Saturday, August 30, 2014

Striped bass and striper hybrids in our James River exhibit

September is the month we do our major exhibit work, including fish moves. Our first priority is to release any animals that will be too large to keep until next spring and replace them with smaller animals that can be kept comfortably at least until next collecting season. The first exhibits to down-size were the James River and James River Shallow exhibits. Earlier this year we added yellow perch that had grown too large for the Yellow Perch exhibit, and walleye that were transferred from the National Aquarium in DC when it (sadly) closed.

Two year old yellow perch
A walleye in James River exhibit

But we also acquired some captive bred striped bass (~30) and hybrids (~ 12 white bass x striped bass) from a hatchery to replace the adult striped bass which are the signature species in this exhibit. These hybrid and striper juveniles were initially about 4 inches when we got them but have been growing rapidly in our James River Shallow exhibit. They are now large enough to replace the striped bass adults in the main exhibit which have grown too large for the exhibit and were released last week. Below is a video of the very active school of stripers and hybrids just put in the main portion of the exhibit.
video
Stripers and hybrids school in their new exhibit

It is difficult to discern the hybrids from the pure bred striped bass, especially in the video. Generally, the hybrids demonstrate physical traits of the white bass that differ from pure bred striped bass: a higher shoulder profile, more irregular stripes, and a darker back in adults. All three species, white, striped, and hybrid are very aggressive predators and grow rapidly. Next spring we will have to remove a portion of this school to make room as they grow and by next fall we may have to start the process all over again.

The iconic striped bass


A hybrid striper 
Striper above, hybrid below

The shallow portion of the exhibit has been thoroughly scrubbed, cleaned, re-decorated and re-populated with a variety of smaller fishes and plants from our collection including a new female wood turtle taking the place of the irreplaceable "Woody" who recently passed away of old age.

"Woody" was the mischeivious, charasmatic long-time resident male wood turtle in James River