Category Archives: In The Water

Threadfin jack juvenile

Threadfin Jack juvenile

This is the time of year when juvenile threadfin jacks can sometimes be seen in inland waters. I’ve been on the lookout for them since May, but haven’t seen any. This doesn’t mean they’re not there; so small and shimmery, they’re easy to miss in murky shallow water.

Last week, my vigilance was rewarded. While the water wasn’t too clear, the swell was low so I headed among the rocks near the shore and saw my first threadfin of the year. I took the bottom photo which, while not great, does show the shallow area it tends to inhabit and the sun filtering through that water.

Next day, I went back to the same spot but didn’t see the fish. So I turned and headed out toward deeper water and almost bumped into it coming the other way. I quickly snapped the top photo as it went by, not sure if it was even in the frame, before it disappeared into the shallows.

In the past, these juveniles have stuck around for several weeks, so I’ll hopefully get to see this one a few more times. Ultimately, it will head out to deep water and grow up to be a stocky four-footer living up to 200 feet down.

Threadfin Jack Juvenile in sunlight

Fish farm

Fish farm net pen and boat

Not far off the Kona coast, near the airport, one or more of these nets can often be seen. They’re the submersible net pens of a fish farm run by Blue Ocean Mariculture. The farm raises Almaco jack which it markets under the name Hawaiian Kanpachi.

In the wild, the fish is prone to ciguatera, a toxin that can cause diarrhea, vomiting, numbness, and other unpleasant symptoms. This is the reason almaco jacks aren’t fished commercially. But the farmed fish are free of this problem. I have mixed feelings about farmed fish, but this farm seems to be well regarded and is approved by Monterey Bay Aquarium’s Seafood Watch.

Part of my ambivalence may be down to the fact that, last year, one of the few resident monk seals living around the island became trapped in a pen and drowned. I’ve since heard that when work is being done on a pen, it should be raised so part is above the surface. That way, if something swims into a pen and can’t get out again, it can at least surface inside the pens to breathe. Whether that happened in this case, I can’t say. The official word is that mariculture projects in Hawaii are under review by the Army Corps of Engineers and NOAA.

Fish farm net pens

Three green turtles and a passenger

Three green turtles

It’s not unusual to see green turtles hauled out on shore. Sandy beaches are prime resting spots, but these three chose this rocky bay, only a few hundred yards from some of the best beaches on the island. Perhaps they valued quiet over easy access.

The middle one of the three had gained a passenger that I didn’t notice until I processed the photos, an a’ama crab, making the most of its excellent vantage point.

Green turtle and A'ama crab

A flowery flounder and lobe coral

Flowery Flounder and lobe coral

A small flowery flounder passes over what I think are patches of lobe coral. Those two bumps casting shadows on the top of the fish are the flounder’s eyes, which sit on the end of small stalks. As you can see in the photo, the two eyes are pointing in different directions. This isn’t a case of wandering eyes; they work independently.

However, flounders, like other flatfish, do indeed have the most remarkable wandering eyes. Flatfish start out looking like regular fish, with one eye on each side of the head. As they transition from the larval to juvenile stage, one of the eyes migrates over the head to join the other one on what ends up being the top side of the fish.

The eyes migrate to different places, depending on the kind of flatfish. Some are left-eyed and some right-eyed, which refers to the eyes’ relationship to the mouth. Flowery flounders are left-eyed flatfish, the eyes being to the left of the mouth when seen from head on.

There are pros and cons to photographing flounders and other fish that rely on camouflage for protection. On the plus side, once they settle, they tend not to move so it makes it easier to get a photo. On the downside, because they blend in so well, it’s not easy to get a photo where the fish is clear. The best hope is to see one on the move, as I did with this one, not only to get a photo, but also to enjoy their elegant motion as they ripple through the water.

Hawaiian zebra blennies and padina japonica

Hawaiian Zebra blennies and Padina japonica

A few weeks ago, I posted a photo of a dead blenny floating in a tide pool filled with ‘delicate creamy shells.’ Recently, I returned to that area and I realized that the creamy shells were not shells, but something growing.

It turns out they’re a kind of seaweed, padina japonica, which both surprised and delighted me, since I think of seaweed as being stringy and brown. I learn something every day.

To celebrate, I went back and took some more photos, including these two Hawaiian zebra blennies, both very much alive, and both as delightful as the seaweed, with their little blue dots under the eyes and those oh-so-charming expressions.

Thanks to Jeanne at http://hawaiinaturejournal.weebly.com/ for help with the padina japonica identification.

Hawaiian Zebra blennies with Padina japonica

Monk seal scars

Monk seal scars

Monk seal with scarsThese are older photos, but still interesting to me. I spotted this monk seal one day, not too far from a second seal that is a regular around the Big Island.

The top photo shows some lighter marking on the side of the seal, below and behind the two dark marks. This lighter marking is bleaching, which is applied to seals when possible, to help researchers monitor the population and keep track of their travels. The bleaching only lasts a year as seals molt annually. In addition to the bleaching, most seals have red tags placed in their rear flippers, to help identify them. It can be a hit and miss method as these photos show. This seal has tags in both flippers, but they were never visible to me.

The other interesting thing is those two dark circles on the seal’s back. They’re made by cookiecutter sharks. Cookiecutter sharks are small dogfish sharks, less than two feet in length. They feed by gouging round plugs, hence the name, out of larger creatures such as monk seals.

Cookiecutter sharks live in the deep ocean during the day, sometimes at depths over two miles. At dusk they rise up toward the surface, before descending to the depths again around daybreak. Another reason not to go swimming at night.