Saturday, March 5, 2016

Virginia trout: Brook, brown, rainbow - from the hatchery to the exhibit

We display all three Virginia trout species: brook, brown and rainbow. Although brook trout Salvelinus fontinalis are the only native Virginia trout species (and our state fish), both rainbow trout Oncorhynchus mykiss (introduced from the western US) and brown trout Salmo trutta (introduced from Europe) have been in Virginia long enough (since mid 1800's) that they are now well established Virginians. Though they are still actively stocked for sport in many rivers popular to anglers, rainbow and brown trout often out-compete native brook trout and may even prey upon them when they share the same habitat. In some cases, efforts are underway to remove non-native trout and restore habitat of the wild brook trout.

Brook trout male (center)

Brown trout

Adult (4 year old) male rainbow trout 

Juvenile (4 month old) rainbow trout on exhibit acquired Tuesday from the hatchery 

From a husbandry standpoint each species has its own behavioral characteristics. Brooks are the easiest to keep; they are disease resistant, readily spawn in captivity, and are the most peaceful with each other and the other trouts. Brook trout are also strikingly beautiful, making them an excellent display species. Rainbows are simply eating machines: given the opportunity rainbows will eat until they can barely swim. Rainbows also tend to have more health issues than any native species we rear; they have long been captive bred for distribution throughout the the US and the world - for sport and for food - a factor that has made captive strains considerably less hardy. Aside from the fact that they are susceptible to disease, they are generally easy to keep as well. Browns are the outlier of the three. They aren't as overtly colorful as brooks, as well known as rainbows and  may vary widely in color and patterning: some browns are vivid gold with a plethora of black spots all over their bodies, while others may be drab olive-brown with little spotting. Regardless of their physical appearance browns have charisma. Thought to be the hardest to catch in the wild of the three trout species, they are the most reclusive and seemingly least tame. Browns have a tendency to hide, lay motionless much more frequently than brooks or rainbows, and will eat surprisingly large tank mates. And they jump! - out of the exhibit and sometimes into another. Several times overnight a brown trout has leaped into the Mountain Stream exhibit where they are found in the morning among the smaller stream fishes. Thus they require barriers to keep them from leaping onto the floor overnight. Did I mention browns are most active at night?

Brook, brown and rainbow trout on exhibit

All three trout species generally spawn in the spring and have traditionally done so on exhibit as well, driven by their internal clocks and triggered by the lengthening daylight in our glassed-in exhibit. However, trout are notoriously glutinous and gobble up each others eggs almost as soon as they are released by a female. Even if the eggs manage to hatch and mature, they rarely survive even a few weeks unless we remove them and raise them elsewhere. Trout grow very quickly with an abundance of food and they may mature in only a year or two. The males can become aggressive towards tankmates and may even seriously injure one another, which is not a good look for fish on public display. So we occasionally downsize our trout population and get younger, smaller trout from a local state hatchery...
View from Spy Rock a peak on the Appalachian Trail, accessed on Hatchery Road.

A side tributary of the Tye River, many of which are wild brook trout streams.

Montebello Hatchery is located just a few miles past Crabtree Falls (Tye River) and is also the access point to a hiking trail spur leading to Spy Rock on the Appalachian Trail. It is a beautiful area and the facility is open to the public. This hatchery raises all three species of trout and generously gives us fingerling trout when we need them. This visit we only needed only rainbows, with plenty of brooks and browns currently on exhibit. Below is a video of the rainbow trout fingerlings at the hatchery; we brought back about 200 of these guys!

video



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