Abstract

The study area is the aqueduct in Northumberland used by Brown and Bowler (Proc. 3rd. Int. Symp. Freshwater Crayfish, Kuopio 1976: in press). Samples were hand-caught during 1976-77 and were timed to fall after the end of the growth season (October), before and immediately after the first moult period (June) and before and after the second moult period (August-September). Animals were marked initially with date-specific uropod marks and with individual specific carapace marks when recaptured. Changes in the size, structure, mortality rate and recruitment of the population are discussed. Estimates of population size varied between 9508 ± 1303 on 12 May 1977 and 17421 ± 1842 on 12 August 1977. Overwinter mortality -was estimated at 1.42% week^-1 whilst mortality during the period of the second moult of the year rose to 4.25% week^-1. Estimates of recruitment to the population, which occurred during August and September, are discussed.

Supplemental Documents

• There are no supplementary documents for this article

Cited By

Citations: