Sagittal Otoliths Research Articles

Bomb Radiocarbon, Otolith Daily Increments and Length Modes Validate Age Interpretations of Chilean Jack Mackerel (Trachurus murphyi)

Ages of Chilean jack mackerel (Trachurus murphyi) in the southern Pacific Ocean were validated using three methods: 1) daily microincrement readings in sagittal otoliths of young-of-the year (YOY) fish to validate the first annulus; 2) modal progression of strong year-classes (PSYC) to validate the first, second and third annuli, and 3) bomb radiocarbon analysis of otolith cores to validate the absolute age in older fish >38 cm fork length (FL). A Laird-Gompertz (LG) model was fitted to fork length (cm) at age (days) relationship in fish ranging from 3.4 to 25.0 cm FL and from 56 to 550 days in age. The LG model estimated a mean FL of 22 cm at the end of the first year of life, which was large compared with the mean FL estimated through conventional ageing in whole otoliths. The comparison between daily age with annual growth bands from whole otoliths, showed a false increment formed at 185 ± 34 days and a second translucent increment formed at 352 ± 79 days, corresponding to the first annulus for fish with the mean FL of 21.4 ± 1.8 cm. The PSYC coinciding with the recruits of 2008 (age 0), was tracked through three subsequent years with high accuracy, attaining 23, 27 and 30 cm FL in 2009, 2010 and 2011, respectively. These modes identified as age 1, age 2 and age 3 in the PSYC, matched to the mean length of fish with 2, 4 and 5 translucent increments in sagittal otoliths. Results from bomb radiocarbon analysis confirmed that most of the ages were correct, because the Δ14C content of adult otolith core matched the reference chronology. The absolute mean ages for the assayed otoliths, based on the comparison with the reference chronology, ranged from 7 to 13 years for sizes between 39 and 60 cm FL. The age validation for T. murphy as addressed in the current study provided crucial information for enhancing stock assessment output of this important transboundary commercial species.

A bone to pick with age estimation using hard parts: A case study of swordfish, Xiphias gladius, in the southwest Pacific Ocean

Life history parameters of fish can vary spatially, and these differences have been used to identify separate stocks for management. However, inconsistency in the methods used to obtain the parameters is often overlooked as a possible explanation for the variability in parameters. Here, we sought to understand whether large differences in growth parameters obtained for broadbill swordfish (Xiphias gladius) in the southwest Pacific Ocean and central Pacific Ocean were due to methodological differences in estimating age, and to evaluate the most appropriate hard part for providing annual age estimates. Sectioned anal fin rays were obtained from an earlier study undertaken in the southwest Pacific (1995–2003) and the assumed annuli were re-counted for a subset, using criteria confirmed through an inter-laboratory calibration exercise. Sagittal otoliths were also obtained from the same study (in which otoliths had been collected but annual age had not been estimated) and the assumed annuli present in transversely sectioned otoliths were counted using new criteria for reading growth zones. Ray-based growth curves were different to the curves obtained in the original 1995–2003 study, confirming that methodological differences exist among studies that use fin rays in the Pacific. More importantly, a direct comparison of the new age estimates from fin rays and otoliths showed a clear bias; ray age was lower on average than otolith age for females > 7 years and males > 4 years. Considering that otoliths have been shown to be more reliable than alternative hard parts for estimating the age and longevity for many species, the results suggest that swordfish live longer and grow more slowly than previously estimated in the Pacific. A maximum age of 21 years was obtained from otoliths and 14 years from rays. We recommend that protocols are established to ensure that hard part reading methods are standardised among laboratories and that otolith-based age estimation is investigated and validated for all billfish stocks, and potentially other fish species.

Age and Growth of Diaphus brachycephalus in the South China Sea Using Sagittal Otolith Microstructure

To obtain the growth and age characteristics of Diaphus brachycephalus in the South China Sea (SCS), specimens of D. brachycephalus were collected by a mid-water trawl in January and June 2015. The relationship between standard length (L) and body weight (W) was W = 0.00002699L2.8789, with no significant differences between the two survey stations and the sexes. Microscopic observation of the sagittal otoliths revealed that the daily growth increments in each period were divided into the central zone, middle zone, and external zone. The age was determined by summing the daily growth increments of the three areas. The von Bertalanffy growth curve fitted to the relationship between age and L was shown as: L = 65.6[1 − exp{−0.0132(t − 6.94)}], r2 = 0.935. The growth rate decreased from juvenile to adult, with a maximum rate of 0.436 mm day−1. The back-calculated hatching dates of specimens were speculated to be from March to November, but predominantly occurred from April to May and from September to October.

First record and otolith morphometric description of an adult lightfish, Ichthyococcus ovatus (Actinopterygii: Stomiiformes: Phosichthyidae), caught in the Strait of Sicily (central Mediterranean Sea)

On July 2018, one specimen of Ichthyococcus ovatus (Cocco, 1838) was caught in the Strait of Sicily during the International Bottom Trawl Survey in the Mediterranean (MEDITS). The adult I. ovatus measured 49 mm in total length and weighed 1.44 g. In this context, the presently reported study constitutes the first and deepest record of an adult of I. ovatus as well as the morphometric description of its sagittal otoliths. In addition, we provide an age estimation as well as an update of the geographical distribution of this bathypelagic species around the Mediterranean Sea. Based on the growth increments of sagittal otoliths, the estimated age was five years. Specifically, the otolith from the presently reported specimen of I. ovatus tended to be elliptic in shape related to aspect ratio and high rectangularity while circularity showed high complexity of otolith contour complexity. The absence of economic value of rarely reported species may underestimate their abundance. Therefore, more studies and research surveys would be necessary to fill the information gap on the biology of these deep-water species.

Varying frequency of vateritic otoliths in the Baltic herring Clupea harengus membras.

We report observations of vateritic crystallization in the sagittal otoliths of the Baltic herring Clupea harengus membras in the northern Baltic Sea. While the existence of vaterite in the calcium carbonate matrix of sagittal otoliths has been observed in various species globally, reports from the brackish Baltic Sea are few in number. Large variation in the frequency of vaterite in 1984, 1988, 1997, 2010 and 2017 was observed, suggesting that the phenomenon is not static and more long‐term studies should be conducted in search of the ultimate causing factors.

Comparison of Structures Used to Estimate Age and Growth of Yellowstone Cutthroat Trout

Abstract Understanding age and growth of fishes is critical for making meaningful management decisions. Obtaining useful information is dependent on using the best structure (e.g., scale, otolith). The objective of this study was to evaluate precision and reader confidence in age estimates from sagittal otoliths (i.e., whole, sectioned) and scales for Yellowstone Cutthroat Trout Oncorhynchus clarkii bouvieri collected from Henrys Lake, Idaho. We also sought to compare growth estimates among structures sampled during annual gill net surveys in May 2019 and 2020. We removed sagittal otoliths and scales from 416 Yellowstone Cutthroat Trout. Two readers without prior knowledge of fish length independently aged scales, whole otoliths, and sectioned otoliths. Each reader also provided a confidence rating of 0 (not confident) to 3 (completely confident). Percent exact agreement between readers was highest for sectioned otoliths (85.3%), followed by scales (68.5%) and whole otoliths (66.1%). Average confidence rating was highest for sectioned (mean ± SD = 2.2 ± 0.6) and whole (1.4 ± 0.5) otoliths and lowest for scales (1.0 ± 0.2). Among structures, percent exact agreement (i.e., consensus age) was highest between whole and sectioned otoliths (66.7%), followed by scales and sectioned otoliths (58.9%). Exact agreement was lowest between scales and whole otoliths (51.2%). Differences in back-calculated length at age estimates between sectioned otoliths and scales were minimal, particularly for ages 1–4. Although sectioned otoliths required more time to prepare than scales or whole otoliths, sectioned otoliths produced the most precise age estimates for Yellowstone Cutthroat Trout, with the highest reader confidence.

Orta Ege Denizi’nde kral balığı Caranx rhonchus’un yaş, büyüme ve eşeysel olgunluğu (Teleostei: Carangidae)

This study investigates the age, growth and maturity of false scad (Caranx rhonchus Geoffroy Saint-Hilaire, 1817) in the İzmir Bay, the Central Aegean Sea. The total length of 392 fish varied between 12.8-36.0 cm and their weights were measured as 23.51-455.44 g. Sex ratio was 1:0.8 (F:M). Sagittal otoliths were used for age determination. Fish were between I-V age groups in the bay. The length-weight relationships were calculated as W= 0.0145*L2.8911 for females; W= 0.0168*L2.8425 for males, and W= 0.0132*L2.9259 for all fish. The von Bertalanffy growth parameters were found as L∞= 40.86 cm, K= 0.2181 years-1, to= -1.0584 years for females; L∞= 39.54 cm, K= 0.2156 years-1, to= -0.963 years for males; and L∞= 41.12 cm, K=0.2061 years-1, to= -1.0548 years for all fish, respectively. The growth performance index values (Φ) were 2.532 for females, 2.555 for males, and 2.542 for all fish. The length at first maturity was calculated as 18.53 cm for females, and 18.95 cm for males.

Influence of food quality on larval growth of Atlantic bluefin tuna (Thunnus thynnus) in the Gulf of Mexico

AbstractLarval abundances of Atlantic bluefin tuna (ABT) in the Gulf of Mexico are currently utilized to inform future recruitment by providing a proxy for the spawning potential of western ABT stock. Inclusion of interannual variations in larval growth is a key advance needed to translate larval abundance to recruitment success. However, little is known about the drivers of growth variations during the first weeks of life. We sampled patches of western ABT larvae in 3–4 day Lagrangian experiments in May 2017 and 2018, and assessed age and growth rates from sagittal otoliths relative to size categories of zooplankton biomass and larval feeding behaviors from stomach contents. Growth rates were similar, on average, between patches (0.37 versus 0.39 mm d−1) but differed significantly through ontogeny and were correlated with a food limitation index, highlighting the importance of prey availability. Otolith increment widths were larger for postflexion stages in 2018, coincident with high feeding on preferred prey (mainly cladocerans) and presumably higher biomass of more favorable prey type. Faster growth reflected in the otolith microstructures may improve survival during the highly vulnerable larval stages of ABT, with direct implications for recruitment processes.

Multiscale analysis on otolith structural features reveals differences in ontogenesis and sex in Merluccius merluccius in the western Adriatic Sea.

Otolith biomineralization results from biochemical processes regulated by the interaction of internal (physiological) and external (environmental) factors which lead to morphological and ultrastructural variability at intra- and interspecific levels. The aim of this study was to conduct a multi-scale analysis of the sagittal otoliths of the Merlucius merlucius (European hake) from the western Adriatic Sea in order to correlate otolith features with fish ontogeny and sex. We show that otoliths of sexually undifferentiated (non-sexed) individuals having a fish body total length (TL) less than 15 cm had faster growth in length, width, area, perimeter, volume and weight and a higher amount of organic matrix compared with otoliths of sexually differentiated individuals (females and males) having a fish size range of 15–50 cm. Most importantly, with increasing fish TL, female saccular otoliths contained a higher number of protuberances and rougher surface compared with male specimens, which showed more uniform mean curvature density. The differences between females and males discovered in this study could be associated with fish hearing adaptation to reproductive behavioural strategies during the spawning season. The outcomes of this research provide insights on how size and sex-related variations in otolith features may be affected by fish ecological and behavioural patterns.

Age, growth, mortality, and yield‐per‐recruit of red spotted grouper Epinephelus akaara in the central Seto Inland Sea, Japan

The red spotted grouper Epinephelus akaara is important for commercial and recreational fishing in the coastal waters of East Asia. In Japan, approximately 850,000 juveniles are released annually for stock enhancement, and the catch in several release areas has increased. Life-history traits are important for fisheries management and stocking programmers. The age, growth, and mortality of fish collected from the central Seto Inland Sea from June 2012 to November 2014 were examined using 1022 sectioned sagittal otoliths, and the yield-per-recruit (YPR) was calculated. The opaque zones in the otoliths were confirmed to be annuli, formed mainly between June and July. The oldest fish was 16 years old. The percentage of those between two and five years was approximately 80%, whereas that of more than ten years was only 0.6%. The five parameters von Bertalanffy growth equation was calculated as: TLt = 390 {1 − 0.23[(t − 3.78)2 + 1]−1}{1 − exp [−0.34 (t + 0.28)]}, where TLt is the total length (mm) at t (year). The total, natural, and fishing mortality rates were calculated to be 0.80, 0.24–0.31 and 0.49–0.56 year−1, respectively. The YPR analysis indicated that the current fishing mortality rate (Fcurrent) was higher than F0.1 and Fmax, and that increasing the age at first capture is more effective than decreasing F for increasing the YPR. These results provide important information for fisheries management and the stocking of E. akaara.

Age, growth and diet of crevalle jack (Caranx hippos) in the Gulf of Mexico

AbstractThe goals of this study were to generate baseline population dynamics parameters for Gulf of Mexico crevalle jack Caranx hippos and examine the foraging habits of Mississippi and Alabama crevalle jack. Specimens were collected from Mississippi, Alabama and Florida, and age was estimated from sagittal otoliths. Stomachs from some specimens were retained for dietary analyses. Age classes spanned 0–20 years. Overall growth was best represented by the logistic growth model, whereas sex‐specific growth was best represented by a version of the von Bertalanffy growth function that allowed L∞ to vary by sex while holding k and t0 constant between sexes. Fishes were more important to crevalle jack diet than invertebrates, and diet varied among locations and years. These findings will address fundamental knowledge gaps to inform age‐based stock assessments for crevalle jack and ecosystem approaches to fisheries management in the Gulf of Mexico.

Spatial Variations in the Shape and Chemistry of Sagittal Otoliths in Channa punctatus (Channidae) Populations of Ganga Basin, India

Spatial Variations in the Shape and Chemistry of Sagittal Otoliths in Channa punctatus (Channidae) Populations of Ganga Basin, India

Age, Growth, and Utility of Otolith Morphometrics as Predictors of Age in the European Barracuda, Sphyraena sphyraena (Sphyraenidae): Preliminary Data

Age and growth of the European barracuda, Sphyraena sphyraena, were determined by examining sagittal otoliths belonging to fish sampled in the eastern Adriatic Sea, as the northernmost region of the Mediterranean. A total of 113 specimens (59 females, 53 males, and one individual of indeterminate sex), ranging from 23.4 to 42.5 cm in total length, were analyzed. The maximum observed age was 5 years for both females and males, and this barracuda population was dominated by 3 year old fish. Growth was described by the von Bertalanffy growth curve (L∞ = 55.58 cm, K = 0.12 year−1, t0 = −4.29 year, R2 = 0.580), and the growth performance index (Φ’) was 2.57. Otolith length, width, and mass were measured, and the utility of these morphometrics as predictors of age in S. sphyraena was evaluated. The results showed that counting otolith annuli produced a better estimation of age than proposed linear models based on relationships between observed fish age and otolith morphometrics. In comparison with age and growth data available in the literature for S. sphyraena, our results from the Adriatic Sea provide more insights into the life-history traits of this species and can be used in the future effective management and conservation.

Effect of egg size on the growth rate and survival of wild walleye pollock Gadus chalcogrammus larvae

AbstractTo clarify the survival process of walleye pollock larvae of the Japan Pacific stock in relation to the individual egg size, we estimated the original relative egg diameter from the diameter of the hatch check formed on larval sagittal otoliths. Significant positive correlations were obtained between egg diameter and embryonic body length, yolk sac volume, and lapillar otolith diameter in 3‐year groups (2013–2015 year classes) collected with a plankton net in Funka Bay. Embryos before hatching were without a check; however, checks were observed on all larval otoliths just after hatching. The check diameters showed significant positive regressions to age at collection (days after hatching) in 2014 and 2015 year classes, however not in the 2013 year class. Diameters of eggs collected with a ring net in Funka Bay gradually increased from 2013 to 2015 year classes. During the 2013–2015 spawning seasons, the proportion of adult females of the 2007 and 2009 year classes, which had relatively high abundances, gradually increased to higher proportions with age (43%, 57%, and <73%, respectively), indicating that the mechanism by which the eggs gradually became larger. The low water temperature experienced by the spawners ca. 2 months earlier, advancement in spawner age, and increase of repeat spawners (at least twice in their life time) would contribute to the increase in egg size and growth and survival rate of walleye pollock larvae.

Key Life History Attributes and Removal Efforts of Invasive Lionfish (Pterois volitans) in the Flower Garden Banks National Marine Sanctuary, Northwestern Gulf of Mexico

Indo-Pacific lionfish (Pterois volitans and P. miles) are the first marine teleost to have successfully invaded and become established in the Western Atlantic Ocean of the United States, Gulf of Mexico (GoM), and Caribbean Sea. Pterois volitans were first reported in the Flower Garden Banks National Marine Sanctuary (FGBNMS), a protected coral reef system in the northwestern GoM, in 2011. Little is understood about the life history characteristics of lionfish in this ecosystem. This study assessed population characteristics (size, density, age and growth) and removal efforts of lionfish (n = 1,665) at two coral reef sites within FGBNMS for 2015, 2016, and 2018. The annual increment formation in sagittal otoliths was examined to assess the age and growth of lionfish collected in 2018 (n = 100). Lionfish ranged in size from 75 to 444 mm total length (TL) and 4–1,153 g in total weight (TW). Six hundred and ten fish were randomly dissected for sex determination (females = 256, males = 354), females ranged in size from 137 to 348 mm TL and 21–586 g, while males ranged from 118 to 444 mm TL and 18–1,153 g. Interannual variation in mean lionfish density ranged from 26.7 individuals per hectare (ind ha–1) in 2016 to 81.1 ind ha–1 in 2018, while removal effort significantly increased ranging from 1.92 to 5.42 kg diver h–1. Lionfish age ranged from 0 to 10 years, with a mean age of 3.9 years. The observed values of the asymptotic maximum total length (L∞) and Brody’s growth coefficient (K) were 345 mm and 0.30 for females and 415 mm and 0.18 for males. Results suggest lionfish from FGBNMS exhibit markedly lower mean densities, a lower L∞ and growth rate, but attain older ages than lionfish in the Caribbean Sea, Western Atlantic Ocean, and other ecoregions in the northern GoM. This study describes the first key life history parameters and removal efforts for lionfish in a protected, healthy coral reef system in the northwestern GoM that may provide insight into environmental population controls (e.g., ecological resilience). Metrics from this study could be integrated into mechanistic ecological models to determine if FGBNMS is in fact exhibiting natural resilience to the lionfish invasion.

Population Structure of Indian Mackerel (Rastrelliger kanagurta) in Java and Bali Island, Indonesia Inferred from Otolith Shape

The Indian mackerel, Rastrelliger kanagurta, is a commercially important resource across Indonesia's archipelagic waters. Despite its essential role in the fisheries industry, information regarding its population structures for management purposes is still limited. The present study investigates the variability of otolith shape as an efficient tool for stock discrimination. A total of 159 pairs of sagittal otolith were sampled at four localities along the southern Java-Bali coastal waters. Otolith outline was modeled by using Wavelet coefficients and was compared between localities using ANOVA-like permutation test, Canonical Analysis of Principal Coordinates (CAP), and classification test performed using linear discriminant analysis. The results showed significant differences in the shape of otolith between populations, reflected explicitly in the morphological feature of the excisura major. The differences in otolith shape were examined from all localities (ANOVA-like, p<0.001, and CAP p>0.05), except those otoliths between Palabuhanratu and Pacitan, thus, a mixed stock may occur in these two locations. These findings were also confirmed by the low classification success rate using LDA 44.26%. These results suggested that at least two distinct stocks potentially contributed to the fishery, impacting species management and conservation.

The Effect of Largemouth Bass Virus on Bass Populations in Kansas Impoundments.

Largemouth Bass virus (LMBV) first became a concern in Kansas when it was identified as a potential cause of decreased catch rates at Crawford State Fishing Lake in 2007. The discovery of LMBV in eight additional impoundments from 2008 to 2017 increased concern about the prevalence and effects of LMBV in Kansas. In response, the Kansas Department of Wildlife, Parks, and Tourism tested 25 Largemouth Bass Micropterus salmoides impoundments for the presence of LMBV. The objectives of this study were to quantify the incidence of LMBV and examine differences in population metrics (i.e., body condition, relative abundance, and growth). A total of 1,260 Largemouth Bass were collected by using standard spring electrofishing surveys, and sagittal otoliths were collected from all of the sampled fish to estimate growth rates. Of the 25 study impoundments, 14 tested positive for LMBV. There was no evidence of LMBV effects on body condition, relative abundance of quality-length fish, or growth rates. The initial dates of LMBV infection of Largemouth Bass in these impoundments are unknown. The LMBV-positive populations in Kansas may have been exposed to the virus many years ago, and the fish may be in the process of rebounding from any potential negative effects.

Queen triggerfish Balistes vetula: Validation of otolith-based age, growth, and longevity estimates via application of bomb radiocarbon.

Ensuring the accuracy of age estimation in fisheries science through validation is an essential step in managing species for long-term sustainable harvest. The current study used Δ14 C in direct validation of age estimation for queen triggerfish Balistes vetula and conclusively documented that triggerfish sagittal otoliths provide more accurate and precise age estimates relative to dorsal spines. Caribbean fish samples (n = 2045) ranged in size from 67–473 mm fork length (FL); 23 fish from waters of the southeastern U.S. (SEUS) Atlantic coast ranged in size from 355–525 mm FL. Otolith-based age estimates from Caribbean fish range from 0–23 y, dorsal spine-based age estimates ranged from 1–14 y. Otolith-based age estimates for fish from the SEUS ranged from 8–40 y. Growth function estimates from otoliths in the current study (L∞ = 444, K = 0.13, t0 = -1.12) differed from spined-derived estimates in the literature. Our work indicates that previously reported maximum ages for Balistes species based on spine-derived age estimates may underestimate longevity of these species since queen triggerfish otolith-based ageing extended maximum known age for the species by nearly three-fold (14 y from spines versus 40 y from otoliths). Future research seeking to document age and growth population parameters of Balistes species should strongly consider incorporating otolith-based ageing in the research design.

The effect of ontogenetic diet shifts on sagittal otolith shape of European perch, Perca fluviatilis (Actinopterygii: Percidae) from Lake Ladik, Turkey

European perch undergoes several ontogenetic dietary shifts during its lifetime. The present study focused on the variability in otolith shape caused by ontogenetic dietary changes in this species. A total of 172 specimens (7.5 to 27.5 cm TL) were caught by local fishermen in Lake Ladik from April to November 2019. Shape indices (SIs) and elliptic Fourier coefficients (EFCs) were calculated for each otolith. To detect ontogenetic changes in otolith shape, SIs and EFCs were compared among the three defined size classes (I, II, and III). Size-related groups were distinguished by both SIs and EFCs. Otolith shape analysis was more effective than morphometric analysis in distinguishing ontogenetic groups. Simultaneous use of both methods improved the classification success of each method alone. This study demonstrated that otolith shape of European perch is influenced by ontogenetic changes in diet. However, sexual maturity of the fish is also responsible for these variations in otolith shape.

Otolith shape analysis supports three cryptic species in the Stellifer punctatissimus complex (Acanthuriformes: Sciaenidae)

Abstract Sciaenidae species (croakers and drums) are known for specializations in their sensory apparatus, such as otoliths and lateral line. Within this family, some Stelliferinae members remain taxonomically unresolved due to their cryptic aspects and low phenotypic disparities. Stellifer punctatissimus comprises a species complex putatively formed by three species on morphological grounds, but molecular data have indicated only two evolutionary lineages. Herein, we tested the hypothesis that this complex is composed of Stellifer gomezi (GM), S. menezesi (MN), and S. punctatissimus (PC), using the otolith shape and morphology to differentiate them. Seventy-seven sagittal otoliths (GM = 30, MN = 30, PC = 17) were photographed to outline the otolith contour by Elliptical Fourier descriptors. Ten otoliths for each group were used to detect shape variation in the sulcus acusticus through semilandmarks. Differences in otolith shape contour were recorded among the species by PERMANOVA (Pseudo-F = 4.02, df = 2, p < 0.001) and corroborated by the Linear Discriminant Analysis, which demonstrated three partially segregated groups with satisfactory re-classification rates. A larger sulcus acusticus (GM and MN), rounded projection (PC), and distinct rectangularity pattern were also recorded. Our results support the morphological hypothesis and thus contribute to narrowing the taxonomic gaps in Sciaenidae.