Linear Discriminant Function Analysis Research Articles

Evaluation of a Seismic Event, 12 May 2010, in North Korea

We assess seismological evidence bearing on claims that North Korea conducted a small nuclear test on 12 May 2010 in the vicinity of known underground nuclear tests (UNTs) in 2006, 2009, 2013, and 2016. First, we use Lg ‐wave cross correlation and more traditional methods to locate the 2010 event between about 4 and 10 km southwest of the 2009 test. Second, we compare the relative sizes of regional P and S waves, using stations within 400 km of the known North Korean nuclear tests, to assess the nature of the event. We measured P / S ratios at different frequencies, at first using data from the open station MDJ in northeast China, for training sets of earthquakes and of explosions. We developed a linear discriminant function (LDF) that, in application to P / S measured at MDJ, is most effective in separating the earthquake and explosion populations. MDJ lacks usable data for the event of interest, but we obtained regional data from stations of the nearby Dongbei Broadband Seismographic Network (DBSN) for the 12 May 2010 event and for nearby UNTs conducted in 2006 and 2009. When our LDF is applied to DBSN data, and to data from stations SMT and NE3C in China, the LDF values measured from P / S ratios from known explosions are explosion‐like; but for the 12 May 2010 event, the LDF values are earthquake‐like for frequencies between 6 and 12 Hz. Our method for characterizing earthquakes and explosions on the basis of their regional signals can be widely applied. Measurements of P / S based on the three‐component waveform data provide better discrimination power than do those based on vertical‐component data alone. [Electronic Supplement:][1] Tutorial material on the Mahalanobis distance‐squared measure, three‐component linear discriminant function (LDF) analysis, tables of measurements of the log10 P / S spectral ratios obtained from waveforms recorded at station MDJ for the two training sets and three‐component discrimination analysis, and figures of log ( P / S ) values measured at 8 Hz from vertical‐component waveforms at station MDJ for two training sets and probability distributions for D . [1]: http://www.bssaonline.org/lookup/suppl/doi:10.1785/0120160111/-/DC1

Artificial neural networks and geometric morphometric methods as a means for classification: A case-study using teeth from Carcharhinus sp. (Carcharhinidae).

Over the past few decades, geometric morphometric methods have become increasingly popular and powerful tools to describe morphological data while over the same period artificial neural networks have had a similar rise in the classification of specimens to preconceived groups. However, there has been little research into how well these two systems operate together, particularly in comparison to preexisting techniques. In this study, geometric morphometric data and multilayer perceptrons, a style of artificial neural network, were used to classify shark teeth from the genus Carcharhinus to species. Three datasets of varying size and species differences were used. We compared the performance of this combination with geometric morphometric data in a linear discriminate function analysis, linear measurements in a linear discriminate function analysis, and a preexisting methodology from the literature that incorporates linear measurements and a two-layered discriminate function analysis. Across datasets, geometric morphometric data in a multilayer perceptron tended to yield modest accuracies but accuracies that varied less across species whereas other methods were able to achieve higher accuracies in some species at the expense of lower accuracies in others. Further, the performance of the two-layered discriminate function analysis illustrates that constraining what material is classified can increase the accuracy of a method. Based on this tradeoff, the best methodology will then depend on the scope of the study and the amount of material available. J. Morphol. 278:131-141, 2017. ©© 2016 Wiley Periodicals,Inc.

Zonal trend-agrometeorological models for wheat yield estimation in Haryana

An attempt has been made to assess the impact of weather variables for district-level wheat yield estimation in Haryana. Fortnightly weather data and trend based yield were used for developing the zonal trendagrometeorological (agromet) models within the framework of multiple linear regression and discriminant function analyses. The district level wheat yield forecasts, percent deviations from the real time wheat yield (s) and root mean square error(s) at zonal level show a preference of using discriminant/weather scores as regressors in almost all the considered districts of the state. Zonal trend-agromet models provided considerable improvement in district-level wheat yield prediction moreover the yield estimates may be obtained 4-5 weeks in advance of the harvest time. The estimated yield(s) from the selected zonal models showed good agreement with State Department of Agriculture (DOA) wheat yields by showing less than 5 percent deviations in 9 districts and 6-11 percent deviations in the remaining 9 districts under consideration.

Depositional Features in Tourist Beaches of Chennai Metropolis, SE Coast of India: Inferences from Grain Size Studies

Abstract: The present study was undertaken to examine the depositional and transportation pattern in the tourist beaches of Chennai in SE coast of India. Twenty four samples were analyzed for textural parameters, Linear discriminate function (LDF), C-M plots and heavy/light minerals from beach, berm and dune regions. Results of textural parameters indicate that they are coarse grained in the three regions. Majority of the samples indicate that they are moderately well sorted, symmetrically skewed and leptokurtic. The LDF analysis allowed in identifying areas that are characterized by: (1) beach, (2) shallow agitated environment and (3) fluvial deposits. C-M plots indicate that the sediments in the beaches were deposited from the near shore environment. Heavy mineral analysis suggests that the heavy and light minerals were in the range of 0.5 to 16.9% and 82.08 to 98.14% and the light/dark layers are controlled by the prevailing tidal conditions in the coastal region. It is observed that sand is accumulating from the shallow agitated environment, while the transportation and deposition of sediments is mainly due to the interaction of tidal activities at the same time. C-M plots suggest that the sediments fall in the graded suspension and the saltation activities in the region also facilitate to understand the hydrodynamics of the region suggesting that they are deposited by high-energy activities.

NMR spectroscopy of filtered serum of prostate cancer: A new frontier in metabolomics.

To address the shortcomings of digital rectal examinations (DRE), serum prostate-specific antigen (PSA), and trans-rectal ultrasound (TRUS) for precise determination of prostate cancer (PC) and differentiation from benign prostatic hyperplasia (BPH), we applied (1) H-nuclear magnetic resonance (NMR) spectroscopy as a surrogate tactic for probing and prediction of PC and BPH. The study comprises 210 filtered sera from suspected PC, BPH, and a healthy subjects' cohort (HC). The filtered serum approach delineates to identify and quantify 52 metabolites using (1) H NMR spectroscopy. All subjects had undergone clinical evaluations (DRE, PSA, and TRUS) followed by biopsy for Gleason score, if needed. NMR-measured metabolites and clinical evaluation data were examined separately using linear multivariate discriminant function analysis (DFA) to probe the signature descriptors for each cohort. DFA indicated that glycine, sarcosine, alanine, creatine, xanthine, and hypoxanthine were able to determine abnormal prostate (BPH + PC). DFA-based classification presented high precision (86.2% by NMR and 68.1% by clinical laboratory method) in discriminating HC from BPH + PC. DFA reveals that alanine, sarcosine, creatinine, glycine, and citrate were able to discriminate PC from BPH. DFA-based categorization exhibited high accuracy (88.3% by NMR and 75.2% by clinical laboratory method) to differentiate PC from BPH. (1) H NMR-based metabolic profiling of filtered-serum sample appears to be assuring, swift, and least-invasive for probing and prediction of PC and BPH with its signature metabolic profile. This novel technique is not only on a par with histopathological evaluation of PC determination but is also comparable to liquid chromatography-based mass spectrometry to identify the metabolites. Prostate 76:1106-1119, 2016. © 2016 Wiley Periodicals, Inc.

Discriminating nursery grounds of juvenile plaice (Pleuronectes platessa) in the south-eastern Irish Sea using otolith microchemistry

Nursery grounds are valuable habitats providing sources of food and refuge during early life stages for many commercially caught marine fish. Distinguishing between different nursery grounds and identifying habitat origin using trace elemental concentrations in aragonite structures of teleost fish has proved valuable in fish ecology and fisheries. This study aimed to (1) compare chemical signatures (elemental fingerprints) within sagittal otoliths of juvenile European plaice Pleuronectes platessa sampled from known nursery habitats in the south-eastern Irish Sea and (2) assess their potential and robustness as natural tags for identifying nursery grounds for the putative south-eastern Irish Sea plaice stock. Otoliths from juvenile plaice (‘1-group’, 6 to 15 cm total length) were obtained from 8 nursery grounds in coastal areas off north-west England and north Wales (including Anglesey) between June and August 2008. Solution-based inductively coupled plasma-mass spectrometry determined the concentrations of 10 elements (Li, Na, Mg, K, Mn, Zn, Rb, Sr, Sn, Ba), with significant differences in otolith element composition observed between all nursery grounds. Cross-validation linear discriminant function analysis (CV-LDFA) classified fish to their nursery ground of capture (46.2 to 93.3%), with a total group CV-LDFA accuracy of 71.0%. CV-LDFA between regions (north-west England and north Wales) classified fish with 82% accuracy. The discrimination of juvenile plaice from all 8 nursery grounds within the south-eastern Irish Sea using otolith microchemistry offers significant opportunities in the development of future effective fisheries management strategies through understanding the supply of juveniles from specific nursery grounds and adult plaice in the south-eastern Irish Sea.

Do vertebral chemical signatures distinguish juvenile blacktip shark (Carcharhinus limbatus) nursery regions in the northern Gulf of Mexico?

Identifying and protecting shark nurseries is a common management strategy used to help rebuild overfished stocks, yet we know little about connectivity between juvenile and adult populations. By analysing trace metals incorporated into vertebral cartilage, it may be possible to infer natal origin based on nursery-specific chemical signatures. To assess the efficacy of this approach, we collected juvenile blacktip sharks (Carcharhinus limbatus; n = 93) from four regions in the Gulf of Mexico in 2012 and 2013 and analysed their vertebral centra with laser ablation–inductively coupled plasma–mass spectrometry. We observed significant regional differences in six element:Ca ratios in both 2012 and 2013. Multi-element chemical signatures were significantly different among regions and between year-classes. Year-class-specific linear discriminant function analysis yielded regional classification accuracies of 81% for 2012 and 85% for 2013, although samples were not obtained from all four regions in 2012. Combining year-classes resulted in an overall classification accuracy of 84%, thus demonstrating the usefulness of this approach. These results are encouraging yet highlight a need for more research to better evaluate the efficacy of vertebral chemistry to study elasmobranch population connectivity.

Different approaches on pre harvest forecasting of wheat yield

Agriculture is backbone of Indian economy, contributing about 40 per cent towards the Gross National Product and provide livelihood to about 70 per cent of the population. According to the national income published in Economic survey 2014-15, by the CSO, the share of agriculture in total GDP is 18 percent in 2013-14. The Rabi crops data released by the Directorate of Economics and Statistics recently indicates that the total area coverage has declined; area under wheat has gone down by 2.9 per cent. Therefore needs to be do research to study weathersituation and effect on crop production. Pre harvest forecasting is true essence, is a branch of anticipatory sciences used for identifying and foretelling alternative feasible future. Crop yield forecast provided useful information to farmers, marketers, government agencies and other agencies. In this paper Multiple Linear Regression (MLR) Technique and discriminant function analysis were derived for estimating wheat productivity for the district of Varanasi in eastern Uttar Pradesh. The value of Adj. R2 varied from 0.63 to 0.94 in different models. It is observed that high value of Adj. R2 in the Model-2 which indicated that it is appropriate forecast model than other models, also the value of RMSE varied from minimum 1.17 to maximum 2.47. The study revealed that MLR techniques with incorporating technical and statistical indicators (Model 2) was found to be better for forecasting of wheat crop yield on the basis of both Adjusted R2 and RMSE values.

Selecting Color-based Tracers and Classifying Sediment Sources in the Assessment of Sediment Dynamics Using Sediment Source Fingerprinting.

The use of sediment color as a fingerprint property to determine sediment sources is an emerging technique that can provide a rapid and inexpensive means of investigating sediment sources. The present study aims to test the feasibility of color fingerprint properties to apportion sediment sources within the South Tobacco Creek Watershed (74 km) in Manitoba, Canada. Suspended sediment from 2009 to 2011 at six monitoring stations and potential source samples along the main stem of the creek were collected. Reflectance spectra of sediments and source materials were quantified using a diffuse reflectance spectrometry, and 16 color coefficients were derived from several color space models. Canonical discriminant analysis was used to reclassify and downsize sediment source groups. After the linear additive test and stepwise discriminant function analysis, four color coefficients were chosen to fit the Stable Isotope Analysis in R model. Consistent with the conventional fingerprinting approach, the color fingerprint results demonstrated a switch in the dominant sediment source between the headwaters and the outlet of the watershed, with the main sources being topsoil in the upper reaches, whereas outcrop shale and stream bank materials dominated in the lower reaches. The color fingerprinting approach can be integrated with conventional fingerprints (e.g., geochemical and fallout radionuclide properties) to improve source discrimination, which is a key component for source ascription modeling. We concluded that the use of color fingerprints is a promising, cost-effective technique for sediment source fingerprinting.

Morphometric variation of the endangered Caspian lamprey, Caspiomyzon wagneri (Pisces: Petromyzontidae), from migrating stocks of two rivers along the southern Caspian Sea.

Morphological studies on fishes are important from various viewpoints. Studies carried out on the Caspian Sea fishes show that many species possess speciation and population formation microprocess running. Morphologicalcharacteristics of the native endangered Caspian lamprey, Caspiomyzonwagneri Kessler1870, from migrating stocks of two major rivers in the southern Caspian Sea were analyzed to investigate the hypothesis population structure and morphologic sexual dimorphism. Univariate analysis of variance of 180 adult specimens showed significant differences between the means of the two studied groups for 15 standardized morphometric measurements out of 31 (P < 0.05). In morphometric trait linear discriminant function analysis, the overall assignments of individuals into their original groups in male and female specimens were 77.1 and 84.0 %, respectively. The discriminant analysis showed a morphological segregation of the studied populations based on the characters predorsal length, interdorsal, interorbital distance, tail length, and first dorsal fin length. The principal component analysis, scatter plot of individual component score between PC1 and PC2, showed the specimens grouped into two areas but with high and moderate overlap between two localities in males and females, respectively. The present study indicated that there are at least two types of morphological forms of Caspian lamprey that had high morphometric differentiation in the rivers across the southern Caspian Sea, which can be considered in conservational policy of this valuable species.

Gender identification from high-pass filtered vowel segments: the use of high-frequency energy.

The purpose of this study was to examine the use of high-frequency information for making gender identity judgments from high-pass filtered vowel segments produced by adult speakers. Specifically, the effect of removing lower-frequency spectral detail (i.e., F3 and below) from vowel segments via high-pass filtering was evaluated. Thirty listeners (ages 18-35) with normal hearing participated in the experiment. A within-subjects design was used to measure gender identification for six 250-ms vowel segments (/æ/, /ɪ /, /ɝ/, /ʌ/, /ɔ/, and /u/), produced by ten male and ten female speakers. The results of this experiment demonstrated that despite the removal of low-frequency spectral detail, the listeners were accurate in identifying speaker gender from the vowel segments, and did so with performance significantly above chance. The removal of low-frequency spectral detail reduced gender identification by approximately 16 % relative to unfiltered vowel segments. Classification results using linear discriminant function analyses followed the perceptual data, using spectral and temporal representations derived from the high-pass filtered segments. Cumulatively, these findings indicate that normal-hearing listeners are able to make accurate perceptual judgments regarding speaker gender from vowel segments with low-frequency spectral detail removed via high-pass filtering. Therefore, it is reasonable to suggest the presence of perceptual cues related to gender identity in the high-frequency region of naturally produced vowel signals. Implications of these findings and possible mechanisms for performing the gender identification task from high-pass filtered stimuli are discussed.

Tracing the effects of Sefidrud dams on Capoeta gracilis (Cyprinidae) populations using Truss distances in southern Caspian Sea basin

It is postulated that building of Manjil and Tarik dams on Sefidrud River has led to morphological divergence of Siah Mahi, Capoeta gracilis of up-and downstream populations due to isolation. To test this, a total of 97 individuals of C. gracilis were collected from three sampling sites, including upstream of Manjil dam, upstream of Tarik dam and downstream of Tarik dam, in November 2013. A 13-landmark morphometric truss network system was used to investigate the hypothesis. Principal component analysis (PCA), canonical variates analysis (CVA), linear discriminant function analysis (DFA) and clustering analysis (CA) were used to examine morphological differences among the populations. Univariate analysis of variance showed significant differences among the means of the three groups for 48 standardized morphometric measurements out of 78 characters studied. In, DFA the overall assignment of individuals into their original groups was 77.8%. The PCA scatter plot of individual component scores between the first and second factors showed 97 fish specimens grouped into three areas but with a relativity low degree of overlap among the three populations. Cluster analysis indicating different populations of C. gracilis in up- and downstream Manjil and Tarik dams in Sefidrud River. The present study indicated the presence of morphologically different populations of C. gracilis in up and downstream of Manjil and Tarik dams in Sefidrud River, probably, is due to their limited downstream dispersal and elimination of upstream migration altogether, due to the construction of the dams.

Elemental fingerprints of otoliths from smolt of Atlantic salmon, Salmo salar Linnaeus, 1758, from three Maritime watersheds: Natural tag for stock discrimination

The utility of otolith elemental fingerprintsfor discriminating sub-regional stocks of Atlantic salmon was examined. Otoliths were removed from Atlantic salmon smolts collected from three individual river watersheds in the Canadian Maritimes during spring and analyzed for 27 elements using inductively coupled plasma mass spectrometry (ICP-MS) and inductively coupled plasma emission spectrometry (ICP-ES). Calcium and minor and trace elements were precisely measured in whole otoliths at concentrations well above detection limits. Six elements (Ba, Pb, Li, Mn, Rb, and Tl) were significantlydifferent among watersheds. Linear discriminate function analysis based on otolith elemental concentrations of Li, Mn, Rb, and Tl correctly classifiedsmolts to their river of origin with an average accuracy of 73%. At a slightly greater spatial scale of large watersheds, correct mean classificationrate was 92% based on a fingerprintof four elements (Ba, Li, Mn, and Rb). Results indicate that elemental fingerprintsof otoliths can be used to discriminate among river management stocks which may be important in the future since dried or frozen stored otoliths retain their signature indefiniely and otoliths are often available from previous studies. Otolith elemental fingerprintswould be effective as a natural tag of a river system or biogeoclimatic zone of origin when applied to the study and management of Atlantic salmon in the North Atlantic Ocean.

Identification of high-pass filtered male, female, and child vowels: The use of high-frequency cues.

Vowels are characteristically described according to low-frequency resonance characteristics, which are presumed to provide the requisite information for identification. Classically, the study of vowel perception has focused on the lowest formant frequencies, typically F1, F2, and F3. Lehiste and Peterson [Phonetica 4, 161-177 (1959)] investigated identification accuracy of naturally produced male vowels composed of various amounts of low- and high-frequency content. Results showed near-chance identification performance for vowel segments containing only spectral information above 3.5 kHz. The authors concluded that high-frequency information was of minor importance for vowel identification. The current experiments report identification accuracy for high-pass filtered vowels produced by two male, two female, and two child talkers using both between- and within-subject designs. Identification performance was found to be significantly above chance for the majority of vowels even after high-pass filtering to remove spectral content below 3.0-3.5 kHz. Additionally, the filtered vowels having the highest fundamental frequency (child talkers) often had the highest identification accuracy scores. Linear discriminant function analysis mirrored perceptual performance when using spectral peak information between 3 and 12 kHz.

Seasonal Variation in Textural Characteristics and Sedimentary Environments of Beach Sediments, Karnataka Coast, India

Seasonal (post- and pre-monsoon) changes in texture and environment of deposition of beach sediments of Karnataka coast have been studied using various statistical parameters (Mean size, Standard deviation, Skewness and Kurtosis). These parameters were obtained for all the sieved sediment samples (68 for each season), using GradistatV8.0 and G-Stat software packages. Based on the range of variability of these statistical parameters, the studied coast has been divided into four sectors. Sector I extends from Talapady to Surathkal; sector II includes beaches from Mukka to Kota. Sector III comprises Marvanthe and Nesther beaches and those lying between Murdeshwara and Devbagh fall in sector IV.Passega's CM and Tractive current diagrams were prepared to understand the energy condition of depositional currents and mode of transportation of sediment respectively. Linear Discriminant Function (LDF) plots were used to understand the environment of deposition of sediments. TheCM diagram reveals predominance of beach and tractive currentconditions along the entire coast. The Tractive current diagram indicates that deposition of sediment takes place by rolling and bottom suspension during post-monsoon, whereas by graded suspension and no rolling conditions during pre-monsoon season in sector I. In sector II, deposition of sediment takes place by bottom suspension and rolling during both the seasons. In sector III, the sediments show change in energy conditions with time where they are deposited by rolling during post-monsoon, whereas prevailing of low energy condition during pre-monsoon season as deposition of sediment takes place by bottom suspension and rolling. In sector IV, bottom and graded suspensions have been the dominant mode of deposition during both the seasons. The LDF analysis of sediment samples indicates dominance of shallow marine environment of deposition for both the seasons. The LDF plotsreveal that sector I predominantly belongs to beach shallow to beach littoral environment for both the seasons. Shallow marine agitated environment of deposition was observed for the post-monsoon season in sector II, while increase in energy conditions at this sector led tobeach shallow environment of deposition during the pre-monsoon season. Sector III shows predominance of beach littoral environment of deposition for the post-monsoon, while beach shallow environment of deposition during the pre-monsoon indicating decrease in energy conditions. Sector IV plots show little or no change for both the seasons and the samples predominantly fall in shallow marine agitated environment of deposition.

A morphology-based hypothesis for homeward migration success and population differentiation in the anadromous kutumRutilus kutum(Pisces: Cyprinidae) along the southern Caspian Sea, Iran

The anadromous Rutilus kutum Kamenskii, 1901 is the most important fish in north of Iran with the highest economic value. Ignoring the natural process of reproduction due artificial propagation, catching some migrating broodstocks from the sea (not from the estuaries) and mixing the produced fingerlings in culture ponds within restocking programs in the last 30 years have caused an uncertainty about homing success and population differentiation in the fish. A 13-landmark morphometric truss network system was used to investigate the hypothesis of homeward migration success and population differentiation, while the previous studies revealed low genetic variability among the fish populations. A total of 504 adult specimens were caught from four localities along the southern Caspian Sea in the reproductive period. Univariate analysis of variance showed significant differences among the four groups for 78 standardized morphometric measurements. In linear discriminant function analysis (DFA), the overall assignments of individuals into their original groups were 73.3 % and 80.3 % in males and females, respectively. The principal component analysis (PCA) and clustering analysis based on Euclidean square distances showed that the 504 examined specimens grouped into distinct areas. The results showed that each sampling site represents independent population which confirmed the success of homeward migration. The high grouping ranges suggests that almost all populations return to their birthplace river to breed, which results in high inbreeding. The results can be interesting for management and conservation programs of this valuable species in the Caspian Sea.

Stable isotopes reveal regional movement patterns in an endangered bustard

AbstractStable isotope analysis is a valuable technique to infer animal movement between isotopically distinct landscapes. For birds in terrestrial systems, it is usually only applied at continental scales, often relying on global isotopic patterns. In contrast, we used this technique to investigate movement patterns of Ludwig's bustard (Neotis ludwigii) at a regional scale, where such information is needed to improve the conservation status of this species. We analysed carbon and nitrogen isotopic compositions of feathers from bustards across two biomes of the semi‐arid rangelands of the Karoo, South Africa, to investigate movement and explore sex and age movement strategy differences. We used a linear discriminant function analysis based on growing feathers to classify fully grown feathers to a Succulent or Nama Karoo biome origin. Six of 12 birds for which all primary feathers were analysed had at least one feather classified as having grown in the Succulent Karoo, supporting the theory that these birds are partial migrants. Feathers from two satellite‐tracked bustards broadly supported the conclusions of the analysis, although food base differences resulting from local rainfall variation probably obscured geographic signals at finer scales. There was no apparent difference in movement strategies between the sexes, but juvenile feathers were almost exclusively assigned to the Nama Karoo, suggesting that most breeding occurs in this biome. Adult and juvenile feathers also had significantly different isotope ratios, which could relate to diet or to differing metabolic processes. This study demonstrates that with a good understanding of the system, carbon and nitrogen stable isotopes can be useful to infer general movement patterns of birds at a regional level.

Large‐scale multivariate analysis reveals sexual dimorphism and geographic differences in theGray's beaked whale

AbstractGray's beaked whales (Mesoplodon grayi) are medium‐sized odontocete (toothed) cetaceans that are members of the family Ziphiidae. These animals inhabit deep oceanic waters and are rarely seen at sea. Most information is derived from stranded animals and there has been no systematic study of their morphology. We present a multivariate analysis of the morphology ofGray's beaked whales using 80 cranial measurements from 22 individuals and 13 external measurements from 50 individuals. Sparse principal component and linear discriminant function analyses were used to classify samples into sexes. Males and females have markedly different cranial morphology. In particular, females have longer skulls with longer more slender rostra (beaks) in comparison to males. Two variables, depth of the rostrum at mid‐length and tip of rostrum to the right temporal fossa, can classify sex with 100% accuracy. The external body measurements used in this study are more prone to error as they were recorded by a number of observers on carcasses in differing states of decomposition and this is reflected in the level of variance in most measurements. However, analyses of these measurements showed a significant difference between sexes in the distance between (1) the tip of the rostrum to the genital slit, (2) the tip of the rostrum to the blowhole, as found in the cranial analyses and (3) tail fluke width where males have absolutely wider tail flukes than females. Differences in these same measurements were also found between animals stranded on the east and west coasts suggesting a degree of population separation across New Zealand. Finally, we present two linear models that enable the assignment of sex from either skull or external measurements. These models will be useful for future studies as well as the management of these whales and can be applied to archived data where genetic sex assignment is not possible.

Otolith geochemistry in young‐of‐the‐year peacock bass Cichla temensis for investigating natal dispersal in the Rio Negro (Amazon – Brazil) river system

AbstractThis study examined otolith geochemistry as a natural marker of natal origins in young‐of‐the‐year (YOY) Cichla temensis in the Negro River Basin of Brazil. We analysed trace element and isotopic composition of otoliths of YOY collected off spawning nests from the main stem and major tributaries. These were compared with regional bedrock geologic composition to explore underlying mechanisms of differences in otolith geochemistry. Our results suggest that spatial differences in otolith geochemistry can be used to distinguish natal origins based on 87Sr/86Sr, Sr/Ca and Ba/Ca ratios. This approach allowed us to correctly classify 99% of juvenile fish to their natal streams using cross‐validation in a linear discriminant function analysis (LDFA). Patterns of otolith isotopic composition correspond with patterns in regional geology as expected based on previously demonstrated correlations, although some fine‐scale spatial differences cannot be accounted for by available geologic information. These results demonstrate that otolith chemistry is valuable as a natural marker of natal origins in this system and suggest that inferences from geologic maps may be useful for interpreting movements based on otolith geochemical signatures. This information provides the basis for future work to investigate the early life history and spatial ecology of this important cichlid.

Otolith chemistry can discriminate signatures of hatchery-reared and wild spotted seatrout

A central goal of stock enhancement is to increase species abundance and potential harvest by supplementing recruitment of wild populations. The efficacy of these efforts is predicated upon the survival of these hatchery-reared organisms after release, and determining their fate is essential to understanding the success of these programs. Along the northern Gulf of Mexico, spotted seatrout (Cynoscion nebulosus) represent the number one recreational fishery and in Texas are stocked in coastal bays and estuaries to enhance natural fish abundance. The natural chemical properties of fish otoliths represent one mechanism to track the fate of hatchery-reared fish in the wild and make inferences about their movement and survival. Establishing a baseline signature pattern to discriminate hatchery-reared from wild fish is an essential first step in this process. Spotted seatrout fingerlings were collected from three Texas bays and three Texas saltwater fish hatcheries. Sagittal otoliths were analyzed for stable isotopes (δ13C and δ18O) and a suite of twelve trace elements. Multivariate and univariate analysis of variance tests indicated significant differences among natal origins and reduced the number of chemistry predictors to nine. Linear discriminant function analysis using jack-knife cross-validation successfully classified 92% of fish to their correct natal origin. These results show that otolith chemistry is a powerful tool for discriminating hatchery-reared from wild spotted seatrout; therefore, chemical signature patterns reflected in the otoliths establish a baseline for tracking the fate of hatchery-reared fish in the wild. This information can provide more quantifiable estimates of stock enhancement success to fishery managers by improving our understanding of the fate and contribution of hatchery-reared fish to wild populations.