Age estimates derived from hard parts of swordfish Xiphias gladius from the north-western Mediterranean Sea

Accurate age estimates for fish are critical for properly understanding stock dynamics and health; this is particularly true for larger billfishes. Here we determined the most accurate aging estimation methods for swordfish (Xiphias gladius). We compared age estimates obtained from fin-ray sections, otolith sections, whole otoliths, and vertebrae collected from 87 swordfish off the east coast of Corsica. Age estimates from otolith sections were most consistently estimated across different readers (lowest average percentage error), followed by fin-ray sections, third vertebrae, and whole otoliths. When the age estimates from the otolith sections were compared with the other three age sclerochronological methods, we found the average percentage error to be lowest between the otolith section and fin-ray methods. However, age estimates from fin rays proved most useful for estimating swordfish younger than 6 years, as the fin ray-based age diverged from that of the otolith sections as the swordfish aged. Combining fin ray and otolith section techniques, we estimated the growth parameters of 1–12-year-old females (L_∞ = 259.412, k = 0.113, t₀ = −2.499) and 1–7-year-old males (L_∞ = 175.543, k = 0.202, t₀ = −2.239). We found that females grew significantly faster than males after 3 years and remained larger thereafter. Our calculated growth rates for this region of the north-western Mediterranean Sea were lower than those of the Atlantic, Pacific, and eastern Mediterranean Sea swordfish populations, and similar to growth rates recorded for the western Mediterranean Sea populations. Our study provides critical knowledge on biological-related parameters to serve as a guide for preserving the swordfish population in the Mediterranean Sea.     

Age and growth of the Black Sea turbot, Psetta maxima (Linneaus, 1758) (Pisces: Scophthalmidae), estimated by reading otoliths and by back-calculation

Age and growth of the Black Sea turbot, Psetta maxima, were determined from a total of 1445 individuals collected along the eastern Black Sea coast between 1990 and 1996. Age was estimated by interpreting growth rings in whole and broken sagittal otoliths. The former method underestimated the age over 5 years, and a maximum age of 11 years was observed by the latter. Marginal increment analysis clearly showed that a single annulus is formed in early summer each year. Growth in length differed between sexes, and females attained a larger size than males at the same age. No significant difference was found between the mean observed total length (TL), the back‐calculated TL derived from radius measurements and the TL estimated from otolith size–fish size relationship. The von Bertalanffy growth parameters estimated by the length‐at‐age data were: L_∞ = 96.24 cm; K = 0.119 year^?1; t₀ = ?0.01 year for the entire population.     

Age at recruitment of Hawaiian freshwater gobies

Synopsis Very little is known about the dynamics of native Hawaiian stream fishes. Five species are restricted, as adults, to freshwater streams and estuaries on the major islands of the Hawaiian archipelago. This paucity of information is partly due to difficulties inherent in determination of age and subsequent determinations of life history characteristics. In the present study, we determined the age of newly recruited Hawaiian gobies,Stenogobius genivittatus andAwaous stamineus using otolith microtechniques. Internal otolith increments were enumerated using scanning electron microscopy (SEM). Increments of newly recruited juveniles were deposited on a daily basis as validated through a marking study. Results showed recruitment at an average age of 135 and 161 days for these two species, respectively, with more rapid growth following recruitment to freshwater. Chemical analyses of otolith carbonate of the Hawaiian gobies by electron microprobe for strontium and calcium concentrations provided valuable insights into a fish's past history. A combination of structural and chemical analyses makes it possible to link growth and recruitment to nutritional and environmental factors. Such information developed as a broad model would be applicable to the management of Hawaiian gobies and would greatly improve the quality of information available for these unique fish populations and other fish populations     

Fluctuating asymmetry and fitness correlations in two Engraulis encrasicolus populations

Correlations among several measures of fluctuating asymmetry (FA) and fitness‐related variables were assessed in two populations of the European anchovy Engraulis encrasicolus with fast growth (Aegean Sea) and slow growth (Ionian Sea), respectively. FA levels were borderline significantly higher in the Ionian than in the Aegean for some variables. Variation in otolith shape (deviation from population norm) was lower in the Ionian than the Aegean, contrary to expectation. Within the Aegean, there was no relation between any of the FA indexes and fitness estimators, while in the Ionian a composite otolith FA index was significantly negatively correlated to standard length at age only in 2 year‐old individuals. This difference between the Aegean and Ionian may have been related to the lower growth rate in the Ionian, as FA–fitness relations may be more apparent in less‐beneficial environments. The absence of significant correlations in the Aegean and the low correlation in one age group in the Ionian suggests that FA is not a sensitive indicator of individual fitness in adult E. encrasicolus.     

Geographic variation in otolith morphology among freshwater populations of Aphanius dispar (Teleostei,Cyprinodontiformes) from the southeastern Arabian Peninsula

Aphanius Nardo is a large genus of teleost fishes in the Old World, with 19 described species. Several of these species have only recently been recognized and additional species can be expected from isolated populations in remote areas. We show here that otolith morphology and statistical analyses of otolith variables can contribute to the detection of genetic differentiation in Aphanius. We studied samples of eight Aphanius dispar populations from the southeastern part of the Arabian Peninsula. Two populations originate from freshwater habitats far inland and probably have been isolated since the late Holocene some 4,000 years ago, three populations come from freshwater habitats with occasional connections to the sea, one population originates from a coastal site, and two were artificially introduced populations. The coastal population is interpreted as possessing the basic otolith type of A. dispar. The basic otolith type also occurs in fishes from the freshwater habitat which is located closest to the coast. Otoliths from the two other freshwater populations with occasional connections to the coast differ slightly from the basic type. However, the two populations from the long‐term isolated freshwater habitats far inland show distinct morphological changes. Our results are consistent with the hypotheses that i) otolith morphology is primarily genetically determined and is little influenced by physical parameters of the habitat, and ii) isolated A. dispar populations may be capable of evolving into new species within short periods of time. J. Morphol., 2009. © 2008 Wiley‐Liss, Inc.     

The use of sectioned otoliths to age barramundi (Lates calcarifer) (Bloch, 1790) [Centropomidae]

The relationship between the number of rings present in sagittal otoliths and the age of barramundi, Lates calcarifer (Bloch, 1790) [Centropomidae], was investigated by examining cross sectioned otoliths of 37 tagged fish of known age between 1 and 5 years from the Johnstone River, north Queensland. Concentric rings were clearly visible in all otolith sections and were validated as annual marks. The technique was then used to estimate the age and calculate von Bertalanffy growth parameters for 70 barramundi from the Fitzroy River, central Queensland. Growth appeared to be rapid but variable in the first year; the von Bertalanffy growth parameters for length versus age were L =690 mm, K=0.53, t ₀= 0.003 years. October 1 was designated as the birth date. Whole otolith length, width and thickness were also approximated well by the von Bertalanffy equation. We suggest that examination of otoliths is a useful technique for ageing barramundi but note that further validation of the ageing method is still needed for fish older than six years.     

Distribution and population structure of the Chlorophthalmus agassizi (Bonaparte, 1840) on an unexploited fishing ground in the Greek Ionian Sea

The distribution and population structure of the shortnose green eye, Chlorophthalmus agassizi, were studied in the Greek Ionian Sea using data collected during experimental trawl surveys carried out from December 1996 to November 1997. The length–frequency distribution ranged between 45 and 201 mm total length (TL). The significant increase in average size linked with depth has been observed, supporting the general ‘bigger‐deeper’ phenomenon. Specifically, 1528 individuals were measured in the 300–400 m depth zone with a mean TL = 101 mm, 2351 individuals in the 400–500 m depth zone with a mean TL = 132 mm and 1889 individuals in the 500–600 depth zone with a mean TL = 145 mm. Age and growth of the population were determined by otolith readings. Twelve age groups were identified. The von Bertalanffy growth function (VBGF) parameters were L_∞=202.22 mm, K=0.20 and t_o=?1.6 years. Natural mortality was estimated at 0.285 per year, while total mortality was estimated at 0.65. The reproductive period of C. agassizi extends from spring to autumn, with greater activity in the summer.     

ORGANIZATION OF GENETIC DIVERSITY WITHIN AND AMONG POPULATIONS OF GLEDITSIA TRIACANTHOS (LEGUMINOSAE)

This study describes levels of allozyme diversity and patterns of genetic structure within and among populations of honey locust (Gleditsia triacanthos L.). Using data from starch gel electrophoresis, honey locust was found to have high genetic diversity within populations (HM_E = 0.198), and low, but significant genetic differentiation among populations (Γ_ST = 0.059). Temporal and spatial substructuring were also investigated in two populations from eastern Kansas. Few genetic differences were found among nine age classes in one population and between juveniles and adults in the second population. Separate autocorrelation analyses of juveniles and adults revealed significant spatial substructuring in both age classes. Three conclusions were reached from these analyses. First, even small amounts of clonal growth can cause large increases in the amount of substructuring in populations. Second, spatial genetic substructuring among juveniles at both sites most likely represents the presence of family groups. Last, the overall level of spatial genetic substructuring at both sites was somewhat greater in the juvenile classes than in the nonclonal adult classes. This latter conclusion is consistent with theoretical studies suggesting that limited gene movement causes a steady increase in spatial structure from generation to generation.     

Asteriscus v. lapillus: comparing the chemistry of two otolith types and their ability to delineate riverine populations of common carp Cyprinus carpio

The chemical composition of common carp Cyprinus carpio asteriscus (vaterite) and lapillus (aragonite) otoliths from the same individual and reflecting the same growth period was measured to (1) determine whether there are differences in the uptake of trace metals (Mg:Ca, Mn:Ca, Sr:Ca and Ba:Ca ) and Sr isotope ratios (⁸⁷Sr:⁸⁶Sr) in co‐precipitating lapilli and asterisci and (2) compare the ability of multi‐element and isotopic signatures from lapilli, asterisci and both otolith types combined to discriminate C. carpio populations over a large spatial scale within a river basin. Depth profile analyses at the otolith edge using laser‐ablation inductively coupled plasma mass spectrometry showed that asterisci were enriched in Mg and Mn and depleted in Sr and Ba relative to lapilli, whilst ⁸⁷Sr:⁸⁶Sr values were nearly identical in both otolith types. Significant spatial differences among capture locations were found when all trace element and Sr isotope ratio data were aggregated into a multi‐element and isotopic signature, regardless of which otolith type was used or if they were used in combination. Discriminatory power was enhanced, however, when data for both otolith types were combined, suggesting that analysis of multiple otolith types may be useful for studies attempting to delineate C. carpio populations at finer spatial or temporal scales.     

Growth and longevity in freshwater mussels: evolutionary and conservation implications

The amount of energy allocated to growth versus other functions is a fundamental feature of an organism's life history. Constraints on energy availability result in characteristic trade‐offs among life‐history traits and reflect strategies by which organisms adapt to their environments. Freshwater mussels are a diverse and imperiled component of aquatic ecosystems but little is known about their growth and longevity. Generalized depictions of freshwater mussels as ‘long‐lived and slow‐growing’ may give an unrealistically narrow view of life‐history diversity which is incongruent with the taxonomic diversity of the group and can result in development of inappropriate conservation strategies. We investigated relationships among growth, longevity, and size in 57 species and 146 populations of freshwater mussels using original data and literature sources. In contrast to generalized depictions, longevity spanned nearly two orders of magnitude, ranging from 4 to 190 years, and the von Bertalanffy growth constant, K, spanned a similar range (0.02–1.01). Median longevity and K differed among phylogenetic groups but groups overlapped widely in these traits. Longevity, K, and size also varied among populations; in some cases, longevity and K differed between populations by a factor of two or more. Growth differed between sexes in some species and males typically reached larger sizes than females. In addition, a population of Quadrula asperata exhibited two distinctly different growth trajectories. Most individuals in this population had a low‐to‐moderate value of K (0.15) and intermediate longevity (27 years) but other individuals showed extremely slow growth (K = 0.05) and reached advanced ages (72 years). Overall, longevity was related negatively to the growth rate, K, and K explained a high percentage of variation in longevity. By contrast, size and relative shell mass (g mm^?1 shell length) explained little variation in longevity. These patterns remained when data were corrected for phylogenetic relationships among species. Path analysis supported the conclusion that K was the most important factor influencing longevity both directly and indirectly through its effect on shell mass. The great variability in age and growth among and within species shows that allocation to growth is highly plastic in freshwater mussels. The strong negative relationship between growth and longevity suggests this is an important trade‐off describing widely divergent life‐history strategies. Although life‐history strategies may be constrained somewhat by phylogeny, plasticity in growth among populations indicates that growth characteristics cannot be generalized within a species and management and conservation efforts should be based on data specific to a population of interest.     

Thirteen polymorphic microsatellite loci in the Neotropical fish Prochilodus argenteus (Characiformes,Prochilodontidae)

Prochilodus species inhabit the main river systems of South America and usually present commercial value to inland fishing. In the present study, we describe the isolation and characterization of 13 novel microsatellite loci in Prochilodus argenteus. The number of alleles per polymorphic locus varied from four to 22 and the observed heterozygosity ranged from 0.333 to 0.893. Additionally, cross‐species amplification was successful in two other Prochilodus species. These loci will be useful for studies of the population genetic structure in this fish group.     

Age, growth and mortality of a semi-isolated lagoon population of sand smelt, Atherina boyeri (Risso, 1810) (Pisces: Atherinidae) in an estuarine system of northern Greece

Age, growth and mortality of the sand smelt, Atherina boyeri (Risso, 1810), were studied in the Vistonis estuarine system in northern Greece from February 1989 to August 1990. Overall male : female sex ratio was 1 : 2.5, statistically different from unity. Total lengths ranged between 13 and 105 mm. Age determination based on scale readings showed that the population comprised five age‐groups. Sand smelt grew allometrically (b = 3.22) and rapidly during the first year, achieving 60% of their growth. Growth parameters of the population were: L_∞ = 116.97 mm, K = 0.35 year⁻¹ and t_o = −0.99 years. Growth index ϕ′ was 3.69 of all individuals studied. The mean growth index was significantly lower for the Mediterranean lagoon (ϕ′ = 3.73, SD = 0.1) than for Atlantic populations (ϕ′ = 3.92, SD = 0.06). Total mortality rate was Z = 1.29 year⁻¹ and natural mortality M = 0.95 year⁻¹. Males had a lower life span than females, the latter dominating length classes >60 mm. Exploitation rate of the studied population was E = 0.26, suggesting that stock size might increase and generate improved possibilities for exploitation.     

Unmasking continental natal homing in goliath catfish from the upper Amazon

1. Amazonian goliath catfishes are widespread in the Amazon Basin. Recently, otolith ⁸⁷Sr:⁸⁶Sr analyses using laser ablation–multi-collector–inductively coupled plasma mass spectrometry (LA-MC-ICPMS) revealed a >8,000 km trans-Amazonian natal homing in Brachyplatystoma rousseauxii among fish caught and hatched in the largest Amazon River tributary, the upper Madeira basin. Although also suspected for fish in the upper Amazon, homing could not be demonstrated owing to less distinct environmental ⁸⁷Sr:⁸⁶Sr gradients along the Amazon mainstem. Using scanning X-ray fluorescence microscopy (SXFM), a separate study provided evidence that Se:Ca and Sr:Ca are useful markers for identifying migration into Andean headwaters and the estuarine environment.
2. We analysed otoliths of known ⁸⁷Sr:⁸⁶Sr profiles using SXFM mapping to test if Sr:Ca and Se:Ca patterns could demonstrate natal homing for three fish caught in the upper Amazon, using as reference two individuals that were natal homers and two forced residents (hatched after the construction of hydroelectric dams on the Madeira River) from the upper Madeira River.
3. As hypothesised, although the Sr isotope profiles of the upper Amazon individuals were uninformative, two of them presented similar alternating mirror patterns of Sr:Ca and Se:Ca to those of the upper Madeira natal homers, indicating migrations out of the Andean region and into the estuary area. Both were therefore natal homers from the upper Amazon.
4. The third individual from the upper Amazon presented similar Sr:Ca and Se:Ca patterns to those of the upper Madeira residents, suggesting it was a natural resident from the upper Amazon.
5. By combining the results of ⁸⁷Sr:⁸⁶Sr analyses (LA-MC-ICPMS) and Sr:Ca and Se:Ca mappings (SXFM) that are completely independent of one another, we demonstrated that B. rousseauxii also performs natal homing in the upper Amazon. Our results indicate that the life cycle of B. rousseauxii is more complex than previous literature hypothesised, with the existence of partial migration, even in absence of physical barriers. Quantifying the relative importance of these different life-history strategies will have important implications for fisheries management. Our results also lay the groundwork for conservation efforts in the context of hydropower development in the Amazon Basin and set testable hypotheses of the potential impacts of the Madeira River dams.

     

Age validation and growth of Micropogonias furnieri (Pisces – Sciaenidae) in a temporally open coastal lagoon (South‐western Atlantic – Rocha – Uruguay) based on otolith analysis

In this work 228 individuals of the whitemouth croaker Micropogonias furnieri collected in the Rocha coastal lagoon (Uruguay) from October 1997 to September 1998 were analysed. The species formed annuli in the otolith (sagitta) associated with the opaque zone (narrow opaque annulus), mainly in early winter when water temperature decreased, and reached the lowest values in July–August. The period of greatest growth occurred from December to June, partially overlapping with the spawning period (December–March) and in coincidence with the increase in marginal increment. Growth parameters determined for all individuals were K = 0.19, L _∞ = 30.2 and t₀ = ?2.12. Annual growth increments showed that individuals grew rapidly and attained over 50% of their maximum observed size in the second year of life. In the third year, individuals attained sizes of first maturity at 11–12 cm less than estimates for the Río de la Plata spawning area and coastal areas of Brazil. The increment in length‐at‐age in the Rocha coastal lagoon was smaller than in individuals inhabiting the continental shelf (up to 50 m depth).     

Age,growth and reproduction in creole perch (Percichthys trucha) in the Negro River,Argentinean Patagonia

Age, growth and reproductive characteristics of creole perch, Percichthys trucha, were investigated in the Negro River, southern Argentina from samples collected seasonally, December 1994–December 1995. Age was estimated via scale and whole otolith reading methods. Total length (n = 413) ranged from 103 to 432 mm, and weight from 12 to 1042 g. Significant differences between the length‐weight relationships of males and females were detected (P < 0.05). Isometric growth was observed in juveniles and males, whereas total population and females exhibited positive allometric growth. The marking pattern in scales and otoliths followed an annual rhythm, with the formation of only one annulus in scales and only one hyaline band in otoliths during autumn‐winter. The oldest males were 5 years old whereas maximum age in females was 12 years from scales and 15 years from otoliths. Because scales were found to underestimate age in individuals older than 4 years, otoliths were considered to be the best structures for creole perch age determination. Gompertz growth parameters based on otolith data were L∞: 428.0 mm, k = 0.46 and t₀ = 0.43 for total population (r = 0.90), L∞: 410.7 mm, k = 0.42 and t₀ = 0.46 for males (r = 0.91), and L∞: 434.1 mm, and k = 0.49 and t₀ = 0.43 for females (r = 0.91). Lengths at first maturity (TL₅₀) were 260 and 241 mm in males and females, respectively, both of which corresponded to ages between 1 and 2 years. Macroscopic gonad inspection and the high percentage of juveniles captured during summer indicated that spawning begins at the end of spring.     

Genetic Diversity and Natural Population Structure of Cacao (Theobroma cacao L.) from the Brazilian Amazon Evaluated by Microsatellite Markers

A sample of 94 accessions of Theobroma cacao L. (cacao), representing four populations from the Brazilian Amazon (Acre, Rondônia, lower Amazon and upper Amazon) were analyzed using microsatellite markers to assess the genetic diversity and the natural population structure. From the 19 microsatellite loci tested, 11 amplified scorable products, revealing a total of 49 alleles, including two monomorphic loci. The Brazilian upper Amazon population contained the largest genetic diversity, with the most polymorphic loci, the highest observed heterozygosity; and the majority of rare alleles, thereby this region might be considered part of the center of diversity of the species. The observed heterozygosity for all the Brazilian populations (H _o = 0.347) was comparable with values reported for other similar upper Amazon Forastero cacao populations, with the Acre and Rondônia displaying the lowest values. The lower Amazon population, traditionally defined as highly homozygous, presented an unexpectedly high observed heterozygosity (H _o = 0.372), disclosing rare and distinct alleles, with large identity with the upper Amazon population. It was hypothesized that part of the lower Amazon population might derive from successive natural or intentional introduction of planting material from other provenances, mainly upper Amazon. Most of the loci exhibited a lower observed heterozygosity than expected, suggesting that self-pollination might be more common than usually assumed in cacao, but excess of homozygotes might also derive from sub-grouping (Wahlund effect) or from sampling related individuals. Most of the gene diversity was found to occur within groups, with small differentiation between the four Brazilian Amazon populations, typical of species with high gene flow.     

Demography of Oenocarpus bataua and implications for sustainable harvest of its fruit in western Amazon

Oenocarpus bataua is the seventh most abundant tree in the Amazon and one of the most used palms in the region. The main resource obtained from the species is the fruits that are harvested from wild populations for human consumption. Across its distribution area adults are most frequently felled to obtain the racemes, which may affect the palm's populations. In this paper we studied the demography of two populations of Oenocarpus bataua to assess the harvest potential of its fruits and the density variation in different habitats in the western Amazon to estimate fruit yields in different forest types. Non-inundated lands held the greatest densities with an average of 11 adults ha⁻¹ (0–132 adults ha⁻¹). The population finite growth rate (λ) in Amacayacu, Colombia, was 0.9103 because of slow growth and low survival of stemless individuals and low recruitment. On the contrary, in Yasuní, Ecuador, we found a growing population with λ = 1.0368. According to our simulations, adult felling reduced transient population growth (λ_t) in both populations, especially when harvest was frequent even at low intensities. In Amacayacu a simulated harvest of 60 % year⁻¹ of the fruits by climbing did not modify λ_t substantially, while in Yasuní, a regime of 80 % of annual harvest did not diminish λ_t below one and the initial number of adults. The results help to understand the demography of useful palms and to address sustainable management. For instance high yields can be obtained by shifting to non-destructive harvest techniques that can meet the increasing demand and maintain the populations.     

Age and growth of the spotted goatfish, Pseudupeneus maculatus (Bloch, 1793) in Brazil, validated through marginal increment and oxytetracycline dyes in the sagittae

A sample composed of 4973 specimens of the spotted goatfish, Pseudupeneus maculatus (4.5–29.2 cm fork length) was collected off northeastern Brazil from 1999 to 2002. Sagittae (398) were analyzed for age and growth estimation using both annuli and microincrements. For the first approach, the mean monthly marginal increment ratio analysis suggested that one band is formed annually from May to June. With the microincrements analysis, 15 specimens were reared (3–71 days) for validation of periodicity using oxytetracycline. Fluorescent dyes were observed in 10 specimens (7.5–16.9 cm). After testing, one microincrement was found to form daily. Otolith sections were polished and analyzed using a light microscope (100–1200× magnifications). Individuals larger than 22.6 cm (4 years) showed heavily overlaid increments on the otolith edge, which hampered the counts. There was agreement on the size from counts on an annual and daily basis. The von Bertalanffy function provided the following parameters: L_∞ = 33.23 cm; K = 0.265; t₀ = 0.0883 year. The sample was composed of 0⁺ to >5‐year‐old specimens. Age at first maturity was 3.6 years (20 cm), whereas the recruitment age for fisheries was 3.9 years. Juveniles represented about half of the catch (48.7%), which may have implications for population equilibrium.     

Scales and otoliths as identity cards of the Indian oil sardine Sardinella longiceps (Teleostei: Clupeiformes) populations: Ultrastructure and ornamentation characteristics using light and scanning electron microscopy

Scale and otolith morphology and morphometry of Indian oil sardine Sardinella longiceps (Clupeidae) were investigated and described using light and scanning electron microscopy from eight different body regions for scales and the right and left otoliths. Scales of the Indian oil sardine show general characteristics of the other studied clupeids sand that are easily distinguishable from other fish groups, by having striae in the posterior field. The studied cycloid scales of S. longiceps were classified into three types based on the overall shape including circular (e.g. true circular and cordate), pentagonal and quadrilateral in the different body regions. The circular shape was the most common shape (87.5%), while the quadrilateral and pentagonal forms constituted 6.25% each. The results also showed that the relative scale size (J-index) plays a desirable contribution in separating the examined populations. The results showed that the mean (or relative) scale size for all the eight regions in the Oman Sea population is larger than the Arabian Sea population. Also, another scale variable, the scale shape index (Si index), demonstrated variation (a mean of 0.86 to 1.1) in different regions of both populations from the Oman and Arabian Seas. Interestingly, here, we found that scale characters of S. longiceps not only differ from its other congeneric species, but also differ in the populations from both sides of the Oman Sea (Iran and Oman) and the Arabian Sea. It shows a positive signal for the presence of different taxonomic and management unit in the Oman and Arabian Seas. The idea should be approved by using integrated molecular and morphological traits. The otolith morphology of S. longiceps from the Oman and Arabian Seas was more conservative than the scales, which can be due to its function actin primarily as a balance organ and also enhancing hearing. The overall shape of S. longiceps otolith was lanceolate, with an elongated morphology and a well-developed rostrum, an ostial sulcus acusticus that opens to the anterior/ dorsal margin. These morphological characters are also found in the Iranian population of S. longiceps. However, otolith displayed variation in biometric parameters among two populations and left and right otoliths and the RRL parameter were important characters to discriminate the Oman and Arabian Sea populations. Thus, the structural/biometrical variability of the otoliths may be used for population distinctness, especially in water bodies with various environmental factors, and the otolith has turned out to be a useful tool to track the life history of teleostean fishes in environments with physicochemical gradients.