DOI: 10.5061/dryad.t1d8k
title: Data from: Ontogenetic development of otoliths in alligator gar

description: Alligator Gar Atractosteus spatula is a species of conservation concern
 throughout its range and an examination of otoliths during early
 development would aid understanding its life history and ecology. We
 conducted X-ray computed tomography (CT) scans, scanning electron
 microscopy (SEM), and light microscopy to examine the three pairs of
 otoliths and how they developed over time in relation to fish size and
 age. The sagittae are the largest, with distinct dorsal and ventral lobes,
 and covered with small otoconia concentrated in the sulcul region. The
 sagittae exhibited allometric growth, increasing more rapidly in the
 ventral lobe than in the dorsal. The asterisci were smaller and also
 exhibited small otoconia on their surface, but much less than the
 sagittae. The lapilli were oriented laterally, in contrast to the sagittae
 and asterisci that were oriented vertically, with a hump on the dorsum and
 very large otoconia on the lateral surface that appeared to fuse into the
 main otolith as the fish grew. Based on size measurements and ring counts
 in all three pairs of otoliths from known-age Alligator Gar sampled weekly
 through 91 days after hatch (N =101), we developed regression models to
 examine otolith growth and predict age. All relationships were significant
 and highly explanatory (r² ≥ 0.93), but the strongest relationship between
 otolith and fish size existed for measurements from sagittae (r² = 0.98)
 and age predictions from the lapillus (r² = 0.99). Age prediction models
 all resulted in a slope near unity, indicating that ring deposition
 occurred approximately daily. The first ring in sagittae and lapilli
 corresponded to swim-up whereas the first ring formed in asterisci
 approximately 8 days after swim-up. These results fill a gap in knowledge
 and can aid understanding of evolutionary processes as well as provide
 useful information for management and conservation.
description: Alligator gar daily age
 dataData from daily age
 estimates, including precision, accuracy, and relations between otolith
 and fish size for hatchery-reared Alligator Gar. The excel file contains 3
 tabs, each labeled descriptively.AL Gar daily
 age_final.xlsxCT Xray images
 1of21
 of 2 zip file archives of CT x-ray scans of the head of an Alligator Gar.
 Images are in 16bit TIFF format: Scan parameters: NSI scanner. Feinfocus
 source, high power, 150 kV, 0.18 mA, no filter, Perkin Elmer detector, 0.5
 pF gain, 2 fps (499.893 ms integration time), no binning, no flip, source
 to object 293.346 mm, source to detector 1066 mm, continuous CT scan, no
 frames averaged, 0 skip frames, 3600 projections, 6 gain calibrations, 15
 mm calibration phantom, data range [-1.671085, 8.845427], beam-hardening
 correction = 0.1. Voxel size = 0.066 mm. Slices = 1-942 in this
 archive.16bitTIFF_1of2.7zCT Xray images 2of22 of 2 zip file archives of CT x-ray scans of the head of an Alligator Gar. Images are in 16bit TIFF format: Scan parameters: NSI scanner. Feinfocus source, high power, 150 kV, 0.18 mA, no filter, Perkin Elmer detector, 0.5 pF gain, 2 fps (499.893 ms integration time), no binning, no flip, source to object 293.346 mm, source to detector 1066 mm, continuous CT scan, no frames averaged, 0 skip frames, 3600 projections, 6 gain calibrations, 15 mm calibration phantom, data range [-1.671085, 8.845427], beam-hardening correction = 0.1. Voxel size = 0.066 mm. Slices = 942-1883 in this archive.16bitTIFF_2of2.7z