Aquatic Vertebrate Inventory
of
Williamson and Laurel Creeks
Rainbow Trout, Williamson Creek
Supplement to:
Endangered and Threatened Animal Species Inventory
Laurel Creek Project, Transylvania County, NC
North Carolina
by
Chistopher R. Wilson, Consulting Zoologist
Appalachian Ecological Consultants
425 Roxanna St., Boone, NC. 28607. (828) 264-0928
critterfro@interpath.com
17 August 2000
Study Streams and Methodology
Conducting an aquatic survey of Sylvan Habitat.
On 15 July 2000 and 7 August 2000 aquatic vertebrate surveys were conducted in Laurel Creek, Williamson Creek, and a small tributary to Williamson Creek on the Laurel Creek Project near Brevard, NC. The Laurel Creek Project Area is a proposed limited housing development and conservation easement donation in Transylvania Co. Streams were sampled with standard electrofishing techniques for the purpose of detecting species presence. Brook Trout are the only rare species with a known potential to exist in the study area (see Wilson C. , July 2000. Endangered and Threatened Animal Species Inventory, Laurel Creek Project, Transylvania County, NC) and were targeted in this survey.
Electrofishing is a technique of passing an electric current through the water to attract and stun fish, thus facilitating their capture. It is the most effective technique for detecting species presence in small streams (particularly trout). A direct current (pulsed DC) battery powered (12V) back-pack electroshocker was used for sampling because it is less harmful than AC shockers and has the advantage of causing galvanotaxis (forced swimming) towards the anode. As a fish gets closer to the anode they go into narcosis and can be easily captured. This response helps to draw fish out of complex habitats.
Sampling was conducted with a three person crew. One operated the shocker while the other 2 worked next to the operator with a dip net and a holding bucket. Sampling started downstream and worked upstream so that disturbed debris and sediment did not interfere with observing and catching fish.
One to three 30-40m stretches of stream were sampled in each creek (1 for Williamson Creek Tributary, 2 for Williamson Creek, and 3 for Laurel Creek).
Aquatic Vertebrate Sample Points
All captured vertebrates (fish and salamanders) were identified to species in the field. No animals were collected.
Water quality measurements (Dissolved Oxygen, Temperature, and Conductivity) were taken from each of the three streams with a hand-held digital probe. Stream dimensions were estimated and substrates were qualitatively described.
Results and Discussion
Species observations are listed in Table 1. Water quality, stream dimensions, and substrates are listed in Table 2.
TABLE 1
Vertebrate Species Detected
| | Williamson Creek | Williamson Trib. | Laurel Creek |
| Fish | Rainbow Trout
Black-nose Dace | Black-nose Dace | Rainbow Trout
Mottled Sculpin |
| Salamanders | Red
Shovelnose
Black-bellied | Ocoee
Seal
Spring | Two-lined
Black-bellied |
TABLE 2
Water Quality, Stream Dimensions, and Substrates
| | Williamson Creek | Williamson Trib. | Laurel Creek |
| Dissolved Oxygen (mg/l) | 8.52 | 8.5 | 7.7 |
| Temperature (C°) | 16.5 | 15.8 | 17.6 |
| Conductivity | 13.1 | 16.4 | 11.7 |
| Mean Width (m) | 1.75 | .75 | 2 |
| Mean Depth (cm) | 10 | 4 | 15 |
| Substrate | Sand, gravel, cobble
leaf packs | Sand, gravel
leaf packs | Bedrock, sand, gravel, coble
leaf packs, woody debris |
The State Water Quality Standards state that the temperature for trout waters shall not exceed 20 degrees C (68 degrees F) and DO shall not be less than 6 mg/l. I found no standards for conductivity; the data is simply provided for baseline purposes.
Williamson Creek
Rainbow Trout and Black-nose Dace were found in Williamson Creek.
Black nose Dace are a small minnow, about 2 1/2 inches long, and may be distinguished by the black lateral band which extends around the snout backward through the eye to the tail. Their diet consists primarily of aquatic chironomids, other insect larvae, and diatoms. Commonly the black nose dace is found in the company of brook trout as well as some streams with temperatures above that which brookies can tolerate.
Fish Barrier, Williamson Creek
Rainbow Trout and Dace were only found downstream of the first water fall directly behind the rented house at the entrance to the property. The were no fish in Williamson Creek above the waterfall which indicates this is a fish barrier. Red Salamander larvae and Shovelnose Salamanders were found below the fish barrier while only Black-bellied Salamanders were found above the barrier.
One of the Black-bellies was the largest I have ever seen. Black-bellied Salamanders often take the role dominate vertebrate predators in small first order streams that lack trout; they (along with crayfish) effectively structure and regulate the entire aquatic community.
Black-bellied Salamander, Williamson Creek
The drainage basin of this stream appears heavily forested and un-roaded and the sedimentation within the stream is very low. If there was a chance of Brook Trout inhabiting this stream, it would be above the fish barrier where cooler temperatures and lack of competitors (Rainbow and Brown Trout) may exist. However, the stream substrate above this point is largely bedrock with few pools, appearing to be poor trout habitat.
Williamson Tributary
Black-nose Dace were the only fish species detected in this tributary. The stream also contained adult Ocoee and Seal Salamanders and larval Spring Salamanders. This stream is likely too shallow and ephemeral to support trout and is receiving sediment inputs from the entrance road. Silt fencing and settling ponds may help mitigate the impacts.
Laurel Creek
Rainbow Trout and Mottled Sculpin were the only fish species found in Laurel Creek.
Mottled Sculpin are a bottom-dwelling species that mainly feed on aquatic insect larvae. Larger individuals may also eat crayfish, crustaceans, small fish, fish eggs, and plants. They spawn under rocks or ledges.
Mottled Sculpin, Laurel Creek
Rainbow Trout and are a typical predatory fish community in small heavily shaded streams such as Laurel Creek. While Rainbows mostly eat prey that float downstream, Sculpin are benthic predators (eating prey on the substrate), thus they each have their own niche. This predator community is apparently supported by the high abundance of invertebrates in the creek, which in turn, are supported by the high abundance of leaf-packs and woody debris available.
Laurel Creek had the lowest dissolved oxygen reading (7.7 mg/l) and the highest temperature (17.6° C). There were also few pools over 6 inches deep and the stream was heavily silted. This combination of factors are unfavorable for Brook Trout.
Potential for Brook Trout
In North Carolina, Brook Trout are generally found in isolated, high-altitude (>3000 ft) head-water streams where the water is free of pollution, rich in oxygen, maintains temperatures below 20°C (68° F), and no competing species are found. Brook trout prefer streams with stable water flows, silt-free gravel for spawning, and an abundance of deep pools and riffles with sufficient in-stream cover, such as logs, boulders and undercut banks.
Water temperatures necessary for Brook Trout spawning range from 4.5o to 10oC. They prefer an optimum dissolved oxygen content of >7 mgO2/l at temperatures of <15oC and >9 mgO2/l at temperatures >15oC. Brook Trout also need pools greater than 60 cm deep to accommodate all life stages.
The sections of stream sampled for water quality all had temperatures above the optimum for spawning (there could have been cooler sections further upstream). However, dissolved oxygen was within the trout's preferences in all three streams. Clean gavel substrates were absent in Laurel Creek and the Williamson tributary. Abundant pools, particularly pools over 60cm deep, were lacking in all three streams. The lack of appropriate habitat, the presence of competing Rainbow Trout, and the fact that no Brook Trout were detected, suggest this species does not inhabit the study streams.
Recommendations for Conservation
See (Wilson C. , July 2000. Endangered and Threatened Animal Species Inventory, Laurel Creek Project, Transylvania County, NC)
References
North Carolina Wildlife Resources Commission
Page and Burr, 1991. Freshwater Fishes. Peterson Field Guide series. Houghton Milton Co. New York.
R.J. Rutherford, 1996. ENVIRONMENTAL HABITAT QUALITY REQUIREMENTS / GUIDELINES FOR Brook Trout Salvelinus fontinalis.
Spring Salamander Larva
Dusky Salamander
Ocoee Salamander
Spring Salamander
Southern Appalacian Salamander
Newts
