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)

Aveiro (N)

1

50

11.2 ± 1.5 (7.5–13.5)

12.7 ± 1.6 (10.7–15.4)

2

50

16.4 ± 1.0 (14.3–18.0)

21.8 ± 1.3 (19.5–23.6)

3

50

20.7 ± 1.4 (18.1–23.4)

26.1 ± 0.9 (24.8–28.1)

4

50

24.8 ± 1.0 (22.8–26.5)

30.7 ± 1.2 (28.7–32.7)

5

50

28.3 ± 1.2 (27.0–30.7)

33.5 ± 1.3 (31.5–36.6)

6

50

33.3 ± 1.0 (31.2–34.9)

36.2 ± 0.7 (34.7–37.1)

7

50

36.6 ± 0.8 (35.2–38.0)

38.5 ± 0.9 (36.8–40.2)

8

48

39.4 ± 0.8 (37.7–40.8)

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

L_t = 76.6 [(1−e^{−0.08(t+0.97)}]

L_t = 43.9 [(1−e^{−0.28(t+0.27)}]

Setubal (SW)

1

50

9.5 ± 1.0 (8.1–11.4)

13.2 ± 1.1 (11.5–15.6)

2

50

14.4 ± 1.4 (12.1-17.1)

19.8 ± 2.8 (14.3–23.5)

3

50

19.5 ± 1.4 (17.4–22.1)

27.6 ± 2.7 (23.0–34.1)

4

50

23.9 ± 1.8 (20.2–26.0)

33.6 ± 3.1 (28.3–40.9)

5

50

29.1 ± 1.5 (27.2–31.6)

37.1 ± 3.6 (31.1–45.4)

6

50

33.3 ± 1.4 (31.0–35.1)

39.2 ± 2.8 (34.1–44.3)

7

50

36.4 ± 1.3 (34.2–37.9)

40.1 ± 2.7 (36.0–43.0)

8

47

38.9 ± 1.4 (36.4–41.2)

42.3 ± 3.1 (37.5–45.8)

9

43

41.4 ± 1.2 (38.1–43.0)

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

L_t = 65.8 [(1−e^{−0.11(t+0.37)}]

L_t = 47.1 [(1−e^{−0.30(t+0.2)}]

Faro (S)

1

50

13.8 ± 1.8 (10.5–17.7)

16.0 ± 2.4 (12.2–19.3)

2

50

20.4 ± 2.9 (15.6–28.0)

26.6 ± 2.6 (22.4–29.9)

3

50

27.9 ± 3.5 (23.6–34.9)

33.1 ± 1.7 (30.0–35.8)

4

50

34.4 ± 2.9 (29.8–38.9)

36.9 ± 1.4 (35.0–39.0)

5

40

37.9 ± 2.6 (33.7–42.0)

39.2 ± 0.9 (38.1–40.9)

6

27

39.5 ± 3.0 (35.1–43.2)

41.2 ± 0.0 (41.2–41.2)

VBGF

L_t = 53.3 [(1−e^{−0.23(t+0.23)}]

L_t = 42.9 [(1−e^{−0.50(t−0.07)}]