September 2010

  • _bullnoseray.jpg
     The Bullnose Ray is one of two eagle ray species recorded from Chespeake Bay waters. Eagle rays differ from stingrays by having a head that is distinct from the disk. The Bullnose Ray can attain a disk width of 86 cm (3 ft.).  
  • _bullnoseraytail.jpg
     The Bullnose Ray's whiplike tail has a small dorsal fin at its base, followed by 1 or 2 serrated spines.  
  • _sheepsheadnet.jpg
     Sheepshead populations are distributed from Nova Scotia to Brazil. The species can reach a maximum size of 75 cm (2.5 ft.) and exceed 8 kg (18 lbs.).  
  • _sheepsheadteeth.jpg
     Sheepshead have one row of incisor-like teeth in each jaw and multiple rows of molars. These teeth enable them to crush their prey of barnacles, shellfish, and crabs.  
  • _spotfinbutterflyfish.jpg
     The Spotfin Butterflyfish is found in all tropical and subtropical waters and is the only species in the butterflyfish family to be recorded from Chesapeake Bay. The Spotfin Butterflyfish inhabits coral reefs from Florida to Brazil, but juveniles may be carried northward by the Gulf Stream. The Spotfin Butterflyfish that enter the Bay are juveniles, but the adults can reach a length of 15 cm (6 in.).  
  • _spotfinbutterflyfishhead.jpg
     The highly compressed body and elongated snout of the Spotfin Butterflyfish allow them to access food that may be difficult for other fishes to reach. Their prey includes small invertebrates and algae.  
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The Virginia Institute of Marine Science Juvenile Fish Trawl Survey recently completed their September survey of Virginia’s portion of Chesapeake Bay and its major tributaries.  Along with good numbers of juvenile Summer Flounder and Spot, survey scientists noted several less common catches.  Bullnose Rays, Spotfin Butterflyfish, and large Sheepshead were most notable in this month’s samples.  Bullnose Rays (Myliobatis freminvillei) are common summer visitors to Chesapeake Bay but are only occasionally captured by the scientific crew aboard the R/V Fish Hawk.  Bullnose Rays are members of the eagle ray family and as such are very strong swimmers.   Bullnose Rays possess a single barbed spine just above a long filamentous whiplike tail and could be confused with stingrays, but are easily distinguished from stingrays by having a distinct head that protrudes forward of the disk while stingrays do not.  They are generally dark on top with faint white spots while the underside remains white.  Sheepshead (Archosargus probatocephalus) are common annual visitors to the Bay and are caught with regularity on the Survey, however, two specimens measured this month were 540 and 560mm (21” to 22”) and around 4.5kg (approx. 10lbs) and were therefore worthy of note.  Sheepshead are known to eat barnacles, bivalves and crabs and as such have mouths loaded with large crushing teeth.  Spotfin Butterflyfish (Chaetodon ocellatus) are small, colorful, tropical coral reef fish rarely encountered by the Trawl Survey in Chesapeake Bay.  Two individuals were identified during this month’s sampling efforts.  Spotfin Butterflyfish are small highly compressed (flattened side to side) fish easily identifiable by having several prominent black markings on a white background highlighted with brilliant yellow accents. All Spotfin Butterflyfish records from Chesapeake Bay are of juvenile fishes that have strayed north, presumably on tropical currents.