Index Of Average Percent Error Research Articles

First Estimates of Age and Growth of the Lusitanian Cownose Ray (Rhinoptera marginata) from the Mediterranean Sea

Within the eastern Mediterranean, increased fishing pressure coupled with a lack of basic biological information is threatening the sustainability of the rare Lusitanian cownose ray (Rhinoptera marginata). To provide baseline life-history data for this species, age estimates were obtained from vertebral band counts of 224 rays (size range: 210–998 mm disc width and 140 to 13,600 g weight) collected from Iskenderun Bay. Females ranged in size from 210 to 998 mm disc width and 238 to 13,600 g weight, while males ranged from 130 to 866 mm disc width and 140 to 8250 g weight. The index of average percent error (2.8%) and age-bias plot suggest that the aging method used represents a precise and non-biased approach. Marginal increment analysis indicated that a single opaque band is deposited annually between August and September. The oldest ages obtained for R. marginata were 9 years for males and 19 years for females, which corresponded to total lengths of 866 and 998 mm disc width, respectively. For males, limited samples prevented the accurate calculation of growth rates; however, for combined sexes, observed and disc width-at-age data resulted in the following von Bertalanffy growth parameters: DW∞ = 1102.16 mm, k = 0.148 and t0 = −0.2167. Although additional samples are necessary to determine growth rates in males, the results of the present study indicate that R. marginata females exhibit life history characteristics similar to other Rhinoptera species.

Development of an alternative ageing technique for blue shark (Prionace glauca ) using the vertebra

Accurate determination of age is essential for the comprehensive assessment and management of exploited shark populations. Enhancement of growth bands is necessary to accurately and efficiently determine age. However, most traditional techniques do not describe an efficiency of a series of procedures and the detailed protocol for different-sized sharks. We describe a simple and highly successful technique for ageing vertebrae of blue shark (Prionace glauca) that we refer to as “burn method”, derived from the “break and burn method” and “shadowing method”—a simple procedure requiring an alkaline treatment to clean the vertebral centra and a burning treatment to enhance growth band visualization. We described optimal times for sharks of precaudal length of 50, 100, 150, and 200 cm as 44.9, 88.7, 134.0, 183.5 s of alkaline treatment, and 6.8, 8.9, 10.2, and 11.5 min of burning treatment; both longer and shorter exposure times resulted in higher failed sample frequencies. Using our burn method, it is possible to do ageing a sample from a wide angle, with the reader able to obtain information on growth bands from different perspectives. To critique different technique efficiencies, the index of average percent error (IAPE) and mean coefficient of variation (CV) are compared for independent readers using the burn method and other techniques (silver nitrate impregnation and the unstained shadowing methods). The precision of the burn method (IAPE, 4.1%; CV, 5.7%) was similar to that of silver nitrate impregnation (IAPE, 5.8%; CV, 8.2%) and unstained shadowing method (IAPE, 8.3%; CV, 11.8%). For younger specimens, the IAPE and CV of the burn method were lower than those of the other techniques, but, compared with other ageing methods, precision decreased for older sharks. We demonstrate that the burn method to be accurate for age determination of blue sharks, especially for specimens with less than 10 bands, but recommend simultaneous use of other methods, such as thin sectioning (the most common for structure-based ageing) and bomb carbon dating, to accurately determine the age of older individuals.

Ageing bias and precision for deep-water snappers: evaluating nascent otolith preparation methods using novel multivariate comparisons among readers and growth parameter estimates

Tropical deep-water snappers (Etelinae) support valuable fisheries across the Indo-Pacific, with stock assessments reliant on age-based information in the absence of reliable catch and effort statistics. These long-lived species have been considered notoriously difficult to age. However, nascent developments in ageing protocols, particularly thinner transverse sections of otoliths (∼180–200 µm), are providing improvements in growth zone clarity, interpretation and repeatability of annuli counts. At a recent international workshop, thin sectioned otoliths from three deep-water snappers were read under reflected light by eight fisheries scientists from across the Indo-Pacific, with various levels of fish-ageing experience. Precision and bias were assessed using traditional ageing precision metrics (index of average percent error, IAPE; and coefficient of variation, CV), and a novel approach using multivariate analyses (metric multidimensional scaling, mMDS) based on Euclidean dissimilarity among readers’ counts and subsequent von Bertalanffy (vB) growth parameter estimates. Annuli counts between the primary reader and all other readers were within two for 80% of estimates, with uniform variation across a wide age range for Etelis carbunculus (intraclass correlation coefficient (ICC) = 0.924, n = 20, 3–25 annuli) and Etelis sp. (ICC = 0.933, n = 15, 2–27 annuli). In contrast, annuli counts for Pristipomoides filamentosus (n = 14, 4–49) were less precise (i.e. ICC = 0.835, 66% of counts within two of primary reader) with a bias toward greater variation in younger, pre-maturational life stages (≤5 annuli). Traditionally accepted ageing precision (IAPE ≤ 5.5%, CV ≤ 7.6%) was achieved for each species, but was commensurate with reader experience. The multivariate mMDS ordination was more informative in identifying both distance (i.e. dissimilarity) and direction (i.e. form) of variations in annuli counts and vB growth parameter estimates among readers. The acceptable level of ageing precision and bias achieved among most readers indicated that deep-water snappers can be aged precisely when appropriate otolith preparation methods are used. This study contributes towards ageing protocols that can be used to (i) interrogate bias and precision of age data for stock assessments, and (ii) standardise comparisons of age-based life history characteristics across a species range.

Testing staining techniques to determine age and growth of Dasyatis pastinaca (Linnaeus, 1758) captured in Iskenderun Bay, northeastern Mediterranean

This study tested the suitability of several staining methods to determine the age of common stingray (Dasyatis pastinaca) from Iskenderun Bay, Turkey. A total of 384 specimens (16.6 cm–69.3 cm disc width) were obtained by trawling between September 2010 and December 2011. Sex ratio of the samples was 53% males and 47% females. Appropriate age determination was firstly demonstrated using Safranin-O staining. Age readings were made by two independent readers and the index of average percent error (IAPE) determined as 6.3% for Safranin-O, 6.8% for Crystal Violet, 7.9% for Alcian Blue, and 9.3% for Silver Nitrate. Safranin-O and Crystal Violet staining methods provided the best results. Verification of temporal growth ring formation was by marginal increment analysis. Disc width–weight relationships were determined by W = 0.0272*DW3.06 for females and W = 0.0247*DW3.08 for males. Estimates of the von Bertalanffy growth parameters indicated a larger asymptotic disc width (DW∞ = 127.06 cm) for females than for males (DW∞ = 114.54 cm); growth parameters were k = 0.058 year−1, to = −1.508 and k = 0.041 year−1, to = −3.632 for females and males, respectively.

Life-history traits of the long-nosed skate Dipturus oxyrinchus, from the central western Mediterranean Sea

Event Abstract Back to Event Life-history traits of the long-nosed skate Dipturus oxyrinchus, from the central western Mediterranean Sea Andrea Bellodi1, Cristina Porcu1*, Martina F. Marongiu1, Antonello Mulas1, Stefania Vittori1 and Maria C. Follesa1 1 Università degli Studi di Cagliari, Life and Environmental Sciences, Italy Skates are often considered vulnerable to overfishing because of their peculiar life cycle characteristics rendering them susceptible to overexploitation. In this regard, life-history traits of a by-catch species, the long-nosed skate Dipturus oxyrinchus (Linnaeus, 1758) from Sardinian waters, were investigated. The age, growth and reproduction were studied using 706 specimens sampled during experimental and commercial hauls (depths 76-671 metres). Females (10.4-117.5 cm in total length, TL) attained larger sizes than males (14.5-99.5 cm TL). To evaluate the growth, a subsample of 130 individuals (76 females and 54 males) was employed. The age was estimated through the annuli counts on sectioned vertebral centra. A high ageing reproducibility and precision was obtained (Index of Average Percent Error=6.56; %CV=8.9). Four models were applied on length at age data: the von Bertalanffy (VBGF), the Exponential, the Gompertz and the Logistic functions. According to the Akaike’s Information Criterion, the Gompertz model (L∞=127.5±4.9 cm; k=0.14±0.009; inflection point=3.97 y-1±0.9) provided the best fitting curve, showing a higher growth rate and a lower L∞ than what obtained with the VBGF (L∞=144.4±11.5 cm; k=0.08±0.001; t0=-1.09±0.23). The oldest female and male were 17 (115.5 cm TL) and 15 years (96 cm TL), respectively. Lengths at maturity were 103.5 cm (14 years) for females and 91 cm (12.1 years) for males corresponding to 88 and 91.5% of the maximum observed length, respectively. The monthly evolution of maturity stages highlighted an extended reproductive cycle with spawning females and active males almost over the year, as confirmed by the Gonado-somatic Index. Ovarian fecundity reached a maximum of 26 yolked follicles. Given the relative abundance in Sardinian seas, we hope that these results will prove useful for the implementation of basic management measures in order to ensure the sustainability of catches of this species, particularly sensitive to fishing pressure, in the Mediterranean Sea. Keywords: Dipturus oxyrinchus, age, Growth, Reproduction, Mediterranean Sea Conference: XV European Congress of Ichthyology, Porto, Portugal, 7 Sep - 11 Sep, 2015. Presentation Type: Poster Presentation Topic: Life Cycles, Migration and Connectivity Citation: Bellodi A, Porcu C, Marongiu MF, Mulas A, Vittori S and Follesa MC (2015). Life-history traits of the long-nosed skate Dipturus oxyrinchus, from the central western Mediterranean Sea. Front. Mar. Sci. Conference Abstract: XV European Congress of Ichthyology. doi: 10.3389/conf.FMARS.2015.03.00193 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: 16 Nov 2015; Published Online: 02 Dec 2015. * Correspondence: Dr. Cristina Porcu, Università degli Studi di Cagliari, Life and Environmental Sciences, Cagliari, 09126, Italy, cporcu@unica.it 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 Andrea Bellodi Cristina Porcu Martina F Marongiu Antonello Mulas Stefania Vittori Maria C Follesa Google Andrea Bellodi Cristina Porcu Martina F Marongiu Antonello Mulas Stefania Vittori Maria C Follesa Google Scholar Andrea Bellodi Cristina Porcu Martina F Marongiu Antonello Mulas Stefania Vittori Maria C Follesa PubMed Andrea Bellodi Cristina Porcu Martina F Marongiu Antonello Mulas Stefania Vittori Maria C Follesa 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.

Reproducibility of age determination by scale and vertebra in pontic shad (Alosa pontica Eichwald, 1838), from the Danube

Specimens of Pontic shad (Alosa pontica Eichwald, 1838) were collected during April and May of 2006 in the Danube River (rkm 863) just downstream of the Iron Gate (Djerdap) II dam. Twenty-eight scales and 30 vertebrae were prepared and given to five interpreters with fish aging experience of from 3 to 30 years and with shad aging experience of from 0 to 12 years. Interpreters with experience in shad age determination showed lower values for the index of average percent error (IAPE) and an index of coefficient of variation (ICV). In regard to within-interpreter reproducibility, no significant differences were found between scale and vertebrae as structure for age determination. The most experienced reader showed the lowest value for IAPE, while the least experienced reader showed the highest value for IAPE. The results of this work indicate that experience in age determination by particular structure had more impact on age determination precision than specificity of structure, scale or vertebra. More work is needed on adopting standard protocols that must include some sort of common interaction between responsible age readers.

Age and growth of brown meagreSciaena umbra(Sciaenidae) in the Adriatic Sea

Age and growth of the brown meagre Sciaena umbra (Sciaenidae) collected (n = 532) in the north-western Adriatic Sea was studied by means of transverse otolith sections. The maximum age estimated was 19 and 16 years for males and females, respectively. The length at age estimated for each sex indicated that females attain a larger size and grow slightly faster than males. Both marginal increment analysis and edge analysis confirmed that annuli are formed once a year, with opaque zones laid down in summer (June-July). Age readings were very precise, with a percentage agreement of 98% between readers and low values of the index of average percent error (0.9%) and coefficient of variation (1.3%). Von Bertalanffy growth function was fitted to age-length data, and growth parameters were estimated for males (L∞ = 44.9 cm; k = 0.27,t0 = −2.17 years) and females (L∞ = 47.2 cm; k = 0.28, t0 = -1.82 years). In both sexes of brown meagre, growth rate was high until they attain 2–3 years of age, i.e. at sexual maturity. Most of catches were obtained in late summer-early autumn. On the basis of present data, the sampled population of brown meagre mostly consisted of small fish younger than three years of age (about 90%). In addition, landings of this species in recent years largely decreased. As reported elsewhere in north-western Mediterranean, brown meagre stock in the Adriatic Sea showed clear signs of depletion, thus specific management measures for this species are urgently required.

Geographic influences on and the accuracy and precision of age estimates for the red bass, Lutjanus bohar (Forsskal 1775): A large tropical reef fish

The red bass is a large tropical reef fish (Lutjanidae, tropical snappers) that is harvested to varying extents throughout a widespread Indo-Pacific distribution. The aims of this study were to investigate the accuracy and precision of age estimates from transverse sections of sagittal otoliths and to assess effects on these of the geographic area of collection and otolith preparation method. Two independent validation studies suggested an approximately annual formation of annuli in otoliths, predominantly for otoliths with 4–10 annuli but also for one otolith with 29 annuli. Otolith sections produced exceptionally high annulus counts: up to 56 annuli for samples from the Great Barrier Reef (GBR), Australia; and up to 55 annuli from the Seychelles, indicating a high longevity for this species. The precision of otolith readings from the GBR (index of average percent error, IAPE = 3.21 ± 0.26 S.E.) was within commonly accepted bounds for age estimation (IAPE up to 5%) but precision of readings from the Seychelles was significantly lower (IAPE = 9.18 ± 0.47 S.E.) and outside of this “acceptable” range. Age-based biological parameters for red bass from the Seychelles should thus be applied with greater caution than those for red bass from the GBR. If basic demographic properties are assumed relatively constant across the wide geographic range sampled, however, results from the GBR could be used as more reliable preliminary data for precautionary management strategies in the Seychelles and elsewhere.

Age, growth, and sexual maturity of the yellownose skate Dipturus chilensis in the south‐eastern Pacific

The age and growth parameters of Dipturus chilensis were estimated by counting growth rings from thin sections of vertebral centra from 400 fish (246 females and 154 males), ranging from 23 to 124 cm total length (LT), and backcalculating fish lengths at previous ages. Marginal increment analysis lent support to the hypothesis of annual deposition of band‐pairs, which formed during the winter months. The oldest female D. chilensis aged in this study was 21 years and 117 cm LT, whereas the oldest male was 18 years and 93 cm LT. A 4·7% index of average per cent error (IAPE) suggested that this is a precise method for calculating the age of D. chilensis. Observed LT were lower than backcalculated LT, which implies the influence of Lee's phenomenon. The von Bertalanffy growth equations, based on mean length‐at‐age data, were estimated as Lt = 128·3 (1 − e−0·112 (t + 0·514)) for females and Lt = 107·8 (1 − e−0·134 (t + 0·862)) for males where t is age (years). Growth was significantly different between sexes: females reached a larger adult size. Ages and lengths at 50% maturity were estimated at 14 years of age and 106 cm LT for females and 11 years of age and 86 cm LT for males. At c. 14 years, there was a decline in growth rates in females. The factor most likely responsible for this was sexual maturity, which caused a discontinuity in growth of female fish. These results show that this species is slow‐growing, long‐lived, relatively large and of delayed maturity, characteristics that make it vulnerable to exploitation.

Age and size at sexual maturity for the winter skate, Leucoraja ocellata, in the western Gulf of Maine based on morphological, histological and steroid hormone analyses

We determined age and size at sexual maturity in male and female winter skates, Leucoraja ocellata, from the western Gulf of Maine. Age estimated from vertebral band counts resulted in an Index of Average Percent Error (IAPE) of 5.6%, suggesting that this method represents an accurate approach to the age assessment of L. ocellata. Size at sexual maturity was assessed by evaluating three endpoints: steroid hormone concentrations, and morphological and histological criteria. Our results suggest that 50% maturity in males occurs at a total length of 730 mm and at 11 years of age. For females, our results suggest that 50% maturity occurs at a total length of 760 mm and between 11 and 12 years of age. Collectively, our study suggests that analyzing a combination of reproductive parameters offers an accurate estimation of sexual maturity in the winter skate. Moreover, our results indicate that L. ocellata is a late-maturing and long-lived species, characteristics which make it highly susceptible to over-exploitation by commercial fisheries.

Assessing the use of sectioned otoliths and other methods to determine the age of the centropomid fish, barramundi ( Lates calcarifer) (Bloch), using known-age fish

The use of stocked fish of a known age provide an opportunity to determine the practicality of use of otolith morphometrics and fish length to estimate the age of barramundi ( Lates calcarifer) and determine accuracy of sectioned otolith age estimates. Otoliths were collected from 119 stocked barramundi and were compared against the known age of the fish (range: 0.75–8.64 years). The otoliths of barramundi appear to grow in three distinct phases when compared to the total length of the fish (TL), with a final change in otolith growth coinciding at the approximate size of sex change for this species (900 mm TL). Otolith growth is correlated linearly in all directions throughout to total growth of the otolith. Linear relationship of the sectioned otolith age estimates and known ages was highly significant ( r 2=0.89), with nearly 88% of the fish assigned to the correct age class with an index of average percent error (IAPE) of 3.2%. The otolith weight–age relationship for the known-age fish described by the equation, age=17.43 ( otolith weight )+0.981 , accounted for more than 71% of the variability. The use of any of the three otolith dimensions (length, breadth, width), otolith weight or fish total length (TL) provided a similar population age structure to that of sectioned otoliths ages ( P>0.05). Because of significant time savings and costs associated with the techniques, use of otolith weight or even fish TL relationships with fish age offer a real alternative to reading sectioned otoliths, as long as enough samples are used to account for any bias from sampling error. Use of otolith weight alone could reduce laboratory costs by 96% when compared to sectioned otoliths, and has real utility for use in long-term monitoring.

Age and Growth of the Whiskery Shark, Furgaleus macki, from Southwestern Australia

Age and growth of the whiskery shark, Furgaleus macki, from southwestern Australia were examined using vertebral ageing and tag-recapture data. The readability of bands on the vertebral centra varied markedly between individuals. Four readers were used to make band counts, with the most experienced reader having the lowest ‘index of average percent error’ and the highest level of agreement with final counts. Marginal increment analysis indicated that opaque bands form in January. With parturition occurring from August to October, size data suggests that the first band is probably formed 15–17 months after birth. The age at maturity was estimated to be 4.5 years for males, and 6.5 years for females. The oldest male was 10.5 years, and oldest female was 11.5 years. Von Bertalanffy growth parameters for males were L∞=121.5 cm fork length, K=0.423 year−1, t0=−0.472 years, were L∞=120.7 cm fork length, K=0.369 year−1, t0=−0.544 years for females, and were L∞=118.1 cm fork length, K=0.420 year−1, t0=−0.491 years for combined sexes. Data from a tag recapture study were analysed using a maximum likelihood method to verify the estimates of growth parameters from vertebral ageing. Von Bertalanffy growth parameters from the tag recapture study were L∞=128.2 cm fork length, K=0.288 year−1, t0=−0.654 years. The two methods of estimating growth parameters produced similar results, with rapid growth until approximately 5 years of age, after which there was little increase in length.

Interpretability and precision of annulus counts for calcified structures in carp, Cyprinus carpio L.

Scales, opercular bones and whole otoliths of carp from the River Murray, Australia, were analysed for interpretability and reproducibility of annulus counts by three interpreters of disparate experience. Interpretability was least for scales and highest for opercular bones, and annulus counts from scales and opercular bones were more precise than those from otoliths. However, these differences were not statistically significant. Relatively high values of the index of average percent error (IAPE) and of the mean coefficient of variation (V) confirmed that age interpretation in carp is difficult and requires extensive training and experience.

A modified decalcification technique for enhancing growth bands in deep-coned vertebrae of elasmobranchs

A technique for enhancing growth bands on vertebrae was assayed using 477 centra from blackmouth catsharks, Galeus melastomus. Specimens were caught at depths between 200 and 800 meters off the southern Portuguese coast (Algarve) during an IPIMAR research cruise in August 1994. Total lengths ranged from 12 to 71 cm. Standard vertebral ageing techniques, such as silver nitrate impregnation, haematoxylin staining, grinding and shading failed to produce clearly contrasting bands. A method solely based on vertebra decalcification with nitric acid (5%) yielded the most satisfactory results. This technique provided clear band differentiation and was used by two independent readers. The analysis of differences in band counts between readers was based on: percent of disagreements, percent of disagreement by length group, index of average percent error and Wilcoxon's signed ranks test. The majority of differences corresponded to only one band of disagreement and disagreements have been found to increase with length, which stresses the need for a larger sampling effort on the larger and older individuals. The index of average percent error was estimated as 4.6% and no statistical differences were detected between readers' results.

Age Assessment of the Lemon Shark, Negaprion brevirostris, Using Tetracycline Validated Vertebral Centra

Vertebral centra were removed from 55 tag-recaptured lemon sharks, Negaprion brevirostris, that had been injected intramuscularly with tetracycline hydrochloride at a dosage level of 12.5 mg/kg at the time of release. Tetracycline deposited at sites of active calcification on the vertebral centra served as a fluorescent marker along the periphery of each centrum at the time of injection. Thin growth zones, or circuli, were observed in ground and stained sections. A lunar periodicity of approx. 29 d was validated for circulus deposition. Precision of circulus counts was evaluated, with an index of average percent error of 3.4% for a single reader. Age estimates were then obtained using circulus counts for a total of 110 sharks, with a plot of precaudal length against estimated age for both sexes fitting a von Bertalanffy growth curve with the parameters Loo = 317.65, k = 0.057, and to = -2.302. The predicted age at maturity for males is 11.6 yr and for females is 12.7 yr. These results show that this species is slow growing and long-lived.

Age and growth of blue grenadier, Macruronus novaezelandiae (Hector), in south-eastern Australian waters

Blue grenadier, Macruronus novaezelandiae, from south-eastern Australian waters were aged, using their otoliths (whole and in transverse thin sections). The greatest recorded age was 25 years. A double blind test showed that the recorded ages were sufficiently reproducible to use in fitting growth curves (Index of Average Percent Error: 8%), but not sufficiently so to assign individuals to particular year-classes. Von Bertalanffy growth curves were fitted to both length and weight data. For males, Lt = 90.7 (1 - exp[-0.256(t + 1.21)]} and Wt = 2.62 (1 - exp[-0.277(t + 1.39)]}3. For females, Lt = 99.3 {l - exp[-0.203(t + 1.48)]} and Wt = 4.16{1 - exp[-0.157(t + 2.93)]}3. L is the length in centimetres, W is the weight in kilograms and t is the age in years. A comparison with length-frequency modes validated the growth curves for immature fish, but no validation was possible for the adults. The $exes have qignificantly different growth patterns. Their growth parameters are typical of those of commercially exploited, temperate gadoid fishes and show no modification for the deep-water zone inhabited by blue grenadier.

A Statistical Method for Evaluating the Reproducibility of Age Determination

The coefficients of variation and the index of precision provide a statistical test of reproducibility of aging between readers. Because the coefficients of variation and the index of precision incorporate the averaged year-class of a fish species, they are free from the shortcoming of the percent agreement method. Because variance is a better estimator than absolute difference, the coefficient of variation is a stronger estimator than the index of average percent error in providing a test statistic.Key words: age determination, coefficients of variation, index of precision, average percent error, percent agreement

A Method for Comparing the Precision of a Set of Age Determinations

An index of average percent error is a better estimate of the precision of age determinations than the conventional percent agreement method because it is not independent of the age of a species.Key words: age determination, aging errors