A series of laboratory experiments was conducted to determine fertilization
success in the commercial abalone Haliotis tuberculata I,. Fertilization s
uccess is a function of sperm dilution, sperm-egg ratio, gamete age and the
amount of time sperm and eggs are in contact. Sperm density required for o
ptimum fertilization success in vivo, using 10 mi culture volume, was in th
e range 5 x 10(4) to 5 x 10(5) sperm ml(-1). When these experiments were re
peated using 500 ml culture volume, results showed high levels of fertiliza
tion success across a far larger range of sperm dilutions with success >80
% at 10(3) sperm ml(-1). Sperm-egg ratios of >100:1 have little effect on f
ertilization success, but below these levels this factor becomes significan
t. Viability of both sperm and eggs decreased with age so that no fertiliza
tion occurred after 2.5 h. Maximum fertilization success occurred after 30
min sperm-egg contact time. These data suggest that sperm limitation may se
verely compromise reproductive success in exploited populations of H. tuber
culata.