Analysing differences between two age determination methods by tests of symmetry

Hoenig, John M.; Morgan, Michael J.; Brown, C. Andrew

doi:10.1139/f95-038

Cited by 139 publications

(91 citation statements)

References 4 publications

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“…lapillus from Interpreter A vs sagitta from Interpreter B; sagitta from Interpreter A vs lapillus from Interpreter B). For each combination, an age-bias plot [19] was generated and a test of symmetry [20] computed from the corresponding age-agreement table (not shown). In this table, the main diagonal represents the frequency of fish for which the same number of micro-increments is obtained based on the two structures and/or interpreters, whereas each cell off the main diagonal represents a difference in the number of micro-increments between the two structures and/or interpreters.…”

Section: Discussionmentioning

confidence: 99%

Bias, precision and validation of ageing 0+ European barbel Barbus barbus (L.) from their otoliths

Vilizzi

Copp²

2013

Open Life Sciences

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The European barbel Barbus barbus L. is considered a ‘flag’ species for river conservation and sport fishing, but it is increasingly threatened in its native range of distribution. To provide accurate age estimates during early life for appropriate management and conservation measures, the bias and precision of otolith (daily) micro-increment counts were evaluated and age determinations validated on laboratory-reared embryos and larvae. Out of the three pairs of otoliths, the lapillus and sagitta provided reliable age estimates for free embryos and larvae up to 17 days of (known) age post-fertilisation, with first micro-increment formation occurring five days postfertilisation. On the other hand, micro-increments on asterisci formed only 16–17 days post-fertilisation. There was agreement in microincrement counts based on lapilli and sagittae, but not between interpreters, indicating that despite consistency between the two pairs of otoliths extensive training and experience are required for reliable age interpretation. The ability to estimate the ages of 0+ B. barbus from their otoliths will contribute to a better understanding of growth rates from both hatchery-stocked and native/introduced cohorts.

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Section: Discussionmentioning

confidence: 99%

Bias, precision and validation of ageing 0+ European barbel Barbus barbus (L.) from their otoliths

Vilizzi

Copp²

2013

Open Life Sciences

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“…The average percentage error (APE) (Beamish and Fournier 1981), the coefficient of variation (CV) (Chang 1982), and the index of precision (D) (Chang 1982) were used to compare age readings between readers. Bias evaluation was based on age bias plots (Campana et al 1995) which allow visualizing deviation of the age readings from the 1 : 1 equivalence line, and systematic differences on the ages assigned between readers were investigated with the Bowker-type test for symmetry (Hoenig et al 1995). As good agreement between readers was achieved, the remaining otoliths were read twice by the first author.…”

Section: Samplingmentioning

confidence: 99%

Age and growth of small red scorpionfish, Scorpaena notata (Actinopterygii: Scorpaeniformes: Scorpaenidae), a common discard species from the Portuguese fishery

Neves¹

2015

Acta Ichthyol. Piscat.

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“…Bias and precision of annulus counts were analysed by statistical and graphical methods for each pair of replicate counts from the three interpreters. Accordingly, an age bias plot (Campana et al, 1995) was generated and a test of symmetry (Hoenig et al, 1995) computed from the corresponding age-agreement table. In this table, the main diagonal represents the frequency of fish for which the same estimated age is obtained by any combination of two interpreters, whereas each cell off the main diagonal represents a difference in estimated age between the interpreters.…”

Section: > Data Analysismentioning

confidence: 99%

Age and growth of European barbelBarbus barbus(Cyprinidae) in the small, mesotrophic River Lee and relative to other populations in England

Vilizzi

Copp

Britton

2013

Knowl. Managt. Aquatic Ecosyst.

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Key-words:habitat, conservation, scale ageing, recruitment Suspected of being in decline, the European barbel Barbus barbus population of the River Lee, a heavily-modified river in South East England, has been the subject of investigations to identify factors associated with perceived population decreases. Population surveys between 1995 and 1999 captured a total of 912 individuals, and standard length (SL) frequency analyses between years suggested that the population decline was not related to juvenile recruitment but rather to a recruitment bottleneck in fish 300-340 mm SL. This bottleneck probably results from insufficient available habitat suitable to this size class. Of the sampled fish, scales were removed from 764 and were used in a scale ageing exercise among three researchers. Analyses of their independent age estimates revealed variable interpretations, which arose from uncertainties relating to the difficulty of analysing scale patterns from relatively large, slow-growing fish. Nevertheless, error was within published acceptable margins, and age estimates revealed B. barbus in the river to age 10 years, lower than in many UK rivers. The SL-at-age growth curve was characterised by very fast growth in the initial years of life. Thus, the causal factors in the decline of this B. barbus population appear to have been in the adult life-stage habitat and were likely related to the loss of longitudinal connectivity, mainly due to the presence of water retention structures. River and aquatic ecosystem remediation strategies should therefore focus on enhancing longitudinal connectivity in conjunction with the ongoing improvement of water quality and ecosystem integrity. Mots-clés :habitat, conservation, scalimétrie, recrutement Soupçonnée d'être en déclin, la population de barbeau européen Barbus barbus de la rivière Lee, une rivière fortement modifiée dans le Sud Est de l'Angleterre, a fait l'objet d'investigations pour identifier les facteurs associés à la diminution ressentie de la population. Le suivi de population entre 1995 et 1999 a permis la capture de 912 poissons, et l'analyse des fréquences de longueur standard (SL) entre années suggère que le déclin de la population n'était pas lié au recrutement des juvéniles, mais plutôt à un goulot d'étranglement du recrutement chez les poissons de 300-340 mm SL. Ce goulot d'étranglement résulte probablement d'une insuffisance de l'habitat disponible approprié pour cette classe de taille.

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Analysing differences between two age determination methods by tests of symmetry

Cited by 139 publications

References 4 publications

Bias, precision and validation of ageing 0+ European barbel Barbus barbus (L.) from their otoliths

Bias, precision and validation of ageing 0+ European barbel Barbus barbus (L.) from their otoliths

Age and growth of small red scorpionfish, Scorpaena notata (Actinopterygii: Scorpaeniformes: Scorpaenidae), a common discard species from the Portuguese fishery

Age and growth of European barbelBarbus barbus(Cyprinidae) in the small, mesotrophic River Lee and relative to other populations in England

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