water warms up, blaming such losses on perceived high harvest, even when some harvest is witnessed, ignores reality.