Effects of spawning-run delay on spawning migration of Arctic grayling
Fisheries Bioengineering Symposium: American Fisheries Society Symposium 10
Colt J;White RJ;
American Fisheries Society
The paper examines the effects of delay on the spawning run of Arctic grayling Thymallus arcticus in Fish Creek, a tributary of the Jack River, near Cantwell, Alaska. The run was sampled at a weir for 25 d during May 1988. Tagged Arctic grayling were delayed in holding pens for 3, 6, or 12 d, then released; control fish were released within 12 h of capture. During delay, a high proportion of females continued to ripen. Males were usually ripe before delay and remained ripe over a longer period than females. Most changes in maturity occurred within the first 3 d of delay. Distribution and migration of delayed and control fish were monitored by recapture in upstream traps. Females released 'running-ripe' had higher migratory rates but proportionally fewer reached upstream areas compared with 'less ripe' females. Control fish swam farther upstream than fish delayed 3 d or longer. Delay is probably more critical for females than males. Reduction in distances traveled by both sexes as a result of migratory delay may lead to the use of nonpreferred spawning habitats and decreased recruitment. It is suggested that spawning delays for Arctic grayling not exceed 3 d.