The East Australian Current (EAC) hugs our narrow continental shelf, and being so close to shore enables some fundamental discoveries on the fisheries recruitment. The current generates cold upwelled water, that drives a surprising production of plankton for a current that otherwise seems starved of nutrient. Currents transport zooplankton past temperate rocky reefs, such that the majority of fish biomass on the “Great Southern Reef” is based on plankton. This is a fundamental process for the sustainability of new fisheries being established around the burgeoning artificial reef program and future wind farm industry.
The EAC is renowned for its instability, producing eddies large and small, cyclonic and anticyclonic. Along the edge of the EAC is an irregular sequence of many frontal eddies, only 10-30 km in diameter and lasting only 1-3 weeks. The eddies entrain coastal water – even estuarine water – that is preconditioned with zooplankton and coastal fish larvae, forming a temporary offshore nursery before a predator population can establish. The significance of this nursery cannot be determined from larval growth (G) or mortality (M) alone, but only from the ratio of M and G, as a single process. The future of fisheries oceanography is evident in the California Current system, and I will use the M/G ratio of larval pacific hake and recruitment as an example.