Growth of the dolphinfish Coryphaena hippurus from north‐eastern Brazil with an appraisal of the efficacy of scales and otoliths for ageing

Abstract

Age and growth of the dolphinfish Coryphaena hippurus caught off north-eastern Brazil were studied by counting growth increments on scales and otoliths. A sample (n = 2338) measuring 7·7-195 cm fork length (LF ) was collected from September 2001 to February 2003. The scales (n = 69) removed from six different regions of the body were examined and those from the caudal region exhibited greater morphological regularity, symmetry and a smaller rate of regeneration. The regression between caudal scale radius (RS ) and LF displayed was linear (LF = 28·334 RS + 9·186; r(2) = 0·754). Otolith micro-increments were counted assuming daily periodicity. Ages estimated from otoliths ranged from 64 to 659 days. The von Bertalanffy growth model was fitted based on the otolith readings generating L∞ = 194·1 cm LF , k = 0·912 year(-1) and t0 = 0·081 years. Species longevity was estimated to be c. 4 years. Ninety-eight per cent of the overall sample was adult specimens well above the age of first maturity in the study area. The large variability between scale length and LF and the failure to ascertain increment deposition periodicity suggest that scales are not appropriate for ageing C. hippurus and analysis of otolith micro-increments is deemed the best structure for ageing this species in the study area.

Genetic analyses in Lake Malawi cichlids identify new roles for Fgf signaling in scale shape variation

“…Fish scales are diverse, and this diversity has been the focus of an array of biological questions, including species identification 43,44 , taxonomic relationships 45,46 , characterization of extinct taxa 47,48 , age and growth rates 49,50 , fluid mechanics 51,52 , and biomimetics 53–55 to name a few. Despite this long history, the ecological significance of variation in scale shape remains poorly understood.…”

Variações na forma do otólito sagitta de Coryphaena hippurus (Actinopterygii: Coryphaenidae) em uma área de ressurgência na costa sudoeste do Oceano Atlântico

“…Os descritores de forma obtidos dos otólitos de C. hippurus se mostraram excelentes ferramentas preditoras do estrato desembarcado, i.e., temporalmente com diferenças significativas (variação interanual) e espacialmente sem distinção significativa entre as áreas de pesca. Por ser uma espécie oceânica migratória compartilhada por diferentes frotas e de rápido crescimento (Lessa & Santana, 2016), o dourado capturado no sudeste brasileiro encontra-se suscetível às variações das condicionantes oceanográficas desta região que, quando atingem grandes amplitudes (variações sazonais da ressurgência costeira), podem afetar o padrão de desenvolvimento dos indivíduos e consequentemente a morfologia dos otólitos em diversos recursos pelágicos (Palko et al, 1982;Olavo et al, 2005;Callicó-Fortunato et al, 2017).…”

“…Segundo Farrell et al (2014), variações das condicionantes ambientais estão fortemente relacionadas aos padrões de distribuição da espécie, além de estarem correlacionadas com o nível de produtividade dos ambientes marinhos, acarretando em maior disponibilidade de alimento para a espécie. Fatos estes documentados na literatura devido a seu hábito de espécie cosmopolita com diferentes parâmetros de história de vida registrados em diversas localidades do mundo (Palko et al, 1982;Oxenford, 1999;Gatt et al, 2015;Lessa & Santana, 2016). Portanto, podemos concluir que nossos resultados concordam parcialmente com ambas as hipóteses, uma vez que tais padrões de desenvolvimento dos otólitos descritos na literatura podem ser aplicados/ confrontados à espécie alvo devido a seus atributos de história de vida, bem como a suas correlações com as variáveis ambientais.…”

Modeling the temporal periodicity of growth increments based on harmonic functions

“…The difference in the trajectories described by the H2 model suggests the presence of particular factors that influence the formation of the growth band in each species, such as temperature [ 39 , 54 ] and food availability [ 55 ]. Generally, it has been observed in tropical regions that the variance of the data due to the lack of synchronicity in the formation of growth bands makes it difficult to detect a cycle or pattern (e.g., [ 56 , 57 ]); however, even in temperate species, the reading quality due to intrinsic characteristics of the hard structure and/or processing technique may preclude the detection of a pattern [ 58 ].…”