White-Tongued Jack and Other Mysterious Fishes from the Deep

Sport Fishing readers try to stump the Fish Facts experts with strange catches.

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Jack Speaks with White Tongue
Q: A few weeks ago, I came across a school of roughly 10,000 fish while free diving at Keahole Point in Kona. They're all in the 3- to 4-pound range. I've never seen these fish before in 30 years of free diving/spearfishing in Hawaii. At first they appeared solid black with chalky-white mouths. While I hung suspended in the school, the fish would swim tightly around me, flashing a wide range of body colors, many including dark vertical bars. I learned that these fish are called white-mouth jacks, but apparently they go by many other common names as well: white-tongue jacks, white-lip jacks, cottonmouth jacks and "dobe" jacks. These fish are being caught by shore fishermen, and they have all been full of row and sperm sacs. So what species is this? Mark Barville Kona Hawaii (Answer on next page)
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Jack Speaks with White Tongue
A: That's a great account, Mark. You've found trevallies of the genus Uraspis, a distinct outgroup of small carangids. However, there are three species of Uraspis known to occasionally visit Hawaiian waters from time to time, and identifying them can be tricky. The most likely candidate is the white-tongued jack, Uraspis helvola, a pelagic species distributed throughout the Indo-West Pacific region from the Red Sea east to Hawaii, as well as occasionally being recorded from Ascension and St. Helena in the South Atlantic. This species grows to nearly 20 inches and 9 pounds in weight. Another very closely related species that has an even wider distribution (occurring worldwide in tropical waters, including Hawaii), is the cottonmouth jack, Uraspis secunda. Scientific-identification keys point out that adults of U. secunda and U. helvola are virtually impossible to distinguish. Both grow to around the same size, have similar body shapes and coloration as adults, and both have striking white tongues, as well as white floors and roofs of their mouths, with the remainder of their mouth blue/black in color. In contrast, the remaining species in this group is called the white-mouthed jack (Uraspis uraspis), which grows only to around 12 inches long and around 2 pounds, so the fish in your photo are unlikely to be U. uraspis. All species of Uraspis feed mainly on pelagic zooplankton and small fishes and squids, and are reportedly good eating. — Ben Diggles
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When Yellowfin Get Emotional
Q: While diving in May at remote Roca Partida, far off Baja in Mexico's Socorro Islands, we watched a dozen big yellowfin tuna — as long as the reef sharks and much girthier — circling the islet. It was our last dive of the day, at about 5 p.m. The tuna sliced through the current effortlessly, chasing each other back and forth across the north end of the rock, from the surface to maybe 50 feet deep. We had to kick like heck just to hold position in order to watch the show. It was obvious that something was going on. One moment they all would look like "normal" yellowfin — silver with the yellow stripe down the side. But then all of a sudden, vertical tigerlike bars would appear on some of the fish, the pursuers, as in this photo. Every few minutes the tuna would change directions rapidly and seemingly almost collide, or rocket toward the surface and come together in a flurry of activity. Then the fish would mellow out for a bit, cruising lazily, before repeating the whole thing again. What was happening? Brandon Cole Spokane Valley, Washington A: Tuna, like billfish, can "light up" when they change their emotional state — the vertical bars are quite clear. I see billfish do this a lot once I get them alongside a vessel for PSAT (satellite) tagging. In this case, based on your description, my best guess would be that these yellowfin possibly were exhibiting pre-spawning behavior. From their description, these were clearly mature fish. Would have been nice to see a white cloud of milt in the image to confirm this. In any case, that's my take. — Eric Prince (Photo by Jason Arnold / jasonarnoldphoto.com)
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He Looked Down and Saw This
Q: I saw something that just didn't look right swimming in the canal that I live on. After observing light being reflected off its side, I realized that it was a small fish. It was struggling to swim, probably due to the sudden drop in water temperature in early January 2010. Realizing that it had fragile fins, I placed it in a tub of canal water to photograph it with my underwater camera. Its body was about the size of a quarter, with those impressive anterior dorsal and pelvic fins. This juvenile fish resembles a lookdown or moonfish, but I am not sure which; I know juvenile fish can morph into different-looking adults. Capt. Tim Simos
Bluewater Inshore Guide Service Fort Pierce, Florida A: The fish you caught is a juvenile lookdown, Selene vomer, Tim. Juvenile Atlantic moonfish (Selene setapinnis) this size don't have elongated fin rays. Juvenile African pompano (Alectis ciliaris) — sometimes referred to as "threadfins" in the marine aquarium trade — appear similar, with long, filamentous rays in their dorsal and anal fins, as well as elongated and elaborate pelvic fins. In the African pompano's case, the dorsal and anal rays may be many times the length of the body, and (as with lookdown) shorten as the fish grows. However, the forehead profile of African pompano is not as straight or steep as that of these lookdowns. The lookdown ranges from Maine (and possibly as far north as Nova Scotia) through Uruguay, including the Gulf of Mexico and Bermuda, although this species is rare in the Greater Antilles and Bahamas. It has also been reported from the Eastern Atlantic. While lookdown fillets are very thin, they are excellent table fare. Still, there have been reports of ciguatera poisoning caused by consuming lookdown. Juvenile lookdown such as the one you captured make fascinating but delicate additions to large marine aquariums. They should be housed with gentle tank mates that won't nip their fins or otherwise harass them, and the inclusion of tall or sharp decorations such as corals should be avoided. — Ray Waldner
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A Speck's Jack Snack
Q:When we boated a speckled trout, it coughed up this little critter, and I have no clue what it is. We caught the trout in mid-June over an oyster reef in Mississippi Sound, south of Bay St. Louis, Mississippi. My best guess is a juvenile pinfish. If not, any thoughts on what this fish might be? Capt. Sonny Schindler
Shore Thing Fishing Charters Bay St. Louis, Mississippi A:Sonny, your speck coughed up a juvenile jack, either a blue runner (Caranx crysos) or crevalle jack (C. hippos). The darkened area on the opercle (gill-cover bone) is what makes me zero in on these two species, but without counts of fin rays or gill rakers, I can't be sure which one it is. These little guys are extremely abundant in nearshore waters during the summer, especially around river mouths and in sargassum weed. Many jack species have a banding pattern as juveniles that they lose as they mature. Both of these species form huge schools over their ranges, from Canada to Brazil. The crevalle can reach 30 pounds, about three times the maximum size of the blue runner. And although both are great fighters, neither has found much favor as a food fish. Around the northern Gulf, where you picked up your specimen, crevalle jacks are especially unwelcome to tarpon fishermen, because they favor tarpon habitat, and are far more likely to grab a bait before the tarpon does, resulting in an exhausting battle with no tarpon to show for it. — Bob Shipp
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Grouper Guru's Dilemma
Q: Do you know what kind of grouper this is? My friend, Bob Misak of Forked River, New Jersey, caught it on a fiddler crab off the rocks at Barnegat Inlet, New Jersey, in August. It taped out at 9 inches long, and Misak caught another one right afterward. He thinks it might be a juvenile Nassau, but I figured I'd consult your grouper guru.
Nick Honachefsky Clinton, New Jersey A: Your fish appears to be an unusually pigmented gag grouper, Mycteroperca microlepis, but I can't be certain from the photograph. The fish's general proportions, fin color, mouth, and the protuberance at the angle of the preoperculum all fit a gag. Groupers are highly variable in coloration and pattern, and this might account in part for the unusual pigmentation. It's also possible that your fish is a hybrid, since hybridization is known to occur between some members of the genus Mycteroperca. Additionally, based on the relative size of the planks on which the fish is resting, this is a juvenile rather than an adult and, as such, may have a bit different pigmentation than a larger individual. Gags occur from Massachusetts through Brazil, including Bermuda and the Gulf of Mexico, so you're well within this species' range. A good view of its fins would help greatly with the ID. For such purposes, photos should show as many diagnostic features on a fish as possible. This includes spreading a fish's fins and holding them open with pins or small nails. A clear photograph of a fish's entire body, showing its lateral line and where the fins begin and end relative to each other, a detailed photo of the fish's head, and a photo of its spread caudal (tail) fin can be very useful tools for identification purposes. — Ray Waldner
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