Environmental Biology of Fishes

, Volume 95, Issue 1, pp 79–97 | Cite as

Habitat-specific feeding by cownose rays (Rhinoptera bonasus) of the northern Gulf of Mexico

  • Matthew Joseph AjemianEmail author
  • Sean Paul Powers


Past studies have suggested that increases in cownose ray (Rhinoptera bonasus) abundance may pose problems for fisheries management due to their specialized diet of exploitable mollusks. However, more recent work has identified cownose rays as opportunistic generalists, consuming mainly non-commercial prey (e.g. soft-bodied invertebrates) most abundant in their locale. To better assess the generalist vs. specialist foraging behaviors of cownose rays, including their impact to commercial shellfish of the north-central Gulf of Mexico, we conducted gut content analysis on 201 individuals from coastal Alabama. Prey items were analyzed for frequency of occurrence and percent composition by weight, which were used to develop an index of importance. Our diet analysis indicated a minimal impact of cownose rays to exploitable shellfish species of coastal Alabama. Further, we observed important spatial and ontogenetic diet variability: adult diets were dominated by crustaceans along barrier islands and open waters of the Gulf of Mexico, whereas juvenile and young-of-the-year individuals almost exclusively consumed bivalves in riverine and estuarine areas. Individual cownose ray diets were primarily monotypic (54.3%) and appeared selective for amphipods (i.e. Haustorius sp.) when hyperabundant along gulf barrier islands and bivalves at estuarine sites regardless of ambient densities. While this study highlights the importance of locality in determining dietary composition of cownose rays, we do not suggest this species is opportunistic or completely mollusk-specialized. Alternatively, we propose cownose rays exhibit a continuum of foraging behaviors between specialization and generalization, depending on locale and prey availability.


Elasmobranch Feeding Foraging Gulf of Mexico Batoid Cownose ray Opportunism Diet 



This study would have been impossible without the tremendous field support of various students, interns and technicians of the Fisheries Ecology Lab and multiple volunteers and staff at the Dauphin Island Sea Lab. S. Bosarge provided invaluable assistance with benthic invertebrate identification from gut samples. Benthic core data from Point aux Pins was provided by the Marine Ecology Lab at DISL, and offshore core data was provided by the Fisheries Oceanography of Coastal Alabama (FOCAL) program. Benthic trawl data were generously supplied by the Alabama Marine Resources Division, in particular J. Mareska. Some of the equipment and collection gear (e.g. gillnets) was provided by NOAA Panama City Lab. Graduate Fellowship support to MJA was provided by the University of South Alabama department of marine sciences, the Northern Gulf Institute, and the Dauphin Island Sea Lab. We are indebted to advisory members K.L Heck, Jr, J. Valentine, M.R. Heithaus and P.J. Motta for their valuable comments and input. This is contribution No. 402 from the Dauphin Island Sea Lab.


  1. Amundsen PA, Glaber HM, Staldvik RJ (1996) A new approach to graphical analysis of feeding strategy from stomach content data. Modification of the Costello (1990) method. J Fish Biol 48(4):607–614Google Scholar
  2. Anderson MJ (2001) A new method for non-parametric multivariate analysis of variance. Austral Ecology 26:32–46Google Scholar
  3. Anderson MJ, Ellingsen KE, McArdle BH (2006) Multivariate dispersion as a measure of beta diversity. Ecol Lett 9(6):683–693PubMedCrossRefGoogle Scholar
  4. Arthur KA, McMahon KM, Limpus CJ, Dennison WC (2009) Feeding ecology of Green Turtles (Chelonia mydas) from Shoalwater Bay, Australia. Mar Turt Newsl 123:6–12Google Scholar
  5. Blaylock RA (1993) Distribution and abundance of the cownose ray, Rhinoptera bonasus, in Lower Chesapeake Bay. Estuaries 16(2):255–263CrossRefGoogle Scholar
  6. Cave RN (1978) Predator-prey relationships involving the american oyster, Crassostrea virginica (Gmelin), and the black drum, Pogonias cromis (Linnaeus), in Mississippi Sound. Southeastern Louisiana University, HammondGoogle Scholar
  7. Clarke KR (1993) Non-paramentric multivariate analyses of changes in community structure. Aust J Ecol 18:117–143CrossRefGoogle Scholar
  8. Collins AB, Heupel MR, Hueter RE, Motta PJ (2007a) Hard prey specialists or opportunistic generalists? An examination of the diet of the cownose ray Rhinoptera bonasus. Mar Freshwater Res 58:135–144CrossRefGoogle Scholar
  9. Collins AB, Heupel MR, Motta PJ (2007b) Residence and movement patterns of cownose rays Rhinoptera bonasus within a south-west Florida estuary. J Fish Biol 70:1–20Google Scholar
  10. Craig JK, Gillikin PC, Magelnicki MA, May LN (2010) Habitat use of cownose rays (Rhinoptera bonasus) in a highly productive, hypoxic continental shelf ecosystem. Fish Oceanogr 19(4):301–317CrossRefGoogle Scholar
  11. Ferry LA, Caillet GM (1996) Sample size and data analysis: are we characterizing and comparing diet properly? In: MacKinlay DD, Shearer KD (eds) Feeding ecology and nutrition in fish. American Fisheries Society, Bethesda, pp 71–80Google Scholar
  12. Fisher RA, Call GC, Grubbs RD (2011) Cownose ray (Rhinoptera bonasus) predation relative to bivalve ontogeny. Journal of Shellfish Research 30:187–196Google Scholar
  13. Flemer D, Kruczynski W, Ruth B, Bundrick C (1998) The relative influence of hypoxia, anoxia, and associated environmental factors as determinants of macrobenthic community structure in a Northern Gulf of Mexico estuary. J Aquat Ecosyst Stress Recovery (Formerly J Aquat Ecosyst Health) 6(4):311–327CrossRefGoogle Scholar
  14. George GJ (2007) Acoustic tagging of black drum on Louisiana oyster reefs: movements, site fidelity, and habitat use. Louisiana State UniversityGoogle Scholar
  15. Gray AE, Mulligan TJ, Hannah RW (1997) Food habits, occurrence and population structure of the bat ray, Myliobatis californica, in Humboldt Bay, California. Environ Biol Fish 49:227–238CrossRefGoogle Scholar
  16. Grubbs RD (2010) Ontogenetic shifts in movements and habitat use. In: Carrier JC, Musick JS, Heithaus MR (eds) Sharks and their relatives II: Biodiversity, adaptive physiology, and conservation. CRC Press, Boca Raton, p319–350Google Scholar
  17. Heithaus MR, Frid A, Wirsing AJ, Worm B (2008) Predicting ecological consequences of marine top predator declines. Trends Ecol Evol 23(4):202–210PubMedCrossRefGoogle Scholar
  18. Hines AH, Whitlach RB, Thrush SF, Hewitt JE, Cummings VJ, Dayton PK, Legendre P (1997) Nonlinear foraging response of a large marine predator to benthic prey: eagle ray pits and bivalves in a New Zealand sandflat. J Exp Mar Biol Ecol 216:191–210CrossRefGoogle Scholar
  19. Hyslop EJ (1980) Stomach content analysis—a review of their methods and their applications. J Fish Biol 17:411–429CrossRefGoogle Scholar
  20. Iversen ES, Jory DE, Bannertor SP (1986) Predation on queen conchs, Strombus gigas, in the Bahamas. Bull Mar Sci 39(1):61–75Google Scholar
  21. Jolley JW (1972) Exploratory fishing for the sunray venus clam, Macrocallista nimbosa, in Northwest Florida. Florida Department of Natural Resources Marine Research Lab Technical Series, St. PetersburgGoogle Scholar
  22. Kilgen RH, Dugas RJ (1989) The ecology of oyster reefs of the northern Gulf of Mexico: an open file report. U.S. Fish and Wildlife ServiceGoogle Scholar
  23. Kurz RC (1995) Predator-prey interactions between Gray Triggerfish (Baliste capriscus Gemlin) and a guild of sand dollars around artificial reefs in the northeastern Gulf of Mexico. Bull Mar Sci 56(1):150–160Google Scholar
  24. Merriner JV, Smith JW (1979) A report to the oyster industry on the biology and management of the cownose ray (Rhinoptera bonasus, Mitchill) in lower Chesapeake Bay. Special report in applied marine science and ocean engineering. Virginia Institute of Marine Science, Gloucester PointGoogle Scholar
  25. Myers RA, Baum JK, Shepherd TD, Powers SP, Peterson CH (2007) Cascading effects of the loss of apex predatory sharks from a coastal ocean. Science 315:1846–1850PubMedCrossRefGoogle Scholar
  26. Neer JA, Thompson BA (2005) Life history of the cownose ray, Rhinoptera bonasus, in the northern Gulf of Mexico, with comments on geographic variability in life history traits. Environ Biol Fish 73(3):321–331CrossRefGoogle Scholar
  27. Orth R (1975) Destruction of eelgrass, Zostera marina, by the cownose ray, Rhinoptera bonasus, in Chesapeake Bay. Chespeake Science 16:205–208CrossRefGoogle Scholar
  28. Pace ML, Cole JG, Carpenter SR, Kitchell JF (1999) Trophic cascades revealed in diverse ecosystems. Trends Ecol Evol 14(12):483–488PubMedCrossRefGoogle Scholar
  29. Parsons GR (2006) Sharks, skates and rays of the Gulf of Mexico: a field guide. University Press of Mississippi, JacksonGoogle Scholar
  30. Peterson CH, Fodrie FJ, Summerson HC, Powers SP (2001) Site-specific and density-dependent extinction of prey by schooling rays: generation of a population sink in top-quality habitat for bay scallops. Oecologia 129:349–356Google Scholar
  31. Pinnegar JK, Polunin NVC, Francour P, Badalamenti F, Chemello R, Harmelin-Vivien ML, Hereu B, Milazzo M, Zabala M, D’Anna G, Pipitone C (2000) Trophic cascades in benthic marine ecosystems: lessons for fisheries and protected-area management. Environ Conserv 27(02):179–200CrossRefGoogle Scholar
  32. Polis GA, Sears ALW, Huxel GR, Strong DR, Maron J (2000) When is a trophic cascade a trophic cascade? Trends Ecol Evol 15(11):473–475PubMedCrossRefGoogle Scholar
  33. Polis GA, Strong DR (1996) Food web complexity and community dynamics. Am Nat 147(5):813–846CrossRefGoogle Scholar
  34. Powers SP, Gaskill D, Peterson CH, Fodrie FJ (2011) Density-dependent predation by migratory predators creates sink populations in a marine benthic landscape. Marine Ecology Progress Series, in pressGoogle Scholar
  35. Rakocinski C, Heard RW, Simons T, Gledhill D (1991) Macroinvertebrate associations from beaches of selected barrier islands in the Northern Gulf of Mexico: important environmental relationships. Bull Mar Sci 48(3):689–701Google Scholar
  36. Rogers C, Roden C, Lohoefener R, Mullin K, Hoggard W (1990) Behavior, distribution, and relative abundance of cownose ray schools Rhinoptera bonasus in the northern Gulf of Mexico. Northeast Gulf Sci 11:69–76Google Scholar
  37. Salsman GG, Tolbert WH (1965) Observations on the sand dollar, Mellita quinquiesperforata. Limnol Oceanogr 10:152–155CrossRefGoogle Scholar
  38. Shipp RL (1986) Dr. Bob Shipp’s guide to fishes of the Gulf of Mexico. Kme SeabooksGoogle Scholar
  39. Smith JW, Merriner JV (1985) Food habits and feeding behavior of the cownose ray, Rhinoptera bonasus, in lower Chesapeake Bay. Estuaries 8(3):305–310CrossRefGoogle Scholar
  40. Smith JW, Merriner JV (1987) Age and growth, movements and distribution of the cownose ray, Rhinoptera bonasus, in Chesapeake Bay. Estuaries 10(2):153–164CrossRefGoogle Scholar
  41. Steimle F Jr, Terranova R (1985) Energy equivalents of marine organisms from the continental shelf of the temperate northwest Atlantic. J Northwest Atl Fish Sci 6:117–124CrossRefGoogle Scholar
  42. Stevens JD, Bonfil R, Dulvy NK, Walker PA (2000) The effects of fishing on sharks, rays, and chimaeras (chondrichthyans), and the implications for marine ecosystems. ICES J Mar Sci 57(3):476–494. doi: 10.1006/jmsc.2000.0724 CrossRefGoogle Scholar
  43. Strong DR (1992) Are trophic cascades all wet? Differentation and donor-control in speciose ecosystems. Ecology 73:747–754CrossRefGoogle Scholar
  44. Sutter FC, Waller RS, McIlwain TD (1988) Black Drum. Species Profiles: Life histories and environmental requirements of coastal fishes and invertebrates (Gulf of Mexico)Google Scholar
  45. Wheeler KN, Stark CC, Heard RW (2002) A preliminary study of the summer feeding habits of juvenile Florida Pompano (Trachinotus carolinus) from open and protected beachs of the northeastern Gulf of Mexico. Proc - Gulf Caribb Fish Inst 53:661–673Google Scholar
  46. Yamaguchi A, Kawahara I, Ito S (2005) Occurrence, growth and food of longheaded eagle ray, Aetobatus flagellum, in Ariake Sound, Kyushu, Japan. Environ Biol Fish 74:229–238CrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media B.V. 2011

Authors and Affiliations

  1. 1.Dauphin Island Sea LabUniversity of South AlabamaDauphin IslandUSA

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