Table 4.

Semen characteristics and plasma testosterone for aquarium and in situ sand tiger sharks Carcharias taurus during the mating season, April to June.

		Aquarium				In situ
	P *	n	Mean ± SE	Median	Range	n	Mean ± SE	Median	Range
Sperm concentration (106/ml)	0.087	14	12.05 ± 3.71	7.5	0.62–48.8	24	66.57 ± 25.14	17.35	0.08–466
Volume (ml)	0.370	14	209.8 ± 75.2	74.5	20–1000	24	185.1 ± 32.4	125	7.5–580
Morphology (%)	0.000	12	79 ± 4	81	42–96	22	93.95 ± 1.99	97.5	58–100
Plasma membrane integrity (%)	0.010	13	32.7 ± 9.3	20	0–87.9	19	62.6 ± 6.3	75	10–95
Total motility (%)	0.004	14	27 ± 8	11	0–80	23	57 ± 6	70	10–95
Progressive motility (%)	0.002	14	5 ± 2	0	0–26	23	18 ± 3	20	0–50
Status	0.008	14	2.3 ± 0.4	2	0–4	23	3.6 ± 0.2	4	2–4
pH	0.051	14	7.1 ± 0.1	7.12	6.25–7.7	24	6.8 ± 0.1	6.75	6.5–7.75
Osmolarity (mOsm)	0.322	13	1088 ± 25	1060	989–1328	22	1104 ± 16	1108	935–1254
Plasma testosterone (ng/ml)	0.000	13	9.35 ± 6.34	1.2	0.2–84.6	21	28.57 ± 5.83	20.8	1.4–103.4

^*Wilcoxon rank-sum (Mann–Whitney) test P-value.