And another stocked trout stream trying for Class A

[Mike]

A number of years ago we switched a York Co stocked trout stream from mixed species stockings to RT stockings with the idea that this might allow the wild brown trout population to grow to class A, just as had occurred on a couple waters where the switch had been made. Part of Codorus was an example. The latest to venture toward an equivalent Class A biomass is one that we have now found to be the equivalent of twice the Class A minimum biomass, but it has been so long since the species stocked was switched that it can't really be called a cause and effect relationship. Nearly half of the present biomass comes from a large group of 2014 year class yearlings. There were over 110 legal size fish collected in 360 meters of stream. Two consecutive surveys...not necessarily two consecutive yrs... that document Class A equivalent populations are required to remove a stream from the ATW list based on wild trout biomass...and with good reason if you have followed the short-lived Donegal rebirth. It would be difficult to assert with any confidence that the present stockings have been harmful given the population growth. Those who have followed similar situation in York Co will note that Blymire is now off of the ATW list.

 

[SteveG]

Mike, what is the theory behind stocking bows to boost the wild brown population? Does it have to do with stocked browns who are trying, but not succeeding spawning?

 

[Fishidiot]

Mike wrote:
... if you have followed the short-lived Donegal rebirth.

No intent to deflect this thread. . .but I missed the story on Donegal. As far as I recollect, there has been good increase in wild BT biomass. Has this reversed itself?

What's the short version scoop on Donegal?

 

[Mike]

Donegal's wild BT population substantially declined between the 2014 fingerling RT stocking program eval and the 2015 eval. It looks as though it has returned to its former self.

 

[Mike]

RT are more readily caught in cold, early spring water than BT. Also, RT are more readily caught than stocked BT and stocked BT are more readily caught than wild BT. This all comes from related studies or direct studies of vulnerability. To reduce wild trout exposure to angling pressure created by trout stocking yet still maintain a stocking program, one can stock trout species that are vulnerable to angling pressure and will provide a short term fishery when the wild trout are much less vulnerable to angling pressure due to species the species involved (wild BT) and water temps.

 

[pcray1231]

I'd also imagine there are differences in habitat preferences between RT and BT. Hence, ceasing stocking of the BT prevents competition to some degree.