Does eel metamorphosis cause a breakdown in the tenets of otolith applications? A case study using the speckled worm eel (Myrophis punctatus, Ophichthidae)

• Published in: Canadian journal of fisheries and aquatic sciences Vol. 63; no. 7; pp. 1460 - 1468
• Main Authors: Powles, Perce M, Hare, Jonathan A, Laban, Elisabeth H, Warlen, Stanley M
• Format: Journal Article
• Language: English
• Published: Ottawa, Canada NRC Research Press 01.07.2006; National Research Council of Canada; Canadian Science Publishing NRC Research Press
• Subjects: Agnatha. Pisces; Animal, plant and microbial ecology; Biochemistry; Biological and medical sciences; Eels; Fish; Fundamental and applied biological sciences. Psychology; General aspects. Techniques; Genetic aspects; Marine; Marine biology; Metamorphosis; Methods and techniques (sampling, tagging, trapping, modelling...); Myrophis punctatus; Ophichthidae; Otoliths; Physiological aspects; Pigmentation; Validation studies; Vertebrates: general zoology, morphology, phylogeny, systematics, cytogenetics, geographical distribution; ANW, USA, North Carolina, Pivers I; Case study; Aquatic environment; Vertebrata; Investigation method; Pisces; Otolith; Critical study; Microstructure; Growth striation; Metamorphosis
• ISSN: 0706-652X; 1205-7533
• DOI: 10.1139/f06-052

Several basic tenets of otolith research have been questioned recently with regard to eel metamorphosis. Specifically, some researchers have suggested that otolith increment formation is not daily, and otolith material may be resorped during metamorphosis. We conducted a rearing experiment to test the hypothesis that increment formation is daily and that the otolith continues to grow during eel metamorphosis. We marked the otoliths of wild-caught Myrophis punctatus leptocephali and reared these fish through metamorphosis. Metamorphosis was characterized by a decreasing standard length, pre-anal length, and body depth accompanied by an increase in pigmentation and a change in behavior. Increment formation was daily or near-daily through metamorphosis, and the otolith continued to grow during metamorphosis. Thus, the basic tenets of otolith application apply to eel metamorphosis, and non-daily ring deposition and resorption should not be used as explanations for otolith characteristics of eels (e.g., back-calculated hatch dates) unless demonstrated experimentally.