Age and growth of the crocodile shark, Pseudocarcharias kamoharai, in the Eastern Tropical Pacific Ocean

ABSTRACT

The age, growth, and longevity parameters of crocodile shark, Pseudocarcharias kamoharai, from Santa Rosa, Ecuador were estimated. A number of 328 organisms were analyzed, 158 females (69 to 117 cm total length, TL) and 170 males (72.5 to 110 cm TL). The relationship between the vertebra's radius and TL was moderate (r² = 0.63), indicating a relation between structure growth and the organism's size. Females were four to 14 years old and males were four to 12 years. The multimodal approach determined that the suitable equations were: The Von Bertalanffy growth function model with a fixed L₀ (45.5 cm TL), VBGM2P (L_∞ = 118.4 cm cm TL, k = 0.15) for combined sexes with a weight of evidence (W_i) to its favour of 43.9%; logistic growth model (L_∞ = 109.5 cm TL, k = 0.41, L₀ = 33.1 cm TL) for females with Wi = 28.4% and VBGM2P (L_∞ = 110.4 cm TL, k = 0.16) for males with a Wi = 39.4%. No model obtained a sufficient evidence to be declared the best adjusted. The calculated longevities were 18 years for combined sexes, 16 for females, and 14 for males.

KEYWORDS:

• Age structure
• Akaike Information Criteria
• Ecuador
• growth modelling
• shark vertebra
• multi-model approach

Acknowledgements

The authors thank Evelyn Tibán, Biól. Evelyn Intriago, Israel Del Valle, Beatriz Loor, and Ángel Ganchozo, for their help in vertebrae sampling and cleaning in the laboratory. Also, our deepest thanks to the Escuela de Biología, Facultad de Ciencias Naturales, Universidad de Guayaquil and Carrera de Biología Marina, Pontificia Universidad Católica del Ecuador, Sede Manabí, for letting us use their laboratories for sample analysis. MDCM wishes to specially thank Richard Kindong, Shanghai Ocean University, for his invaluable help and training for the first proofreading of the vertebrae. Also, thanks to Luis Daniel Carrillo Colin and Juan Fernando Márquez Farías for their help in the shark vertebrae readings. Furthermore, thanks to Guillermo Rodríguez Domínguez for his help in the advisory for the growth modelling and each one of his advice to improve this research article. FGM thanks the Instituto Politécnico Nacional (COFFA, EDI) for the fellowships granted. Lastly, the first author thanks CONACYT for the scholarship received during his PhD programme at the FACIMAR, UAS. This study is part of his doctoral thesis.

Disclosure statement

No potential conflict of interest was reported by the author(s).