Thursday, January 28, 2016

Goosefish, the Best Animate Fish Trap in the Piscine World, by Don Orth

The Goosefish (Lophius americanus Valenciennes,1837) is a fun and fascinating fish.  It is one of 25 species in the Lophiidae.  The Goosefish occurs in the western Atlantic from Newfoundland south to Florida.  There is a fun assortment of local names, such as the American anglerfish, bellows-fish, devil fish, fishing frog, headfish, molligut, satchel-mouth, wide-game, or monkfish.  Monkfish is the name used in the seafood markets.  There are two closely related species, the European form and the American form. Linnaeus described the European species, Lophius piscatorius in 1758. French zoologist Achille Valenciennes examined North American specimens and found, in 1837, that they differed in teeth, lower lip and spots on its back.  These differences were enough for him to claim that the American form was a distinct species.  It took several decades and additional studies before other Ichthyologists agreed. Today there are seven species of Lophius worldwide and two in North America. The Blackfin Goosefish (Lophius gastrophysus Miranda-Ribeiro, 1915) is distributed in the western Atlantic from Cape Hatteras south to Argentina, including the Gulf of Mexico.

We can speculate about the habits of a fish by carefully examining its body form.   Louis Agassiz, Professor of zoology and geology at Harvard University and founder of the Harvard Museum of Comparative Zoology would often tell the naïve student to “Take this fish and look at it.”     Nathaniel Shaler, in his autobiography, also wrote of Agassiz’s minimalist teaching approach, which my students would find exasperating.  When Shaler asked for explicit instructions, Agassiz replied that he could not be more explicit than saying "find out what you can without damaging the specimen."  Well, the Goosefish is easier to read than most fish. Just look at this fish!
 Left: European Angler Lophius piscatorius illustration by Yarrell (1841)  Right: Photo of Monkfish at Museum of Nature, Ottawa, Canada, by Mike Beauregard
This is one fish that will not be confused with any other fish captured in the same region.  What do we see?   It has a very unique form and a scaleless body.  The head is very depressed and it has large eyes located on top of the flattened head.  Its huge mouth is terminal and the mouth is nearly as wide as the head.   The thick jaws possess long backward pointing teeth. The lower jaw projects well beyond upper.  The skin bears fleshy tendrils or cirri on lateral margins of head, lower jaw, and body.  Its body is flattened dorsoventrally to allow it to hide on the sea floor.  On the midline of the head stand modified anterior dorsal spines that are long and far forward for the normal location of dorsal spines. The first one originates on upper jaw and has a fleshly flattened tip.   The modified spine is called the illicium and the tip is the esca, which serve as fishing rod and lure, respectively.  

Even Aristotle was familiar with this fish and wrote “The accounts commonly given of the so-called  fishing frog are quite true … The fishing frog has a set of filaments that project in front of its eyes; they are long and thin like hairs and are round at the tips; they lie on either side, and are used as baits. Accordingly, when the animal stirs up a place full of sand and mud and conceals itself therein, it raises its filaments and, when the little fish strike against these, it draws them  underneath  into its mouth.... Furthermore, the fishing frog is unusually thin when he is caught after losing the tips of his filaments.”   Eugene Gudger, Ichthyologist with the  American Museum of Natural History described this fish as the “best animate fish trap in the piscine world"  (Gudger 1945).

Ever since the time of Aristotle, we have known (or at least believed) that the lure was used for catching fish prey!  It was not until the Anglerfish was observed carefully in aquaria in the 20th century that its actual “lie-in-wait” and use of lure behaviors were corroborated.   One such observation is based on an astute observer watching a live specimen:
 “An angler when hungry erects the lure immediately any suitable fishes come anywhere near and endeavor to attract one of them close enough to be caught.   The lure is quickly jerked to and fro and, as the rod is almost invisible, the bait  (in my specimens always forked and 'fly-like' not vermiform) simulates some tiny creature darting about.   An attracted fish rushes up in an endeavor to catch it; the bait is skillfully flicked out of its way just in time and, with a final cast, is dashed down in front of the mouth which may open very slightly.  The intended victim, still following the bait, turns slightly head downward; it is now more or less directly head-on to the angler's mouth.  The jaws snap faster than the eye can follow and the tail of the prey is next seen disappearing from sight through the firmly closed mouth.   As far as I have been able to observe, the bait is not actually touched by the victim before it is caught, as has sometimes been supposed.”  Wilson (1937)

Most of the time the Goosefish rests partially buried on soft bottom substrates.  The Goosefish is an opportunistic, non-selective, sit-and-wait predator, luring their prey by raising and moving the illicium.  Watch this video of the European Anglerfish feeding on a goby.  Fishes are the most common diet items.  But one infrequent diet item includes birds, such as the Dovekie (Alle alle), a seabird (see photo).   The Dovekies were preyed on by Goosefish at or near the surface, not the typical habitat or habit (Perry et al. 2013).  Hmm?!  How do you explain this phenomenon?  “Look at the fish” is not sufficient approach to answer the question.   The maximum diving depth of a Dovekie is 20-30 m, not deep enough to ever encounter this benthic predator.   However, those keen observers of the Goosefish know that they are known to rise off the bottom, possibly to ride currents during migration periods in spring and fall or to spawn at the surface (Hislop et al. 2000).  This infrequent behavior leads to infrequent encounters with birds.
Goosefish with Dovekie extracted from stomach.  Photo from Perry et al. (2013)
The whole structural anatomy of the Goosefish is designed to increase efficiency of the habits of the fish.   If you “Take the fish and look at it,” you must say “Wow! Look at those jawbones and pectoral fins and girdle.”   The axial skeleton is very short and the jaws and pectoral skeleton are enlarged. This is not the body of a great swimmer.  The muscles consist of white muscles adapted for non-aerobic swimming.  But the white flesh is moist, firm and very tasty, often marketed as the “poor man’s lobster.”  To prepare a Monkfish before cooking, watch this video.
Skeleton of the Goosefish source 
Lophius species are exploited worldwide; they were first taken as bycatch in trawls and later targeted fisheries with gillnets developed. Given the body form, the yield of tail meat to live weight is only 30%. Monkfish livers are also marketed, yielding another high value product.  The predominant fishing grounds in northeastern US are significantly impacted by human activities.  Offshore dumping of municipal, industrial, and explosive wastes were common from New York to Virginia before the passage of the Ocean Dumping Act in 1988. Consequently, high selenium and mercury levels in Monkfish muscle and livers are contemporary human health concerns (Johnson et al. 2011).    

The US commercial fishery for Monkfish increased in the 1980s.  This was soon after passage of the Magnuson Act (1976), which expanded U.S. management jurisdiction in waters out to 200 miles. The Act opened international markets of Europe and Asia and landings peaked by 1998. At this time Atlantic Cod stocks were in decline and harvesters switched to alternative less-valued species, including the Monkfish.    Recruitment of Monkfish has been below average since 2004 The New Englang Fishery Management Council, Mid-Atlantic Management Council along with the National Marine Fisheries Service published a Monkfish Fishery Management Plan in 1999 to rebuild the stocks.  
Landings reported for monkfish from 1964 to 2009 (Northeast Fisheries Science Center 2010)
The Goosefish provides students of the fishes a great opportunity to “take this fish and look at it!” and learn about connections between morphological traits and habits.  Recent trends in human uses are also instructive. This fish went from a trash fish to targeted high-value product in a decade.   Monkfish are considered a good seafood alternative by the Seafood Watch; however, there are concerns about bycatch associated with Monkfish harvest.  Most are harvested in multi-species trawling or gillnets or scallop dredges, which catch many undersized fish that must be discarded. Further, contaminant levels from legacy contaminants on many US fishing grounds should be further evaluated before you permanently switch from lobster to Monkfish.  The Fresh Lobster Company will ship fresh Monkfish fillets at $18.50/pound or one 3 pound lobster for $38.75 – your choice.  Neither one is a "poor man's" food.

Aristotle 1910. Historia  Animalium, D'Arcy W.  Thompson, trans., Oxford, 620
Fariña, A.C., and seven coauthors.  2008. Lophius in the world: a synthesis on the common features and life strategies.  ICES Journal of Marine Science 65:1272-1280.
Gudger, E.W. 1945.  The Angler-Fish, Lophius piscatorius et americanus, use the lure in fishing.  American Naturalist 79:542-548.
Hislop, J.R.G., J.C. Holst, and D. Skagen. 2000. Near-surface captures of post-juvenile anglerfish in the northeast Atlantic: An unsolved mystery. Journal of Fish Biology 57:1083–1087.
Johnson, A.K., B. Bediako, and E. Wirth. 2011. Metal concentrations in monkfish, Lophius americanus, from the northeastern USA. Environmental Monitoring and Assessment 177:385-397.
Perry, M.C., G.H. Olsen, R.A. Richards, and P.C. Osenton.  2013.   Predation on dovekies by Goosefish over deep water in the Northwest Atlantic Ocean.  Northeastern Naturalist 20(1):148-154.
Wilson, D. P. 1937. Journal of the Marine Biological Association U. K., Vol. 21 (in.s.) 477-496,
Yarrell, W.  1841. "History of British Fishes,' London, 2nd ed., Vol. 1, p. 310.

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