A Colony of Bluestripe Snapper

Jeff Poses with the Octopus, Bonaire 2009. Are we being followed?

    Paul Allen has returned to Kona.  This time he is driving the Octopus, his mega-yacht that looks like a small cruise ship with a helipad on the back.  The Octopus was floating off shore as I swam on Paul's eponymous reef this morning.  I'm hoping that someone will let him know that I am trying to popularize that bit of coastline as Paul Allen's Reef.  Maybe I'll receive an invitation to dine aboard the Octopus with the great man himself.   If you're out there and you know Paul Allen, let him know that I would be delighted to sing (through my trusty snorkel) the octopus doxology as a pre-dinner toast.  I'd love to see that boat.  But I digress.

    The main thrust of this evening's symposium is the Bluestripe Snapper.  At least three game fish have been introduced to Hawaii.  All three are reputed to be ciguatoxic, so from the standpoint of dinner, the experiment has been less than a total success. Looking at pure numbers, though,  the Argus Grouper, has been a remarkably successful transplant.  One sees a gazillion of these blue and silver fish scooting around the reef.

    The other two nouveau fishe are snappers...Blacktail and Bluestripe.  Both used to be fairly common...twenty years ago.  Now their numbers have dwindled. The Blacktail is slightly more common than the Hawaiian Hogfish.  Which is to say just this side of rare.   In the last six months I have seen one immature Hawaiian Hogfish.  Such a rare sighting that it took me an hour with the books to puzzle out the ID.  In that same time I have seen maybe two Blacktail Snapper.  I caught one especially approachable individual at City of Refuge.  Look for his picture in the Summer in the City blog.  Tell Paul, if he would like, that I will sing my version of that great Lovin' Spoonful hit along with his karaoke machine aboard the Octopus as an after dinner treat.  Or not...its totally his choice.

Bluestripe Snapper,  Kailua Kona 2012

    The Bluestripe Snapper is slightly more common than the Blacktail.   But still not a common fish.  Just recently, though, a colony of this black eyed beauty has appeared on the Ironman side of the pier.  I see them every time, just on the shore side of the big orange buoy to which the Body Glove attaches her bow line.  There they reside among some luscious coral,  in ten easy feet of Kona crystal.  I don't mind revealing this location because, as above, they are not safe to eat.  If Paul, or one of his guests would like to take a look, tell them to contact me here at jhill257.  We'll leave a fish out for you.

How can the Great Paul Allen, he for whom is named the magnificent Paul Allen's Reef,  resist these Handsome Snappers?   (Not to mention the photographer and his lovely bride?  Who are awaiting the invite with bells on.)

The Fish Ball

Airman Adrian Cronauer Slurps a Fishball

   For many of us, when we think of a fish ball, we think of something swimming in an excessively spicy Asian soup...the broth that made Robin Williams gag when all he really wanted was to make time with the pretty Vietnamese girl in Saigon.   Here in Kailua this term is applied to a  large conglomeration of fish.  Frequently it is called a bait ball.  For the last month or more, we have been graced by a large, teeming mass of fish right in Kailua harbor.  On several occasions, I have had the opportunity to swim among this multitude.  A week ago, with our daughter Leslie, we had a chance to see something pretty amazing and get some photographs in clear water.

Four Ulua Hunting at Kailua Pier

    That day the mass of fish in question was fairly close in, only as far out as the second swim buoy.  In fact, we swam past it and were attracted back to it by four ulua swimming with purpose.  In Hawaii, the term ulua is applied to several large jacks.  Most commonly Blue Fin Trevally.  This is a handsome fish that is seen frequently, hunting singly or in pairs.  One never sees an ulua with out the sense that it is hunting.  Like a wolf.  (A couple times I have seen ulua that were three feet in length and wondered if they were considering me as a tasty morsel.)  One or two ulua may hunt with some other fish, like a Multibar Goatfish.  However, it is not common to see four hunting together.  So we followed them a few meters and they brought us to the ball of fish.

Blue Fin Trevally with Big Eye Scad

     As we approached the large mass of fish, we had an additional treat.  There were not four trevally hunting the scad, but at least ten.  I had never seen so many Blue Fin Trevally in one place.  I watched them for about fifteen minutes.  Although ulua always look like they are hunting, I have never seen them take a fish as prey.  On this day they swam through the school singly or in larger formations, apparently looking for a weaker fish that would be easy prey.  I was reminded of Richard Dreyfus in Never Cry Wolf explaining how the wolves keep the caribou strong.  These ulua were busy doing their part to keep the scad strong..On my watch, they did not find a weak individual and I still haven't seen a trevally take another fish.

Big Eye Scad, Kailua Kona November 2012

     We had seen this bait ball several times before, but always at least ten feet deep and always in cloudy water.  Today the multitude was swimming in clear water, frequently very near the surface.  These delightful conditions afforded us the opportunity to take a few good pictures.  These photos permit us to identify the fish as Big Eye Scad, another member of the jack family.

   We've been interacting with this group of fish for a while and you may recall that I've been calling them scad.  However, when I repaired to the field guides, I had to admit that the distinction between Big Eye Scad and Hawaiian Flagtail, at least for us amateurs who don't actually have the fish in a lab, is pretty darn subtle.   They are roughly the same size, relatively deep bodied and silvery.  The immature flagtail, a common tidepool fish, has a tail striped black and white.  There is no banner on the caudal fin of the adult.   After a lot of consideration, I have decided that the best field mark is a concavity of the snout  on the flagtail.  Additionally, the caudal fin of the scad is a little finer and more scissor-like, but this is a softer call and relies on judgement.

Big Eye Scad.  No concavity on the snout!

   Furthermore, behavior doesn't help very much.  Both form aggregations in calm shallow water by day and disperse at night to feed.  Both are apparently taken as food fish.  I wonder if the Hawaiians have trouble differentiating the akule from the aholehole?   And how do they taste?  Perhaps I should ask the ulua.

jeff

Today's blog is dedicated to my brother, Chuck Hill, on his big 6 0.  Chuck is a fantastic writer and the Kona Beach Blog was his idea.  He has been an invaluable source of advice and encouragement.  So Happy Birthday, Chuck!  This fish is for you!

jwh
   

Batesian Mimicry in the Immature Flying Gurnard

How far do I have to haul this thing?

   Of late, we have enjoyed some interesting sightings.  On my last swim with Charles, on the Ironman side of the Kailua pier, we found a modestly sized blood crab in an enormous Marlinspike Auger.  Why a hermit crab would choose to haul that 15 cm shell over the coral is a  question for the ages.  But our experience with an immature Flying Gurnard two days ago is even more thought provoking.

   It is widely accepted that some large moths (and a few butterflies) through evolutionary pressure, have developed large spots on their wings as a form of Batesian mimicry.  The large spots suggest the eyes of an owl and in this model deter predators, such as lizards and birds, that are taken by owls as prey.   The polyphemus moth, which ranges over much of North America, is a classic example. 
 

Polyphemus Moth, Dan Mackinnon

   Henry Walter Bates was a British naturalist who studied the insects of the Brazilian rainforest.  He worked for over a decade, collecting and cataloging the insects.  In the process, he noted that the wing pattern of some butterflies closely resembled that of a vastly disparate species.  Back at the Linnaean Society in London, he proposed that one species of butterfly had developed the wing pattern of another less desirable species as a defense mechanism against predators.  While Bates was considering his butterflies, Darwin and Wallace were independently working on the theory of evolution.  Thus, Batesian mimicry was immediately proclaimed as a classic example of this radical new theory of evolution;  the tasty butterflies had evolved the wing pattern of the nearly identical poisonous species.  And, of course, Bates was derided by

God Creating Batesian Mimicry

those who chose not to accept an explanation for the natural world that did not involve a creative deity. (Thanks to Wikipedia from which this information has been condensed.)

    A bit of thought will show that if moths have spots that look like the eyes of an owl, it is not classic Batesian mimicry.  And papers have been written to suggest other adaptive reasons for these large eye-like spots.  Never the less, the idea that the wing spots on large moths have evolved to mimic the eyes of an owl is firmly entrenched.  Not only that, but lots of other animals have eye patterns.  (The Ferruginous Pygmy Owl of Mexico has an eye pattern on the back of his head!)

    With that background, I will bring you back to the cool waters of the inner harbor.  Not out by King Kamehameha's heiau, but right by the sandy beach, where, having completed my swim, I was just getting

Flying Gurnard prior to agitation.

 ready to stand up and remove my fins.  At this climactic moment I looked down to find a small Flying Gurnard.  He was grazing peacefully on the soft sand with his wings tucked in at his sides.  In this posture, he blended in and it required a probing eye to pick him out.  As I approached him for a picture he did something that I had not seen before.  He flitted quickly, simultaneously opened his fins to their full extent and raised his poisonous dorsal spine.  (Gurnards are closely related to scorpionfish.)  Not only that, his colors became instantly more vivid.  I have never seen a more beautiful gurnard!  I proceeded to stalk him across the floor of the lagoon, seeing this behavior four or five more times and capturing a few pictures.

    As a social aside, I spotted the gurnard a few feet away from three chubby adults of a certain age...two matrons and a gentleman.  They had been standing in that very spot, pot belly deep in the lagoon, when I shoved off thirty minutes before, recounting every foible of every person known to them.   And there they stood in full gossip, not the least disturbed that a crazed snorkeler was turning watery doughnuts, hard by their chubby elbows.  (Two ladies taking pictures on the beach were more interested in our exciting observations.)

Flying Gurnard in signal coloration.  Do you see the eyes?

Back at Casa Ono, looking at my photographs, I could not help but be reminded of owl eyes.  Do you see them?  Certainly, the sea is full of classic examples of Batesian mimicry.  Sandra and I saw many Mimic Angelfish in Bali and a few of the poisonous pufferfish that they so faithfully impersonate.  And a few fish (the Devil Scorpionfish with his brilliant red and yellow axillae comes to mind) will flash bright colors, encouraging you to abort your unwise approach. 

Never the less, I can not get away from the image of these eyes peering back at me from the fins of the immature gurnard.  To the best of my knowledge,  there are no owls in the sea.  Thus, I am left wondering just what they might represent from an evolutionary point of view.  And does this similarity between "eyes" on the wings of the gurnard point to the adaptive significance of similar owl eye-like pattern in other animals?

jeff  October 2012