Otolith Size Research Articles

Morphology and evolutionary significance of phosphatic otoliths within the inner ears of cartilaginous fishes (Chondrichthyes)

BackgroundChondrichthyans represent a monophyletic group of crown group gnathostomes and are central to our understanding of vertebrate evolution. Like all vertebrates, cartilaginous fishes evolved concretions of material within their inner ears to aid with equilibrium and balance detection. Up to now, these materials have been identified as calcium carbonate-bearing otoconia, which are small bio-crystals consisting of an inorganic mineral and a protein, or otoconial masses (aggregations of otoconia bound by an organic matrix), being significantly different in morphology compared to the singular, polycrystalline otolith structures of bony fishes, which are solidified bio-crystals forming stony masses. Reinvestigation of the morphological and chemical properties of these chondrichthyan otoconia revises our understanding of otolith composition and has implications on the evolution of these characters in both the gnathostome crown group, and cartilaginous fishes in particular.ResultsDissections of Amblyraja radiata, Potamotrygon leopoldi, and Scyliorhinus canicula revealed three pairs of singular polycrystalline otolith structures with a well-defined morphology within their inner ears, as observed in bony fishes. IR spectroscopy identified the material to be composed of carbonate/collagen-bearing apatite in all taxa. These findings contradict previous hypotheses suggesting these otoconial structures were composed of calcium carbonate in chondrichthyans. A phylogenetic mapping using 37 chondrichthyan taxa further showed that the acquisition of phosphatic otolith structures might be widespread within cartilaginous fishes.ConclusionsDifferences in the size and shape of otoliths between taxa indicate a taxonomic signal within elasmobranchs. Otoliths made of carbonate/collagen-bearing apatite are reported for the first time in chondrichthyans. The intrinsic pathways to form singular, polycrystalline otoliths may represent the plesiomorphic condition for vertebrates but needs further testing. Likewise, the phosphatic composition of otoliths in early vertebrates such as cyclostomes and elasmobranchs is probably closely related to the lack of bony tissue in these groups, supporting a close relationship between skeletal tissue mineralization patterns and chemical otolith composition, underlined by physiological constraints.

Numerical expressions of otolith shape and morphometric relationships for five fish species in tidal‐linked lagoons in the northern Arabian Sea

AbstractOtoliths from five fish species, including Acanthopagrus latus, Daysciaena albida, Ellochelon vaigiensis, Mugil cephalus and Mystus gulio, were used to develop numerical expressions involving otolith shape indices and morphometric parameters. A total of 342 fish specimens in lagoons (24°39′ 0N, 68°50′0E) were sampled from August 2014 to July 2015. A linear model related to fish sizes, otolith sizes and weights were applied, with estimated coefficients of determinations (r2 = 0.99–0.53). Otolith shape indices, including form factor, roundness, aspect ratio, circularity, rectangularity and ellipticity for each fish species, also were analysed. The results of the present study are the first to describe relationships between otolith dimensions, fish morphometrics and shape indices of highly valued fish species and can be an important input for further trophic modelling to study food web dynamics.

Otolith fluctuating asymmetry in larval trout, Oncorhynchus mykiss Walbaum, as an indication of organism bilateral instability affected by static and alternating magnetic fields

The possible effects of disruptions in the geomagnetic field caused by different man-made constructions have been increasing considerably in recent years. These include, among others, the development of wind farms located in the sea and increased numbers of underwater cables. The objective of this study was to determine whether a magnetic field (MF) of 10 mT or a 50 Hz electromagnetic field (EMF) of 1 mT affected the developmental instability of the inner ear organ, which is responsible in fish for hearing and balance, in rainbow trout (Oncorhynchus mykiss) reared in a laboratory for 37 days (13 days in egg stage and 24 days in larval stage). This was done by analyzing the fluctuating asymmetry (FA) of otolith size. The MF and EMF values applied in this study are those recorded in the vicinities of underwater alternating current (AC) and direct current (DC) cables, respectively. The influence of MF on otolith FA was found to be statistically significant, with the highest significance occurring in the group of youngest larvae of 5 dph (compared to larvae 15 and 23 dph). Otolith FA was also higher in larvae exposed to the EMF compared to control conditions, but the differences were not statistically significant. Thus, we can conclude that underwater constructions and cables which emit a MF of 10 mT or higher can affect living organisms that are within a distance of a few meters, especially those (as in the case of trout) in settled life stages.

Otolith oxygen isotope analysis and temperature history in early life stages of the chub mackerel Scomber japonicus in the Kuroshio–Oyashio transition region

To determine the temperature history of early life stages of chub mackerel (Scomber japonicus), otolith stable oxygen isotope ratios (δ18Ootolith) of larval and juvenile fish collected in the Kuroshio–Oyashio transition area during 2004–2015 were analyzed, and experienced temperatures were estimated accordingly. The δ18Ootolith values decreased with otolith growth during the larval stage, whereas those for juveniles were positively correlated with otolith radius and increased with increasing otolith size. Combinations of δ18Ootolith values, average otolith daily increment width, and daily age were representative of the differences between better and poorer recruitment years, the former being characterized by earlier spawning and faster growth (resulting from cooler experienced temperatures), and the latter by slower growth. Analyzed fish were sorted into larval and early juvenile growth stages by cluster analysis; the high-growth cluster exhibited higher δ18Ootolith values than the low-growth cluster. The conversion of δ18Ootolith values to water temperature indicated that the higher growth cluster experienced a water temperature ca. 2.0 °C cooler during the later juvenile stage. Therefore, our results suggest the presence of a growth positive spiral, wherein individuals with high initial growth proactively enter cooler water temperature areas, accessing a highly nutritious diet resulting in further rapid growth.

Shapes of otoliths in some Baltic fish and their proportions

Abstract Otoliths are bony structures inside the fish labyrinth. They are used to determine the age of fish and to identify species based on their remains. The objective of this study was to describe the shape of otoliths in adult European perch (Perca fluviatilis), Atlantic herring (Clupea harengus), European sprat (Sprattus sprattus), lesser sand eel (Ammodytes tobianus), great sand eel (Hyperoplus lanceolatus), round goby (Neogobius melanostomus), European whitefish (Coregonus lavaretus), Atlantic cod (Gadus morhua), haddock (Melanogrammus aeglefinus), European eel (Anguilla anguilla), viviparous eelpout (Zoarces viviparus), turbot (Scophthalmus maximus), European flounder (Platichthys flesus), European plaice (Pleuronectes platessa) and European smelt (Osmerus eperlanus). Fish were caught in the Gulf of Gdańsk. The relationships between the size of otoliths and the length of fish were established for adult European perch, European flounder, Atlantic herring and round goby. Otoliths of taxonomically related species were similar. It was not possible to differentiate otoliths of Ammodytidae, Pleuronectidae, Scophthalamidae, Anguilidae by comparing the presented results with the literature data. Otoliths of Zoarcidae, Osmeridae, Clupeidae, Gadidae, Gobiidae, Percidae and Salmonidae were quite similar but distinguishable. In most of the investigated species, otoliths grow proportionally to the fish size. Their shape does not change during the fish life. The shape of otoliths in the round goby changes significantly. Otoliths of small fish are rounded and significantly lengthen during the growth of fish.

Relationships between fish length, otolith size and otolith weight in Sperata aor (Bagridae) and Labeo bata (Cyprinidae) from the Ganga River, India

The present study was conducted to investigate the relationships between fish length, otolith size and otolith weight. A total of 180 Sperata aor and 171 Labeo bata specimens were collected monthly during January 2016 to March 2017 from the River Ganga at the Narora site. Student’s t-test showed no significant differences in the size of right and left otoliths in the selected fish species, therefore, a single linear regression based on the left otolith was carried out. Fish length was plotted against otolith weight, otolith length and otolith height. Moreover, otolith length was plotted against otolith weight and otolith height. The linear regression model was found to fit the data well for fish length to otolith size in both selected fish species. A strong relationship between otolith length and weight was found in both species (r2 > 0.8). Furthermore, the study revealed that fish length is potentially related to otolith size and a strong relationship between fish length and otolith size exists in S. aor (mean r2 = 0.89) as compared to L. bata (mean r2 = 0.70). Such relationships should be determined for the fish species that are ecologically and socio-economically important in order to understand their trophic relationships, population dynamics and yield estimates.

Long-term acclimation to near-future ocean acidification has negligible effects on energetic attributes in a juvenile coral reef fish

Increased levels of dissolved carbon dioxide (CO2) drive ocean acidification and have been predicted to increase the energy use of marine fishes via physiological and behavioural mechanisms. This notion is based on a theoretical framework suggesting that detrimental effects on energy use are caused by plasma acid-base disruption in response to hypercapnic acidosis, potentially in combination with a malfunction of the gamma aminobutyric acid type A (GABAA) receptors in the brain. However, the existing empirical evidence testing these effects primarily stems from studies that exposed fish to elevated CO2 for a few days and measured a small number of traits. We investigated a range of energetic traits in juvenile spiny chromis damselfish (Acanthochromis polyacanthus) over 3months of acclimation to projected end-of-century CO2 levels (~ 1000µatm). Somatic growth and otolith size and shape were unaffected by the CO2 treatment across 3months of development in comparison with control fish (~ 420µatm). Swimming activity during behavioural assays was initially higher in the elevated CO2 group, but this effect dissipated within ~ 25min following handling. The transient higher activity of fish under elevated CO2 was not associated with a detectable difference in the rate of oxygen uptake nor was it mediated by GABAA neurotransmitter interference because treatment with a GABAA antagonist (gabazine) did not abolish the CO2 treatment effect. These findings contrast with several short-term studies by suggesting that end-of-century levels of CO2 may have negligible direct effects on the energetics of at least some species of fish.

Morphology and morphometric relationships for sagitta otoliths in Lutjanus argentiventris (Pisces: Lutjanidae) and Hyporthodus acanthistius (Pisces: Serranidae) from the Colombian Pacific Ocean

Fish earstones, or otoliths, are inner ear structures that can be studied to determine a fish’s age and are a source of taxonomically informative data. In the present work, sagitta otoliths of the Yellowtail snapper (Lutjanus argentiventris) and the Red grouper (Hyporthodus acanthistius) were collected in the Colombian Pacific, and their key morphological features were studied. Otoliths of the Yellow tail snapper were distinctly concave by their distal surface, revealing features shared with species of its genus (Lutjanus). Red grouper otoliths were elliptic and compressed laterally by their proximal surface, bearing similarities to those of other Serranid species. Morphometric relationships between otolith size weight and whole fish size and weight were also studied. In Red groupers significant statistical morphometric relationships between otolith and body features were found via power regression models; successfully relating otolith length with total fish length, otolith weight with total fish length, otolith length with total fish weight, and otolith weight with total fish weight. No significant morphometric relationships were found for the Yellow snapper data. In both fish species, otolith transversal sections proved best to identify its internal features and to distinguish otolith growth rings, as a method for determining the specimen’s age.

Relationships Between Otolith Dimensions and Body Growth of North African Catfish Clarias gariepinus (Burchell, 1822) from the Upper Basin of the Sakarya River, Turkey

Abstract The relationships between otolith size and body length of North African catfish Clarias gariepinus (Burchell, 1822), collected from Sakaryabaşı (the main spring area of the Sakarya River) between July 2014 and November 2014, were examined. Length-weight relationship was also calculated for overall specimens. The wild fish were captured by electrofishing using SAMUS 725MP. A total of 132 individuals ranging from 13.6 to 59.0 cm in total length and from 15.9 to 1755.0 g in weight were sampled. The lagenar otolith (asteriscus) length and height, and the utricular otolith (lapillus) length and width were recorded for each fish. The relationships between otolith measurements and fish somatic growth were described by a non-linear function (power model). The t test revealed no considerable differences in these relationships between left and right otoliths. The ANCOVA test on the relationships between total length and otolith variables did not show significant differences between females and males. All relationships were highly significant and the mean percent prediction errors were less than 7%. The results showed that otolith growth reflected body growth.

Ocean acidification affects somatic and otolith growth relationship in fish: evidence from an in situ study.

Ocean acidification (OA) may have varied effects on fish eco-physiological responses. Most OA studies have been carried out in laboratory conditions without considering the in situ pCO2/pH variability documented for many marine coastal ecosystems. Using a standard otolith ageing technique, we assessed how in situ ocean acidification (ambient, versus end-of-century CO2 levels) can affect somatic and otolith growth, and their relationship in a coastal fish. Somatic and otolith growth rates of juveniles of the ocellated wrasse Symphodus ocellatus living off a Mediterranean CO2 seep increased at the high- pCO2 site. Also, we detected that slower-growing individuals living at ambient pCO2 levels tend to have larger otoliths at the same somatic length (i.e. higher relative size of otoliths to fish body length) than faster-growing conspecifics living under high pCO2 conditions, with this being attributable to the so-called 'growth effect'. Our findings suggest the possibility of contrasting OA effects on fish fitness, with higher somatic growth rate and possibly higher survival associated with smaller relative size of otoliths that could impair fish auditory and vestibular sensitivity.

Ocean acidification alters morphology of all otolith types in Clark's anemonefish (Amphiprion clarkii).

Ocean acidification, the ongoing decline of surface ocean pH and [COn}{}{}_{3}^{2-}] due to absorption of surplus atmospheric CO2, has far-reaching consequences for marine biota, especially calcifiers. Among these are teleost fishes, which internally calcify otoliths, critical elements of the inner ear and vestibular system. There is evidence in the literature that ocean acidification increases otolith size and alters shape, perhaps impacting otic mechanics and thus sensory perception. Here, larval Clark’s anemonefish, Amphiprion clarkii (Bennett, 1830), were reared in various seawater pCO2/pH treatments analogous to future ocean scenarios. At the onset of metamorphosis, all otoliths were removed from each individual fish and analyzed for treatment effects on morphometrics including area, perimeter, and circularity; scanning electron microscopy was used to screen for evidence of treatment effects on lateral development, surface roughness, and vaterite replacement. The results corroborate those of other experiments with other taxa that observed otolith growth with elevated pCO2, and provide evidence that lateral development and surface roughness increased as well. Both sagittae exhibited increasing area, perimeter, lateral development, and roughness; left lapilli exhibited increasing area and perimeter while right lapilli exhibited increasing lateral development and roughness; and left asterisci exhibited increasing perimeter, roughness, and ellipticity with increasing pCO2. Right lapilli and left asterisci were only impacted by the most extreme pCO2 treatment, suggesting they are resilient to any conditions short of aragonite undersaturation, while all other impacted otoliths responded to lower concentrations. Finally, fish settlement competency at 10 dph was dramatically reduced, and fish standard length marginally reduced with increasing pCO2. Increasing abnormality and asymmetry of otoliths may impact inner ear function by altering otolith-maculae interactions.

Relationships between fish and otolith dimensions of Pomatomus saltatrix (Linnaeus, 1766) (Perciformes: Pomatomidae) in southeastern Brazil

ABSTRACT The bluefish, Pomatomus saltatrix (Linnaeus, 1766), was used as a species-specific model to study morphometric relationships between otolith size and relative growth variables. Length-weight relationships between Otolith (Length-OL, Height-OH, and Weight-OW) and fish measurements (Total Length-TL and Total Weight-TW) were determined for fishes captured monthly during the year 2015 off the southeastern coast of Brazil. The ANCOVA and Kruskal-Wallis analysis did not indicate significant differences in the relative growth constants between sexes and length frequency distributions (p > 0.05). The condition factor also did not present significant differences between sexes, and right and left otolith measurements (p > 0.05). A total of 398 specimens were sampled: TL = 43.6-67.0 cm, TW = 365-2400 g, OL = 9.65-15.25 mm, OH = 3.65 - 5.45 mm and OW = 0.03-0.11 g. The LWR for grouped sexes was TW = 0.050TL2.55 and otoliths OW = 6.17E-05OL2.59. The best adjustments were TL vs OL (r2 = 0.90); OL vs OW (r2 = 0.90); TW vs OW (r2 = 0.81); and TW vs OL (r2 = 0.80). These results showed that such relationships are helpful tools for predicting the fish size and weight from otoliths, which may be used in food habits and paleontology studies, and other fisheries management applications.

Population variations of Opal fish, Bembrops caudimacula Steindachner, 1876 from Arabian Sea and Andaman Sea: Evidence from otolith morphometry

Bembrops caudimacula dominates the deep-sea trawl catch in the exploratory surveys and as bycatch in the commercial trawling targeting deep-sea shrimps, in the Indian Exclusive Economic Zone. The intra-species variability in the bathy-demersal fish Bembrops caudimacula collected from two different ecosystems in the Indian Ocean were studied using otolith morphometric analysis. Five otolith size parameters (ferret length, ferret width, area, perimeter and weight), and five shape indices (roundness, rectangularity, ellipticity, form factor and circularity) were taken from forty-seven otoliths collected from two regions. Principal component analysis (PCA) and non-parametric PERMANOVA successfully differentiate the fishes from two regions based on the otolith morphometry. PCA indicated that ellipticity and otolith weight were the major factor responsible for the variation. The study indicated that otoliths of the fishes collected from Andaman Sea (part of Bay of Bengal) were more elliptic and massy compared to those collected from the Arabian Sea. This is the first work on the differentiation of B. caudimacula population from these two unique ecosystems, using otolith morphometry which is highly imperative to understand its population structure. Our study confirmed the suitability of otolith morphometric studies as an easiest and inexpensive method for differentiating the fish populations.

English

The aim of this study was to determine a correlation between the length, width and weight of otoliths and the length and weight of fish samples of Amblypharyngodon mola (Hamilton,1822), a Rasborine fish caught from Middle Ganga region. Total length (TL) measurements were made with a 1mm precision fish length measuring scale. Image J software was used for measuring otolith length and width. This study shows strong correlation between fish length (TL), otolith length (OL) and width (OW), and similarly shows the correlation between Fish weight (TW) with otolith mass   (test, P<0.05).  According to this study, Otolith size depends on the fish length and fish weight and the regression coefficients between the relationship of fish length and fish weight with otolith measurements was found to be the best indicator for estimating the growth of fish.                Key words: Amblypharyngodon mola, Rasborine fish, otolith morphometry. &nbsp

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

Round goby Neogobius melanostomus sagittal (saccular) otolith morphology was compared between males of the two alternative reproductive tactics (termed guarder and sneaker males) and between males captured from sites of high or low contamination. Otolith size increased with fish size and also displayed an ontogenetic shift in shape, becoming relatively taller as otoliths grew in size. Despite a considerable overlap in age between males adopting the two reproductive tactics, size-at-age measurements revealed that guarder males are significantly larger than sneakers at any given age and that they invest more into somatic growth than sneaker males. Controlling for body size, sneaker males possessed heavier sagittal otoliths than guarder males. Subtle otolith shape differences were also found between the two male tactics and between sites of high and low contaminant exposure. Sneaker males had relatively shorter otoliths with more pronounced notching than guarder males. Fish captured at sites of high contamination had otoliths showing slower growth rates in relation to body size and their shapes had more pronounced caudal points and ventral protrusions when compared with fish captured at sites of low contamination. The results are discussed in relation to life-history tradeoffs between the male tactics in terms of reproductive and somatic investment as well as the putative metabolic costs of exposure to contaminants. Overall, this study reveals that male alternative reproductive tactics and environmental contaminants can have small, yet measurable, effects on otolith morphology and these factors should be accounted for in future research when possible.

Analyzing Pellets and Feces of African Royal Terns (Thalasseus maximus albididorsalis) Results in Different Estimates of Diet Composition

A frequently used method to estimate diet composition is based on the identification of fish otoliths present in pellets and feces. However, whether pellets and feces provide similar unbiased estimates of the diet remains poorly understood. The diet of African Royal Terns (Thalasseus maximus albididorsalis) breeding in the Parc National du Delta du Saloum, Senegal, was studied. Prey species composition based on otoliths in freshly regurgitated pellets and a mixture of pellets and feces (excrement) accumulated near nests during the incubation period were compared. Altogether, 59 fish species were identified. Pellets contained far less prey species than excrement. Maximum diet overlap between excrement and pellets varied between 0.34 and 0.43 (mean = 0.36). Differences between minimum and maximum overlap between both sample types were small in all years. Pellets contained almost exclusively large otoliths (widths 3.0–8.5 mm), whereas excrement contained two fractions: large sized ones, identical to those present in the pellets and smaller-sized ones (0.5–3.0 mm) originating from feces. It is hypothesized that large otoliths cannot pass the intestinal tracts of the birds and are therefore regurgitated. Differences in prey species composition in pellets and excrement could potentially be explained by a combination of seasonal changes in availability of prey species and size of otoliths. Neither pellets nor feces alone give an unbiased picture of the diet of African Royal Terns.

Relationship between Sagittal Otolith Size and Fish Size in Engraulis encrasicolus and Sardina pilchardus (Osteichthyes: Clupeiformes) in the Southern Aegean Sea, Turkey

DOI: 10.26650/ASE201812 The objective of this study was to determine the regressions between otolith size (length and height), otolith weight vs. fish length, and weight of European anchovy Engraulis encrasicolus (Linnaeus, 1758) (n=360) and European pilchard Sardina pilchardus (Walbaum, 1792) (n=360), living off Gulluk Bay, Turkey. Fish were caught using a purse seine between January and March 2014 in the southern Aegean Sea. No differences were found between the size and weight of the left and right otoliths. Equations were used to reconstruct the original dimensions of prey from the size of hard structures found in food samples of piscivorous predators living in or in the vicinity of the aquatic habitat. A linear regression model was used to determine the relationship between fish length and otolith size, whereas an exponential regression model was used to describe the relationships between lengths and weights of otoliths and fish for both species. All regressions yielded high coefficients of determination (r2) of 0.78–0.93 for E. encrasicolus and 0.80–0.95 for S. pilchardus. We conclude that otolith length and otolith weight are good indicators of the length and weight of the two species.

Biometric relation between body size and otolith size of seven commercial fish species of the south-western Atlantic

Given the importance and applicability of these biometric relations, the present work aimed to verify the existence of correlations between the length of saggitae otoliths and the body size of seven south-western Atlantic marine fish species and to generate equations to estimate the body size of these species through otolith measurements. Fifty otoliths of Centropomus parallelus, Centropomus undecimalis, Lutjanus analis, Lutjanus jocu, Lutjanus synagris, Chaetodipterus faber and Mugil curema were collected for analysis. Significant relations between otolith length and total length and otolith width and total length were found for all the species. The highest coefficient of determination was observed for Centropomus undecimalis and Lutjanus synagris, for both relations, and the lowest was observed for Mugil curema. The results show that estimates of body size of the species through biometric analyses of otoliths are reliable. Based on this, the equations generated to obtain the total length of the fish using biometric otolith data can be used in dietary studies of top predators and in paleontological recostructions of modern fish.

Early otolith development in the critically endangered tooth-carp, Aphanius farsicus (Teleostei: Cyprinodontidae)

Otolith morphology in the tooth-carp/killifish genus Aphanius is a source of informative taxonomic characters at both the species and population level. Most work on otoliths has focused on adult specimens, while evidence of ontogenetic variation is rarely provided. In this study we describe the development of otolith morphology during the early life stages of an endangered and endemic species, the Fars tooth-carp Aphanius farsicus from southern Iran. The study material comprises 34 larvae and early juveniles representing nine different developmental stages (0–120 days post hatching), all reared under the same laboratory conditions. The results reveal (i) a significant correlation between standard length and otolith size (length) in larval and early juvenile stages, (ii) clear differences in otolith morphology between larvae/early juveniles and adults, and (iii) a temporal link between the appearance of the sulcus on the otolith’s inner face and the emergence of the dorsal and anal fins. Our results indicate that otoliths of Aphanius can be recognized as originating from larval or early juvenile fish based on their short rostrum and antirostrum lengths and wide excisura, in addition to their small size. These immature otoliths are, however, not diagnostic at the species level in A. farsicus, nor most probably in other species of tooth-carp. The outcome of our study is also of interest to palaeontologists working with fossil killifish otoliths, as it can help avoid misinterpretation of ancient species diversity.

The effect of preserving ichthyoplankton samples in alcohol on the accuracy of data obtained from otolith microstructure examinations

Although the effect of ichthyoplankton sample preservation in alcohol on the shrinkage of larval fish has already been well described, no data evaluating the effects of preservation on information derived from otoliths is available. In fact, it is frequently assumed that storing ichthyoplankton samples in alcohol is safe for otoliths. This work compares the results of otolith size measurements and age estimates between otoliths from the same specimens that were preserved for a year inside the larval fish bodies and those that were extracted immediately after sample collection and not preserved. This comparison was conducted on larval herring (12–26 mm SL) divided into four groups (n = 60, 15 in. in each group). The effect of preservation on the analysis was revealed in the high sample density–no alcohol exchange group in which the otoliths dissolved and in the high sample density–alcohol exchange group in which otolith size underestimation led to age underestimation in relatively small specimens <17 mm SL and to growth rate underestimation. Otolith analysis in the other two groups (low sample density–no alcohol exchange and low sample density–alcohol exchange) were not affected by preservation. The conclusion is that for otolith analysis alcohol cannot be considered a fully safe medium for ichthyoplankton sample storage. Estimates using otoliths can be inaccurate, and otolith loss can even occur. To prevent these situations, the volume of alcohol in samples of preserved material should not exceed half of total vial volume according to visual assessment. Exchanging the alcohol is also highly recommended.