The use of otolith shape analysis for ageing juvenile red snapper, Lutjanus campechanus

Abstract

Morphological changes in otolith shape with age, of young (<age 3) red snapper were examined through shape analysis and tested as an objective method for age determination. Otoliths from two collections of juvenile fish (hatchery and wild) were used in the study. First, shape analysis was applied to a series of known-age otoliths from hatchery-reared age 0, 1 and 2 fish. Multidimensional scaling and non-parametric analysis of similarities showed significant shape differences among the three age classes of fish. Discriminant function analysis and cross-validation classification showed 65.6% correct age classification based on shape variables alone, and 86.7% correct age classification with inclusion of otolith weight in the discriminant function (n=90). Subsequently, the method was applied to otoliths from a series of age 0, 1 and 2 wild caught red snapper. Otoliths from wild fish showed a similar age classification success rate of 68.9% based on shape variables alone and 86.7% correct age classification with the inclusion of otolith weight in the discriminant function (n=90). Ageing of juvenile red snapper through otolith increment counts has been difficult in past studies and this study provides an alternative, objective method of otolith shape analysis for ageing young fish of this species.

Relationship between somatic growth and otolith growth: a case study of the ornate jobfishPristipomoides argyrogrammicusfrom the coast of Réunion (SW Indian Ocean)

“…Among snapper species, P. argyrogrammicus showed slower growth. Age estimation using morphological parameters of whole otoliths showed a good precision (CV = 5.5%), similar to that shown for other snappers, namely Lutjanus campechanus (Beyer and Szedlmayer 2010) and Pristipomoides filamentosus (Williams et al 2015). However, using this technique requires calibration based on age readings using traditional techniques.…”

“…This result was expected, based on a study that showed that only the flatfishes had otolith shape differences between head sides (Mille et al 2015). Among the morphometric parameters of whole otoliths, several authors have shown that a significant relationship between the otolith weight (Ow) and fish age exists (Boehlert 1985;Cardinale et al 2000;Labropoulou and Papaconstantinou 2000;Arayaa et al 2001;Cardinale and Arrhenius 2004;McDougall 2004;Ochwada et al 2008;Steward et al 2009;Beyer and Szedlmayer 2010;Williams et al 2015;Mahé et al 2016a). The species in these studies were long-lived , whereas P. argyrogrammicus is short-lived, with maximum observed age of five years, according to our observations.…”

Growth and otolith morphology vary with alternative reproductive tactics and contaminant exposure in the round goby Neogobius melanostomus

“…For example, sagittal otolith morphology ( i.e., size and shape) has been used to identify various prey species and their size classes in the diets of predators based on recovered undigested otoliths from faecal samples (Radhakrishnan et al, ; Suter & Morel, ). Though otolith shape generally varies less within‐species compared with between‐species, intraspecific variation in sagittal otolith shape has also been used to discriminate between fish stocks, populations, sexes and age‐classes in many species ( e.g., Atlantic cod Gadus morhua L. 1758; Campana & Casselman, ; Cardinale et al, ; haddock Melanogrammus aeglefinus (L. 1758); Begg & Brown, ; red snapper Lutjanus campechanus (Poey 1860); Beyer & Szedlmayer, ; plainfin midshipman Porichthys notatus Girard 1854; Bose et al, ). However, in order to confidently use otolith morphology to discriminate between species, populations, sexes, age classes, etc ., it is important to understand the numerous factors that can affect otolith size and shape (Mille et al, ).…”

Factors affecting morphological development of the sagittal otolith in juvenile and adult small yellow croaker (Larimichthys polyactisBleeker, 1877)

“…Ontogenetic allometry is considered an important factor in otolith shape determination (Gauldie, ; Tuset et al., ; Monteiro et al., ; Capoccioni et al., ). Otolith shapes vary to some extent according to age (Beyer and Szedlmayer, ; Ye et al., ), size (Tuset et al., ; Gonzalez Naya et al., ), and year‐class (Gonzalez‐Salas and Lenfant, ; Montanini et al., ). The morphology, morphometry and microstructure of otoliths are affected by habitat characteristics, e.g.…”