Whitebait and the extinction debate: Why the whitebait fishery debate may not alleviate conservation concerns

Abstract

A recent NZ Geographic article has stirred up an already vigorous debate (see the full article here goo.gl/TcWWU8). “What we call ‘whitebait’ are the juveniles of five fish species: giant kōkopu, banded kōkopu, shortjaw kōkopu, īnanga and kōaro. The first is predicted to go extinct by 2020, the second by 2023, and the rest by 2034”. The key point here is extinction. It refers to the death of the last individual. If the above predictions were correct this would occur in 3, 6 and 17 years for these species. Such extinction might occur through one of these 3 events: 1) all adult fish die before spawning 2) spawning occurs but the eggs die 3) eggs hatch but larvae and juvenile (whitebait) mortality causes extinction (or contributes to #1) The presence of whitebait shows that adult fish have successfully bred. Whitebait numbers have declined since historical times yet the current trend is impossible to gauge and likely fluctuates between years. The life cycle depends of producing lots of juvenile whitebait, most of which will die. Those making it to adulthood are the breeders for the next generation.