Thursday, September 24, 2015

What's for Dinner? Eat Local Seafood! by Don Orth

I'm out of town and don't know where or what to eat.   Do I stick with a chain restaurant and get the predictable fare or should I try something uniquely local?     Thanks to the Monterey Aquarium Seafood Aquarium I have seafood recommendations available.    These recommendations are based on a number of sustainability criteria, so I may eat guilt-free.   I'm in Baltimore at the inner harbor and right across the street is Phillips Seafood.    The history is interesting and starts over a century ago when A.E. Phillips & Son processing plant sourced wild crabs, fish and oysters in season from Hoopers Island on the Eastern Shore.  At that time fresh seafood traveled by steamship. The business grew and the restaurant now has a rich tradition and a superb location.    I ordered the Rockfish blackened,  with pineapple and mango salsa, fresh vegetables and mashed potatoes ($27).
After. I used to eat the skin of fish, but a variety of contaminants concentrate in the skin.
No complaints about this entree.   The Rockfish is known to scientists as the Striped Bass Morone saxatilis.  It is the state fish of Maryland and Virginia's state saltwater fish.  Striped Bass support one of the most important commercial and recreational fisheries along the east coast.  Each year the harvest by recreational fishers far exceeds the harvest by commercial fisheries.   They are also farm raised as striped bass x white bass hybrids.   Due to over-harvest and habitat degradation, striped bass populations suffered severe declines in the 1970's and a moratorium was established.  After millions of dollars and many years of study, they concluded that overfishing was responsible for population declines.  Well duh?!  Current harvest management involves individual transferable quotas for commercial fisheries and size and bag limits for recreational fisheries. 

The next night I visited Alewife Baltimore, where the proprietor focuses on locally sourced foods.    On arrival I see on the menu that they "support Maryland's best fishermen, farmers, hunters, and gatherers whenever possible.  Our menu includes invasive species as well as sustainably sourced seafood in order to aid in the preservation and protection of our ecosystems."   The menu includes local crabs, as well as a few species labeled "invasive" including feral hogs, Blue Catfish, and Northern Snakehead.     In other words "snakeheads are evil, eat them!"  This unique solution was popularized in Jackson Lander's Eating Aliens book and the idea has begun to catch on.   See the PBS special A New Wild.  

I order the Blue Catfish tacos, which the menu describes as Potomac River Blue Catfish, with  chimichurri, blistered corn salsa, chipotle cabbage slaw, and sweet potato strings for $13. I also ordered the Southwest style potato fish cakes, warm corn and bacon salad with dill avocado puree.    The combination of flavors on the Blue Catfish taco were very good together, as good or better than other fish tacos I've eaten.  The Snakehead Cakes were also very good, but I had to wonder "if snakeheads are really such a terror, shouldn't they be making an entree with more snakehead meat instead of mixing it with potatoes?"
Blue Catfish Tacos
Snakehead Cakes
So where did these two non-native fish come from?   The Blue Catfish Ictalurus furcatus is native to large rivers of the Missouri, Mississippi, and Ohio drainages and some rivers draining into the Gulf.   At a time when Striped Bass populations were at historical lows on the east coast,  North Carolina and Virginia stocked the Blue Catfish in several tidal rivers.   The populations of Blue Catfish exploded in the 1990's and today have spread to the Potomac and other Chesapeake Bay waters.    Recently the Monterey Bay Aquarium awarded the Blue Catfish the Green Seafood rating.   The green rating means the fish are abundant and there is minimal environmental impact associated with the fisheries.  Annual harvest of Blue Catfish in Virginia easily exceeds 2 million pounds per year, second only to Louisiana.  That's a lot of Blue Catfish Tacos!

Headlines that state that the "Blue Catfish are destroying the Bay" move lightning fast on the internet,  though we know most of the Bay's problems stem from agricultural or stormwater runoff and other discharges.   "Save the Bay" has been a rallying cry for over 50 years and attempts to place blame on the Blue Catfish now misses the big picture.   Decisions made 40 years ago are irreversible and we need to learn to live with and wisely manage the Blue Catfish and to minimize our effect on the Bay. 
Blue Catfish (top) with one of its many prey items, the Alewife (bottom)  Photo by Jason Emmel
The other fish on the menu, the Northern Snakehead Channa argus, is native to northern China.    Yet in 2002 the Northern Snakehead made national news after an angler at a pond in Crofton, Maryland, caught an 18-inch specimen.  Where did it come from?  What should we do?  These questions plagued the staff of the Maryland DNR until any action was mute.  The Northern Snakehead was now in North American waters.  In 2004, Snakehead Terror horror movie was released and today at least 14 states prohibit possession of all live snakehead species.   The fear was they would decimate all native fish with their voracious appetite.   They are established in the Potomac River and, according to one study, eat mostly Banded Killifish (66%).  A Snakehead Tournament is held regularly.   We have a National Management Plan, yet the only uncertainty today is just how far the Northern Snakehead will spread in North America.   So eat more Snakeheads!   But is that our only option?
Northern Snakehead. Photo by Donald Orth
The Snakehead is likely to develop a specialized following of anglers and bowfishers.   It has a mystique.  Just watch this video with Jeremy Wade of River Monsters, if you doubt me.

So we humans will continue to purposefully move fish around, whether it is prohibited or not.   We will continue to debate how to manage our new collection of plants and animals in our modified aquatic ecosystems.    It won't be easy.  We never approach the nirvana of an equilibrium.  The answer will not be found in name calling or blaming the fish.   It's the people who make the decisions.   Call them "invasives" if you wish, but that doesn't change the fact that they are now part of the ecosystem.   Chesapeake Bay and the Great Lakes are perhaps the center of non-native biodiversity in North America.  Whether the non-natives become beneficial to communities and local economies is ultimately up to us.

Thursday, September 17, 2015

Is there a Gasterosteologist in the house? That is, someone to help us understand the Three-Spined Stickleback, Gasterosteus aculeatus Linneaus 1758 by Don Orth

The Three-Spined Stickleback is the only Stickleback that occurs in Virginia and furthermore, it is also the most widespread Stickleback in the world.    It’s name Gasterosteus is derived from the Greek words (gastro and osteo) that literally translate to “belly” “made of bone,” while aculeatus means “spiny.”  I believe that each fish has something to teach us, if we just observe closely and ask the right questions.  However, the Three-Spined Stickleback has so much to teach us.   In fact, in today’s library search on  “Three-Spined Stickleback Gasterosteus aculeatus” I learned that there are 5,267 journal articles, 1,042 books, and 336 doctoral dissertations written on this species alone!  In this short post, I will briefly describe many of the lessons the species can teach us.   How to be a fantastic Dad?  How to teach kids self defense?  How to be a good househusband?   How to court the ladies? How to keep embryos well oxygenated?  How to wear red to attract a mate? How to cooperate with others to avoid predators? How to see all four major wavelengths of light including ultra-violet?

Three-Spined Stickleback Photo by by Lubomir Hlasek
The Three-Spined Stickleback is easy to identify by its laterally compressed body with a very slender caudal peduncle, large terminal mouth, large eye, and three spines anterior to a soft-rayed dorsal fin.   It has no scales on the body; instead it has bony plates on its back, flanks, and belly.   The number of plates on its flanks varies widely across its range and that is another story worth telling.    The pelvic fin is unique as it is made up of only a single spine.   Dorsal colors are drab olive or a silvery green, sometimes with brown or black mottling.  Flanks and belly are silvery.  During breeding, the eyes of males become blue and the lower head, throat, and anterior belly turn bright red.    Do the Sticklebacks reflect the origin of a human preference for a blue-eyed mates?   

The Three-Spined Stickleback inhabits fresh, brackish, or salt water along coasts of North America, Europe, and northern Asia.  There are both freshwater and anadromous forms.   Freshwater forms exist in waters with connections (current or past) to the coasts.   In Virginia, it occurs in the York and James basins and tributaries of the eastern shore.   The anadromous form spends most of its life in the sea, and returns to freshwater to breed.   This form shows less geographic variation in number of lateral bony plates (usually 30-40) and has long dorsal and pelvic spines.   Freshwater forms of the Three-Spined Stickleback have larger variation in bony armor and shorter dorsal and pelvic spines.     Apparently, since the end of the last ice age, Three-Spined Sticklebacks have repeatedly colonized new streams and lakes forming unique populations. 

Because it is a small fish, there are many predators including fish, birds, and even dragonflies.  Predation pressure is a strong selective pressure on the species and is reflected in the variation in size and number of bony armor plates and size of spines.    These anti-predator defense mechanisms have been widely studied.  
Photo by Marcin Lenart
Photo by David Moreton
In fact the difference in the bony skeletal patterns of closely-related populations of Three-Spined Sticklebacks reflects a difference in a single gene.  This gene is called a “tool-kit” gene because it possesses all the tools to program all processes involved in bone formation.  Interestingly, two forms of the Three-Spined Stickleback, which differ in the size of their pelvic fins, have repeatedly evolved in freshwater lakes.    Mike Shapiro and David Kingsley showed that long pelvic spines protect the open-water form from attack by other fish. Yet in the bottom-dwelling form (lower image), whose principal predator is dragonfly larvae rather than other fish, the tool-kit gene controlling the formation of the pelvic fin has been selectively turned off.
    Two forms of Three-Spined Sticklebacks.  The bony plates in are shown in red.  
from David Kingsley, modified from Cuvier (1829)  

The love life of the Three-Spined Stickleback is complicated to say the least. The male Three-Spined Stickleback  first digs a pit and begins to assemble nest materials from algae and vegetation.   During the nest builder phase he has inconspicuous colors.  The nest materials are glued together with spider-web-like threads in a spherical shape with a tunnel for he and his mate to enter.   The “glue” is called spiggin (the Swedish name for Stickleback), which is a proteinaceous substance secreted from the kidney.    In more than a few experiments on nest-construction, the male Stickleback demonstrated a preference for brightly colored nest materials to decorate the nest entrance.   After the nest is constructed, the male develops a bright red throat, which is a sign that he is ready to breed.   When the male develops bright colors he becomes very aggressive and defends his territory from other males. 

Photo of Three-Spined Stickleback gluing materials in nest.

The breeding male will attack anything with red color that gets near its territory.  This is called a fixed action pattern in ethology to denote an “instinctive behavioral sequence that is relatively invariant within the species and almost inevitably runs to completion.”     Ethologist Nikolass Tinbergen first described this automatic behavior in sticklebacks and also witnessed sticklebacks attacking red mail trucks they observed through the glass aquarium walls and windows.  The fixed action pattern has a proximate explanation --  the red color causes the male to respond aggressively.   The ultimate explanation is that the male behavior decreases the chance that eggs laid in his nesting territory will be fertilized by another male.

Close up of male Three-Spined Stickleback with nuptial coloration. Photo (c) Ecomare.
Females are courted and encouraged to deposit eggs in that nest, but that courtship too is complicated.     In order to successfully court a female, the male must demonstrate traits of the superb, hypervigilant house-husband.     The male performs a courtship ritual  to entice females to lay their eggs.    This includes a dance (or swim) that has been named the “zigzag” dance.  The male approaches with a zigzag dance, bites the female, and then swims to the nest site with the same zigzag dance.   The male hopes the female follows him to the nest. 
Nuptial male Three-Spined Stickleback biting potential mate.
The female selects a mate based on red throat color and other visual signals, such as the nest decorations.  The red nuptial coloration is clearly a cue to females as experiments have shown that ripe females were more likely to follow a “dummy” stickleback to a fake nest if the dummy had a red belly.    Further, dominant males express redder colors than subordinates.  Maybe she is also attracted to his intense blue eyes – though this hypothesis has not been tested.  But there is more to the reproductive behavior than color variations.  Remember, the love life of the Three-Spined Stickleback is complicated.   The male may receive eggs from more than one female but all parental care is  provided by the male. 

After the female lays her eggs and leaves the nest, the male changes from sexual phase to a parental phase and his color again becomes dull and cryptic.  These changes are associated with a dramatic drop in plasma testosterone levels.     The parental (low testosterone, dull color) phase includes parental duties, guarding the fertilized eggs, fanning them with his pectoral fin and/or tail to provide them with oxygen, and protecting eggs from predators.    The parental phase may last 5-10 days until the eggs hatch and the phase is energetically very costly.

Because of these costs associated with being the perfect house-husband, the Three-Spined Stickleback male may engage in other “bad” behaviors to more easily pass on genes.  These bad behaviors include nest raiding to steal fertilizations in other nests, stealing eggs from other nests, and eating eggs from other nests.

Another lesson learned from numerous studies of the Three-Spined Stickleback is the potential for rapid speciation.  This is often apparent in the existence of closely associated species pairs.   In Paxton Lake, Texada Island, southwestern British Columbia, two distinct sympatric forms were derived after glacial retreat.  Anadromous Three-Spined Stickleback repopulated lakes after poisoning and rapidly adapted to the new environment through natural selection.  For more information, view this video.  

Limnetic male (top left) and female (top right) and benthic male (bottom left) and female mature (bottom right) sticklebacks. The limnetics are about 65 mm total length and the Benthics about 75 mm. Photo by G. Velema, UBC

Recently biologists discovered ultraviolet (UV) receptors in the eyes of some fishes, including the Three-Spined Stickleback.   The nuptially colored male reflects UV radiation from parts of his body and this may permit short-range communication between male and potential mates. 
One of the anti-predation strategies used by Three-Spined Sticklebacks is cooperation (tit for tat) in keeping a watch on potential predators.   In this behavior pairs of sticklebacks reciprocate as each takes turns watching for predators. 

The Three Spined Sticklebacks teach us that evolution is occurring on a timescale much faster than we might imagine.   For example, marine and freshwater forms are maintained in downstream and upstream locations with extensive hybridization at intermediate sites.   We can expect future studies that take advantage of recent sequencing of the entire genome (Jones et al. 2012) allowing further study of the molecular basis for evolution of this species.


Jones et al. 2012. The genomic basis of adaptive evolution in threespine sticklebacks.  Nature 484:55-61.   doi:10.1038/nature10944

Ostlund-Nilsson, S., I. Mayer, and F.A. Huntingford, Editors.  2006. Biology of the Three-Spined Stickleback.  CRC Press.   408 pp.

Friday, September 11, 2015

Such a long nose and such big teeth, it can only be the Longnose Gar, by Don Orth

The Longnose Gar Lepisosteus osseus (Linnaeus, 1758) never fails to fascinate the nature observer.  The Gars have many unique traits making them unlike most other fishes.  They are easily distinguishable by the extremely long snout, numerous sharp teeth, long cylindrical body form, bony scales and the abbreviated heterocercal tail.   Along with the Sturgeons, Paddlefish, and Bowfin, they are living representatives of some of fishes that existed over 100 million years ago.     Say what?  Yes they possess traits that were present on ancenstral Gars over 100 million years ago!
Longnose Gar captured in Virginia (photo by J.D. Schmitt)
In Virginia, the Longnose Gar is the only native Gar and is the most widespread species in North America.  The name Lepisosteus comes from a combination of the two words lepis the Greek word for "scale", and osteos which is Latin for "bony".  Similarly Lepidoptera is an order of insects, butterflies and moths, named for scale and greek pterin for wing.  In the case of the Gars, the name is used to describe the extremely hard ganoid scales.  The specific epithet osseus is also Latin for the word "bony".  Thats redundant, but you cant blame it on Linnaeus; Carolus Linneaus originally classified this fish as Esox osseus, or Gar Pike.    

No other fish in Virginia has such a hard bony covering.  The ganoid scale emerged at a time when very large toothy aquatic reptiles, the large pliosaurs and relatives were still around.   This bony covering is extremely difficult to pierce even with a sharp filet knife.   Each ganoid scale is rhomboid in shape and has an articulating dorsal peg that articulates with a ventral socket joint on the adjacent, dorsally-placed scale.  Ganoid scales have a bony basal layer, a layer of dentine, and an outer layer of ganoine (an inorganic bone salt).  Ganoid scales in gar are tightly overlapping on all parts of the body creating the diamond-shaped pattern and the rather inflexible body form.

Top: Lateral scales of Longnose Gar (photo by Uland Thomas.  Bottom: Close up of Longnose Gar scales (photo by D.J. Orth)
The gar body form is a long flexible cylinder, not designed for sustained swimming. The dorsal and anal fins are both set well back on the body, and with a large rounded tail fin that provides stability during caudal thrust.     The gar is an ambush predator that sits and waits motionless until potential prey are near.   With a rapid tail thrust andhead sweep they impale the prey fish in their long toothy mouth.    The Longnose Gar relies more on the speed of lateral movement rather than biting to impale a prey fish; there is very little biting force at the tip of its jaw.    Recently a diet study on Longnose Gar  in Charleston harbor and associated estuaries of South Carolina confirmed that the adults are opportunistic piscivores.  In this location the dominant in the diet were Atlantic Menhaden, shad, drum, killifishes, mullet, and Penaeid shrimp.   In Virginia tidal populations, the top five prey consumed by adult Longnose Gar were White Perch, Menhaden, Fundulus spp., Atlantic Croaker and Spot.
 Longnose Gar is easily distinguishable from other gars by its long, narrow snout.  The snout length is more than 13 times its narrowest width in specimens 50 mm long or larger.  Juveniles have a shorter snout, which grows proportionally faster than the body.   Other species gar can be distinguished by snout shape and pigment patterns.  The spots on the body of the Longnose Gar are smaller and generally less well developed than on Spotted Gar.

Top; Four Gars compared (Source Kentucky Dept of Fish & Wildlife Resources).
Bottom:  Skulls of Longnose Gar in lateral view and dorsal view (photo: D.J. Orth)
Gars have a bimodal system for respiration.  They can obtain oxygen via gills or via air breathing.   The lung is highly vascularized and homologous to the tetrapod lung. It occupies 10% of the volume of the fish.   It is this use of bimodal respiration that allows the Longnose Gar to be successful in many waters with low oxygen content that would otherwise be inhospitable.  Yet in hypoxic (low oxygen) conditions they may continue with normal levels of activity as they rely on air breathing.    Consequently they are widely dispersed in the lowland lakes, rivers, and streams of the Atlantic and Gulf slopes and throughout the Mississippi River and lower Great Lakes basins.

Distribution of the Longnose Gar (Source: US Geological Survey)
Longnose Gar are primarily freshwater fish; however, they have been captured in tidal rivers at a maximum salinity up to 15-21 ppt.  In some studies, they appear to move significant distances.  There also tends to be a springtime movement to smaller tributaries for spawning.     

Do not eat Gar eggs!   Unlike the Paddlefish, Sturgeon and Bowfin, the eggs of Gars are not used for caviar.  In fact they are highly toxic to mammals and birds, but not fishes.     This remains an unsolved mystery.   One  presumes that fishes would be a primary source of predation on Gar eggs,  yet this egg toxin does not deter fishes from eating the eggs.  Why evolve an egg toxin specific to mammals and birds?  

Many authors suggest that there is no sexual dimorphism in Longnose Gar other than females being larger than males .  However, Long and Ballard  in collections of breeding Longnose Gar, reported that adult females possessed a silvery body coloration, while males had a golden cast to their scales.   Patrick McGrath analyzed morphometrics of male and female Longnose Gar and demonstrated that males had a longer anal-fin base and wider heads and mid-snouts than females.   

Longnose Gar may spawn in relatively barren shorelines or quiet vegetated habitats.  Longnose The female spawns with one to several males who use their snout to nudge and position the female, followed by a simultaneous release of eggs and sperm.     Gar lay sticky eggs on bottom, often in weedy bays on submerged vegetation.  The dark eggs are about 3mm in diameter and poisonous for humans to eat.   The may hatch in 6 days at temperatures between 18-20C.  By day four the embryo still has a large yolk sac and has developed an adhesive organ on the head.  The adhesive organ is larger than the embryonic eye.  By the time of hatching and yolk sac absorption, the eye size is larger than the adhesive organ.  The adhesive organ on its head helps the embryo to attach to vegetation and other structures where they hang vertically.  They lose the adhesive organ when snout and mouth is fully formed and feeding can commence. 
Top: Drawings to two stages of larval Longnose Gar with (left) and without (right) adhesive organ. Bottom: Photograph of larval Gar with adhesive organ.  (Source).

The smallest juveniles have an appearance very different from adults.  The small juveniles have a long lateral stripe, shorter snout, and long caudal ray filament.     At this stage, the Longnose Gar are surface feeding on copepods, cladocerans, and aquatic insects before making the transition to piscivory.

Longnose Gar are not classified as a game fish; however, in recent decades they have begun to gain a specialized following.  The Texas State Record Longnose Gar was a 50 pound 5 ounce specimen taken from the Trinity River in 1954.   The Longnose Gar is a special challenge for the interested angler.    However, this specialized fish is best pursued with a specialized fishing technique.   You simply do not want to embed a treble hook into the bony jaw of the Gar.  Neither you nor the Gar will be happy about the outcome.  One of the alternative techniques is the use of a rope lure.   With this method the unbraided rope gets tangled in the teeth as the Gar attacks the bait.  
Rope lures used specifically to target Gars (source)

Also, bowfishers have always known that the Gars are a suitable target as they lie motionless near the water surface -- easy targets for an accurate bowfisher.   While bowfishers have quietly targeted Gars for sport and an occasional meal, recently bowfishing tournaments have become popular.   And the tournaments have raised an ethical dilemma regarding the harvest and subsequent waste of native Gars.   We will  see if tournament organizers treat Longnose Gar and other Gars differently in future tournaments. 

Jason Emmel with a Longnose Gar bowfished in Virginia. (Photo: J.D. Schmitt)
Can I eat them?   Yes, but it takes a very different approach to cleaning.  First you nail the head and tail to a board.   Then you use sharpened tin snips to cut through scale jacket straight along the backbone to the tail.  This will reveal two strips of white flesh.  Meat is firm and has a color and texture that resembles chicken or alligator more than a flaky fish filet.  Gar fillets may be dredged in a batter and fried in hot oil.    For more about catching, cleaning, and eating Gars, view this video. 

Fossil Gars have been found in North America, South America, Africa, India, and Europe, though the origins of this group remain highly uncertain.    Perhaps the ancestral Lepisosteiform fish arose before or during the Cretaceous, which began 145 million years ago.   This ancestral fish arose in the late Jurassic before the breakup of the supercontinent Pangea.    Closest relatives to the Gars are Bowfin (Amia calva).  The most recent phylogenetic analyses support the hypothesis that these two groups have a common ancestor and form a basal-sister group (Holostei) to all other bony fishes (Teleostei).   
Longnose Gar have largely been ignored in the development of fisheries management programs.   Although other Gars (Alligator Gars and Tropical Gars) are declining in many areas, there is little directed effort to monitor status of Longnose Gar populations throughout its range.  No estimates exist for sport or commercial harvest and the effect on populations.   

Scales may have been used as arrow points by Native Americans    Some artisans are using Gar scales to make earrings.   
If you are interested in more information about the family Lepisosteidae, the Gars, then check out this website now!