Abstract
Populations of 86 Atlantic Ocean marine fishes have changed during the last 45 years off North Carolina. Examination of the ocean conditions and its fish faunal interrelationships explain reasons for these changes.
INTRODUCTION
Based on 45 years of Atlantic Ocean observations off North Carolina, changes have occurred to 86 fish specie's (Table 1). Are these changes the result of changing ocean conditions, overfishing, fish faunal cycles, or other factors? Examination of ocean conditions and fish fauna abundances may explain these observations.
Status of 86 marine fish species frequenting North Carolina waters in 2011. S = scarce, A = absent, R = rare.
OCEAN: The ocean is a vast conveyor belt referred to as the Meridional Overturning Circulation (MOC) (Fig. 1a) that oscillates between the northern and southern hemispheres and transports vast amounts of heat, carbon, nutrients and other substances around the globe (Fig. 1b) that comes out. It connects the ocean surface that also contains the Gulf Stream, with the deep sea (Schmittner et al. 2007). Wunsch (1918, 1996, 2007), Sverdrup (1942), Stommel (1948, 1958), Munk (1950), Wust (1955) and Bumpus (1955, 1970) were stalwarts that studied these ocean conveyor systems. Gnanadesikan et al. (2007) and Longworth and Bryden (2007) discovered ocean circulations were effected by winds, eddies, upwelling, thermothickness, flow speed, forcing, freshwater inflow and their interactions and interrelationships. Fresh water inflow could effect MOC presence for up to 500 yrs (Latif et al. 2007). Cold freshwater flow from/over the Labrador Shelf, coupled with the NAO (North Atlantic Oscillation index) affect temperatures and salinities, while strong NAOs cause strong winds, severe winters, and high salinities that slow the Gulf Stream and move it farther South, and vice versa (Rossby and Benway 2000). Cold shelf waters can deflect the Gulf Steam offshore (Matthews and Pashuk 1984). Heat loss by melting ice caps of the North Pole (Fig. 1b) decreases the MOC flow and increases rainfall, monsoons and drought in various parts of the world (Delworth et al. 2007). Latif et al. (2007) expected a northward increase of the MOC by 25% until 2010 and the variability of the MOC would not exceed the level of variability until 2050. Frantantoni (2001) (Fig. 2) documented shoreward shifts in Atlantic Gulf Stream ocean waters between 1991–1999 (Wunsch 2007).
Schematic of global overturning circulation, in Schmitterner et al. 2007 Amer. Geophysical Union Monogr. 173. p. 3.
Schematic of global overturning circulation, in Schmitterner et al. 2007 Amer. Geophysical Union Monogr. 173. p. 3.
Global thermal haline circulation pattern. in Sarnthein et al. 2007. Amer. Geophysical Union Mongr. 173. p. 177.
Global thermal haline circulation pattern. in Sarnthein et al. 2007. Amer. Geophysical Union Mongr. 173. p. 177.
Trajectories of surface drifters in the North Atlantic 1990–1999, in WUNCH 2007. Amer. Geophysical Union Monogr. 173. p.61. Note movement of waters near shore between 1995–1999.
Trajectories of surface drifters in the North Atlantic 1990–1999, in WUNCH 2007. Amer. Geophysical Union Monogr. 173. p.61. Note movement of waters near shore between 1995–1999.
EARLY FISH LITERATURE: Early literature accounts dealing with fishes of the North Atlantic and North Carolina were: Jenkins (1855, 1887); Yarrow (1887); Jordan and Gilbert (1879); Smith (1907); Gudger (1910, 1910–1911, 1912, 1913); Coles (1910, 1913, 1915, 1926); Radcliffe (1913, 1916); and Brimley (1935a,b).
Jenkins (1885) listed 20 species of fishes occurring off North Carolina, such as the smallmouth sawfish, Pristis pectinata, Atlantic bumper, Chloroscombrus chrysurus, Man-of-war, Nomeus gronovi, yellow jack, Caranx bartholomei and ocean sunfish, Mola mola. Gudger (1912) added the American eel, Anguilla rostrata. Gudger (1913) commented on the occurrences of sandbar shark, Carcharhinus plumbeus, barndoor skate, Raja laevis, (now Dipterus laevis), yellow stingray Urophysis garnoti (now Urobatis jamaicensis), spotted eagle ray, Aetobatus narinari, Atlantic sturgeon, Acipenser oxyrinchus, gold spotted eel, Ophichthus ocellatus (now Myrichthys ocellatus), spotted moray Lycodontes moringa (now Gymnothorax moringa), hardhead catfish, Felichthys felis (now Ariopsis felis), leather jacket, Oligoplites saurus, Atlantic threadfin, Polydactylus octonemus and trunkfish, Lactophrys tricornis. Gudger (1915) added the Atlantic midshipman, Porichthys poroissimus (now Porichthys plectrodon) to the faunal list. Coles (1915) collected the lesser electric ray, Narcine brasiliensis (now Narcine bancroftii). Radcliffe (1916) commented on Cole's capture of several lesser devil rays Mobula olfersi (now Mobula hypostoma) at Cape Lookout (Fig. 3). Brimley (1935a,b) noted basking sharks Cetorhinus maximus and whale sharks, Ryncodon typus in North Carolinian waters.
Capture of Mobula hypostoma at Cape Lookout, NC 16 July 1913, in Bull. US Bur. Fish. Vol 34, 1916 (Public domain).
Capture of Mobula hypostoma at Cape Lookout, NC 16 July 1913, in Bull. US Bur. Fish. Vol 34, 1916 (Public domain).
RECENT FISH LITERATURE: Recent important studies of fishes of the North Atlantic are: Colton (1972); Clarke and Brown (1977); Murawski (1992, 1993); and McBride and Able (1998); Marsh et al. (1998); Parker and Dixon (1998); Mountain (2002); Hare and Whitfield (2003); Schwartz (1972, 1997, 2001, 2008); Schwartz et al. (1990); Schwartz and Lindquist (2000); Schwartz et al. 2010) and Poluakis et al. (2011).
Most recent literature on fishes of the North Atlantic documents the effects of warming waters on fishes (Colton 1972; Mountain and Murawski (1992) and Murawski and Able (1992). Murawski (1993) noted northward movement of 36 fish species during a 33 yr period along the Atlantic coast. McBride and Able (1998), Mountain (2002) and Murawski et al. (1999) expounded on the effects of cold water, especially during the severe winter of 1882 that killed many golden tilefish, Lopholatilus chamaeleonticeps. McBride and Able (1990) reported the effects of cold water on six species of Butterfly fishes. Clarke and Brown (1997) noted drastic changes in fish populations resulting from overfishing. Parker and Dixon (1998) documented changes in 85 fish species frequenting an offshore rock reef off North Carolina. Warming substrates waters were the possible causes of the changes. Hare and Whitfield (2003) reported changing populations of 95 reef fishes between 1970 and 1990 off North Carolina and attributed the changes to the increase and abundance of the marine introduced lionfish Pterois volitans that has decimated local and many reef fishes. Schwartz (1970) noted the decline of the Atlantic sturgeon Acipenser oxyrinchus as a result of habitat destruction and overfishing. Schwartz (1972) noted the decrease of the Cubera snapper Lutjanus cynopterus. Schwartz (2003) commented on the scarcity of flying gurnards Polydactylus volitans, gafftopsail catfish, Bagra marina as well as the hardhead catfish Galeichthys felis ( now Ariopsis felis), that is absent today. (Schwartz 2003) described the capture of the last adult smalltooth sawfish Pristis pectinata North Carolina in 1963 (a 1.2 m specimen was captured in 1999 at Cape Lookout) and ocean sunfish, Mola mola, once common and now rare. Schwartz et al. (2010) documented changes in shark populations off North Carolina pre and post 1910 when water temperatures changed from cold to warm; major influences were 11 yr sunspot activity affecting local water conditions. Poluakis et al. (2011) documented the only remaining Pristis pectinatus population in the United States in southeastern Florida.
TODAY: The demise or presence of 86 marine fish populations have occurred off North Carolina (Table 1), many authors attribute changes to overfishing, water temperature changes, reproduction and climate change. I offer another explanation. Once scientists and the public realize the existence of the great conveyor belt (MOC) and (NAO) that regulate and cause so called climate in all parts of the world, there will be less histrionics related to global warming. Today, heated waters are causing fish faunal changes in the Northern Hemisphere, but this is a natural event because of the great conveyor belt has shifted to the Northern Hemisphere carrying heated surface waters with it. Heat is being given off, that in turn is melting the Artic glaciers causing inflow of freshwater which with the NAO, is building up causing the MOC to slow. Cold waters flowing southward have influenced benthic fishes such as the golden tilefish while surface waters are carrying temperate and tropical fishes northward. How long this condition will last is unknown, it may take years to correct. Meanwhile modelers try to fit observations in order to explain changes that nature determines. Remember, “a model is a lie that causes you to see the truth. Models are simplifications, by definition, under representing the capacity of nature” (Hansen et al. 1998). Meanwhile, a report (IPCC SREX) by the 29 member International panel for climate change, meeting in Kampala, Uganda in 2011, examined Managing the risks of extreme events and disasters to advance climate adaptation (SREX). Had they been aware of MOC and NAO effects their work would have been easier and/or unnecessary. Given time nature will right itself and we may see the return of many species such as golden tilefish or lesser devil ray, not seen for many decades, unless man continues to decimate them in the interim.
Acknowledgments
Joe Smith (NMFS Beaufort) reviewed the paper. Librarians P. Marraro (NOAA) and Janel Miller (Duke Marine Lab, Beaufort) helped retrieve several references. Figures 1, 2, and 3. were excerpted from Ocean Circulation published by The American Geophysical Union. S. Borenstein, Washington DC., provided the IPCC SREX report. Glenn Safrit typed the manuscript.
