The Crappies

The names: bachelor, campbellite, white bass, camp lighter, sac-a-lait, silver crappie, speckled bass, tinmouth, bar fish, Oswego bass, razorback, grassback, shiner, john demon, calico bass, strawberry bass and "crap'pee," along with 10-20 others, all refer to two rather than one species of fish. Most Maryland fishermen when applying these time honored names do not realize they are referring to two distinct species of fish. These species are the black crappie, Pornoxis nigromaculatus, and the white crappie, Pornoxis annulars. Contrary to common belief, the white crappie does not change into a black crappie during parts of the year nor are these two fish just color phases of one species. Crappies are members of the freshwater sunfish family of fishes, Centrarchidae. (PDF contains 4 pages

Maryland Turtles

Since McCauley's 1945 publication, now out of print, on the "Turtles of Maryland," little has appeared on this interesting component of Maryland's vertebrate fauna. This work is thus an attempt to bring up to date the information that has accumulated during the interval. Each species has been treated in a similar vein regarding name, drawing, distribution, life history and biology. Additional information not usually found in texts or manuals has been added, especially that on folklore, uses and commercial value. Comments on environs, identification, species which should not be considered part of the turtle fauna, and the five known introduced species are included. A key to all the material and introduced species and subspecies is presented for the first time. The distribution maps have been made following the present limits of a species' known range. Dots were not used to illustrate ranges since so many species can and do move about readily. Those species whose ranges are expected to be larger than presently known are so indicated. These species and specimens thereof from the latter areas should be kept arid called to the attention of qualified personnel. All levels from the high school to scientist will find material of interest herein. (PDF contains 43 pages

Extensions of a result of Elekes and R\'onyai

Many problems in combinatorial geometry can be formulated in terms of curves or surfaces containing many points of a cartesian product. In 2000, Elekes and R\'onyai proved that if the graph of a polynomial contains $cn^2$ points of an $n\times n\times n$ cartesian product in $\mathbb{R}^3$, then the polynomial has the form $f(x,y)=g(k(x)+l(y))$ or $f(x,y)=g(k(x)l(y))$. They used this to prove a conjecture of Purdy which states that given two lines in $\mathbb{R}^2$ and $n$ points on each line, if the number of distinct distances between pairs of points, one on each line, is at most $cn$, then the lines are parallel or orthogonal. We extend the Elekes-R\'onyai Theorem to a less symmetric cartesian product. We also extend the Elekes-R\'onyai Theorem to one dimension higher on an $n\times n\times n\times n$ cartesian product and an asymmetric cartesian product. We give a proof of a variation of Purdy's conjecture with fewer points on one of the lines. We finish with a lower bound for our main result in one dimension higher with asymmetric cartesian product, showing that it is near-optimal.Comment: 23 page

Records of the Allegheny Brook Lamprey Ichthyomyzon Greeleyi Hubbs and Trautman, from West Virginia, with Comments on its Occurrence with Lampetra Aeptypera (Abbott)

Author Institution: Chesapeake Biological Laboratory, Solomons, Marylan

Homing Behavior of Tagged and Displaced Carp, Cyprinus carpio, in Pymatuning Lake, Pennsylvania/Ohio

Author Institution: Institute of Marine Sciences, University of North CarolinaPymatuning Lake, located on the Pennsylvania/Ohio border, is noted for the large numbers of bread-eating carp that frequent the Linesville Causeway carp bowl from May to November. Carp were trapped in 1952 and 1984 at the carp bowl, tagged, and relocated varying distances away from the bowl in Sanctuary, Middle, and Lower lakes. Carp traversed the return distances of up to 9 km in less than 4 or 5 days. Return movements often necessitated swimming around Tuttle Point and across the length of Middle Lake. One carp did migrate northward in 1984, but not 1952, from Lower Lake through the east-west Andover-Espyville Causeway into Middle Lake. Another carp released near the bowl in Middle Lake in 1984 migrated west and south through the Andover-Espyville Causeway and was caught 23 km to the west and south near the Lower Lake dam at Jamestown, Pennsylvania. Larger and older carp frequented Sanctuary and Middle lakes. Carp sizes decreased progressively with distance from the bowl. Visual cues, currents, sounds, sun orientation, follow-the-leader, and schooling behavior did not explain the carp aggregations in the carp bowl or the homing behavior by carp. Odors from feeding carp or other sources may be the causal basis for the homing behavior

Occurrence, Abundance, and Biology of the Blacknose Shark, Carcharhinus acronotus, in North Carolina

The biology of the blacknose shark, Carcharhinus acronotus, is presented for specimens captured by longlining off Shackleford Banks, North Carolina between 1973 and 1982. This entails comments on the number, seasonality, catch rate, color, age, growth, size, maturity, meristics, morphology, reproduction and parasites. C. acronotus frequents North Carolina coastal waters from May to October. Males dominate catches through July; females from August to early fall catches. Catches varied among years, and were probably affected by seasonal water temperatures and salinity variations. Best longline catches occur on morning ebb tides and are depth specific at one depth rather than between depths. Catch per unit effort data indicate more blacknose sharks are caught/100 hooks in North Carolina than in Florida or the Gulf of Mexico; areas previously believed to harbor abundant populations of blacknose sharks. Vertebrae were aged following staining with a modified silver nitrate technique. A linear relationship was found between vertebral radius and shark fork length. Growth curves were constructed from back calculations developed from linear regression and von Bertalanffy equations. The largest male (1,640 mm TL) and female (1,540 mm TL) C. acronotus taken were larger than any previously reported. Near term embryos are about 510 mm TL. Smallest free living males were encountered at 556 mm FL (684 mm TL) and 715 mm FL (877 mm TL) for females. Von Bertalanffy plots predicted 1,640 mm TL males to be 9.6 yr old. Morphometric and meristic data are given for blacknose sharks 65 to 1,400 mm TL. Teeth and vertebral · counts were within ranges reported by others. Developing young 65 to 125 mm TL lack dermal denticles. Specimens 200 mm TL or larger are completely covered with pedunculate three ridged denticles. C. acronotus was a new host for three of the five species of parasites found on adult specimens. Arguments are presented that indicate two breeding and pupping populations; one off North Carolina, the other off Florida and the Gulf of Mexico. A constant exchange of blacknose sharks seems to occur between these two populations and areas. The gestation period is believed to be only nine months

Simultaneous Arithmetic Progressions on Algebraic Curves

A simultaneous arithmetic progression (s.a.p.) of length k consists of k points (x_i, y_\sigma(i)), where x_i and y_i are arithmetic progressions and \sigma is a permutation. Garcia-Selfa and Tornero asked whether there is a bound on the length of an s.a.p. on an elliptic curve in Weierstrass form over Q. We show that 4319 is such a bound for curves over R. This is done by considering translates of the curve in a grid as a graph. A simple upper bound is found for the number of crossings and the 'crossing inequality' gives a lower bound. Together these bound the length of an s.a.p. on the curve. We then use a similar method to extend the result to arbitrary real algebraic curves. Instead of considering s.a.p.'s we consider k^2/3 points in a grid. The number of crossings is bounded by Bezout's Theorem. We then give another proof using a result of Jarnik bounding the number of grid points on a convex curve. This result applies as any real algebraic curve can be broken up into convex and concave parts, the number of which depend on the degree. Lastly, these results are extended to complex algebraic curves.Comment: 11 pages, 6 figures, order of email addresses corrected 12 pages, closing remarks, a reference and an acknowledgment adde