Robust estimates of a high / ratio in a top marine predator, southern bluefin tuna.

Genetic studies of several marine species with high fecundity have produced "tiny" estimates (≤10) of the ratio of effective population size () to adult census size (), suggesting that even very large populations might be at genetic risk. A recent study using close-kin mark-recapture methods estimated adult abundance at ≈ 2 × 10 for southern bluefin tuna (SBT), a highly fecund top predator that supports a lucrative (~$1 billion/year) fishery. We used the same genetic and life history data (almost 13,000 fish collected over 5 years) to generate genetic and demographic estimates of per generation and (effective number of breeders) per year and the / ratio.