Age and Growth Validation of Newborn Sharks Held in Laboratory Aquaria, with Comments on the Life History of the Atlantic Sharpnose Shark, Rhizoprionodon terraenovae

Abstract

Neonate Rhizoprionodon terraenovae, Carcharhinus plumbeus, and C. limbatus were held in laboratory aquaria for a 16 mo study on the periodic formation of bands found in the vertebral centra. The sharks were injected with tetracycline to mark the vertebrae, and the aquarium situation mimicked seasonal environmental fluctuations. The tetracycline incorporated within a 3 d period, and a definable annual mark formed between Oct. and Dec. which was visible just off the edge of the centra by Jan. Age/growth data for R. terraenovae from a concurrent field study produced a von Bertalanffy growth curve with an Loo = 108 cm TL, K = 0.359, and to = -0.985 yr; values similar to known life history characteristics. Growth of the lab-reared R. terraenovae closely matched this curve. RECENT expansions in recreational and commercial efforts for sharks in the Gulf of Mexico prompted a study initiated in 1981 to better define the age and growth of the most commonly taken species. Sharks were aged by enumeration of the alternating calcified (opaque) and less calcified (translucent) bands discernable in the centra. Band pair periodicity must be verified and/or validated for each species (Brothers, 1983; Cassleman, 1983; Smith, 1983) and for all age/size classes (Beamish and McFarlane, 1983). In either sagittal or frontal sections cut from centra, a distinct mark cor