Groping with Multiple Risks on Grouper Populations, by Don Orth

According to the FAO, fisheries provide at least 15% of the animal protein consumed directly or indirectly by humans.  As demand grows we must deal with the fact that fishing drives down fish populations leading to a global fisheries crisis. John Shepherd, a fisheries biologist, once said “Managing fisheries is hard: it’s like managing a forest, in which the trees are invisible and keep moving around.”   Fisheries on groupers are even harder to manage.

Overfishing is driven by biological and social factors.  Therefore, fisheries management must be grounded in principles of fisheries science melded with social-ecological theories.  In this post, I explore this fundamental truth as it plays out in the management of grouper fisheries throughout the world.    Groupers are fish in the subfamily Epinephelinae (Serranidae) that are widely distributed in warm seas.   Familiar genera include the Epinephelus and Mycteroperca.

 

Black Grouper Mycteroperca bonaci  Photo by Alfonso Gonzalez   Flickr

Changing density and size structure of reef fish top predators, such as groupers, is often observed but in subtropical and tropical nations there may be no official landings records.   But local fishers are often aware of declines, reporting that grouper catches were abundant many years ago (Aguilar-Perera et al. 2009; Amorim et al 2018; Bender et al. 2014).  So managers must struggle to manage without a fair determination of baseline conditions (Pinnegar and Engelhard 2008). 

Food and Agricultural Organization of the United Nations (FAO) capture production landings data for groupers 1950–2009. (Sadovy de Mitcheson et al. 2013) 

Vulnerability and value lead to rapid depletion and overfishing in snapper and grouper (Coleman et al 2000; Sadovy de Mitcheson et al. 2013).  Groupers are highly regarded for the mild quality of their flesh. Therefore, they are most heavily exploited among other high-priced reef fishes.  Vulnerability is related to ease of capture and a slow life history.  Most species take a long time to attain high reproductive values. In shallow coral reefs many groupers can easily be approached and speared by spear fishers, hook and line, and cyanide. Fisheries target adults captured and marketed directly for food, but also juveniles for mariculture grow-out operations (Sadovy and Pet 1998). Because it takes a long time to obtain needed life history information, fisheries independent survey data, and catch history, the groupers may be overfished long before data are even available for a stock assessment. 

 

Trends in largest fish caught (a) and highest daily catch (b) for Black Grouper  (Bender et al. 2014). 

Value to humans is related to wide cultural acceptance of the grouper and other human demographics, such as distance to markets and local human population density.  Of the 163 species of groupers, 20 risk extinction if current trends continue, and an additional 22 species are considered to be Near Threatened (Sadovy de Mitcheson et al. 2013). Because of its popularity, groupers are often mislabeled or substituted with lower valued fish.  Over 50 species of groupers worldwide may be marketed and sold in the US as grouper (FDA Seafood List).  Here are tips for avoiding fake grouper.

Pan fried grouper. Photo by Kirk K. Flickr

If slow life history and high value create a double jeopardy for groupers, one additional trait adds a triple jeopardy condition.   Groupers display predictable spawning aggregations, temporary gatherings of large numbers of grouper for spawning.   These spawning aggregations make groupers extremely vulnerable at the same time when reproductive values are highest (Erisman et al. 2017).   Watch this video of a spawning rush of groupers.   Groupers move around and local fishers learn their patterns and can use GPS to re-locate these locations and target the spawning aggregations. Fisher knowledge will influence the extent to which aggregations are perceived as predictable and exploited by fishers (Robinson et al 2014). In some cases, fishers have known for centuries where and when aggregations form (Erisman et al. 2017).  Therefore, effective management requires understanding and consideration of life history, and ecological and socioeconomic drivers.     

Echogram depicting the locations of spawning aggregation of Nassau Grouper (red) and Horse-eye Jacks (blue) along transect off Little Cayman Island   (Egerton et al. 2017)

The collapse of the now endangered Nassau Grouper Epinephelus striatus was due to overfishing on spawning aggregations.   The population collapse resulted in the loss of an important fishery and many spawning aggregations.  Grouper supported many Bahamians for centuries, currently providing over $1 million in landings per year,  and are part of the social fabric (Stump et al. 2017).

Spawning aggregations have indirect effects on marine ecosystems.  Eggboons are large though temporary concentrations that provide highly nutritious fatty acids that suppport multiple trophic levels. Loss of groupers translates to a loss of trophic redistribution via eggboons (Fuiman et al. 2015).

Eggboons from grouper spawning aggregations create immense redistribution of trophic resources to all lower trophic levels.  Dashed arrows represent typical trophic pathways and solid arrows represent flow through eggboons (Fuiman et al. 2015).

From numerous investigations on grouper fisheries throughout the world, we are more aware of the challenges.   In particular, we need to examine how to add the social and cultural aspects to fisheries management efforts.  Examining local fishers knowledge of local groupers may provide better understanding of historical baselines (Robinson et al. 2014).

(Top) A catch of Atlantic Goliath Grouper made on the charter boat Gulfstream in the 1950's. Photo from the Wil-Art Studio, gift of Angie Marine. Florida Keys Public library.   (Bottom) Spearfishing catches in a single day in 1972 at fishing village in southeastern Brazil (Giglio et al. 2017).

The functional extinction of the critically endangered Atlantic Goliath Grouper in many parts of the  range has attracted much attention and fishing moratoria are in place. Recovery of populations depend on conditions in nursery areas (Koenig et al. 2007; Shideler et al. 2015; Lobato et al. 2016) and at far distant spawning aggregations. Research that combines local ecological knowledge and takes advantage of technologists, such as bioacoustics, biotelemetry, sonar, and remote and autonomous underwater vehicles may lead to more accurate information on grouper spawning aggregations (Erisman et al. 2017).   Photo-identification is widely used for non-invasive mark-recapture analysis and appears to be well suited for the sedentary, large Goliath Grouper in marine parks frequented by divers (Hostim-Silva et al. 2017).

Photos and corresponding sketches of Goliath Grouper heads used for individual recognition (Hostim-Silva et al 2017)  

In closing, fishing and lack of effective management leads to rapid overfishing of many species of groupers.  Many measures are being implemented, such as minimum and slot size limits, recreational bag limits, commercial fishing quotas, gear and seasonal controls, marine protected areas, and limited entry, the effectiveness will depend on local context.  Illegal fishing continues to be a problem (Giglio et al. 2014).  In the case of the critically endangered Atlantic Goliath Grouper, we need to:  (1) protect coastal lagoons with fringing mangrove nursery areas; (2) locate spawning aggregations and learn from traditional ecological knowledge; (3) adopt large no-take protected areas and evaluate diving tourism as the presence of large, emblematic fish is an attraction (Heyman et al. 2010; Shideler and Pierce 2016); and (4) halt poaching.  However, leadership, social networks, and co-management at the local level are the glue that will make these plans successful (Gutiérrez et al. 2011).  There are signs of recovery off  Florida where a fishing moratorium on Atlantic Goliath Grouper has been in place since 1990.  Grouper are only one of many valuable residents of threatened coral reef ecosystems. Restoring coral reefs will require reducing and reversing carbon emissions that are driving global climate change (Knowlton and Jackson 2008). 

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References

Amorim, P., P. Sousa, M. Westmeye, G.M. Menezes. 2018. Generic knowledge indicator (GKI): A tool to evaluate the state of knowledge of fisheries applied to snapper and grouper.   Marine Policy 89:40-49.

Aguilar-Perera, A., C. González-Salas, A. Tuz-Sulub, and H. Villegas-Hernández. 209.  Fishery of the Goliath grouper, Epinephelus itajara (Teleostei: Epinephelidae) based on local ecological knowledge and fishery records in Yucatan, Mexico. International Journal of Tropical Biology  57:557–566.

Bender, M.G., G.R. Machado, P.J.A. Silva, S.R. Floeter, C. Monteiro-Netto, O.J. Luiz, and C.E.L. Ferreira.  2014. Local ecological knowledge and scientific data reveal overexploitation by multigear artisanal fisheries in the southwestern Atlantic. PLoS ONE 9(10): e110332. doi:10.1371/journal.pone.0110332

Coleman, F.C., C.C. Koenig, G.R. Huntsman, J.A. Musick, A.M. Eklund, J.C. McGovern, G.R. Sedberry, R.W. Chapman, and C.B. Grimes. 2000. Long-lived reef fishes: the grouper-snapper complex. Fisheries 25:14–21.

Egerton, J.P., A.F. Johnson, L. LeVay, C.M. McCoy, B.X Semmens, S.A. Heppell, and J.R. Turner. 2017. Coral Reefs 36:589-600.

Erisman, B., W. Heyman, S. Kobara, T. Ezer, S. Pittman, O. Aburto-Oropeza, and R.S. Nemeth. 2017. Fish spawning aggregations: where well-placed management actions can yield big benefits for fisheries and conservation. Fish and Fisheries 18 128–144.

FAO. 2009. The state of world fisheries and aquaculture 2008. FAO Fisheries Department. Rome (Italy) 162 p.

Fuiman, L.A., T.L. Connelly, S.K. Lowerre-Barbieri, and J.W. McClelland. 2015. Egg boons: central components of marine fatty acid food webs. Ecology 96:362–372.

Giglio, V.J., A.A. Bertoncini, B.P. Ferreira, M. Hostim-Silva, and M.O. Freitas. 2014.  Landings of goliath grouper, Epinephelus itajara, in Brazil: despite prohibited over ten years, fishing continues.  Brazilian Journal of Nature Conservation 12:118-123.

Giglio, V.J., M.G. Bender, C. Zapelini, and C.E.L. Ferreira. 2017.  The end of the line? Rapid depletion of a large-sized grouper through spearfishing in a subtropical marginal reef. Perspectives in Ecology and Conservation 15:115-118.  
Gutiérrez, N.L. R. Hilborn, and O Defeo. 2011. Leadership, social capital and incentives promote successful fisheries. Nature DOI: 10.1038/nature09689

Heyman,W.D., Carr, L.M., Lobel, P.S., 2010. Diver ecotourism and disturbance to reef fish spawning aggregations: it is better to be disturbed than to be dead. Marine Ecology Progress Series 419, 201e210. http://dx.doi.org/10.3354/meps08831.
Hostim-Silva, M., A.A. Bertoncini, M. Borgonha, J.R. Leite, M.O. Freitas, F. A. Daros, L. S. Bueno, A. P. C. Farro, and C. C. Koenig. 2017.  The Atlantic Goliath Grouper: Conservation strategies for a critically endangered species in Brazil.   Pages 367-405 in M.R. Rossi-Santos, and C. W. Finkl, editors, Advances in Marine Verebrate Research in Latin America.  Springer.

Knowlton, N, and J.B. Jackson. 2008. Shifting baselines, local impacts, and global change on coral reefs. PLoS Biology 6: e54.
Koenig, C.C., F.C. Coleman, A.-M. Eklund, J. Schull, and J. Ueland, 2007.  Mangroves as essential nursery habitat for the goliath grouper (Epinephelus itajara).   Bulletin of Marine Science 80:567-585.

Lobato, C.M.C., B.E. Soares, T.O.R. Begot, and L.F. de Assis Montag. 2016. Tidal pools as habitat for juveniles of the goliath grouper Epinephelus itajara (Lichtenstein 1822) in the Amazonian coastal zone, Brazil.  Brazilian Journal of Nature Conservation 14:20-23. 
Sadovy, Y., and J. Pet.1998.  Wild collection of juveniles for grouper mariculture: just another capture fishery?  Live Reef Fish Information Bulletin 4:36-39

Sadovy de Mitcheson, Y., M.T. Craig, A.A. Bertoncini, K.E. Carpenter,W.W.L. Cheung, J.H. Choat, A.S. Cornish, S.T. Fennessy, B.P. Ferreira, P.C. Heemstra, M. Liu, R.F. Myers, D.A. Pollard, K.L. Rhodes, L.A. Rocha, B.C. Russell, M.A. Samoilys, and J. Sanciangco. 2013. Fishing groupers towards extinction: a global assessment of threats and extinction risks in a billion dollar fishery. Fish and Fisheries 14:119–136. http://dx.doi.org/10.1111/j.1467-2979.2011.00455.x.

Mora, C., R.A. Myers, M. Coll, S. Libralato, T.J. Pitcher, R.U. Sumaila, D. Zeller, R.Watson, K.J. Gaston, B. Worm. 2009. Management effectiveness of the world's marine fisheries, PLoS Biology 7 e1000131, http://dx.doi.org/10.1371/journal.pbio.1000131.

Pinnegar, J.K., G.H. Engelhard. 2008. The ‘shifting baseline’ phenomenon: a global perspective. Reviews in Fish Biology and Fisheries 18: 1–16.

Robinson, J., J.E. Cinner, and N.A.J. Graham. 2014.  The influence of fisher knowledge on the susceptibility of reef fish aggregations to fishing.   PLOS ONE  9(3): e91296.

Robinson, J., N.J. Graham, J.E. Cinner, G.R. Almany, P. Waldie. 2015. Fish and fisher behaviour influence the vulnerability of groupers (Epinephelidae) to fishing at a multispecies spawning aggregation site. Coral Reefs 34:371–382.

Shideler, G.S., S.R. Sagarese, W.J. Harford, J.Schull, and J.E. Serafy. 2015. Assessing the suitability of mangrove habitats for juvenile Atlantic goliath grouper. Environmental Biology of Fishes  98:2067-2082.
Shideler, G.S., and B. Pierce. 2016.  Recreational diver willingness to pay for goliath grouper encounters during the months of their spawning aggregation off eastern Florida, USA.  Ocean and Coastal Management 129:36-43.

Stump, K., C.P. Dahlgren, K.D. Sherman, C.R. Knapp. 2017. Nassau grouper migration patterns during full moon suggest collapsed historic fish spawning aggregation and evidence of an undocumented aggregation.  Bulletin of Marine Science 93:375-389.

Clupeids From Freshwaters of Virginia, by Don Orth

Herrings and shads have existed on the North American continent since the Paleocene (66-56 MYBP).  The state fossil of Wyoming is an extinct clupeid fish Knight eocaena.  Clupeomorph fishes arose in the early Cretaceous Period.  All members of the Clupeidae are silvery and laterally compressed and have sharp scutes on their bellies. The countershaded coloration, silvery mirror scales, and schooling behavior are effective anti predator devices.  In the freshwaters of Virginia, you may encounter six clupeid fishes. Four are anadromous species that spend most of their life cycle in salt water while the other two are freshwater. All the herrings and shads are highly prolific and their abundance may change erratically. The anadromous species are particularly important because they transfer marine-derived nutrients to freshwater in addition to serving as prey for numerous coastal birds, mammals, and fishes.   

The American Shad Alosa sapidissima is the largest of the clupeids. The flesh and roe of the American shad is highly sought as food, hence the specific epithet means "most savory."   The lower jaw shape and mouth are key characteristics to distinguish them from Hickory Shad Alosa mediocris.   American Shad spawn in rivers from Canada to Florida.  American Shad commercial fisheries were important to the history of the American colonies.  John McPhee's The Founding Fish (2002) blended descriptions of the natural history of the American Shad with American history and our obsession with this fish.  George Washington fished for American Shad in the Potomac River.  During the Revolutionary War, Washington and his troops were spending winter near the Schuylkill River at Valley Forge and replenished their food supplies with an early run of American Shad. 

Unfortunately, landings of American Shad peaked in 1897 and have declined ever since.   Major causes of declines were overfishing, construction of dams, pollution, concentrated commercial fisheries near the mouths of rivers (Mansueti and Kolb 1953).   By 1943, an estimated 77% of American Shad entering Chesapeake Bay were harvested.   In the 1950s and 1960s, the shad sport fishing increased due to popularity of spin fishing.  Recruitment overfishing was occurring for many decades before regulations were imposed (Foerster and Reagan 1977).  In the 1980s and the 1990s landings from ocean intercept fisheries doubled and mean age and incidence of repeat spawning among American Shad started to decline (Limburg et al. 2003).  Conservation efforts and dam removals were slowly implemented  and recent monitoring efforts show no signs of recovery (Lipsky et al. 2016; Hilton et al. 2017).  Stocking alone has been inadequate to increase wild populations of American Shad in the James River (Aunins et al. 2014) as concerns about inter-basin transfer of American Shad remains a serious problem.  Currently there is a harvest moratorium on American Shad in Virginia waters, although some limited bycatch is permitted.  

American Shad caught on fly rod.  Source

Head of American Shad showing shape of lower jaw.  Photo by Mitchell Blake. 

Hickory Shad is the next largest clupeid fish in Virginia. They are also known as the shad herring or the fall herring and spawn in rivers from Maryland to Florida.  Hickory Shad resemble American Shad but their distribution and feeding niche are different.  Note that in the photo below their lower jaw extends past the upper jaw when closed.  This is the easiest way to reliably distinguish Hickory Shad from the American Shad.  Hickory Shad also has fewer gill rakers than the American Shad and its diet is mainly fish and crustaceans while the American Shad is planktivorous. Sand lance, anchovies, cunners, herring, scup, silversides, and other small fish, squid, fish eggs, and even small crabs have been observed in Hickory Shad guts.   The species epithet mediocris translates to mediocre, referring to its desirability as a food fish.  

Hickory Shad. Photo by NCFishes.com

Hickory Shad (top) and American Shad (bottom).  Photo by NCFishes.com

Blueback Herring Alosa aestivalis, once known as the glut herring, historically ranged from the Gulf of St. Lawrence to the St. Johns River, Florida.   It has a blue-green colored back and silvery sides and easily confused with the Alewife.  The Alewife Alosa pseudoharengus, also known as the Gaspereau and the Branch Herring, historically ranged from Labrador to South Carolina.  Distinguishing the two species is often confusing and fisheries have lumped the two into 'river herring.'  River herring were listed as species of concern by the National Marine Fisheries Service in 2006 and a harvest moratorium was enacted in 2012.  

The two species can be distinguished.  The back of the Alewife is typically gray-green. The Alewife has a larger eye; it is broader than the distance from its forward edge to the tip of its snout.  The lining of the belly is sooty or black in the Blueback Herring and pale gray or pinkish white in the Alewife.   

The distribution and abundance of both Alewife and Blueback Herring have been highly altered by overfishing, dams, culverts, and introductions.  Both Alewife and Blueback Herring have been introduced in freshwater reservoirs to provide a land-locked populations to support many piscivorous sport fish.  However,  anadromous populations appear most at risk.  Each major Atlantic slope river supports genetically distinct populations, which show declines in abundance and mean size (Palcovacs et al. 2014).    Declines are most dramatic and widespread for the Southern New England Stock of Alewife.  Efforts are underway to reduce the incidental catch of river herrings during their coastal migrations where they overlap with Atlantic Herring Clupea harengus trawlers (Turner et al. 2017). Recently, hybridization between the Blueback Herring and Alewife raised  an additional management concern (McBride et al. 2014).  In New England,  the most heavily dammed region of the world, the freshwaters support only 6.7% of historical capacity of anadromous alewife biomass and abundance (Mattocks et al. 2017). 

Blueback Herring (top) and Alewife (bottom). Photo by Chris Bartlett.

Gizzard Shad Dorosoma cepedianum occurs in freshwater and brackish waters.  It has a deep body, with a silvery-green coloration above fading to plain silver below.  The small mouth is subterminal to inferior and it filter feeds on phytoplankton when young and switches to zooplankton as it grows larger.  A better common name might be the Bluntnose Shad, as the small blunt snout distinguishes it from other shads and herrings.   Gizzard Shad have a distinguishingly long dorsal fin ray occurs at the back of the dorsal fin.  But the 'gizzard' name refers to the muscular gizzard that aids in the breakdown of consumed foods.  Gizzard Shad may deplete zooplankton when very abundant and switch to detrital feeding.  As detrital deposit feeders they resuspend benthic nutrients into the water column where they may stimulate plankton growth.   

Gizzard Shad are readily consumed by Walleye and Black Bass, but may quickly grow beyond the size available to many predators.  Consequently, they are not the ideal forage fish for gape-limited piscivorous fish.  However, Bald Eagles, Ospreys, and Great Blue Heron can capture and eat a large Gizzard Shad. Coleman Sheehy photographed a Great Blue Heron that just captured a Gizzard Shad from James River in Richmond, Virginia.  In tidal freshwater and oligohaline sites, diet of the Osprey was 28% Gizzard Shad (Glass and Watts 2009).

Gizzard Shad. Photo by Uland Thomas. 

Gizzard Shad are widely distributed and have been introduced in many other drainages outside its native range.  They are native to all drainages in Virginia except the New River. However, they were introduced into the New River in the late 1980s.  Gizzard Shad school in large numbers and are caught with cast nets and used for cut bait by those fishing for catfish.  They rarely are hooked by anglers.  However, this rare photo proves that they can be. 

Small Gizzard Shad caught via microfishing in Lake Erie.  Photo by Sean Phillips. 

Threadfin Shad Dorosoma petenense are smaller, southern versions of the Gizzard Shad with different coloration and mouth shape. The principal distinctions are the mouth, which has a terminal position,  and the bluish-gray dorsum and yellowish coloration in caudal fin.  The upper jaw does not project beyond the lower jaw. Threadfin shad have a prominent purple to black spot on the upper side of the body just beyond the operculum and a distinguishingly long dorsal fin ray occurs at the back of the dorsal fin.   The Threadfin Shad are distributed in the lower Mississippi and other Gulf drainages, south to Guatemala.  Because of their small size, they have been introduced widely as a forage fish.  In Virginia, there are populations in Lake Anna, Back Bay, and the James drainage. Threadfin Shad are sensitive to cold temperature and often die in mass during cold winters in the northern part of the range (McLean et al. 1985). 

Threadfin Shad. Photo by Uland Thomas. 

Clupeid fishes are adapted for life in well-lit pelagic zones of lakes, rivers, and the ocean. Throughout life these fishes are eaten by numerous piscivores, including our national bird, the Bald Eagle (Markham and Watts 2008).  Anadromy, coupled with high fecundity, permits development of large populations.  Although these fishes are adapted for heavy predation mortality, the major long-term threats to population viability appear to be connectivity with spawning and rearing habitats and by catch from ocean fisheries.  

If you have been reading carefully, you should be able pass these two quizzes. 

Quiz One

Six clupeid fishes found in freshwaters of Virginia.  Name each one.

Quiz Two

One of these is an Alewife, the other is a Blueback Herring.  Which is which?

References

Glass, K.A., and B.D. Watts. 2009.  Osprey diet composition and quality in high- and low-salinity areas of lower Chesapeake Bay. Journal of Raptor Research 43:27-36.

Hilton, E. J., R. Latour, P. McGrath, B. Watkins, and A. Magee. 2017. Monitoring the abundance of American shad and river herring in Virginia's rivers 2016 Annual Report. Virginia Institute of Marine Science, College of William and Mary. https://doi.org/10.21220/V5788B

Limburg, K.E., K. A. Hattalaand, and A. Kahnle. 2003. American shad in its native range.  Pages 125–140 in K. E. Limburg and J. R. Waldman, editors. Biodiversity, status, and conservation of the world's shads, American Fisheries Society, Bethesda, Maryland, Symposium 35.

Markham, A.C., and B.D. Watts. 2008.  The influence of salinity on the diet of nesting Bald Eagles. Journal of Raptor Research 42:99-109.

Mattocks, S., C.J. Hall, and A. Jordan. 2017.  Damming, lost connectivity, and the historical role of anadromous fish in freshwater ecosystem dynamics.  BioScience 67(8):713-728. https://doi.org/10.1093/biosci/bix069

McLean, R.B., J.S. Griffith, and M.V. McGee. 1985. Threadfin shad, Dorosoma petenense Günther, mortality: causes and ecological implications in a South-eastern United States reservoir.  Journal of Fish Biology 27:1-12.

McBride, M. C., T.V.Willis, R.G. Bradford, and P. Bentzen. 2014. Genetic diversity and structure of two hybridizing anadromous fishes (Alosa pseudoharengus, Alosa aestivalis) across the northern portion of their ranges. Conservation Genetics DOI 10.1007/s10592-014-0617-9.

Palcovacs, E.P., D.J. Hasselman, E.E. Argo, SR. Gephard, K.E. Limburg, D.M. Post, T.F. Schultz, and T.V. Willis.  2014. Combining genetic and demographic information to prioritize conservation efforts for anadromous alewife and blueback herring.  Evolutionary Applications 7:212-226.

Turner, S.M., J.A. Hare, J.P. Manderson, J.J. Hoey, D.E. Richardson, C.L. Sarro, and R. Silva. 2017. Cooperative research to evaluate an incidental catch distribution forecast.  Frontiers in Marine Science  http://dx.doi.org/10.3389/fmars.2017.00116

Swampfish: A Lesson in Preadaptation, by Don Orth

When I think of dark stained waters, my mind always brings up an image of the Creature from the Black Lagoon, a 1954 movie.  But the star of that movie, Gill-Man, was humanoid with gills and webbed hands. The fishes of the dark stained waters of the coastal plain are Swampfish Chologaster cornuta.   A movie about the Swampfish would have to take us into the subterranean world of the cavefishes. Let's learn more about the world of the Swampfish. 

Gill-Man, the main character from Creature from the Black Lagoon 

Swampfish are small fish (1- 2 ½ inches) that live only two years.  They are easily distinguished from other local fishes by the brown coloration dorsally and creamy-yellow belly with three dark longitudinal stripes on each side.   The body shape is distinctive with a combination of flattened head, small eyes, upturned mouth, no pelvic fin, and a rounded caudal fin.  

Swampfish  Photo by Scott Smith NCFishes.com 

The Swampfish is found in acidic blackwater swamps, sloughs, and streams of the coastal plain from southeast Virginia to east-central Georgia. These waters are stained from high levels of organic matter and often have dense aquatic vegetation and coarse woody debris.  The best way to sample Swampfish is with a dipnet because they are so closely associated with cover, a reaction known as thigmotaxis.   The largest series of Swampfish collected from Virginia were taken during application of the ichthyocide, rotenone (Jenkins and Burkhead 1994).

The family Amblyopsidae is most closetly related to the Pirate Perch.  The Swampfish ancestor was likely adapted for life in the changing coastal plain habitats  and changing sea levels after the Cretaceous-Palogene extinction event. There are currently between 7 and 9 species of Amblyopsidae, all of which are geographically isolated from the Swampfish and at least partially cave-adapted. The most recent cavefish, the Hoosier Cavefish, was discovered in Indiana by Chakrabarty et al. (2014). Now there's a movie plot.  Cue the music!  Millions of years before emergence of cavefish, there were ancestral swampfish that give rise to the diversity of amblyopsids we see today.   Rise of the Cavefish -- that's a good movie title. 

 

 Range map of the Swampfish (Niemiller and Poulson 2010). 

Many of the weird characteristics of the Swampfish seem be preadaptions for life in caves. Feeding may be nocturnal or crepuscular.  Amphipods, chironomid larvae, and cladocerans were the most frequent diet items reported by Ross and Rohde (2003). Swampfish have tiny black spots for eyes and are negatively phototactic. They possess numerous rows of neuromasts, or sensory papillae, on their head, body, and caudal fin. Nostrils are tubular. The vent (anus) is located in the throat position, similar to the Pirate Perch, its sister group. Why?  Keep reading!  The mature male possesses a strange appendage on the snout; its function is still unknown. It may be revealed in the movie.  The small size, small eyes, nocturnal behavior, and enhanced sensory receptor for feeding and orientation in a dark environment are preadaptations for cave-dwelling descendent species (Poulson 1963). All species of Amblyopsidae occur in regions that were not glaciated.  The cave-dwellers in the family occur in regions of karst where the limestone and dolomites have dissolved to create caves with sufficient water to support a simple food web (Noltie and Wicks 2001). 

What about the vent location? Young are born with the vent (i.e., anal–genital pore) positioned just anterior to the anal fin and it migrates forward as the Swampfish matures (Ross and Rohde 2003). You read that correctly.  All excreta, egesta, and gametes are released near the head region. This vent location facilitates transfer of eggs directly to the gill chamber cave-dwelling Northern Cavefish Amblyopsis spelaea (Eigenmann 1909).  However, the Swampfish with a similar vent location never carried eggs or yolk-sac fry in its gill cavity (Ross and Rohde 2003).  Interesting plot twist for the movie.  

View of the dorsal surface of the snout in male and female Swampfish from April sample.  Ross and Rohde (2003).

Unlike the small, isolated populations of cavefishes, the Swampfish populations appear to be more secure.  Channelization and removal of streamside forest and riparian vegetation have altered the lowland swamps and streams, but the populations are resilient.  Native fish enthusiasts can easily collect and keep Swampfish, which adapt well in dimly lit aquaria with peat moss to increase acidity (Goldstein 2000).  They may keep you entertained until the release of Rise of the Cavefish. 

References

Agassiz, J.L.R. 1853. Recent researches of Prof. Agassiz. American Journal of Science and Arts 16: 134.

Eigenmann, C.H. 1909. Cave vertebrates of America, a study in degenerative evolution. Carnegie Institute of Washington Publication 104:1-241.

Goldstein, R. J. 2000.  American aquarium fishes.  Texas A&M University Press. College Station, Texas. 

Jenkins, R.E. and N.M. Burkhead. 1994. Freshwater Fishes of Virginia. American Fisheries Society, Bethesda, Maryland, 1079 pp.

Niemiller, M.L., and T.L. Poulson. 2010. Subterranean fishes of North America: Amblyopsidae.  Pages 169-280 in E. Trajano, M.E. Bichuette, and B.G. Kapoor, editors.  Biology of Subterranean Fishes.  CRC Press, Science Publishers.

Noltie, D.B., and C.M. Wicks. 2001. How hydrogeology has shaped the ecology of Missouri’s Ozark cavefish, Amblyopsis rosae, and southern cavefish, Typhlichthys subterraneus: insights on the sightless from understanding the underground. Environmental Biology of Fishes 62:171-194.

Poulson, T.L. 1963. Cave adaptation in amblyopsid fishes.  American Midland Naturalist 70:257-290.

Chakrabarty P., J.A. Prejean, and M.L. Niemiller. 2014. The Hoosier cavefish, a new and endangered species (Amblyopsidae, Amblyopsis) from the caves of southern Indiana. ZooKeys 412: 41–57. doi: 10.3897/zookeys.412.7245

Ross, S.W. and F.C. Rohde. 2003. Life history of the swampfish from a North Carolina stream. Southeastern Naturalist 2: 105-120.