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Table 1 Mean shell length-at-age (SL) and von Bertalanffy growth function (VBGF) of D. exoleta from three locations along the Portuguese coast (Aveiro, Setúbal and Faro) obtained using two ageing techniques (shell surface rings and acetate peels)

From: Age and growth in three populations of Dosinia exoleta (Bivalvia: Veneridae) from the Portuguese coast

Location Age (years) Surface rings Acetate peels
Number of observations Mean SL (mm) Number of observations Mean SL (mm)
Aveiro (N) 1 50 11.2 ± 1.5 (7.5–13.5) 50 12.7 ± 1.6 (10.7–15.4)
2 50 16.4 ± 1.0 (14.3–18.0) 50 21.8 ± 1.3 (19.5–23.6)
3 50 20.7 ± 1.4 (18.1–23.4) 50 26.1 ± 0.9 (24.8–28.1)
4 50 24.8 ± 1.0 (22.8–26.5) 50 30.7 ± 1.2 (28.7–32.7)
5 50 28.3 ± 1.2 (27.0–30.7) 50 33.5 ± 1.3 (31.5–36.6)
6 50 33.3 ± 1.0 (31.2–34.9) 50 36.2 ± 0.7 (34.7–37.1)
7 50 36.6 ± 0.8 (35.2–38.0) 43 38.5 ± 0.9 (36.8–40.2)
8 48 39.4 ± 0.8 (37.7–40.8) 18 40.1 ± 1.2 (38.1–41.7)
9 21 41.3 ± 1.0 (40.0–43.0)   
10 5 43.7 ± 1.3 (42.8–44.6)
VBGF   Lt = 76.6 [(1−e−0.08(t+0.97)]   Lt = 43.9 [(1−e−0.28(t+0.27)]
Setubal (SW) 1 50 9.5 ± 1.0 (8.1–11.4) 50 13.2 ± 1.1 (11.5–15.6)
2 50 14.4 ± 1.4 (12.1-17.1) 50 19.8 ± 2.8 (14.3–23.5)
3 50 19.5 ± 1.4 (17.4–22.1) 50 27.6 ± 2.7 (23.0–34.1)
4 50 23.9 ± 1.8 (20.2–26.0) 50 33.6 ± 3.1 (28.3–40.9)
5 50 29.1 ± 1.5 (27.2–31.6) 50 37.1 ± 3.6 (31.1–45.4)
6 50 33.3 ± 1.4 (31.0–35.1) 46 39.2 ± 2.8 (34.1–44.3)
7 50 36.4 ± 1.3 (34.2–37.9) 29 40.1 ± 2.7 (36.0–43.0)
8 47 38.9 ± 1.4 (36.4–41.2) 25 42.3 ± 3.1 (37.5–45.8)
9 43 41.4 ± 1.2 (38.1–43.0) 11 44.4 ± 4.9 (38.8–47.4)
10 30 43.9 ± 0.5 (43.1–44.5)   
11 13 46.1 ± 1.2 (44.6–47.3)
VBGF   Lt = 65.8 [(1−e−0.11(t+0.37)]   Lt = 47.1 [(1−e−0.30(t+0.2)]
Faro (S) 1 50 13.8 ± 1.8 (10.5–17.7) 50 16.0 ± 2.4 (12.2–19.3)
2 50 20.4 ± 2.9 (15.6–28.0) 50 26.6 ± 2.6 (22.4–29.9)
3 50 27.9 ± 3.5 (23.6–34.9) 50 33.1 ± 1.7 (30.0–35.8)
4 50 34.4 ± 2.9 (29.8–38.9) 45 36.9 ± 1.4 (35.0–39.0)
5 40 37.9 ± 2.6 (33.7–42.0) 17 39.2 ± 0.9 (38.1–40.9)
6 27 39.5 ± 3.0 (35.1–43.2) 1 41.2 ± 0.0 (41.2–41.2)
VBGF   Lt = 53.3 [(1−e−0.23(t+0.23)]   Lt = 42.9 [(1−e−0.50(t−0.07)]
  1. Data presented as mean ± SD and size range