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Sagittal otoliths from a farmed Atlantic salmon juvenile. The left otolith (a) is entirely aragonite. The right otolith (b) is approximately 90% vaterite by planar area, and the red line marks the border between the aragonite core (dashed) and the surrounding vaterite (solid).  

Sagittal otoliths from a farmed Atlantic salmon juvenile. The left otolith (a) is entirely aragonite. The right otolith (b) is approximately 90% vaterite by planar area, and the red line marks the border between the aragonite core (dashed) and the surrounding vaterite (solid).  

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The rapid growth of aquaculture raises questions about the welfare status of mass-produced species. Sagittal otoliths are primary hearing structures in the inner ear of all teleost (bony) fishes and are normally composed of aragonite, though abnormal vaterite replacement is sometimes seen in the wild. We provide the first widespread evaluation of t...

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... otoliths in farmed and wild salmon. Norwegian Atlantic salmon yearlings raised in hatcheries had 3.7 times higher incidence of vateritic otoliths than wild populations (Fig. 2b, p < 0.0001). The percentage of Norwegian fish affected increased with fish size, with 66% of small fish, 75% of medium fish and 100% of large fish having at least one vateritic otolith. Average level of vaterite replacement also increased with fish size, from 47% in small fish to 56% in medium fish and 88% in large fish, so that large fish had 1.9 ...

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... Sagitta otoliths are normally composed of CaCO3 crystals arranged as aragonite. However, in aberrant sagitta, vaterite and calcite forms can be found in some species like salmon (Reimer et al., 2016;Austad et al., 2021), trout (Vignon & Aymes, 2020) and herring (Long et al., 2021) among others. Atlantic bluefin tuna (ABFT, Thunnus thynnus) is an oceanic marine species with an expansion in aquaculture. ...
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Gorgonians are one of the most common three-dimensional organisms in circalittoral seascapes that provide key ecological services and human goods. Gorgonian gardens of a new species of the genera Leptogorgia sp. are found in Caleta Pichicuy, Chile. Little is known about these populations including depth distribution, colony abundance, structural attributes, and associated macrofaunal assemblages. Hierarchical sampling was conducted at 20 m depth (maximum colony abundances) in order to assess spatial variability in abundance and colony attributes at two spatial scales (among sites and rocky walls). The abundance and composition of the associated vagile and sessile macrofauna was also examined using univariant (species richness, and Shannon index (H’e)) and multivariant approaches and compared to that of adjacent bare rocky habitats. Our results showed a high abundance of gorgonians (ca. 28.9 to 36.5 colonies m-2) compared to other gorgonian gardens in the world. For structural attributes, our results showed smaller colonies with thicker holdfasts in more exposed sites, suggesting the influence of hydrodynamic forces. Taxa richness and H’e of vagile fauna showed 3-fold and 2-fold, respectively, higher values in gorgonian gardens compared to bare walls, but no differences were observed for sessile fauna. In addition, PCoA and PERMANOVA evidenced a distinctive assemblages’ composition between habitats for both vagile and sessile fauna. Correlation analyses and dbRDA showed, however, little association between structural attributes and associated faunal assemblages (R2=0.06, and ca. 3 to 9.4 % of the total variation explained,respectively). Interestingly, some overfished fish species such as Semicossyphus darwini, Graus nigra, Loxechinus albus and others were only observed in gorgonian habitat, highlighting the importance of this habitat. Our results constitute the first assessment of structural habitat complexity and accompanying fauna in rose gorgonian gardens and establish the baseline for understanding possible future changes associated to human activities.
... aragonite, Baltic herring, mineral composition, otoliths, vaterite, XRD The calcium carbonate (CaCO 3 ) matrix of sagittal otoliths is, in most cases, composed of aragonite, whereas the two other polymorphs, calcite and vaterite, are used relatively infrequently (Carlström, 1963;Gauldie, 1986;Reimer et al., 2016;Strong et al., 1986). Each of these polymorphs have their characteristic crystal structure, and a 'switch' from aragonite to either calcite or vaterite results in the formation or coprecipitation of a translucent or 'glass-like' crystalline matrix, which often also causes considerable distortion to the shape, density, brittleness, and ...
... size of the otolith (e.g., Gauldie, 1986;Tomás & Geffen, 2003). This nonaragonite crystallization, also referred to in the literature as 'aberrant' crystallization, has been documented in the otoliths of several fish species in various environments (e.g., Budnik et al., 2020;Loeppky et al., 2021;Melancon et al., 2005;Reimer et al., 2016;Tzeng et al., 2007), including juvenile Atlantic herring Clupea harengus L. in the Celtic and Clyde Seas (T omas and Geffen, 2003;T omas et al., 2004). Yet, the ultimate factors determining which CaCO 3 polyform is produced are still not completely understood (Thomas & Swearer, 2019). ...
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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. This article is protected by copyright. All rights reserved.
... Vaterite, but not calcite, otoliths are commonly found in many aquaculture-reared fish species (Gauldie et al. 1997;Whitley et al. 1999), and some authors have suggested that vaterite deposition is the result of abnormally high growth rates (Reimer et al. 2017) or high animal density in the farms (Austad et al. 2021). Functionally, transmission of sound waves through otoliths is significantly influenced by the size of the otolith and the presence of non-aragonite CaCO 3 polymorphs, indicating that ocean acidification might have a negative impact on fish hearing and navigation if size and/or CaCO 3 composition are affected (Bignami et al. 2013;Radford et al. 2021;Reimer et al. 2016). Despite advances in understanding the effects of ocean acidification on otolith formation, the vast majority of studies have been focusing on larval and juvenile stages. ...
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... In teleost fishes, the largest pair of otoliths (the sagittae) are usually composed of a polymorph of calcium carbonate called aragonite. However, substitution of aragonite by vaterite, an alternative polymorph, has been documented in several species (1)(2)(3)(4)(5)(6)(7). Vaterite otoliths are larger, are deformed and have a lower density than aragonite otoliths (3,6,8). ...
... However, substitution of aragonite by vaterite, an alternative polymorph, has been documented in several species (1)(2)(3)(4)(5)(6)(7). Vaterite otoliths are larger, are deformed and have a lower density than aragonite otoliths (3,6,8). While relatively rare in wild fish, vaterite deposition is very common in hatchery fish and in aquaculture (2,4,6). ...
... Vaterite otoliths are larger, are deformed and have a lower density than aragonite otoliths (3,6,8). While relatively rare in wild fish, vaterite deposition is very common in hatchery fish and in aquaculture (2,4,6). Previous studies suggest that the presence of vaterite may impair hearing in salmonids (6,8) and alter the escape kinematics (9) in salmonids as young as 6 months old. ...
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... Aragonite and vaterite otoliths differ in their densities and lattice structure; vaterite is less dense than aragonite (Tomas and Geffen 2003;Chakoumakos et al. 2016;Neves et al. 2017), resulting in otolith mass asymmetry (Vignon and Aymes 2020). The vaterite precipitation has a negative impact on auditory sensitivity in fishes (Reimer et al. 2016). Moreover, the functional, behavioural, and ecological implications of vaterite deposition at the organismal level are usually untested experimentally (Vignon and Aymes 2020). ...
... Several studies have reported abnormal otoliths which have different size, shape, and density as compared to normal otoliths in a number of freshwater and marine fishes (Sweeting et al. 2004;Oxman et al. 2007;Ma et al. 2008;Reimer et al. 2016). In the case of abnormal otoliths, the aragonite is replaced by vaterite but in some species, calcite may replace aragonite (Gauldie 1993;Campana 1999;Ma et al. 2008;Reimer et al. 2017). ...
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Otoliths are calcified structures and the information contained within their chemistry or shape can be used to infer life history events, migration patterns, and stock structure of a fish population. Understanding how otolith chemistry is affected by temperature, salinity, interactive effects of abiotic factors, ontogeny, physiology, etc. is essential for the reconstruction of the environment that affected the fish. Otolith shape is also affected by environmental conditions in addition to the genotype. The applications of otolith chemistry and shape for stock discrimination have increased in recent years because of the advancements in analytical methods and the related software. The stock identification methods sometimes provide variable results but if we use complementary approach the information generated could be more reliable which can be used to prepare effective management and conservation strategies. It appears warranted to generate more information on the factors influencing otolith chemistry and shape especially when two or more factors exert synergetic influence. Therefore, the objectives of this review paper were to provide comprehensive information on various factors influencing the otolith chemistry and shape, and the utility of otolith chemistry and shape for fish stock discrimination with an emphasis towards the research areas needing additional studies.
... The other stray (adult 7) had values for otolith 87 Sr/ 86 Sr NATAL and 87 Sr/ 86 Sr profile that overlapped the 87 Sr/ 86 Sr signatures of MANAGEMENT BRIEF several BSC streams, but streams with these 87 Sr/ 86 Sr values are also found in the Klamath-Trinity River basin. Notably, adult 7 had no adipose fin and one otolith was composed largely of vaterite, suggesting that it had been reared in a hatchery (Brown et al. 2013;Reimer et al. 2016). The 87 Sr/ 86 Sr NATAL value for this fish overlapped the predicted 87 Sr/ 86 Sr signature of Trinity River Hatchery after correcting the published 87 Sr/ 86 Sr ratio of the stream for the effects of marine-derived hatchery food on otolith 87 Sr/ 86 Sr ratios (Barnett-Johnson et al. 2008;Hodge et al. 2016). ...
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Straying has been difficult to study directly in natural steelhead Oncorhynchus mykiss populations. We analyzed an opportunistic sample of seven adult steelhead from a small basin on the Big Sur coast of California to determine life‐history traits including whether fish were strays. Otolith natural tags (87Sr/86Sr) and genetic stock identification (GSI) indicated that all seven adults were strays from at least six different sources. Three adults strayed from nearby streams (<72 km) on the Big Sur coast, while three strayed from distant sources including the Klamath River (680 km to the north); the source of one stray could not be identified. Six strays were progeny of steelhead mothers but one was the offspring of a nonanadromous mother. Six were female and one was male, and all that could be genotyped were homozygous (n = 4) or heterozygous (n = 2) for the anadromy‐associated haplotype in a migration‐associated genomic region. While the opportunistic nature and small size of the sample prevents us from inferring the rate of straying into the basin, our study nonetheless demonstrates that steelhead may stray across greater distances than generally appreciated and that nonanadromous females can produce anadromous offspring that stray and hence provide connectivity among basins.
... These structures are of great importance to the sensation of gravity, ability to hear, linear mobility and balance (Reimer et al., 2016). ...
... Salmonids are especially susceptible to producing the vaterite form, and the differences in properties of the different polymorphs may have consequences for the movement of the otoliths in the inner ear (Sweeting et al., 2004). The consequence of this vaterite replacement of aragonite in the sagittal otoliths is loss of hearing sensitivity across most of the hearing range (Oxman et al., 2007;Reimer et al., 2016). In addition, the more prominent the coverage of vaterite in the otoliths, the more severe the hearing impairment likely becomes. ...
... In addition, the more prominent the coverage of vaterite in the otoliths, the more severe the hearing impairment likely becomes. The density differences between vaterite and aragonite may also affect hearing directionality specifically (Reimer et al., 2016). ...
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Otoliths are inner‐ear structures of all teleost fish with functional importance for hearing and balance. The otoliths usually consist of aragonite, a polymorph of calcium carbonate, but may also take the form partly or entirely of vaterite, a different polymorph of calcium carbonate. Vateritic otoliths occur sporadically in wild fish, but with a higher frequency in hatchery‐reared fish. Abnormal otoliths have direct consequences for the inner‐ear functions of fish, and may be a symptom of environmental stress. Here, we assess differences in frequency of abnormal otoliths and degree of abnormality (% vaterite) for different groups of hatchery‐reared Atlantic salmon (Salmo salar) smolt and adults. The groups differed in parental brood‐stock origin (number of generations in hatchery) and treatment temperature. Smolt from the same groups were also released to complete their ocean migration. The otoliths of the returning and recaptured adults were subsequently extracted, in order to assess the difference in frequency and degree of abnormality between the adults and the smolt from corresponding groups. Return rate varied among groups (0.2 – 2.6%). The frequency of vateritic otoliths was high (11.4‐64.4%), and differed among smolt groups. The lowest return rates corresponded with the highest frequency of abnormal otoliths for the groups, suggesting that abnormal otoliths may have negative consequences for marine survival. Furthermore, indications of an effect of fast growth on the formation of abnormal otoliths was found for only one of the experimental groups; for none of the groups after correcting for Type 1 error. This contradicts previous reports suggesting rapid growth as the main cause of abnormal otoliths. Adult return rates were generally low, but abnormal otoliths were common, with high coverage (% vaterite). This article is protected by copyright. All rights reserved.
... Reared fish have a higher prevalence of otolith shape and mineral anomalies (vaterite) that can cause important hearing impairments for the fish (Oxman et al., 2007;Reimer et al., 2016). The prevalence of these anomalies is linked to stressful conditions present in the rearing facilities, such as high population densities, temperature fluctuation, noise, vibration, diseases, poor water quality and nutrition (Sweeting et al., 2004). ...
... Existing literature on the comparison of otolith morphology between reared and wild fish mainly focus on the size of the otoliths and the deposition of calcite or vaterite on them, demonstrating an increased otolith size under rearing conditions (e.g., Arechavala-Lopez et al. 2012;Reimer et al. 2016;Reimer et al. 2017;Tomas and Geffen 2003). In the present study reared fish had larger otolith perimeter than wild-caught specimens, without any obvious depositions of vaterite or calcite. ...
Article
Otolith structure is a useful tool in the discrimination among fish populations, as it is a permanent record of the influence of endogenous and exogenous factors. In the present study we examined otolith morphology and fluctuating asymmetry (FA) for differences between wild‐caught (by bottom trawl) and reared specimens of Gilthead seabream (Sparus aurata). Based on the frequency of regenerated scales (degree of scale regeneration, SRD) on each specimen, a threshold of 30% SRD was used to assign wild‐caught fish individuals as wild (≤30% SRD, LR group) or, as possible aquaculture escapees (>30% SRD, HR group). Based on the analysis of Elliptic Fourier descriptors, significant differences were found in otolith shape between reared (Rr) and the wild‐caught groups (LR, HR). Reared fish had otoliths with significantly larger perimeter (OP) than wild‐caught fish. Furthermore, fluctuating asymmetry (FA) was significantly higher in reared (Rr) than the LR group for OP and all, except one, shape descriptors (harmonics 2‐7). The HR group exhibited intermediate levels of FA between the low and high FA levels observed in the LR and Rr groups. Results are discussed in terms of the value of combining otolith and scale morphology for the identification of escapees in the wild Gilthead seabream stocks.
... Кроме арагонита, основу отолита могут составлять другие кристаллические формы СаСО 3 -ватерит и, гораздо реже, кальцит [Gauldie et al., 1997]. Встречаемость отолитов, состоящих из двух последних форм, в естественных условиях невелика и возрастает у рыб, выращенных в условиях аквакультуры или развивавшихся в условиях стресса, что позволяет использовать частоту встречаемости таких отолитов в качестве соответствующего маркера [Reimer et al., 2016]. ...
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Microchemical analysis of calcified structures of fish is a modern technique for determining the origin of fish species and ontogenetic reconstructions of their habitat that can be applied for such tasks as stocks separation in mixed samples, tracking of fish migrations, determining of spawning, feeding or wintering areas, differentiation of fish of artificial and natural origin, growth analysis, age evaluation, etc. The approach is based on analysis of trace elements concentration between the center and periphery of a calcified structure, or precise measurement of the elements and their isotopes concentration in certain sites of sample. The calcified structures most often used for analysis are otoliths, skeleton bones, scales, and also statoliths of lampreys or beaks and statoliths of cephalopods. Specifics of the method application are described with examples of its use for solving diverse tasks of fundamental and applied science, in particular in complex studies of biological resources in the Amur River basin.