Home
TopKayaker.Net: Guide To Kayak Diving

Striped SnapperInvasive Species in Kauai
by Kayak Diver - Marine Biologist Terry Lilley

Futures reef outside of Hanalei is a well known tow-in surf spot and I often take video of my friends surfing in the winter. During the summer when the surf is flat the reef is one of my favorite kayak diving sites and I take video of the reef and marine life often. The top of the dome-shaped reef is about 25 feet deep and it drops off to the sand at about 55 feet deep.

Over the past year I have observed an increasing number of invasive fish species living on the reef out at Futures. One of these species is called a roi or peacock grouper (Cephalopholis argus). This fish was brought in from Tahiti in the 1950s and released into our waters to be an additional food source for our fishermen. This grouper is very good to eat and grows to about 6 pounds. This fish survives by eating over 30 native reef fish a year but the idea was that our fishermen would catch a lot of them and keep the species under control.

All went terribly wrong within 30 years as the roi tends to carry the ciguatera reef toxin that can make you very sick if you eat the flesh. We do not know how many of the roi carry this toxin but since a few people have gotten very ill after eating them most fishermen have stopped catching the roi.

Purple Leaf Scorpionfish

I was scuba diving at Lumaha'i on the North Shore of Kaua'i in an area few divers visit. It is a tall cliff that drops strait down into the sea about 40 feet to the sand bottom and usually has dangerous waves though on this day it was calm.

At about 30 feet on the underwater cliff I noticed something with an odd coloring. At first I thought it was a piece of plastic, but when went over to check it out it moved. Then I thought it was a piece of purple colored algae but it still did not look right. Once I got within about ten feet I could see it was a 4" long Leaf Scorpionfish - but it was purple! I have video of several of these very cool unusual fish but they are normally brown or white. This fish was just stunning and once I started taking video of it I noticed its psychedelic eyes that look like something out of Star Wars.

It moved very slowly, walking on its fins, using them like hands. Its erect dorsal fin made it look larger than it was and it moved back and fourth with the surge like a piece of seaweed. I was amazed at its slow dance across the reef. This little fish, known as Nohu in Hawaiian, can pack a powerful sting if you were to step on it or touch its dorsal fin so it doesn't need to move fast to stay safe from predators.

I was so enchanted by this fish, when I went in I called a dive buddy and we both went out the next day and found it in the same spot. This time it slowly crawled up the cliff and hid in some coral with a few other fish. I saw this rare fish on three more dives until it finally moved on to a new home. I have only found one other reference by talking with other divers and biologist who have seen a purple Leaf Scorpionfish. A rare find now brought from the ocean to the web!

The roi - without humans as a predator - went wild and began eating up many of our native fish! Last week when I dove at Futures I saw over 12 roi on a single one hour scuba dive! This is really bad for our native reef fish like the aweo aweo that the roi feed on. I have been diving out at Futures for ten years now and I used to see a lot of aweo aweo, but on this dive I didn't even see one!

Along with the roi I also saw over 1,000 ta'ape on the reef! This blue striped snapper was also introduced to Kauai in the '50s and this fish eats the eggs of our native fish! On this dive I observed thousands of invasive species and very few native species! This is a very bad sign for the future of our reefs and marine life here in Kauai!

RoiI have been spearfishing the roi on the reefs in Hanalei now for about 6 months and have removed over 55 specimens. This small effort has saved thousands of reef fish from being eaten, but it's still disconcerting that within this time frame I have seen over 400 Roi on the reefs in Hanalei Bay!

The ciguatera poisoning that some of the roi carry comes from algae that grows on the reef. Reef fish like manini, kole and others eat the algae and then the roi eat them. The roi can build up this toxin for years in their flesh. The roi I collect I send to the University of Hawaii for ciguatera testing so we can figure out how many Roi carry the toxin. We also want to develop a ciguatera test kit that is inexpensive and accurate so fishermen can test the roi and go back to eating the good ones. Currently there is a ciguatera test kit on the market but it is not 100% effective and it is expensive.

If we could tell which roi we could eat then the fisherman would go back to catching them and feeding our Ohana. This would clean the reefs up of many of these invasive species. I have dove with some free diver spear fishermen that can catch 5 to 10 roi in one hour!! These guys would clean up our reefs quickly if they know they could safely feed the roi to the community. We could feed every homeless person roi if it was safe and roi in some markets sells for $8 a pound!

diveWith the quantity of roi and ta'ape I saw on this one dive last week we will loose all our reef fish in Hanalei and along most of our coastline within 30 years!

This problem is larger than anyone expected including myself. Once I started counting and taking video of each Roi I was blown away at how many are out there! We must fund an aggressive roi removal project NOW!

Kauai tourism will be drasticlly effected if the tourist cannot snorkel and dive and see beautiful reef fish. Our beautiful reef fish are dissapearing at an alarming rate. Just dive or snorkel Hanalei Bay and count how many roi and ta'ape you see, and you will know what needs to be done. ~

TerryAbout the author:

Terry Lilley is a 1980 graduate of Cal Poly. A career marine biologist, he has photographed, surfed, and studied wildlife around the world and all over the mainland USA and Hawaii, creating movies from the dive footage for schools, government agencies and the public to educate the public about the ocean, including the health of the reefs, health of the marine life, and invasive species like roi, ta'ape and to'au.

Terry currently works with The Hanalei River Heritage Foundation continuing to do daily underwater studies in Kauai with a concentration on the marine life in Hanalei Bay.

Enjoy Terry's BLOG Under Water 2 Web - Lot's of video & pictures!

More Articles & Resources:

BOOKS - MAPS: Clicking on the link will take you to that book in our book section

We hope you've found this information helpful.
We appreciate your feedback & support.
Using these links to purchase or to participate makes TopKayaker.net possible.


Find more TopKayaker.net Affiliates

TopKayaker.net

Valid HTML 4.01 Transitional