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Growth‐band counts from elephantfish Callorhinchus milii fin spines do not correspond with independently estimated ages
Author(s) -
Francis Malcolm P.,
Ó Maolagáin Caoimhghin
Publication year - 2019
Publication title -
journal of fish biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.672
H-Index - 115
eISSN - 1095-8649
pISSN - 0022-1112
DOI - 10.1111/jfb.14060
Subject(s) - biology , spine (molecular biology) , longevity , anatomy , ageing , juvenile , zoology , ecology , microbiology and biotechnology , genetics
Fin spines from elephantfish Callorhinchus milii were sectioned and viewed with transmitted white light under a compound microscope. The sections displayed growth bands but their interpretation and significance were unclear. Three different methods were used for counting growth bands. The results were compared with reference growth curves based on length‐at‐age estimates for six juvenile year classes derived from length‐frequency distributions, and tagging data that showed longevity is at least 20 years. None of the three ageing methods showed good correspondence with the reference curves and all methods departed markedly from the reference curves at ages above 2 years old. Therefore, growth bands present in C. milii spines are not useful for ageing, at least with the three methods tested here. Spine bands may not represent age marks, but instead may be layers of material deposited irregularly to strengthen the spine.