Pond Boss Forums Thread Like Summary - Scuds vs. PK/Grass Shrimp Trout Forage

Hi folks,

My wife and I have now been the proud owners of a large, high-altitude plot (2,500’ to 3,000’) in the southern Appalachians that is absolutely bubbling up with cold spring water. We bought it because months into one of the worst droughts the region has ever had, it had water flowing in the three springs about which the previous absentee owner knew. Since then, we have found 6 more, and we have only explored one of the three valleys we now own.

We are huge trout anglers, and in addition to wanting homestead and vacation land, we always planned to build trout habitats. We now can certainly construct three spawning-capable large ponds with the water resources we have found, and there is already one 1.5-acre stock pond. This pond is over a century old and as such has a lot of weeds (about 12’ deep in the middle, 5’ to 8’ for most of the rest), but the water is clear and cool, and we are going to deepen, widen, and improve this pond before constructing two larger ones from scratch.

My wife and I have studied forage base since we were literal teenagers dating in undergraduate, as having our own mountain trout fishery is a dream we have had since we were first together, and are planning to go hard on amphipods as the main food for the fish. We currently have in our house in the suburbs flourishing monocultures of Hyalella azteca, Gammarus fasciatus, G. lacustris, G. minus, G. pseudolimnaeus, and Asellus aquaticus. After H. azteca, our first benthic macroinvertebrates were actually G. pulex, but it was from them dying that we learned that basically all Gammarus spp. need chilled water, and so we know have many aquaria with chillers and canister filters. Our U.S. source of G. Pulex doesn’t produce them anymore, and since we won’t stock non-natives in our ponds (plus, importing scuds looks like a red tape nightmare) we probably won’t get more G. pulex, although they are such cool pets.

While the native scuds we keep will be the broodstock for our ponds, until recently I hadn’t given any thought to Palaemonetes kadiakensis. I had read somewhere years ago that they do not contain astaxanthin or beta-carotene, and so are not very nutritious for trout. However, I recently read some literature that showed that they are actually a source of these nutrients, so I am considering them to be part of the forage base community.

I have some concerns, though, and wanted to ask you fine folks whether my worries are justified.

1. Are PK shrimp antagonistic/predatory to scuds and will they compete for the same niche and resources? If this is the case, I’ll not use them, as I know for a fact that scuds in abundance are what makes a trout fishery world-class. If, however, they stick to different habitats and niches, and don’t compete for the same, there will be more biomass of forage, so I definitely would use them.

2. Do the nocturnal habits of PK shrimp make them difficult for trout to utilize? Even if PK shrimp get along with scuds and increase the biomass of forage, if the shrimp are only active at night, this would be wasted.

3. Do PK shrimp burrow and make water cloudy? I have read reports that PK shrimp make the water in a pond turbid. While I know scuds do burrow a little (G. fasciatus is the worst offender), they don’t move around once buried, and seem not to make the water cloudy; even in some western alpine lakes in which literally the majority of the surface area of the lake bottom is made up of the wriggling bodies of tens of millions of G. lacustris, the water is glass-clear! While pretty much the entire bottom and sides of our ponds will be composed of limestone and dolomite in the form of gravel, riprap, and boulders, something that will find sand or mud and foul the water is a non-starter for us.

4. Finally, do PK shrimp do well in cool, mountain water? Our springs mean that our water will be coming out at 52 degrees all year, and will stay between 45 and 60 all year. While I know these conditions are perfect for Gammarus growth and year-round reproduction, will this prevent the PK shrimp from multiplying and thriving?

Sorry to be so long-winded, but this is a literal lifelong dream of mine, and I want to give the habitats the best possible start!

Thanks in advance!

The astaxanthin or beta-carotene is what gives the trout their red/pink flesh and really brightens up their colors. You can get commercial food that has that added to it, but the same trout do just as well on food that doesn't have it in it's formulation. I believe that it is just to enhance colors and flesh colors - it's not a critical "need" to have that in their diet.

Well, you probably just saved me some money. I was considering giving PKS a try, but we are pretty acid too.