Age, Growth, and Reproduction in Two Coastal Populations of Longnose Gars

Smylie, Meredith S.; Shervette, Virginia R.; McDonough, Christopher J.

doi:10.1080/00028487.2015.1111256

Cited by 24 publications

(21 citation statements)

References 34 publications

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“…; Smylie et al. ), with mixed results. Whole sagittal otoliths of Alligator and Longnose gars were unreadable (Ferrara ), whereas sagittal otoliths ground along the transverse plane were validated for aging Alligator Gars in Texas (Buckmeier et al.…”

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confidence: 99%

“…Similarly, sagittal otoliths were embedded in epoxy resin and transverse sections were used to age Longnose Gars in estuaries in South Carolina (Smylie et al. ). Age estimates obtained from sectioned pectoral fin rays of Alligator Gars could not be evaluated for accuracy due to the lack of visible OTC marks, but ages were comparable to those from validated sagittal otoliths in fish up to 1,200 mm TL (≤ age 6) (Buckmeier et al.…”

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confidence: 99%

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Relative Bias and Precision of Age Estimates among Calcified Structures of Spotted Gar, Shortnose Gar, and Longnose Gar

2018

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Recreational angling for gars (family Lepisosteidae) has become more popular in recent years; however, the fundamental understanding of their population dynamics needed for effective management and conservation is lacking. Age data are essential for describing population dynamic rate functions, but few studies have addressed the selection of ideal calcified structures for estimating age in gars. We collected Spotted Gars Lepisosteus oculatus, Shortnose Gars L. platostomus, and Longnose Gars L. osseus from 12 Illinois water bodies to assess the relative bias and precision of age estimates derived from branchiostegal rays, pectoral fin rays, cleithra, and sagittal otoliths. Age assignments differed among these calcified structures for all three species. Branchiostegal rays underestimated the age of young fish and overestimated the age of old fish relative to all other structures. Pectoral fin rays consistently underestimated age relative to other structures and produced the lowest mean and maximum age estimates. Although there was low relative bias between readers for all structures, age assignments showed greater variability between readers for old age‐classes when age estimates were derived from cleithra and otoliths. Between‐reader precision was highest using pectoral fin rays, whereas cleithra and otoliths generated lower coefficients of variation and percent agreement values. These findings reveal a need to improve or modify structure processing methods to increase readability when cleithra and otoliths are used for age estimation. Given these results, future validation studies should target branchiostegal rays and pectoral fin rays to determine the most accurate calcified structure for aging gars.

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confidence: 99%

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confidence: 99%

Relative Bias and Precision of Age Estimates among Calcified Structures of Spotted Gar, Shortnose Gar, and Longnose Gar

2018

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“…(), and Smylie et al. (). A subsample of fish were sacrificed in November 2010, and the remainder were sacrificed in August 2011.…”

Section: Methodsmentioning

confidence: 99%

“…; Smylie et al. ). Historically, most age data for these species were derived from branchiostegal rays because this bone tends to have obvious growth increments that can be consistently interpreted by readers (Netsch and Witt ; Klaassen and Morgan ; Johnson and Noltie ; Love ; Sutton et al.…”

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Are Age Estimates for Longnose Gar and Spotted Gar Accurate? An Evaluation of Sagittal Otoliths, Pectoral Fin Rays, and Branchiostegal Rays

Buckmeier

Snow²,

Smith

et al. 2018

Trans Am Fish Soc

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We evaluated the accuracy and precision of age estimates from ground sagittal otoliths, sectioned pectoral fin rays, and whole branchiostegal rays of Longnose Gar Lepisosteus osseus and Spotted Gar Lepisosteus oculatus using fish marked with oxytetracycline (OTC). The presence of OTC time stamps in these calcified structures and the ability to correctly identify post–time stamp annuli varied greatly. We identified time stamps in 66.7% and 91.7% of the otoliths and 43.8% and 61.4% of the pectoral fin rays for Longnose Gars and Spotted Gars, respectively; OTC marks were not observed in branchiostegal rays. Annual increment periodicity was validated in ground sagittal otoliths through age 10 for both species. For fish older than age 10, accuracy declined to about 60%, with most estimates being less than the number of post–time stamp annuli by 1 year. Age estimates derived from pectoral fin rays were consistently less than the number of post–time stamp annuli because OTC marks were generally associated with the outer edge of this bone. Overall accuracy from pectoral fin rays was only 14.3% for Longnose Gars and 22.6% for Spotted Gars. Although the lack of time stamps in branchiostegal rays prevented formal evaluation, age estimates derived from this structure were substantially lower than those from otoliths. Precision among readers was poor for all structures, reflecting the difficulties associated with age estimation for these two species. Based on our evaluation, past age estimates from branchiostegal rays and pectoral fin rays should be considered suspect. Ages derived from sagittal otoliths can be reliable through age 10. However, we recommend that readers verify their ability to produce accurate estimates and consider the implications of underestimating age for fish greater than age 10. Future efforts should work to refine or develop alternative preparation procedures for otoliths to improve the visibility of annuli and validate age estimates for older age‐classes.

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An ideal terrestrial thermometer using carbonate clumped isotopes from gar scales

Gray

Brandon

2022

Preprint

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Carbonate clumped isotope thermometry has been calibrated for a wide variety of carbonates, including calcite, aragonite, dolomite, siderite, and many of their biogenic forms. The clumped isotope composition of the carbonate group substituting for phosphate or hydroxyl in bioapatite (Ca(PO4,CO3)(OH,F)) has also been temperature calibrated using vertebrate tooth enamel from a range of endothermic body temperatures. We apply this method to other bioapatite-bearing taxa and the calibrated temperature range is extended to lower paleoclimatologically relevant temperatures. Furthermore, because relatively large bioapatite samples are required for carbonate clumped isotope measurements (Δ47), replicate sampling of thin tooth enamel may not be feasible in many situations. Here, we use gar fish (Lepisosteus sp.) scales to extend the calibration. These fish are unique in that they are entirely covered in ganoine scales, which are >95% hydroxyapatite. Their enamel structure also makes them resistant to diagenesis. Additionally, gar fossils are common in lacustrine, fluvial, and near-shore facies, and have a wide distribution in time (Cretaceous to modern) and location (North America, South America, Europe, India, and Africa). We have developed a reliable lab protocol for measuring Δ47 in gar bioapatite. We estimate the standard error (SE) for a single measurement as 0.027which is based on replicate analyses and Student T-distribution to account for sample size. We report results for modern gar scales from seven North American localities with mean annual water temperatures (MAWT) ranging from 9 to 26 °C. These data give a temperature calibration curve for gar scales of Δ47 = (0.1095 ± 0.0159) x 106/T2 -(0.5941 ± 0.0548) (R2 = 0.74) and a curve for pooled bioapatite of Δ47 = (0.1003 ± 0.0144) x 106/T2 -(0.4873 ± 0.0495) (R2 = 0.76).

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Age, Growth, and Reproduction in Two Coastal Populations of Longnose Gars

Cited by 24 publications

References 34 publications

Relative Bias and Precision of Age Estimates among Calcified Structures of Spotted Gar, Shortnose Gar, and Longnose Gar

Relative Bias and Precision of Age Estimates among Calcified Structures of Spotted Gar, Shortnose Gar, and Longnose Gar

Are Age Estimates for Longnose Gar and Spotted Gar Accurate? An Evaluation of Sagittal Otoliths, Pectoral Fin Rays, and Branchiostegal Rays

An ideal terrestrial thermometer using carbonate clumped isotopes from gar scales

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