BAYESIAN
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Brazilian Guitarfish — Led by Dr. Fabio Caltabellotta, Dr. Siders developed a Bayesian age-growth model for Pseudobatos horkelii, Pseudobatos percellens, and Zapteryx brevirostris in southern Brazil. The resulting model was used to estimate age and growth parameters for these three priority guitarfish species listed as Critically Endangered, Near Threatened, and Vulnerable by the International Union for the Conservation of Nature.
Published in: doi: 10.1111/jfb.14123 
(Above) Bowtie sections of guitarfish vertebrae for the three Brazilian guitarfish species showing off the classic banding patterns left behind by annual growth spurts. (Left) Age-growth relationships for three Brazilian Guitarfish species. Age is on the x-axis in units of years and growth is on the y-axis in units of centimeters of total length.
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Brazilian Electric Ray — Led by Dr. Fernanda Rolim, a postdoc at Universidade Estadual Paulista in São Paolo, Brazil, Dr. Siders extended the Brazilian guitarfish model to estimate two-dimensional growth of Narcine brasiliensis, the Brazilian Electric Ray, in southern Brazil. The joint estimation of length-weight and age-growth parameters was added along with derivations of age at maturity, longevity, and mortality at age. A significant component was incorporating uncertainty in size at birth into the von Bertalanffy growth model.
Published in: doi: 10.1111/jfb.14378 |
Female (left) and male (center) Brazilian Electric Ray with their vertebral section (right) used to age individuals
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(Above) Silhouettes of Goblin Sharks through the ages. (top) 1898 in the description of the species by David Starr Jordan. (top middle) 1904 by King Bragança of Portugal. (top bottom) 1909 by Hussakof and the renaming of Mitsukurina to Scapanorhynchus for a time. (bottom) 1981 by Cadenat and Blache in Requins de Méditerranée et d' Atlantique.
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Goblin Shark — Led by Dr. Siders and Dr. Fabio Caltabellotta, we estimated the first age-growth relationship for Goblin Sharks (Mitsukurina owstoni), one of the largest deepwater sharks. Dr. Caltabellotta developed a method to highlight the classic banding pattern that allowed an age reading on a specimen caught in Brazil in 2008. Dr. Siders developed a Bayesian age-growth model that used back-calculated lengths at age from this specimen, data on maximum male sizes, and data on size at birth to estimate the first age-growth parameters for the species. We are excited to age more specimens in the future.
Published in: doi.org/10.1071/MF19370 |
(Above) Vermilion Snapper otolith
Vermilion Snapper — Led by Dr. Derek Chamberlin and Dr. Will Patterson, we validated the age of Vermilion Snapper (Rhomboplites aurorubens), an important species to Gulf of Mexico reef fish fisheries, using a bomb radiocarbon chronometer. We found the ageing of Vermilion Snapper to be accurate, the oldest fish in our samples was 28 years old. But, we also found the species to exhibit highly variable length-at-age with little differences between sexes, estimated with a Bayesian regression. This has important consequences to fisheries stock assessments, which often use age-length keys to turn large samples of fish lengths to ages.
Published in: doi.org/10.1016/j.fishres.2023.106732
Published in: doi.org/10.1016/j.fishres.2023.106732
(Above) Bomb radiocarbon chronometer for the Gulf of Mexico (black line) with eye lens samples (red circles) and otolith samples (black circles) of Blackbelly Rosefish
Blackbelly Rosefish — Led by Dr. Derek Chamberlin and Dr. Will Patterson, we validated the ageing of and estimated the growth of Blackbelly Rosefish (Helicolenus dactylopterus) in the northern Gulf of Mexico. Dr. Siders led the development of a Bayesian penalized spline model to calculate the bomb radiocarbon chronometer and estimate the accuracy of the age observations. Together, Drs. Siders and Chamberlin used the validated ages to extend the von Bertalanffy growth model used for other species to account for inter-reader error in this incredibly long-lived fish, the oldest sample being 98 years old! Most importantly, this paper showed that the use of eye lens to get birth year estimates was valid and overcame the limits of otoliths, which tend to not work for deepwater fishes.
Published in: doi.org/10.1038/s41598-023-34680-0
Published in: doi.org/10.1038/s41598-023-34680-0
(Above) CT tomography of a Gray Triggerfish highlighting the hard structures used for ageing.
Gray Triggerfish — Led by Dr. Derek Chamberlin, we validated a new ageing protocol for Gray Triggerfish (Balistes capriscus) developed by Jennifer Potts and Walter Rogers at the NOAA Southeast Fisheries Science Center Beaufort Lab using bomb radiocarbon. This validation is critical for using the dorsal spines to age Gray Triggerfish moving forward as the historical protocol tended to underestimate age especially for older fish. Otolith protocols were suggested as an alternative but these take three times longer if you can even remove the tiny otoliths successfully to begin with. The Bayesian penalized spline method developed for Blackbelly Rosefish by Dr. Siders was redeployed here to validate the new spine method and the otolith methods.
Published in: doi.org/10.1016/j.fishres.2024.107123
Published in: doi.org/10.1016/j.fishres.2024.107123
River Cooters — Led by Eric Munscher through the Turtle Survival Alliance North American Freshwater Turtle Research Group, 20 years of mark-recapture sampling was conducted on four Pseudemys species (P. c. suwanniensis, P. nelsoni, P. peninsularis, P. texana) at five freshwater springs, four in Florida and one in Texas. Dr. Siders led the development of a hierarchical Bayesian von Bertalanffy mark-recapture growth model to separate out the species-specific growth from individual variation and influences of the environment on growth across all species and sites simultaneously. Growth estimates were the first for three of the taxa, first mark-recapture for four of the taxa, the sampling found larger specimens than ever recorded for all of the taxa, and the length at maturity estimates matched well previous studies indicating that life-history invariants are a viable strategy for estimating age at maturity in freshwater turtles. In all, this publication is a substantial gain in information on the life history of these abundant species.
Published in: doi.org/10.3390/biology/12070965
Published in: doi.org/10.3390/biology/12070965
(Above) Predicted length at age for four Pseudemys species (River Cooters) for females and males of each taxa.
(Above) Predicted carapace length at age for Pseudemys gorzugi (Rio Grande Cooter) for females and males
Rio Grande Cooters — In collaboration with Dr. Ivana Mali and MJ Suriyamongkol, a multivariate Bayesian von Bertalanffy growth model was estimated using mark-recapture of Rio Grande Cooters (Pseudemys gorzugi) from the Black River in New Mexico, the northern part of the species' range. We found incredibly slow growth in this species but a similar pattern of sexual dimorphism as other Pseudemys, with females far larger than males at their average maximum size. Novel to this model was a joint likelihood modeling the growth in carapace length, plastron length, and body depth while handling the correlations between the different growth parameters. Differences in habitat across the study site led to differences in growth as most individuals had high site fidelity.
Published in: doi.org/10.1007/s10750-024-05486-6
Published in: doi.org/10.1007/s10750-024-05486-6