Otolith Morphometry Research Articles

Otolith morphometry for the determination of the theoretical growth curve of fish

During the period from November 2019 to August 2021, a total of 43 specimens of Leporinus friderici, 18 of Prochilodus lineatus, 17 of Hoplias intermedius and 8 of Cichla kelberi were caught in the Verde River basin (Mato Grosso do Sul, Brazil) using various types of fishing equipment. Data collection consisted of measuring fish lengths (LOa, mm) and area (Oa, mm2) of their respective sagitta otoliths. The modified Von Bertalanffy equation (1938) was used to determine the theoretical growth curve as a function of the otolith area. The results indicate that the length of the fish increases in relation to the increase in the otolith area, resulting in a strong logarithmic regression for all species studied. The values of the theoretical growth curve of the fish (observed and estimated) as a function of the areas of the otoliths showed adjustments of R2>75 for the measured and R2>90 for the estimated values. Therefore, the otolith area proved to be adequate for the estimation of growth for the species, which can also facilitate the evaluation of fish length, band is a useful tool for the evaluation of fish stocks.

Length-Weight and Otolith Morphometry Relationships of Hoplostethus mediterraneus Cuvier, 1829 from the Saros Bay, Northern Aegean Sea

Length-Weight and Otolith Morphometry Relationships of Hoplostethus mediterraneus Cuvier, 1829 from the Saros Bay, Northern Aegean Sea

Otolith morphometry and its role in determining the growth of Periophthalmus chrysospilos distributed in some coastal provinces in the Mekong Delta

This article first provided information on otolith shapes, the variation of otolith weight by sex, fish size, season, and sampling site, and the linear relationship between otolith weight and fish size. A total of 815 Periophthalmus chrysospilos specimens from Duyen Hai, Tra Vinh; Tran De, Soc Trang; Dong Hai, Bac Lieu; and Dam Doi, Ca Mau in the Mekong Delta ranged from 4.20 to 12.50 cm total length and from 1.26 to 16.88 g weight were analysed. The analysis results revealed that Ps. chrysospilos had a square otolith, deeply notched at the anterior apex and flat at the posterior apex. The weight of the left otolith showed a statistical difference according to survey factors, including gender, fish size, season, and sampling site. The otolith weight had a proportional relationship with to the total length, body weight, and head length of mudskippers (r2 =0.7~0.9), which meant that fish size could be predicted from the otolith weight and about 70-90% of the otolith weight of Ps. chrysospilos varied corresponded the growth of the fish.

Otolith Shape Indices of Japanese Threadfin Bream (Nemipterus japonicus, Bloch 1791) from the Makassar Strait, Indonesia

Japanese threadfin bream (Nemipterus japonicus) is a demersal fish that plays a very important role in maintaining ecosystem stability related to webs and food chains. This fish often becomes prey for predatory fish. In efforts to reveal the relationship between predators and prey in food webs and food chains, there is still limited information due to the difficulty of identifying digested food. In connection with this, this study aims to identify the morphology shape index value otolith of Japanese threadfin bream. Sampling was carried out at the Labuang Maros Fish Landing Site with 150 samples and morphometric data were collected from 150 pairs of otoliths in April and May 2023. The calculation of the shape index uses six descriptors, which include form factor (FF), roundness (RO), circularity or compactness (C), rectangularity (Rt), ellipticity (E), and aspect ratio (AR). The results showed that there was no significant difference in the otolith morphometry of the right and left otoliths (P>0.05). Based on the shape index value obtained, it explains that the morphometric shape of the otolith of Japanese threadfin bream tends to be oval, elongated, and has an irregular surface.

Relationship between otolith morphometry and fish total length of Chelon auratus from two localities (Mediterranean Sea and Ain Ziana Lake) in Libyan waters

ABSTRACT The relationship between fish total length and otolith length, width, and weight were inspected in the golden grey mullet, Chelon auratus, collected from the Mediterranean Sea coast of Libya and Ain Ziana, an inland lagoon located northeast of the Libyan coast. Chelon auratus is considered a valuable marketable fish in Libya. The main aim of the study was to estimate the statistical relationship between fish total length and the otolith length, width, and weight. This information will be noteworthy in the upcoming analyses on the biology of this species, which will provide critical information about feeding, age and growth of this species. Linear and non-linear regression models were used. The regression equations for each locality were significantly different, with exception of the right and left weight of individuals collected from the Mediterranean Sea coast as well as for the Ain Ziana Lagoon. The regression relationships were more homogeneous in Ain Ziana Lagoon than in the Mediterranean Sea, where there was greater variation in total length and otolith characteristics. The results obtained from this investigation were the first to address the relationship between otolith morphometric and total length for golden grey mullets collected from two localities in the Libyan waters.

Otolith morphometry and Fourier transform near-infrared (FT-NIR) spectroscopy as tools to discriminate archived otoliths of newly detected cryptic species, Etelis carbunculus and Etelis boweni

Cryptic speciation was recently verified in Etelis carbunculus, an important component of federally managed bottomfish fisheries in the Pacific Territories of the United States. As a result, archived otolith collections used for fishery assessment are now contaminated with newly described E. boweni in areas where these species co-occur. We compared the efficacy of otolith morphometrics and Fourier transform near-infrared (FT-NIR) spectroscopy to discriminate species first using voucher (i.e., known species) otoliths (n = 93) from the SW Pacific, then applied optimal models to archived otoliths (n = 91) collected around Guam. Significant and distinguishable differences in otolith morphometrics as well as FT-NIR spectral absorbance patterns were observed between E. carbunculus and E. boweni voucher samples. Classification models applied using both morphometric measurements (quadratic discriminant analysis) and FT-NIR spectral data (partial least squares discriminant analysis) were able to predict species with a high (93 – 100%) degree of accuracy despite a relatively large spatial area of specimen collection ( ± 10° latitude and longitude) and regardless of whether otoliths were whole (i.e., unbroken). Further, each method identified members of newly described E. boweni in the archived collection of E. carbunculus otoliths captured around Guam, providing strong evidence that the species’ distributions overlap in this region. The purported identification of both E. carbunculus and E. boweni in the archived catch from Guam has important implications for fisheries management; therefore, it is imperative that the corresponding otolith collections are examined to ensure that the otoliths are assigned to the correct species.

Otolith morphometry and body size relationships of Rasborine fishes in Ganga River water

Otolith morphometry and body size relationships of Rasborine fishes in Ganga River water

Morphometry and morphology of fish otoliths on the coast of the state of Maranhão, Brazil.

The main objective of this study was to evaluate the biometric relationships between the species Bagre bagre, Lutjanus synagris and Nebris microps and their otoliths. The relationship between the size of the otolith (length and weight) and the size of the fish (standard length and total weight) was determined using the linear regression model (y = a + bx). For the morphological description, the otoliths of three specimens were selected by standard length class (10mm). The morphological characters analyzed were chosen according to traditional literature. Three hundred eight specimens of B. bagre, 200 of L. synagris and 237 of N. microps were analyzed. Throughout the collection period, the source of the capture of individuals was the municipality of Raposa. The linear correlations for fish and otolith length for B. bagre were 0.9129 and 0.9652, respectively. For L. synagris, the coefficients were 0.8634 and 0.8672, while for N. microps, 0.9597 and 0.8636, respectively. The morphological classification of L. synagris and N. microps is of the Saggita type, and the B. bagre species is of the Lapillus type. From the data presented here, it is possible to observe that otolith morphometric and morphological data can serve as a parameter to estimate the relationship between the fish and the otolith in terms of its biomass and the length of an individual and a population.

Untangling the taxonomic ambiguities of the spotted seerfish Scomberomorus guttatus with the description of a new species from India.

Scomberomorus guttatus has been subjected to a series of synonym assignations over the years. Its taxonomy has been mired with ambiguities due to the greater-than-average morphological variations observed in samples from different regions. An integrated taxonomic revision with molecular support indicated that the species that was thought to be a single entity, in reality, is a complex of three distinct species. They are morphologically distinct with respect to the body depth and elongation, cephalic morphometry, and meristic characteristics. Otolith morphometry and phylogenetic evidence further established the taxonomic divergence within the spotted seerfish complex. The phylogenetic characteristic as indicated by the mitochondrial Cytochrome c Oxidase subunit I (COI) sequence unveiled that S. guttatus had a high intraspecific divergence of 11.1% from its two identical congeners and a divergence of 2.34% between the congeners, indicating scope for categorizing them as separate species. Based on the morphological and molecular evidence, S. guttatus is redescribed; the senior synonym Scomberomorus leopardus is resurrected as a valid species; and a new species Scomberomorus avirostrus n. sp. is described with keys for species distinction.

Efficacy of otolith morphometry for rapid discrimination of cryptic fishes

The cryptic external morphology of fishes poses challenges for accurate species identification. This study assessed whether the morphometry of otoliths (and body length) could be used as a method to distinguish among closely related, morphologically similar species that are highly valued by commercial or recreational fishers. The otolith morphometry of fishes within four genera (Centroberyx, Lethrinus, Polyprion and Sillago) were compared. Canonical Analysis of Principal Coordinates that included combinations of morphometric variables (i.e., otolith length, width, thickness, weight, and fish length) produced highly accurate species prediction rates ranging from 92.5 to 99.9% across all genera. When different combinations of morphometric variables were modelled, changes in species prediction accuracy rates were minimal (i.e., up to 3%) for the Centroberyx, Polyprion and Sillago species. The exclusion of otolith weight from the multivariate analysis did not significantly decrease prediction accuracy within all four genera. In contrast, the prediction accuracy of the two lethrinids reduced by 7–25% when fish length was excluded, which may be attributable to the larger size attained by L. nebulosus in comparison to its congener L. punctulatus, as well as the very similar ovate shaped otoliths in younger fish of both species. Simplifying data collection to only length-based otolith measurements (and fish length for lethrinids) would provide a more rapid and cost-effective method for discrimination and be more practical when sampling at sea where obtaining accurate weight measurements of otoliths is typically unfeasible. Spatial variation in otolith morphometrics was evident for C. gerrardi, L. punctulatus, P. oxygeneios and S. vittata, which might be attributed to the differences in length distributions of fish samples from different regions. The misclassified specimens within the species groups were notably smaller individuals, suggesting the complexity of otolith shape increases with ontogeny. Hence, further investigation of variations in morphological characteristics, other than otoliths, may be required for the discrimination of cryptic species during the juvenile stage. This study highlights the robustness of multivariate analysis of otolith morphometric data for discriminating closely-related, cryptic species.

Utility of body and otolith morphometry to discriminate cryptic juveniles of two sympatric red snappers (Perciformes: Lutjanidae).

The sympatric red snappers, Lutjanus erythropterus and Lutjanus malabaricus, are highly valued by commercial and recreational fishers along the tropical northern coasts of Australia and throughout their distribution. Studies on the life history and ecology of these congeners are confounded by difficulties in distinguishing the cryptic juveniles of each species (i.e., < 200 mm total length). This study aimed to validate a robust and cost-effective method to discriminate these juveniles using body and/or otolith morphometric data in a multivariate analysis. Juvenile samples were collected from the northwest (n = 71) and northeast (n = 19) coasts of Australia, and species identification was confirmed using DNA barcoding. The most parsimonious multivariate models achieved accurate species prediction rates of 98.8%, which consisted of just three body variables (dorsal fin length, the distance from the snout to the anterior edge of the eye, and either jaw length or distance from the snout to the preoperculum). The high level of discrimination for these cryptic juveniles highlights the robustness of this morphometric approach. The slightly lower rate of discrimination using otolith morphology (84.9%) was associated with greater regional variation in L. malabaricus between the northwest and northeast coasts. Slight variations in otolith shape are typically used to determine stock structure, which highlights the potential need to collect samples over a broader area of a species geographic range when using an otolith morphometric discrimination model. The method outlined in this study could be applied to distinguish other cryptic congeneric fish species, including from archived otolith collections. Moreover, this method has the potential to be utilized in assessing species compositions using body measurements from in situ stereo-video.

Distinct Stocks of the Redtail Scad Decapterus kurroides Bleeker, 1855 (Perciformes: Carangidae) from the Northern Sulu and Southern Sibuyan Seas, Philippines Revealed from Otolith Morphometry and Shape Analysis

A recent study was performed to assess the morphometric variation of otoliths of the Decapterus kurroides collected in the northern Sulu and southern Sibuyan seas in delineating fish stocks. Seven of the otolith morphometric descriptors (otolith length, OL; otolith height, OH; otolith weight OW; otolith area, OA; otolith perimeter, OP; ellipticity, EL; and aspect ratio, AR) demonstrated a significant positive correlation with fish length and six (rectangularity, RE; squareness, SQ; roundness, RO; circularity, CI; compactness, CO; and form factor, FF) demonstrated a significant negative correlation. In terms of intraspecific comparisons, almost all the otolith morphometric descriptors were significantly different between the two sites (except RE and OH). Further, principal component (PC) analysis showed that direct otolith morphometric descriptors such as OL, OH, OW, OA, and OP explained 61.71% of the differences (PC1). In contrast, derived otolith descriptors such as EL, AR, and CO explained 22.00% of the variations (PC2) for a total of 83.71% explained variations with the eight otolith morphometric descriptors. Statistics reveal that D. kurroides from the Sibuyan Sea have significantly larger, heavier, and more elliptical otoliths than those from the Sulu Sea. Results suggested that the D. kurroides from Sulu and Sibuyan seas are two different phenotypic stocks. Further studies such as otolith microchemistry, genetics, other life history-based studies, and present exploitation levels should be carried out to supplement the results of this study to fully establish the D. kurroides stock structures within Philippine waters.

Size frequency, length‐weight relationships, condition factor and relationships between fish size and otolith dimensions in the Pama croaker Otolithoides pama (Hamilton, 1822) from Lower Meghna River Estuary, Bangladesh

AbstractThe relationships between fish size, weight and otolith morphometry are useful for fisheries management, predator–prey studies and feeding habits. Accordingly, the main purpose of the present study was to determine the relationships between body length, body weight and otolith dimensions, and to calculate the length‐weight relationship and condition factor for a Sciaenid fish Pama croaker, Otolithoides pama (Hamilton, 1822) from the Lower Meghna estuary, Bangladesh. Field sampling was conducted from September 2019 to March 2020. The length, breadth and weight were measured for each pair of sagittae, as well as the total length (TL), standard length (SL) and body weight (BW) for each specimen. A total of 246 fish samples were collected. The TL and BW of collected individuals ranged from 14.40 to 27.40‐cm and 21 to 175‐g, respectively. The calculated growth coefficient (b = 3.018 for males; 3.052 for females) were &gt;3, indicating the fish follow a positive allometric growth. The mean Fulton's condition (Kn) values ranged from 0.674 ± 0.06 to 0.776 ± 0.07, exhibiting similar trends for all size classes. The relationships for fish size and otolith morphometry were described by linear regression models as TL = 0.048OL – 0.308 (r2 = 0.921); BW = 0.047OL + 6.252 (r2 = 0.929); TL = 0.003OW – 0.414 (r2 = 0.836); BW = 0.003OW + 0.039 (r2 = 0.81). The otolith length and weight exhibited a strong correlation (0.929 &gt; r2 &gt; 0.805) with total length and body weight, while the otolith breadth exhibited a weak correlation. No significant differences between left and right otolith were observed (p &gt; .05). Because the results of the present study indicated fish length and otolith growth have a positive relationship, this finding can be a valuable tool to evaluate fish growth by back‐calculating the length of a fish from its otolith characteristics.

Sex dimorphism and evidence of sexually selected traits: A case study on the killifish Aphaniops stoliczkanus (Day, 1872)

AbstractSex dimorphism is found in many organisms and is an important source of intraspecific variation. Among freshwater fishes, all members of the Aphaniidae (killifishes, Cyprinodontiformes) are known for their pronounced sex dimorphism, and it has been proposed that sexual selection has played a role in their diversification. However, few studies have assessed their sex dimorphism in detail. Here, we use Aphaniops stoliczkanus (Day, 1872) to analyse morphological variability within and between sexes and within the total sample using statistical analyses of body morphometry, meristic traits and otolith data. We found that sex dimorphism (i) is significant in many body morphometric variables, but (almost) absent in meristic traits and otolith morphometry, (ii) is most marked in anal‐ and dorsal‐fin lengths (larger in males), and in anal‐ and dorsal‐fin positions (more anteriorly positioned in males) and (iii) does not alter the overall variance of the population unless the character concerned is highly divergent. Our data also suggest that anal‐ and dorsal‐fin lengths in males of A. stoliczkanus are sexually selected traits. Together with literature data, this reinforces the idea that sexual selection plays a role in the diversification of aphaniid species. Our results are also relevant to work on fossils, in which morphological variability is often difficult to interpret.

Lagenar Otolith Morphometry of Gibel Carp, Carassius gibelio (Cyprinidae): Comparisons among Four Populations in Samsun Province (Turkey)

Lagenar Otolith Morphometry of Gibel Carp, Carassius gibelio (Cyprinidae): Comparisons among Four Populations in Samsun Province (Turkey)

Inferring ecological strategies of Psenopsis spp. (Teleostei: Centrolophidae) inhabiting Indian waters from morphological features

ABSTRACT Morphology of the fish and otoliths are popularly used in the discrimination of species/stocks/populations and also to gather meaningful conclusions about their ecology. This approach is useful to enhance our understanding of the relationship between form and function in fishes when a direct assessment is impossible. Inter-species variation was analysed using geometric morphometric analysis for fish body shape, while morphometry and wavelet functions for sagittae morphology. A clear ecomorphological pattern in the body, as well as otolith shape, is evident among species as deeper inhabiting species possess a deeper body with oblong otoliths compared with shallower species that possess a more streamlined body with fusiform otoliths. We also observed that deeper species (P. obscura) possess bigger eyes for the optimum use of available light and bigger otoliths with higher otolith sensory area and otolith area ratio (S:O) for better sound reception capacities. Our hypothesis supports that the differences in fish morphological as well as sensorial traits (otoliths), which are closely related to their locomotion, foraging pattern and depth of habitation, lead to trophic segregation which in turn encourages their coexistence. This is the first work that discusses the relationship between body shape, otolith morphometry and morphology in deep-sea fishes and their ecomorphological interpretations. http://zoobank.org/lsid:zoobank.org:pub:663DD393-80B0-407D-907C-51E3F33ECCFB

Combined Use of Otolith Morphometry and Microchemistry to Study the Origin of Spring‐Spawning Atlantic Herring in the St. Lawrence Estuary and the Gulf of St. Lawrence

AbstractAn important goal for the conservation of marine fish metapopulations is to maintain the diversity of components spawning in areas subjected to different environmental pressures. The usefulness of otolith morphometry combined with microchemistry to generate new information on the diversity of spawning components was assessed in declining spring‐spawning Atlantic Herring Clupea harengus in the St. Lawrence Estuary (SLE), Restigouche Estuary and adjacent areas (RE), and southern and northern Gulf of St. Lawrence (SGSL and NGSL). Mature Atlantic Herring (6–10 years old) were captured during the spring spawning season from 2013 to 2015 at nine sites with different salinity and temperature conditions along estuarine–marine and southern–northern gradients. Otoliths were measured by image analysis, and various shape indices were calculated. Elemental concentrations (Sr, Ba, and Mg) in the otolith cores were measured using laser ablation inductively coupled plasma mass spectrometry. Natal groups were inferred by hierarchical clustering analysis conducted on shape and microchemical variables separately or combined. Both types of analysis indicated the presence of two main natal groups: one predominant in the SLE and the other predominant in the RE. Proportions of fish having the characteristics of each natal source decreased with increasing distances from the head of the SLE and RE, respectively. Shape analysis provided higher discrimination in the SLE/NGSL, revealing temporal stability of a specific “pygmy” morphotype in the SLE that was previously described in the 1980s and 1990s. Microchemical analysis was more discriminating in the RE/SGSL, revealing a group of fish within the RE that had low Sr in the otolith core. Thus, otolith morphometry and microchemistry provided concordant and complementary information on natal groups, and both markers indicated the potential importance of estuaries as nursery grounds for the recovery of spring‐spawning Atlantic Herring stocks in the SGSL and NGSL.

Description of a new species of queenfish, Scomberoides pelagicus from Indian seas

Aim: The study was carried out to ascertain whether morphotype of Scomberoides commersonnianus (Talang queenfish) existing along the Indian coast is a new species or not. Methodology: Talang queenfish and the morphotype were tested for their uniqueness using systematic and molecular tools. The morphometric and meristic details including otolith morphometry were analysed and compared for taxonomic divergence and Cytochrome Oxidase I and Cytochrome b gene sequences for quantifying genetic divergences. Results: The systematic analysis indicated significant morphometric differences between both. The otolith morphometry and phylogeny also confirmed the divergence between them, and qualified the morphotype as an independent species status and named Scomberoides pelagicus sp. nov. Interpretation: The new species is distinct by deep ovate body, concave dorsal head profile, anal fin origin anterior to second dorsal fin and pelvic to pectoral fin, helical arrangement of body scale and stout and less numerous gill rakers on the first gill arch. The phylogeny as on Cytochrome b and Cytochrome Oxidase 1 sequences are very distinct, with 11.2% and 2.0% divergence respectively. Their known distributional range are peninsular region of Indian coast, Malaysian region of the South China Sea and Manila Bay, Philippines.

Relative growth and morphometry of sagittae otoliths of weakfishes, Cynoscion guatucupa (Cuvier, 1830) and Cynoscion jamaicensis (Vaillant &amp; Bocourt, 1883), in the Southwestern Atlantic Ocean, Brazil

The weakfishes, Cynoscion guatucupa and C. jamaicensis, are important demersal fishery resources and are targeted by multifleet operations in the Southwest Atlantic. This study describes the length-weight relationships between sagittae otoliths (length-OL, height-OH, thickness-OT, and weight-OWT) and the sizes of the fish (total length-LT, standard length-LS, and total weight-WT). The proportion between otolith length and height (aspect ratio-OAR) was also compared between species. The samples were obtained monthly from March 2017 to February 2018 from small-scale commercial fisheries from landings of bottom trawls and gillnets on the continental shelf in the Rio de Janeiro state, southeastern coast of Brazil. The ANCOVA did not indicate significant diferences in relative growth between sexes for both species (p > 0.05) while the length frequency was diferent (p < 0.001). Cynoscion guatucupa showed positive allometry, WT = 4E-06LT3.21 and C. jamaicensis negative allometry, WT = 2E-05LT2.90 (p < 0.05). Both species showed diferences in the condition factor between the sexes (p < 0.05). Significant diferences were observed in the measurements of the otoliths between the two species (p < 0.001). All regressions between fish measurements and otolith morphometry were highly significant (p < 0.001) for both species. The best estimates of fish size and weight were related to the otolith length: OL vs LT (r2 = 0.93; 0.96); OL vs LS (r2 = 0.92; 0.96); OL vs WT (r2 = 0.91; 0.93) for C. guatucupa and C. jamaicensis, respectively. This information adds useful biological data for multiple types of studies, e.g., food ecology (prey-predator), age and growth, reproduction, fisheries assessment and long-term landing monitoring. Our results confrmed the historical pattern of relative growth, supporting that otolith growth reflects the somatic growth of weakfishes in the study area, reinforcing the importance to determine these reference points.

Relationships between length-weight, length-length, and fish length to otolith morphometry in Rita rita (Hamilton, 1822)

The present study deals with fish length-weight, length-length, length-otolith size and length-otolith weight relationships in Rita rita. Specimens (N = 117) were collected monthly from September 2018 to August 2019 from Narora site of the River Ganga, India. The slope (b) in length-weight relationship equation was 2.40, suggesting a negative allometric growth pattern. The Student’s t-test showed no significant differences in the size of right and left otoliths in Rita rita, therefore, a single linear regression based on left otoliths was used. Fish length was plotted against otolith length, otolith height and otolith weight. The linear regression model was found to fit the data well for fish length to otolith size. Fish length was positively correlated with otolith height (R2 = 0.97), otolith length (R2 = 0.94) and otolith weight (R2 = 0.91). The mean value of condition factor was 1.13, which suggested a good condition of the target fish species in the River Ganga. Findings of this study could be used to study the population characteristics of Rita rita, and to explore the food and feeding biology of piscivores based on correlating the otolith morphometry of the prey items to the fish length at age.