Batch fecundity of Lutjanus carponotatus (Lutjanidae) and implications of no-take marine reserves on the Great Barrier Reef, Australia

This study investigated body size to fecundity relationships of a reef fish species targeted by line fishing, and examines the potential benefits of increased batch fecundity in no-take reserves compared to fished areas around the Palm, Whitsunday and Keppel Island Groups, Great Barrier Reef, Australia. Lutjanus carponotatus batch fecundity increased with fork length in a non-linear relationship that was best described by a power function. Batch fecundity differed by more than 100-fold among individuals, with a range from 7,074 to 748,957 eggs in fish ranging from 184 to 305 mm fork length. Furthermore, egg diameter increased with fish size. Based on underwater visual census, the potential batch fecundity per unit area in all three island groups ranged from 1.0 to 4.2 times greater in the no-take reserves than in the fished areas between 2001 and 2004. In 2002, a mean 2.3-fold difference in biomass between no-take reserves and fished areas converted to a mean 2.5-fold difference in batch fecundity per unit area. Greater batch fecundity, longer spawning seasons and potentially greater larval survival due to larger egg size from bigger individuals might significantly enhance the potential benefits of no-take marine reserves on the Great Barrier Reef.