Ask an expert: fishy questions!
Author and native-fish enthusiast Stella McQueen answers our most burning fishy questions…
How do I tell New Zealand’s two native eels apart?
Stella says: On a longfin, the fin on the back comes two thirds to three quarters of the way up the body. With shortfins, it only comes just over halfway up. Also, look at the skin when the body bends: big loose wrinkles mean longfin; tight wrinkles mean shortfin.
But here’s a handy trick for identifying eels if all you see is a head poking out from under a bank… If the mouth is long and goes way past the eye then it’s a longfin. With shortfins, the mouth is shorter – it doesn’t really go past the back edge of the eye. Also, longfins have flabby lips and shortfins have thin lips.
If mudfish are so good at hiding and surviving out of water, why are they endangered?
Stella says: Mudfish are amazing, but they can’t survive out of water for more than a few months. They can’t feed out of water, and if they dry out too much they die. The single biggest past and present threat to mudfish is drainage of wetlands.
Mudfish live in wetlands, and only in wetlands. Around 95% of New Zealand’s wetlands have been drained and destroyed, mainly for farming, but also for urban areas. Climate change is also a really serious threat to these species. Climate change is likely to cause longer, more serious and more common droughts.
Why are Canterbury mudfish the most threatened?
Stella says: Canterbury mudfish are in trouble. After record droughts in recent years, all of the Canterbury mudfish populations in natural springs and streams have been wiped out. The few populations of Canterbury mudfish left are in the water races – old channels that criss-cross the Canterbury plains, which were dug for irrigation and stock water. Thankfully, enthusiastic farmers and schools are helping to create new wetlands and moving the fish into them.
Stella McQueen is the author of A Photographic guide to freshwater fishes of New Zealand, with photographs by Rod Morris. You can also find out lots more about our freshwater treasures at her Facebook page.