Christian M. Jones

Validated age, growth and maturity of the bonnethead Sphyrna tiburo in the western North Atlantic Ocean

The age, growth and maturity of bonnetheads Sphyrna tiburo inhabiting the estuarine and coastal waters of the western North Atlantic Ocean (WNA) from Onslow Bay, North Carolina, south to West Palm Beach, Florida, were examined. Vertebrae were collected and aged from 329 females and 217 males ranging in size from 262 to 1043 mm and 245 to 825 mm fork length, LF , respectively. Sex-specific von Bertalanffy growth curves were fitted to length-at-age data. Female von Bertalanffy parameters were L∞  = 1036 mm LF , k = 0·18, t0  = -1·64 and L0  = 272 mm LF . Males reached a smaller theoretical asymptotic length and had a higher growth coefficient (L∞  = 782 mm LF , k = 0·29, t0  = -1·43 and L0  = 266 mm LF ). Maximum observed age was 17·9 years for females and 16·0 years for males. Annual deposition of growth increments was verified by marginal increment analysis and validated for age classes 2·5+ to 10·5+ years through recapture of 13 oxytetracycline-injected specimens at liberty in the wild for 1-4 years. Length (LF50 ) and age (A50 ) at 50% maturity were 819 mm and 6·7 years for females, and 618 mm and 3·9 years for males. Both female and male S. tiburo in the WNA had a significantly higher maximum observed age, LF50 , A50 and L∞ , and a significantly lower k and estimated L0 than evident in the Gulf of Mexico (GOM). These significant differences in life-history parameters, as well as evidence from tagging and genetic studies, suggest that S. tiburo in the WNA and GOM should be considered separate stocks.

On the attribution of authorship for several elasmobranch species in Müller and Henle's Systematische Beschreibung der Plagiostomen (Chondrichthyes, Elasmobranchii).

Even in light of the recent peak in new species descriptions of elasmobranchs (summarized in White & Last, 2012), Johannes Muller and Friedrich Henle’s Systematische Beschreibung der Plagiostomen (1839–1841) stands as a major achievement in chondrichthyan taxonomy. This volume included all elasmobranch species then known as well as descriptions of 61 new species (for a total of 214 species), and established many of the family-level groups still in use today. Muller & Henle’s work, however, would not have been possible without the collaboration of other naturalists who provided specimens for examination, detailed notes, and illustrations (Muller & Henle, 1841). Four men in particular made significant enough contributions to warrant Muller & Henle attributing the authority of several species to them: Achille Valenciennes (1794–1865), Gabriel Bibron (1805–1848), Heinrich Burger (1806–1858), and Andrew Smith (1797–1872). In nearly every case however, authority is currently placed on Muller & Henle themselves, and not the gentlemen to whom they gave credit.

Clarification on the Fecundity of Rhinoptera bonasus (Mitchill)

Abstract Accurate fecundity estimates are necessary for the proper assessment of fish stocks. Despite all recent investigations of the reproductive biology of Rhinoptera bonasus (Cownose Ray) indicating a maximum fecundity of 2 embryos per brood, maximum fecundity estimates of 6 per brood persist. All reports of 6 embryos per brood seem to stem from a single account. It is the purpose of this paper to present evidence indicating that the report of 6 embryos is based upon a misidentification in the field, and that maximum fecundity estimates for the Cownose Ray are therefore up to six-fold higher than actually observed.