Otolith Elemental Fingerprints Research Articles

Spatiotemporal variability in otolith elemental fingerprint and the potential to determine deepwater redfish (Sebastes mentella) origins and migrations in the Estuary and Gulf of St. Lawrence, Canada

Connectivity processes have major implications in defining the resiliency of fish populations to overexploitation. A preliminary estimate of population exchange rates can be done by identifying the natal origin of adult fish. In this study, otolith elemental fingerprints were used as natural marker of origins and movements of Deepwater redfish (Sebastes mentella) in the Gulf of St. Lawrence (GSL). We specifically targeted the strong 2011–2013 cohorts that supported the rapid recovery of the GSL stock after its collapse in the 1990s. Elemental fingerprints were extracted from the core (proxy for larval origin) and edge (proxy for capture location) of otoliths using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). We observed an East to West gradient in the multi-elemental fingerprint of the otolith edge in the GSL, as well as evidence of temporal variation between 2016 and 2018. Cluster analysis of the core fingerprint revealed the existence of two chemically distinct natal sources of variable contribution between the Saguenay Fjord, the western GSL and the eastern GSL. This new insight on the population structure of redfish in the GSL at an ecologically relevant scale constitutes important knowledge for the assessment and sustainable management of a key recovering resource.

Otolith elemental fingerprints reveal source-sink dynamics between two Greenland halibut nurseries in the St. Lawrence Estuary and Gulf

In fisheries science, it is important to understand the population dynamics of commercial species and also their movements from the nursery to the population, especially for juvenile individuals, to avoid overfishing. To determine their migration patterns among nurseries, we collected juvenile Greenland halibut Reinhardtius hippoglossoides from 2 nurseries inside our study area, the Estuary and Gulf of St. Lawrence, in the summer of 2016. We measured the concentrations of chemical elements in their otoliths along a margin-core transect and used the margin elemental fingerprints of Mg, Mn, Sr, and Ba to infer migratory behaviour between 2 sample sites, the Estuary and North Anticosti nurseries. Using a random-forest analysis, we achieved an overall reclassification success of margin elemental fingerprints to their capture site of 77%. Most fish sampled from both sample sites originated from the estuary (82.5%), suggesting an important asymmetry in the source-sink dynamics between these nurseries. Juvenile Greenland halibut migrate towards the North Anticosti nursery at a smaller-than-expected size (approximately 26 cm) corresponding to 2.5-3 yr old fish. Despite sexual dimorphism in growth, sex does not affect migratory behaviour or timing of migration before sexual maturation. Our study highlights the recruitment dynamics of Greenland halibut and confirms the estuary as the main nursery in the St. Lawrence system.

Stock discrimination and connectivity assessment of yellowfin seabream (Acanthopagrus latus) in northern South China Sea using otolith elemental fingerprints.

Connectivity between fish stocks is fundamental to the understanding of population dynamics and the implementation of sustainable fisheries management. Otolith microchemistry is a promising tool as it can provide information on the continuous growth of otoliths and the environmental effects on otolith composition. Such elemental fingerprints can help distinguish different stocks or life history stages, identify the origins or nursery areas of fish, and assess population structure. In this study, we examined the stock discrimination and spatial connectivity of cage-cultured and wild stocks of yellowfin seabream (Acanthopagrus latus) from the coastal waters of Shantou, Yangjiang, and Zhanjiang in China southern province Guangdong during 2012–2014, based on otolith trace-elemental signatures using multivariate statistical analysis and machine learning approaches. The concentrations of 13 elements (7Li, 23Na, 24Mg, 40Ca, 55Mn, 56Fe, 59Co, 59Ni, 64Cu, 65Zn, 88Sr, 122Sb, and 137Ba) in the natal spot of fish otoliths, representing the embryonic and paralarval stages of fish, were analyzed using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). Stepwise discriminant analysis and random forests were used to distinguish the cultured and wild stocks of yellowfin seabream, and non-metric multidimensional scaling (NMDS) and cluster analysis were used to determine the spatial variation and connectivity of yellowfin seabream stocks. Overall, the cultured and wild stocks of yellowfin seabream could be identified with classification accuracy of 80.7% and 99.2% by using stepwise discriminant analysis and random forests respectively. When we compared site difference between cultured and wild stocks (site × stock interactions), the classification success was 60.4% for stepwise discriminant analysis and 85.7% for random forests. The misclassification of cultured and wild stocks within the three sites suggested the spatial connectivity between stocks and among sampling locations. Our findings suggested that the three wild stocks of yellowfin seabream from Guangdong coastal waters could be considered as one unit for management, and the difference between cultured and wild stocks was significant for yellowfin seabream from Shantou and Yangjiang, but less significant for yellowfin seabream from Zhanjiang. This study demonstrated that otolith elemental fingerprints can help improve our knowledge on the spatial connectivity, population structure, and life history of fish stocks, and random forests can be a useful tool for identifying cultured and wild stocks compared to the traditional stepwise discriminant analysis.

Contribution of the nursery areas to the main fishery ground of the Brazilian sardine (Sardinella brasiliensis) in Southeastern Brazilian Bight through otolith fingerprinting

Event Abstract Back to Event Contribution of the nursery areas to the main fishery ground of the Brazilian sardine (Sardinella brasiliensis) in Southeastern Brazilian Bight through otolith fingerprinting Inês Ferreira1, 2, Paulo Schwingel3, André M. Vaz Dos Santos4, Paul Hamer5 and Alberto T. Correia1, 2, 4* 1 Universidade Fernando Pessoa (UFP), Portugal 2 Centro Interdisciplinar de Investigação Marinha e Ambiental (CIIMAR), Portugal 3 Universidade do Vale de Itajaí (UNIVALI), Brazil 4 Universidade Federal do Paraná (UFPR), Brazil 5 Primary Industries, Australia In the wider context of marine conservation and fisheries management, the current research aims to provide the knowledge baseline that will fill the gap on the status of an ecologically and fish along the Brazilian southern coast, the Brazilian sardine (Sardinella brasiliensis). This species can be found along the continental shelf of the Southeastern Brazilian Bight, the area between Cape São Tomé (22°S) and a little further south of Cape Santa Marta Grande (28°30’S). It is one of the major commercial pelagic species in the country, supporting important fisheries in the South and Southeast of the Brazilian coast involving industrial fleets based in the States of Rio de Janeiro, São Paulo, Santa Catarina and Rio Grande do Sul. However, despite the importance of this species, information about sardine movements and connectivity between their main juvenile recruitment areas and the adult fishing grounds is currently scarce. The small size of the fish larvae and the oceanographic conditions under which dispersal takes place make direct monitoring almost impossible. Assessing the population structure of this species by specifically linking the contribution of the nursery areas to the adjacent coastal areas, which work as fishery grounds, is important for the effective management and conservation of the species. To this end, otolith elemental fingerprints (core analysis) of young of the year (ages 0+) and adults (age 3+) collected along its three main spawning areas in the Brazilian coast (descending order of importance: 26°-28°S, 24°-25°S and 22°-23°S, respectively) ) were used to demonstrate regional population structure by comparing the elemental signatures of recruits with the ones from adult fish of the same cohort to estimate connectivity between juvenile recruitment areas and regional adult populations. The obtained data represent an important knowledge to achieve a sustainable and rational fisheries management for the Brazilian sardine. Acknowledgements Research grant CNPq 305403/2015-0 Keywords: pelagic fish, Fisheries, Sagitta, Microchemistry, Rational management Conference: XIX Iberian Symposium on Marine Biology Studies, Porto, Portugal, 5 Sep - 9 Sep, 2016. Presentation Type: Poster Presentation Topic: 4. FISHERIES, AQUACULTURE AND BIOTECHNOLOGY Citation: Ferreira I, Schwingel P, Vaz Dos Santos AM, Hamer P and Correia AT (2016). Contribution of the nursery areas to the main fishery ground of the Brazilian sardine (Sardinella brasiliensis) in Southeastern Brazilian Bight through otolith fingerprinting. Front. Mar. Sci. Conference Abstract: XIX Iberian Symposium on Marine Biology Studies. doi: 10.3389/conf.FMARS.2016.05.00200 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 12 May 2016; Published Online: 03 Sep 2016. * Correspondence: Prof. Alberto T Correia, Universidade Fernando Pessoa (UFP), Porto, Portugal, atcorreia.ciimar@gmail.com Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Inês Ferreira Paulo Schwingel André M Vaz Dos Santos Paul Hamer Alberto T Correia Google Inês Ferreira Paulo Schwingel André M Vaz Dos Santos Paul Hamer Alberto T Correia Google Scholar Inês Ferreira Paulo Schwingel André M Vaz Dos Santos Paul Hamer Alberto T Correia PubMed Inês Ferreira Paulo Schwingel André M Vaz Dos Santos Paul Hamer Alberto T Correia Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Evidence for meta-population structure of Sardina pilchardus in the Atlantic Iberian waters from otolith elemental signatures of a strong cohort

The European sardine is one of the most important clupeoid fish captured by the Portuguese and Spanish purse-seine fleets in the Atlantic waters of the Iberian Peninsula. Despite the importance of this species, and substantial decrease in catches over the last two decades, knowledge about sardine movements and connectivity between their juvenile recruitment areas and the adult fishing grounds is scarce. In this study otolith elemental fingerprints (both whole and core) of juvenile recruits (ages 0+ and 1+) and adults (age 3+) collected along the Portuguese coast (North, Central and South regions) were used to demonstrate regional population structure. The whole and otolith core analyses represented the entire life-history prior to capture and the larval/recruitment phases (first 2 months of life), respectively. Molar ratios of Sr/Ca, Mg/Ca, Mn/Ca and Ba/Ca provided location-specific elemental signatures, although otolith elemental compositions were not temporally stable within a year-class, particularly for Mg/Ca and Ba/Ca. Classification accuracy rates obtained from quadratic discriminant function analysis of core and whole otolith chemistry data of adults were relatively high (63% and 79% mean accuracy percentages, respectively). The results support the hypothesis of meta-population structure of the sardine stock in the Atlanto-Iberian waters. However, because there was evidence of some mixing among adult aggregations, and adult aggregations were largely derived from a common northern juvenile recruitment area they cannot be classified as entirely separate stock units for fisheries management purposes. The maximum likelihood analysis suggested for the 2004 cohort that replenishment of adult populations of sardine along the Portuguese coast was mostly derived from a single northern recruitment area.

Temporal stability of otolith elemental fingerprints discriminates among lagoon nursery habitats

The chemical composition of fish otoliths reflects that of the water masses that they inhabit. Otolith elemental compositions can, therefore, be used as natural tags to discriminate among habitats. However, for retrospective habitat identification to be valid and reliable for any adult, irrespective of its age, significant differences in environmental conditions, and therefore otolith signatures, must be temporally stable within each habitat, otherwise connectivity studies have to be carried out by matching year-classes to the corresponding annual fingerprints. This study investigated how various different combinations of chemical elements in otoliths could distinguish, over three separate years, between four coastal lagoon habitats used annually as nurseries by gilthead sea bream (Sparus aurata L.) in the Gulf of Lions (NW Mediterranean). A series of nine elements were measured in otoliths of 301 S. aurata juveniles collected in the four lagoons in 2008, 2010 and 2011. Percentages of correct re-assignment of juveniles to their lagoon of origin were calculated with the Random Forest classification method, considering every possible combination of elements. This revealed both spatial and temporal variations in accuracy of habitat identification, with correct re-assignment to each lagoon ranging from 44 to 99% depending on the year and the lagoon. There were also annual differences in the combination of elements that provided the best discrimination among the lagoons. Despite this, when the data from the three years were pooled, a combination of eight elements (B, Ba, Cu, Li, Mg, Rb, Sr and Y) provided greater than 70% correct re-assignment to each single lagoon, with a multi-annual global accuracy of 79%. When considering the years separately, discrimination accuracy with these elemental fingerprints was above 90% for 2008 and 2010. It decreased to 61% in 2011, when unusually heavy rainfall occurred, which presumably reduced chemical differences among several of the lagoons. This study highlights the need for multi-annual sampling, and multi-elemental analysis, when developing otolith microchemical fingerprints to explore nursery habitat use in coastal fishes.

Otolith elemental fingerprints distinguish Atlantic cod spawning areas in Newfoundland and Labrador

We used laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) to analyse the otolith composition of four key spawning aggregations of cod in Newfoundland and Labrador waters in inshore, offshore, north and south locations. A group-specific fingerprint was established for each spawning location, using the elemental ratios of Mg, Mn, Sr, and Ba to Ca and fish growth rates. The fingerprint differed among groups but showed some variations through time. Cod of three cohorts collected in two consecutive years were correctly assigned to their spawning group with 66% accuracy and increased to 78% when inshore spawning areas were merged. Our findings suggest that otolith signatures coupled with growth rates have potential to enable tracking of cod movements over time, identification of distribution shifts that may occur with changing climate, and potentially determine the contribution of each spawning group to fisheries.

Can otolith elemental chemistry retrospectively track migrations in fully marine fishes?

Otolith microchemistry can provide valuable information about stock structure and mixing patterns when the magnitude of environmental differences among areas is greater than the cumulative influence of any vital effects. Here, the current understanding of the underlying mechanisms governing element incorporation into the otolith is reviewed. Hard and soft acid and base (HSAB) theory is employed to explore the differences in chemical behaviours, distributions and affinities between elements. Hard acid cations (e.g. Mg(2+) , Li(+) and Ba(2+) ) tend to be less physiologically influenced and accepted more readily into the otolith crystal lattice but are relatively homogeneous in seawater. Soft acid cations (e.g. Zn(2+) and Cu(2+) ) on the other hand, exhibit more varied distributions in seawater, but are more likely to be bound to blood proteins and less available for uptake into the otolith. The factors influencing the geographical distribution of elements in the sea, and their incorporation into the otoliths of marine fishes are reviewed. Particular emphasis is placed on examining physiological processes, including gonad development, on the uptake of elements commonly used in population studies, notably Sr. Finally, case studies are presented that either directly or indirectly compare population structuring or movements inferred by otolith elemental fingerprints with the patterns indicated by additional, alternative proxies. The main obstacle currently limiting the application of otolith elemental microchemistry to infer movements of marine fishes appears to lie in the largely homogeneous distribution of those elements most reliably measured in the otolith. Evolving technologies will improve the discriminatory power of otolith chemistry by allowing measurement of spatially explicit, low level elements; however, for the time being, the combination of otolith minor and trace element fingerprints with alternative proxies and stable isotopic ratios can greatly extend the scope of migration studies. Among the otolith elements that routinely occur above instrument detection limits, Ba, Mn and Li were deemed the most likely to prove reliable geographic markers in marine species.

Connectivity between estuaries and marine environment: Integrating metrics to assess estuarine nursery function

Natural or anthropogenic induced variations in estuaries and the dynamics of marine fish populations potentially promote differences in connectivity between estuaries and marine areas, i.e. in their importance as nursery grounds. Within this context, an integrated assessment of the differential nursery function of the main estuaries along the Portuguese coast for commercial fish species common sole Solea solea, Senegalese sole Solea senegalensis, flounder Platichthys flesus and sea bass Dicentrarchus labrax was performed through several indicators based on available data. Contribution of individual estuaries to marine subpopulations was measured with potential metrics (juvenile density, habitat quantity, juvenile number and habitat quality within estuaries) and effective metrics (estuarine source of young adults in marine environment measured via otolith elemental fingerprints). The relationship between the two types of metrics was also assessed. Estuaries identified as important nursery and/or effective juvenile habitat (EJH) differed with species and no single estuary was best for all, highlighting species-specific regulation of nursery function. Multiple species assessment of nursery and EJH function differed among estuaries. Management and conservation of estuaries should focus on sites with higher contributions to adult subpopulations of multiple species. The importance of defining precise scientific and management objectives was emphasized by the different rankings of estuaries obtained with nursery or EJH criteria. Potential and effective contribution of estuaries were not significantly correlated, but in a quantitative analysis juvenile densities and number of juveniles seem related with effective contribution in some species. An agreement between potential and effective contributions of estuaries is concurrent with the acknowledged minor role of juvenile stage processes in regulation of recruitment to adult subpopulations.

An otolith microchemistry study of possible relationships between the origins of leptocephali of European eels in the Sargasso Sea and the continental destinations and relative migration success of glass eels

Martin J, Daverat F, Pécheyran C, Als TD, Feunteun E, Réveillac E. An otolith microchemistry study of possible relationships between the origins of leptocephali of European eels in the Sargasso Sea and the continental destinations and relative migration success of glass eels. Ecology of Freshwater Fish 2010: 19: 627–637. © 2010 John Wiley & Sons A/SAbstract – Little is known about the extent to which Atlantic eels coming from different European rivers converge on the same spawning site. Our aim was to evaluate the spatial homogeneity of eel spawning area(s) with an otolith microchemistry approach. This work compared the elemental signatures of otolith’s core region of Anguilla anguilla leptocephali caught in the Sargasso Sea in 2007 with those of glass eels and elvers sampled in European estuaries during 2006, 2008 and 2009. Using laser ablation inductively coupled plasma mass spectrometry, the same annular ablation trajectory along the first feeding mark was applied on otoliths of glass eels, elvers and leptocephali. The concentrations of thirteen isotopes in the otoliths of glass eels/elvers did not vary among three annual cohorts collected in eleven European locations. However, otolith elemental fingerprints of leptocephali differed significantly from glass eels otolith’s signature. Although the mechanisms that regulate the differences in trace element signatures among leptocephali and glass eels/elvers are unknown, we propose that the sampled glass eels/elvers were born in a spawning site or region where favourable transport and/or feeding conditions occurred. Conversely, the leptocephali may have been sampled in a less favourable region in the Sargasso Sea, with a low probability of reaching continental growth areas.

Role of mangroves as nurseries for French grunt Haemulon flavolineatum and schoolmaster Lutjanus apodus assessed by otolith elemental fingerprints

Juvenile French grunt Haemulon flavolineatum and schoolmaster Lutjanus apodus were captured in mangrove and seagrass stations in St. Croix, and Puerto Rico in 2006 and 2007 to deter- mine whether areas for juvenile fish can be discriminated by means of otolith chemistry. Concentra- tions of 16 elements were determined in 0-group fish otoliths using laser ablation-inductively coupled plasma mass spectrometry. Two stable isotopes, δ 18 O and δ 13 C, in French grunt and schoolmaster otoliths were also analyzed. Multi-elemental signatures for both species differed significantly (p < 0.001) among mangrove and seagrass stations within both islands. Furthermore, concentrations of 6 el- ements (Sr, Ba, Cu, Mg, Co, Na) as well as δ 18 O and δ 13 C for both species within each year differed sig- nificantly among mangrove and seagrass stations within islands (p < 0.001). Classification success for French grunt and schoolmaster juvenile areas within St. Croix across years ranged from 87 to 92% and from 76 to 77%, respectively, whereas in Puerto Rico, classification success for French grunt and schoolmaster for the 2 years ranged from 80 to 84% and 84 to 87%, respectively. Classification success between mangrove and seagrass habitats (stations combined) in Puerto Rico for French grunt ranged from 84 to 91%, and for schoolmaster ranged from 94 to 99%. In St. Croix, classification success for French grunt was 95 to 96%, and for schoolmaster was 86 to 89%. The percentages of French grunt subadults collected from forereef stations in St. Croix, identified as having resided as juveniles in man- grove habitats in 2006 and 2007, were 40 and 68%, respectively, while for Puerto Rico, these percent- ages were 70 and 74%. By contrast, for schoolmaster almost 100% of all fish in both islands resided as juveniles in mangrove habitats in both years. This study contains the first direct evidence of postsettle- ment fish movement connecting mangrove habitats to the reef using otolith chemistry.

Interspecific variations of otolith chemistry in estuarine fish nurseries

Otolith chemical composition differed between juveniles of five fish species (Solea solea, Solea senegalensis, Platichthys flesus, Diplodus vulgaris and Dicentrarchus labrax) in nursery areas of six estuaries along the Portuguese coast (Douro, Ria de Aveiro, Mondego, Tejo, Sado and Mira). Spatially consistent patterns in the concentration of some elements were responsible for differences between species. Discrimination of estuaries using data from all species simultaneously averaged 44·7% of correctly classified cases, whilst discrimination of species averaged 76·2%. Moreover, species‐related patterns in otolith fingerprints were highlighted when comparing species for each estuarine nursery area, with intra estuarine species discrimination averages ranging from 86·2 to 100·0%. Similarities in the otolith elemental fingerprints were larger between species with close phylogeny and ecology, particularly between flatfish and perciform species. In addition to the differences in physiological regulation of species, specific microhabitat use in a common environment was suggested as a relevant factor for the differentiation of otolith chemistry among species occurring in the same locations. Despite positive results in specific estuaries, variation in otolith composition limited the use of species as proxies to classify others to their system of origin.

Evidence of estuarine nursery origin of five coastal fish species along the Portuguese coast through otolith elemental fingerprints

Connectivity is a critical property of marine populations, particularly for species with segregated juvenile and adult habitats. Knowledge of this link is fundamental in understanding population structure and dynamics. Young adults of commercially important fish species Solea solea, Solea senegalensis, Platichthys flesus, Diplodus vulgaris and Dicentrarchus labrax were sampled off the Portuguese coast in order to establish preliminary evidence of estuarine nursery origins through otolith elemental fingerprints. Concentrations of Li, Na, Mg, K, Mn, Cu, Zn, Sr, Ba and Pb in the otolith section corresponding to juvenile's nursery life period were determined through laser ablation inductively coupled plasma mass spectrometry. Element: Ca ratios in coastal fish differed significantly amongst collection areas, except for Platichthys flesus, and were compared with the elemental fingerprints previously defined for age 0 juveniles in the main estuarine nurseries of the Portuguese coast. Identification of nursery estuaries was achieved for four of the species. Assigned nursery origins varied amongst species and differences in the spatial scale of fish dispersal were also found. Diplodus vulgaris was not reliably assigned to any of the defined nurseries. Overall, results give evidence of the applicability of estuarine habitat tags in future assessments of estuarine nursery role. Research developments on the links between juvenile and adult habitats should contribute for the integrated management and conservation of nurseries and coastal stocks.

Discriminating estuarine nurseries for five fish species through otolith elemental fingerprints

Chemical composition of otoliths may provide valuable information in establishing con- nectivity between nursery grounds and marine coastal stocks. Juveniles of the commercially impor- tant fish species Solea solea, S. senegalensis, Platichthys flesus, Diplodus vulgaris and Dicentrarchus labrax were captured in 8 estuarine nursery grounds along the Portuguese coast in July 2005. Con- centrations of Li, Na, Mg, K, Mn, Ni, Cu, Zn, Sr, Cd, Ba and Pb were determined in whole juvenile otoliths using solution-based inductively coupled plasma mass spectrometry. Significant differences in the concentration of several elements were found between estuaries and species using ANOVA and MANOVA. Linear discriminant function analysis classified otolith fingerprints between estuaries for all species with good cross-validated results. Depending on the species, 70.2 to 92.0% of individ- uals were correctly assigned to their estuary of origin, with discrimination success varying with species, estuaries and number of estuaries in the analysis. Since accurate classification of juvenile fish to their nursery estuary was achieved, fingerprint analysis can be used as a natural habitat tag in assigning adult fish to their estuarine nursery. Ultimately the connectivity between Portuguese estuarine nursery grounds and coastal areas may be estimated, with possible implications for future fisheries and coastal management plans.

Tracking seasonal migrations of redfish (Sebastes spp.) in and around the Gulf of St. Lawrence using otolith elemental fingerprints

Large concentrations of beaked redfish (Sebastes mentella and Sebastes fasciatus) overwinter in the Cabot Strait and the approaches of the Gulf of St. Lawrence each year. Synoptic research vessel surveys indicate that redfish are distributed more widely in the summer than in the winter, particularly within the Gulf. Significant differences in the trace element composition of the otolith ("otolith elemental fingerprint") were observed among summer aggregations, indicating that the aggregations maintained some degree of separation while in the Gulf. Sebastes mentella and S. fasciatus were readily distinguished based on otolith elemental fingerprints. Using the elemental fingerprints of the summer samples as a natural tag, we found that S. mentella tended to move out of the Gulf in the winter. Aggregations of S. mentella found in the east during the summer were not found in our winter collections. The elemental fingerprints of S. mentella from the Saguenay Fjord were clearly distinct from redfish further east in the Gulf of St. Lawrence, indicating that this group had been separated from other redfish for much of their life. The implications of our findings extend not only to the fisheries management of redfish, but also to the extent of movement expected of deepwater fish species.

Individual-based dispersal patterns of larval gobies in an estuary as indicated by otolith elemental fingerprints

Otolith trace elements were used as natural tags to study the dispersal patterns of goby larvae in an estuary. Ninety-six larval gobies representing 10 species were collected in the estuary of Gongshytyan Creek in northwestern Taiwan in September 1997. Fifteen trace elements in fish otoliths were analysed with solution-based ICPMS. Trace elemental composition in otoliths differed significantly among the species. Habitat use by the larvae of the 10 species can be divided into four groups, based on principal component analysis of otolith elemental composition. All 10 goby species used the estuary as a nursery area irrespective of the fish being amphidromous or non-amphidromous. A part of the population may be lost during larval dispersal, as indicated from trace elemental composition recorded in the otolith.

Otolith elemental fingerprints of juvenile Pacific swordfish Xiphias gladius

The trace element composition of young‐of‐the‐year (YOY) juvenile swordfish Xiphias gladius sagittal otoliths were analysed as a preliminary test of the value of otolith elemental fingerprints for determining swordfish nursery ground origins in the central Pacific Ocean. A suite of five elements (Mg, Zn, Sr, Ba and Pb) was assayed with isotope dilution ICP‐MS; all elemental concentrations were roughly comparable to otoliths of other marine fishes. Multivariate analyses of elemental fingerprints based on Ba and Sr revealed differences between sample sites, and the magnitude of the differences increased with latitudinal separation. With more comprehensive sampling of nursery grounds, it should be possible to identify origin of nursery ground for adult swordfish by analysing the YOY juvenile portion of the sagittal otolith.

Habitat Fingerprints for Lake Superior Coastal Wetlands Derived from Elemental Analysis of Yellow Perch Otoliths

AbstractAssessing the ecological importance of coastal habitats to Great Lakes ecosystems requires an understanding of the ecological linkages between coastal and offshore waters. Elemental analysis of fish otoliths has emerged as a powerful technique that can provide a natural tag for determining nursery area affiliation, population structure, and movement of individual fish. Since the elemental composition of fish otoliths reflects some of the environmental conditions under which a fish was reared, otolith chemistry can record differences in ambient water conditions specific to habitats used during a fish's life history. Although few studies have been conducted in freshwaters, trace element analysis of marine fish otoliths has proven useful in identifying the chemical signatures unique to particular spawning and nursery habitats. To examine the utility of this method in freshwater, sagittae were removed from 275 young‐of‐the‐year yellow perch Perca flavescens captured from eight wetlands in western Lake Superior during August 2001. They were analyzed for Ca and 13 minor and trace elements using inductively coupled plasma mass spectrometry (ICPMS) and inductively coupled atomic emission mass spectrometry (ICPAES). Otolith concentrations of Ba, K, Mg, Mn, Na, and Sr differed significantly among wetlands (ANOVA, P &lt; 0.001). Interwetland differences were also pronounced when analyzed as a multivariate fingerprint (MANOVA, P &lt; 0.001). Discriminant function analysis revealed relatively distinct chemical fingerprints associated with each wetland. Wetland classification accuracy based on a five‐element model (Sr, Mn, K, Ba, and Mg) ranged from 62% to 100% and averaged 76%. Differences in fingerprints between wetland types (river‐influenced versus lagoon) were also distinct (MANOVA, P &lt; 0.001). Classification accuracy for wetland type was 81% based on a five‐element model that included Ba, Mg, Mn, Na, and Sr. Our results suggest that otolith elemental fingerprints may be useful for quantifying the relative contributions of different wetland nursery areas to recruitment in adjacent lake populations.

Identification of riverine, estuarine, and coastal contingents of Hudson River striped bass based upon otolith elemental fingerprints

Elemental fingerprints of otoliths from Hudson River striped bass Morone saxatilis were used to define resident, estuarine, and ocean migratory contingents, which had previously been de- termined by otolith microprobe analysis of Sr:Ca. Using solution-based inductively coupled plasma mass-spectrometry, 7 metals were quantified in whole otoliths. Discriminant analysis of elements showed a high degree of separation among the 3 migratory contingents. Barium was significantly higher in otoliths from the freshwater resident group, while Sr and Na were significantly lower in comparison to mesohaline and ocean contingents. Identification of contingents by the bulk chemistry method indicated that divergent migratory patterns persist over lifetimes for Hudson River striped bass.

Otolith elemental fingerprints as biological tracers of fish stocks

Specific trace elements incorporated into the growing surface of the fish otolith reflect the physical and chemical characteristics of the ambient water, although not necessarily in a simplistic manner. Since fish which spend at least part of their lives in different water masses often produce otoliths of different elemental composition, the otolith elemental composition (‘elemental fingerprint’) can serve as an environmentally induced tag of groups of fish. On the basis of isotope dilution ICPMS (ID-ICPMS) assays of nearly 2500 dissolved adult cod ( Gadus morhua) otoliths, it has become clear that cod otolith elemental fingerprints based on the elements Li, Mg, Mn, Sr and Ba are physically stable, reproducible and consistent between left and right otoliths. Highly significant differences existed among the fingerprints of all of the spawning aggregations, resulting in a characteristic marker for each aggregation. Long-term stability (4–13 years) of the fingerprints for a given spawning group was not evident, indicating that the fingerprint was not a proxy for genetic identity. However, the fingerprint was very stable over the short-term (up to 1 year), suggesting that it could serve as a seasonally stable biological tracer, or natural tag, of pre-defined groups of fish, even during situations of extensive stock mixing. As an illustration of the tracer approach, a maximum likelihood-based stock mixture analysis was applied to feeding (summer) and over-wintering stock distributions, using the fingerprints of the spring spawning aggregations as known-stock reference samples. The results of the summer stock mixture analyses suggested that the mixture analysis was accurate within 1%, while the stock mixture analysis of the over-wintering schools produced stock-specific distributions which would have been difficult to obtain using alternative approaches. While the use of elemental fingerprints as natural tags is not suited to all stock mixing situations, suitability can probably be determined beforehand on the basis of existing environmental and biological information.