Hello,
I am starting my MSc in Ecology in New Zealand. My thesis topic is focused on seeing if our native fish use the spaces between stones in gabion baskets as habitat.
(Gabions are wire-mesh cages filled with rocks, ususally used as bank-stabilisation walls, or sometimes to restore channel morphology and create salmonid spawning areas)

New Zealand native freshwater fish are mostly nocturnal and benthic, and during the day the shelter under stones in the substrate, it seems highly likely that they would also use gabions as day refuges.

Now here is the bit why I am asking you guys:
The group most likely to use the gabions are the bullies. These guys are amazingly similar to your darters, even down to the spawning behaviours. I am wondering if anyone knows of any studies or anything relating to darters (or indeed anything else) and gabions?
Of course I have been doing lots of searching, but there is plenty of stuff not online.

This is our most colourful bully, Gobiomorphus huttoni

Hey Stella,

I've occasionally seen cottids and juvenile centrarchids (particularly Ambloplites rupestris and Lepomis cyanellus) using gabion cages, particularly when the cobble size is really big. When they're filled with fines they're essentially a big block of unusable habitat. FWIW, Electrofishing isn't a particularly effective way to assess what's in the interstices; fish don't come out of the pockets. Rotenone or cyanide might work better for documenting use. Good luck, and let us know how the thesis is progressing!

Like Dave, I've seen small Lepomis, Micropterus and Ambloplites in gabions and among un-caged "riprap" (US term for loose erosion-control stone). I haven't noticed minnows or darters in there, but haven't especially looked.

Use may depend on the availability of natural rock substrata. If the stream bed is silted and interstitial space among rocks is a limiting resource, then gabions might be an important artificial habitat for some species.

Thanks

Actually you guys have both mentioned important aspects of my research.
I am going to be placing sets of temporary small gabions in streams. After colonisation will be wrapping and pulling them apart to see what lives in them (agreed, electrofishing won't work).

One part will be seeing if rock size affects their use by fish, so I will have three different rock sizes in the gabions.

And sedimentation is a big problem in New Zealand, and I figure that gabions would be a significant addition of habitat to a highly sedimented stream, but not that great in a stream with high porosity. For this I will compare proportions of fish in the gabion to fish in the surrounding area.

The third aspect is changes of the fish community over time with addition and removal of the gabions.

At the moment I am at the proposal stage. I am guessing I will be done this time in 2012.....