No abstract

Experimental removal of woody debris from a small, gravel-bed stream in a forested area resulted in a four-fold increase in bedload transport at bankfull discharge. This was caused by increased transportability of sediment previously stored upslope of debris buttresses or in low-energy hydraulic environments related to debris. Bank erosion delivered additional sediment to the channel, and transport energy was increased by an inferred increase in the component of total boundary shear stress affecting grains on the bed. Increased transport following debris removal in May 1987 continued throughout the entire autumn storm season through late November 1987, indicating persistent adjustment of the stream bed and banks despite marked response to earlier flows as large as bankfull. Stream bed adjustments included development of a semi-regular sequence of alternate bars and pools, many of which were spaced independently of former pool locations.

Survival of larval trout through the swim-up stage was determined for eyed eggs of brown trout (Salmo trutta) planted both in the streambed and in Whitlock Vibert boxes. Tests were made in first-, second-, and third-order streams and intragravel environmental factors were evaluated. Direct plants produced 2 times more sac fry than box plants and 3.5 times more swim-up fry. Sediment deposition was approximately 100% greater in first-and second-order streams than in third-order streams, and sediments accumulated disproportionately in box plants. This seemed to accolmt for survival differences between planting techniques and among stream orders.

Vibert boxes are commonly used in planting trout eggs in streams for incubation. We compared survival of eggs, embryos, and swim-up fry of brown trout (Salmo trutta) in direct intragravel plants and in Vibert boxes. We found that egg mortality increased disproportionately in Vibert boxes after 4 weeks until time of hatching. Direct intragravel plants yielded the highest survival to the swim-up stage.Conservation groups and agency fisheries personnel have planted fertilized trout eggs into stream gravels to introduce, restock, or supplement populations of stream salmonids. Eggs have either been planted in box-containers of some type (Vibert 1949; Anon. 1951;Rasmussen 1970) or deposited directly into the gravel (Stockley 1954;Sedgwick 1960). Boxes are usually used, but there are no data suggesting that this method is better than planting eggs directly in stream gravels (J. D. Mclntyre, unpublished data). The purpose of this study was to determine whether one of the two methods resulted in greater egg and fry survival. MethodsThis study was conducted in conjunction with the planting of 1 million eyed eggs of brown trout (Salmo trutta) over a 9.5-km reach of the South Mills River in Henderson and Transylvania counties in western North Carolina. The river is a fourth-order stream, draining a forested watershed of 9159 ha. Channel gradient averages 2% over substrates of about 20% sand, 7% gravel, 70% rubble, and 3% boulder. Seven planting locations were selected in the fall of 1977 on the basis of spawning-size gravels, apparent subsurface flow (as indicated by topography), and protection from freezing. Vibert boxes and the methods described by Stockley (1954) and Sedgwick (1960) were used to introduce eggs into sites prepared by digging depressions 1 m in diameter and 25 cm deep in the stream bed. Both types of Vibert boxes were tested-the original single-compartment box (Vibert 1949) and the new two-compartment box designed by Whitlock (Federation of Fly Fishermen 1975).At each planting location, each of the following treatments was replicated three to five times: a plant of four two-compartment Vibert boxes, each containing 500 eggs; a plant of two one-compartment Vibert boxes, each containing 500 eggs; and a direct plant of 5000 eggs. Each replicate shared comparable substrate and overgravel and subsurface water flow. The remaining eggs were planted in boxes and with direct plants in the most expeditious manner possible. All plantings were.numbered and marked with metal stakes for future sampling.To estimate the number of fry leaving the gravel, we selected one replicate at each of three locations and installed a fry trap (Phillips and Koshki 1969) on each treatment for the duration of the study. An attempt was made to excavate and evaluate at least two complete replications every 2 weeks. Waterborne eggs and fry were collected in a fine-mesh seine placed immediately downstream from the planting.Eggs were planted in early December, about 20 days before scheduled hatching. Colder than normal weather, how...

Bryant, M.D.; Porter, P.E.; Paustlan, S.J. 1990. Evaluation of a stream channeltype system for southeast Alaska. Gen. Tech. Rep.