Strange, Beautiful and Frightening Fishes from March Fish Facts

Southern flounder, grenadier, yellow-spotted rock cod -- Let the experts tell you about these unusual fishes.

Strange, Beautiful and Frightening March Fish Facts

Hot and Cold Seatrout

Q: Down here in central Florida, our seatrout become lethargic much of the winter, and even die if the water gets really cold. Yet at the same time, my buddies up in Virginia are bundling up in the dead of winter and catching some huge gators (trout) in waters that must be far colder. How does that happen? I’m sure it’s the same species. Can that degree (pardon the pun) of acclimation account for such a discrepancy? Doris Fleebus_
Melbourne, Florida_ A: Spotted seatrout, Cynoscion -nebulosus, range from Florida to New York, so the fish in question could well be the same species. Assuming this is the case, here's what's likely responsible for your observation. Animals most often die from cold temperatures because the chemical reactions necessary to maintain their cells slow down as the temperature drops, until the reactions become too slow to keep cells — and the organisms they comprise — alive. Cellular reactions are catalyzed by enzymes, which are protein-based regulatory molecules that are also temperature dependent. Members of a single animal species living in different geographic areas may have slightly different enzymes — termed isozymes or isoenzymes — which perform the same functions but work best at different temperatures. In other words, while the basic chemical reactions that occur in the cells of spotted seatrout from Virginia and central Florida might be the same, differences in isozymes could make individuals from the northern portion of the species' range better adapted to cooler water than those from the south, and vice versa. A widely distributed species may be divided into populations that are best adapted to different environmental conditions. Factors including the rate and duration of water temperature change in each area also could play a part. _— Ray Waldner, _Palm Beach Atlantic University, Florida Photo by Matt Lusk
Matt Lusk
Strange, Beautiful and Frightening March Fish Facts - 2

Playing For Both Sides

Q: Recently I caught a fish in southwest Florida waters that looked like a flounder and tasted like a flounder, but in more than 55 years of fishing in Florida and other coastal states, among hundreds of flounder, I’ve never seen one that looked like this one. I showed these photos to inshore guides who have each seen thousands of flounder, and none had ever seen the like. The “top” side of this 14½-inch fish looked like any flounder, but the other (bottom) side was mostly pigmented rather than white. Only the head was normal in lacking dark pigment. Also strange was that both fillets were the same thickness. **Bob Nudelman
**Cape Coral, Florida A: A very unusual catch, Bob. This appears to be a southern flounder, Paralichthys lethostigma, a member of the family Paralichthyidae, the sand flounders. Sand flounders used to be included in the family Bothidae, the left-eyed flounders, so named because during their embryological development, the eye on the right side the head migrates to the left side. The fish's left side then becomes its upper side. A southern flounder is normally well camouflaged, as its dark, blotched upper side will match the coloration of the substrate it's lying on. Its lower (right) side, which normally rests on the bottom, is pale. The lower side is also typically flatter than the upper side, so metamorphosis and post-metamorphic development entails more than just a pigment change and the migration of an eye. Although I've never seen a flounder with pigmentation such as yours, -aberrant pigmentation in flatfishes is well documented and may involve a fish's upper or lower side. However, the situation in your fish is a bit different. In effect, your catch appears to have two upper sides, while its head appears to have undergone the normal metamorphic process that occurs following the right eye's migration. My guess is that a genetic signaling mistake occurred that involved certain genes turning on or off, and the cells on the right-hand side of the body didn't "get the message" to differentiate following the migration of the right eye. Thus, while the fish's head underwent the normal developmental process associated with flatfishes, its body didn't. — Ray Waldner Ed. note: Ray Waldner and geneticist Gary Goss say that this condition is unusual enough that they’re considering publishing Nudelman’s photos of this remarkable flatfish in a peer-reviewed scientific journal.
Strange, Beautiful and Frightening March Fish Facts - 3

Oh My Cod — It’s a Grouper

Q: While fishing off southwestern Australia, I caught this fish. I’m pretty sure it’s a snapper of some type, but even our hosts, who live and fish these waters, weren’t sure of its ID. It came from about 250 feet of water; the reel offers some size reference. What the heck is it? **Ben Secrest
** San Clemente, California A: What you have there, Ben, is a nice yellow-spotted rock cod (Epinephelus areolatus). Otherwise known as the areolate grouper, E. areolatus is a relatively small and slow-growing member of the family Serranidae, less than 20 inches at most, and living to a maximum age of around 15 years. This species has a wide distribution in the Indian Ocean, seasonally as far south as the southwest corner of Australia. Areolate grouper also occur in the Pacific as far north as Japan. They are also becoming an important aquaculture species in Southeast Asia, where they are reared for the live-reef-fish trade. Adults sometimes frequent deeper waters to 650 feet deep. This species can be distinguished from other small groupers not only by its distinctive coloration pattern, but also by the fact that it has a crescent-shaped (almost concave) tail margin, unlike the usual rounded tail of other similar species. — Ben Diggles
Strange, Beautiful and Frightening March Fish Facts - 5

Rats from the Abyss

Q: Young Makana Oye and his dad, Alton — -residents of Kamuela, Hawaii — showed up at my house with this fish, wondering what it is, where it lives, how big it gets, and so on. Makana scooped it up in the waters off Kawaihae, where he found it floating. **Jim Rizzuto
** Kamuela, Hawaii A: That's a grenadier from the family Macrouridae. These deepwater fishes are identified by their characteristic large pointed heads and relatively short bodies with long tapering tails (giving them their common name of rattails). Rattails are among the most abundant of deepwater fishes, found worldwide at depths from around 600 feet to at least 20,000 feet, where they are usually seen swimming just above the ocean floor. At those depths there is no light, and many rattails have developed light organs populated by bioluminescent bacteria. About 300 species are currently described. Most species of rattail average 10 to 12 inches long, but a few species such as the giant rattail, Albatrossia pectoralis, grow to more than 4 feet long. Your fish is almost certainly a member of the genus Coryphaenoides. Though edible, they are not generally used as food fish. Floating rattails found at the water surface are usually discarded bycatch from deepwater trawlers, though rattails may be kept and used in the fishmeal trade. — Ben Diggles
Strange, Beautiful and Frightening March Fish Facts - 6

Quick Sand Retreat

Q: I found this fish on the Chesapeake Bay shoreline in Virginia Beach, Virginia. A friend saw the fish on the sand close to the surf and put it back in the water, whereupon it wiggled out of the water and buried itself backward into the sand. Can you identify it? **Capt. J. Godwin
** Virginia Beach, Virginia A: That critter is Ophidion -marginatum, the striped cusk eel, a species with which I have some familiarity. They have no commercial value, but still, I'm ashamed to admit I've never tasted one. They might be very good-eating. Your photos perfectly display one of the diagnostic behaviors of this cusk eel: It spends much of its time by day burrowing in sand. By night it emerges and forages for food. At any time, when confronted by danger, it quickly "backs into" the sandy substrate for protection. Reproductive behavior in these fishes includes very audible "calling," often while both members of a pair are still buried. Eggs are encased in a buoyant, viscous gelatinous mass. After hatching and a brief pelagic period, the young descend to the bottom on the continental shelf, where they overwinter, buried in the substrate. At the first sign of spring warming in March and April, the juveniles emerge and migrate into nursery areas in -estuaries. Important prey for a number of bottom-dwelling fishes, cusk eels have been known to burrow out of stripers' stomachs, causing damage to internal organs. — Mike Fahay