valves to close. The mussel remains on the hook \mtil forcibly removed. 

 Because of the numerous hooks used^ almost complete coverage is achieved 

 when the brail is dragged over the bottom. Catch success is dependent 

 upon the characteristic habit of mussels to embed with their posterior 

 end oriented upstream with valves open to feed. However, only a portion 

 of a population at a given time may feed and be oriented in a vulnerable 

 position when a brail traverses their bed. In spite of these limitations, 

 the crowfoot brail is an effective method of harvesting from areas con- 

 taining an abundant population of mussels. 



METHODS AND MATERIALS 



Most of the studies described in this report were carried out on 

 Wheeler Reservoir between mile points 308 and 316 (see figure l) . A 

 limited amount of material was collected on Chickamauga (mile ij-98 to 519) ^ 

 Guntersville (mile 379 to 389), and Kentucky (mile I90 to I96) Reservoirs, 

 all impoundments of the Tennessee River. Methods used in the studies are 

 briefly described: 



Commercial catch . --Monthly catch records were obtained from a 

 mussel camp on Wheeler Reservoir. These records represented the total 

 catch of all mussels of commercial value harvested from the river between 

 mile points 308 and 316 during the years of 1956 and 1957* The total 

 available harvest area was estimated by planimetric method using a detailed 

 stream map provided by the Tennessee Valley Authority. The fishing area 

 was calculated to be 7^^80,000 square yards. Mussel catch was measured 

 by boxloads; a standard box holds approximately 200 pounds of mussels. 

 An estimate was made of the number of pigtoe mussels harvested, based on 

 sample counts of 28 representative boxloadsj the average mmiber per box- 

 load was then multiplied by total boxloads to calculate the total catch 

 of pigtoes. The total number caught was then divided by the total fish- 

 ing area (in square yards) to calculate the total catch of pigtoes per 

 square yard for 1956 and 1957 • 



Brail sampling. --Quantitative sampling was accomplished with a 

 crowfoot brail to determine the rate of catch per drag from a given area. 

 All equipment was rented from and fished by a commercial fisherman. Each 

 brail sample consisted of dragging a measured distance of 100 yards, then 

 sorting and counting the catch. The area sampled was calculated in square 

 yards by multiplying the length of the brail by 100 yards. Catch success 

 was expressed in terms of the average catch of mussels per square yard per 

 drag . Brail sampling was randomized within fishing areas and by time 

 periods during two complete harvest seasons (March through August) with 

 1^4-2 samples taken in 1956 and lij-9 samples taken in 1957 from Wheeler 

 Reservoir. 



Brail samples were also taken in commercial fishing areas on 

 Chickamauga, Guntersville, and Kentucky Reservoirs in 1957* Collections 

 consisted of ll,i<01 mussels from all locations. 



