Thursday, 18 February 2016

Bitten by a Banded Kokopu!

The cool thing about working at Rotokare is that lots of different scientists come to visit. On Monday morning when I arrived at Rotokare, there was already a group of people gathered outside, one of whom was Stella McQueen. Stella is a fresh water ecologist and author, currently working with DOC in Taranaki. Stella had brought out a troop of fish enthusiasts to check out the Banded Kokopu fish in the stream at Rotokare.

I had seen these fish and photographed them a few days earlier, but I hadn't known much about them at all! The Banded Kokapu are one of 5 species of fish that, when they are babies, are known as whitebait! This is what whitebait look like if they are given the chance to grow up. I was surprised to hear that 4 out of 5 of the whitebait species are threatened (Banded Kokopu are the one that is not listed as threatened). Banded kokopu are normally nocturnal, but the interesting thing about the Rotokare fish is that they unusually like to come out in the day. Stella is passionate about educating the public about the risk that our native fish face, not only from whitebating, but from habitat loss. Check out her Facebook page New Zealand Native Fish.

Stella told me that the kokopu have a lateral line that leads to a cell to detect vibrations and water movement and allows the fish to orientate themselves in their environment. When the fish are young especially, they can climb. They can travel up waterfalls and even across land, breathing through their skin. These fish really fascinated me! At Rotokare (where whitebaiting doesn't take place), the introduced perch are one of the greatest threats to the native fish population, as well as the water quality in the lake. Small perch eat zooplankton in the lake. The zooplankton usually feasts on phytoplankton, but if the perch have eaten the zooplankton, the population of the phytoplankton will explode, causing an algal bloom (as is the current case at Rotokare). The large perch feast on other (native) fish and sometimes even turn to cannibalism.

We fed the fish the worms that Stella had brought along, and mealworm beetles from Rotokare. The longer we stayed, the more confident (or greedy) the fish became, and they would jump right out of the water to grab our fingers! I may have squealed a wee bit the first time one bit onto my finger, but it didn't really hurt at all! What a cool experience. I'll be spending some time researching how we can go about improving the habitat for these native fish at Rotokare.

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