Recruitment is particularly important because of the extraordinary life cycle of both shortfin and longfin eels.
Recruitment is the process by which glass eels arrive from the East Coral Sea spawning areas and make their way into and up our rivers and waterways.
There is enormous natural mortality in this journey and whilst variable only a very small percentage make it.
Recruitment is incredibly important as an indicator of fishery health. Whilst oceanographic conditions enormously affect the numbers arriving each year, the number of elvers arriving at dams are a reflection of how many breeding females are getting to the spawning grounds and how well eels are replacing themselves.
All spawning eels die in the open ocean after their one and only breeding migration (heke).
Along with Niwa, MPI, electricity generators and other concerned groups, EECo collects elvers in traps at the dam face. Catches are analysed for shortfin or longfin proportions and the babies stuck at the base of the obstruction are given a helping hand into the waterways above.
Annual returns to each dam face allow us to construct a recruitment index representing fishery health. The index has been maintained since 1992 with considerably better recruitment over recent years.