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Density, Growth and Reproduction in Populations of Astacus astacus and Pacifastacus leniusculus in an Isolated Pond

1971; Wiley; Volume: 22; Issue: 3 Linguagem: Inglês

10.2307/3543861

1600-0706

Sture A. A. Abrahamsson,

Parasite Biology and Host Interactions

Pacifastacus leniusculus females mature in the third summer and males in the second. Corresponding ages for Astacus astacus are the fourth and the third summer, respectively. A positive correlation was obtained between the size of females and the number of pleopod eggs in both Astacus and Pacifastacus. Comparison of eggbearing females of Pacifastacus of the 90-99 mm size group with Astacus showed a lower egg production for Astacus. The differences in Rogle Ponds, Sweden were probably accentuated by pressure of food shortage on the dense Astacus population. Both males and females of Astacus and Pacifastacus reproduced every year after attaining adult size. Adult females of Pacifastacus had a greater relative abdominal width and a smaller egg diameter. The size of the adult population of Pacifastacus was estimated as 9,000 individuals. Before the outbreak of crayfish plague, the Astacus population was calculated as about 12,400 individuals. One-summer juveniles of Astacus were about 23 mm long, and of Pacifastacus about 40 mm. Two-summer males of Astacus averaged 49 mm, females 47 mm. The corresponding values for Pacifastacus were 82 and 79 mm, respectively.