scholarly journals Macroscopic vs. microscopic identification of the maturity stages of female horse mackerel

2009 ◽  
Vol 66 (3) ◽  
pp. 509-516 ◽  
Author(s):  
Ana Maria Costa
Keyword(s):  
Horse Mackerel ◽  
Percentage Error ◽  
Maturity Stage ◽  
Trachurus Trachurus ◽  
Microscopic Identification ◽  
Maturity Stages ◽  
Stock Biomass ◽  
Spawning Stock ◽  
Macroscopic Identification

Abstract Costa, A. M. 2009. Macroscopic vs. microscopic identification of the maturity stages of female horse mackerel. – ICES Journal of Marine Science, 66: 509–516. The consequences to fisheries management of erroneous macroscopic identification of maturity stages are evaluated. The percentage error in macroscopic identification of maturity stages of female horse mackerel (Trachurus trachurus) from the Portuguese coast was determined and analysed by maturity stage, between the periods January–June and July–December, between research surveys and commercial landings, and between per year and month and by length class, to assess its implications in determination of spawning season, maturity ogives, and spawning-stock biomass. The highest percentage errors in macroscopic identification were between late ripening and partly spent stages, in fish >30 cm, and for all fish collected in 1998 and 2005. Late ripening was generally macroscopically underestimated, and the partly spent stage overestimated. The implications for the information provided to the ICES assessment working group are analysed.

scholarly journals Estimates of batch fecundity and spawning fraction for the southern stock of horse mackerel (Trachurus trachurus) in ICES Division IXa

2009 ◽  
Vol 66 (4) ◽  
pp. 617-622 ◽  
Author(s):  
Patrícia Gonçalves ◽  
Ana Maria Costa ◽  
Alberto G. Murta
Keyword(s):  
Egg Production ◽  
Production Method ◽  
Horse Mackerel ◽  
Batch Fecundity ◽  
Trachurus Trachurus ◽  
Absolute Abundance ◽  
Female Total ◽  
Stock Biomass ◽  
Spawning Stock ◽  
Ovulatory Follicles

Abstract Gonçalves, P., Costa, A. M., and Murta, A. G. 2009. Estimates of batch fecundity, and spawning fraction for the southern stock of horse mackerel (Trachurus trachurus) in ICES Division IXa. – ICES Journal of Marine Science, 66: 617–622. Since 1995 the annual egg production method has been applied triennially to the southern stock of horse mackerel (Trachurus trachurus) in the Northeast Atlantic (ICES Division IXa). This method assumes that fecundity is determinate, but increasing evidence indicates that horse mackerel are indeterminate spawners. The daily egg production method (DEPM) does not rely on the assumption of determinate fecundity, making it the appropriate method for this species. Therefore, we reanalysed samples collected from previous surveys (2002, 2004, 2005, and 2007) to obtain estimates for batch fecundity and spawning fraction, which are important DEPM parameters. The estimates of batch fecundity are around 200 oocytes g−1 of female (total ovary-free weight). Several criteria were used to estimate spawning fraction (migratory nucleus stage, hydrated oocytes, and post-ovulatory follicles) and all showed the same trend among years, varying between 0.10 and 0.30 d−1. The estimates were significantly different among methods, but those differences were similar across surveys, indicating that a consistent bias would be reflected in the final spawning-stock biomass (SSB) estimates obtained from the DEPM. Until further information is available regarding the accuracy of the criteria used to estimate spawning fraction, the southern horse mackerel SSB estimates from the DEPM should only be taken as indicative of trends rather than measures of absolute abundance.

scholarly journals A linked separable–ADAPT VPA assessment model for western horse mackerel (Trachurus trachurus), accounting for realized fecundity as a function of fish weight

2010 ◽  
Vol 67 (5) ◽  
pp. 916-930 ◽  
Author(s):  
José A. A. De Oliveira ◽  
Chris D. Darby ◽  
Beatriz A. Roel
Keyword(s):  
Egg Production ◽  
Direct Conversion ◽  
Assessment Model ◽  
Horse Mackerel ◽  
Population Estimates ◽  
Trachurus Trachurus ◽  
Large Area ◽  
Potential Fecundity ◽  
Fish Weight ◽  
Spawning Stock

Abstract De Oliveira, J. A. A., Darby, C. D., and Roel, B. A. 2010. A linked separable–ADAPT VPA assessment model for western horse mackerel (Trachurus trachurus), accounting for realized fecundity as a function of fish weight. – ICES Journal of Marine Science, 67: 916–930. The western horse mackerel stock covers a large area of the Northeast Atlantic and is characterized by the sporadic occurrence of strong year classes. The only fishery-independent data available for its assessments are the estimates of total annual egg production from triennial egg surveys. Horse mackerel are indeterminate spawners, so a direct conversion of total annual egg production to spawning-stock biomass using prespawning-season estimates of fecundity is not viable. There is also evidence that potential fecundity per kg spawning female increases with fish weight. A linked separable–ADAPT VPA (SAD) model was developed that combines data on total catch, catch-at-age, and total annual egg production with data on potential and realized fecundity to provide population estimates for western horse mackerel. The model accounts for potential fecundity as a function of fish weight and for the development of a targeted fishery on the strong 1982 year class. Simulations confirm that the SAD model is able to reproduce population estimates without bias under a range of scenarios, except where there is a trend in realized fecundity. This underscores the need for improved information on realized fecundity, or alternatively the need to develop management plans that are robust to this source of uncertainty.

scholarly journals Investigating the use of proxies for fecundity to improve management advice for western horse mackerel Trachurus trachurus

2006 ◽  
Vol 63 (1) ◽  
pp. 25-35 ◽  
Author(s):  
J.A.A. De Oliveira ◽  
B.A. Roel ◽  
M. Dickey-Collas
Keyword(s):  
Egg Production ◽  
Stock Assessment ◽  
Biological Indicators ◽  
Horse Mackerel ◽  
Feeding Intensity ◽  
Short Time Series ◽  
Stock Biomass ◽  
Spawning Stock ◽  
Management Advice ◽  
Short Time

Abstract Observations of fecundity from the 2001 western horse mackerel spawning-stock biomass survey suggest that the species is an indeterminate spawner. Therefore, estimates of fecundity based on biological analyses and until recently used in the calibration of the stock assessment are now questioned. The stock is assessed by fitting a linked Separable and ADAPT VPA-based model to the catch-at-age data and to the egg production estimates. Currently, the assumption is that egg production and spawning-stock biomass are linked by a constant but unknown fecundity parameter, estimated within the model. In this study, the effects of introducing relationships linking biological indicators of fecundity, such as lipid content or feeding intensity during the spawning season, to actual fecundity are examined within a simulation framework. Simulations suggest that when the underlying relationships between fecundity and the proxy are poorly described, weak, or based on a relatively short time-series of data, the assumption of constant fecundity will result in better management advice than using the proxy.

scholarly journals Quality, Bioactive Compounds, Antioxidant Capacity, and Enzymes of Raspberries at Different Maturity Stages, Effects of Organic vs. Conventional Fertilization

Foods ◽  
2021 ◽  
Vol 10 (5) ◽  
pp. 953
Author(s):  
María Noemí Frías-Moreno ◽  
Rafael A. Parra-Quezada ◽  
Gustavo González-Aguilar ◽  
Jacqueline Ruíz-Canizales ◽  
Francisco Javier Molina-Corral ◽  
...  
Keyword(s):  
Vitamin C ◽  
Antioxidant Capacity ◽  
Bioactive Compounds ◽  
Defense Mechanisms ◽  
Bioactive Compound ◽  
Physicochemical Characteristics ◽  
Maturity Stage ◽  
Organic Fertilization ◽  
Maturity Stages

Raspberries are important sources of bioactive compounds, whose synthesis is influenced by the fertilization system and the maturity stage. This study evaluated the effect of organic and conventional fertilization systems on raspberries at three maturity stages, pink, ripe, and overripe. Physicochemical characteristics, bioactive compounds (phenolic profile, vitamin C), antioxidant capacity (DPPH, FRAP, TEAC, and ORAC), phenolic-associated enzyme, phenylalanine ammonia lyase (PAL), and antioxidant enzymes (SOD, CAT, GPx, and APX) were evaluated. The physicochemical determination of the fruit did not reveal differences between fertilization systems. Regarding bioactive compounds, higher content of anthocyanins was found in organic raspberries at all maturity stages. Organic fertilization increased the content of ellagic acid and gallic acid at all stages of maturity. Higher content of caffeic, hydroxybenzoic, protocatechuic acid, and vitamin C was observed in organic raspberry at the overripe stage. Raspberries grown with organic fertilization exhibited higher values of antioxidant capacity by the DPPH, FRAP, and TEAC methods at all maturity stages. Raspberries under organic fertilization showed significantly greater activity of CAT, SOD, APX, GPX, and PAL. The present study suggests that organic fertilization induces oxidative stress causing an increase in antioxidant defense mechanisms, enhancing bioactive compound production, and improving antioxidant capacity in raspberries.

scholarly journals Harvest control rules for the Western horse mackerel (Trachurus trachurus) stock given paucity of fishery-independent data

2007 ◽  
Vol 64 (4) ◽  
pp. 661-670 ◽  
Author(s):  
Beatriz A. Roel ◽  
José A. A. De Oliveira
Keyword(s):  
Juvenile Fish ◽  
Management Plan ◽  
Horse Mackerel ◽  
Independent Data ◽  
Trachurus Trachurus ◽  
Total Allowable Catch ◽  
Control Rules ◽  
Constant Proportion ◽  
Spawning Stock ◽  
Harvest Control Rules

Abstract Roel, B. A., and De Oliveira, J. A. A. 2007. Harvest control rules for the Western horse mackerel (Trachurus trachurus) stock given paucity of fishery-independent data. – ICES Journal of Marine Science, 64: 661–670. The Western horse mackerel stock, widely distributed in EU waters, is characterized by spasmodic recruitment. Currently, the strength of a year class cannot be confirmed before it is fully recruited to the fishery and has reached the age of 5 years. The only fishery-independent information available is an estimate of egg abundance made every third year. The state of the stock is considered uncertain, and there is no agreed management plan. Following EU requests, a set of harvest control rules (HCRs) that allows for the increased proportion of juvenile fish taken by the fishery in recent years was tested by simulation. The proposed HCRs are based either on the results of a full assessment (Constant-proportion strategy) or simply on the egg estimate used as an indicator of stock status (Slope strategy). Biological risk is compared for scenarios where: (i) uncertainty regarding stock dynamics and in the relationship between egg data and spawning-stock biomass is high (current situation); (ii) variable fractions of the total allowable catch (TAC) are taken in the areas occupied by juveniles and adults; and (iii) there is an implementation error. Results suggest that taking a larger portion of the TAC in the area occupied by juveniles increases the risk of impaired recruitment. Comparison of the Constant-proportion and Slope strategies suggests that the former is more conservative, if the assessment is unbiased or if bias is low. Given the paucity of fishery-independent data, a strategy resulting in an approximately constant catch may be appropriate for this stock.

The existence and population connectivity of Icelandic spring-spawning herring over a 50-year collapse period

2018 ◽  
Vol 75 (6) ◽  
pp. 2025-2032 ◽  
Author(s):  
Guðmundur J Óskarsson
Keyword(s):  
Theoretical Model ◽  
Population Connectivity ◽  
Maturity Stage ◽  
Stock Size ◽  
Stock Biomass ◽  
Spawning Stock ◽  
Low Levels ◽  
The 1960S ◽  
Source Sink ◽  
Icelandic Waters

Abstract In the late 1960s, two local herring stocks and one seasonal migratory herring stock in Icelandic waters collapsed primarily due to overfishing. While the stocks of Icelandic summer-spawning herring (ISSH) and Norwegian spring-spawning herring (NSSH) have recovered, Icelandic spring-spawning herring (ISPH) has not. The main objective of this work is to explore the existence of ISPH and identify potential signs of recovery. Analyses were based on samples from the autumn fishery and survey data from 1962 to 2016. In the autumn, local ISSH and ISPH cohabitated and mixed in the main fishery, where sampled fish were categorized into stocks on basis of maturity stage. The results indicate that the proportion of ISPH was in the range of 13–33% in the 1960s while below 5% and on average 1.4% during 1970–2016. Several year classes of ISPH exhibit notable differences from the general low levels and caused a slight increase in ISPH spawning-stock biomass for corresponding years. An increase in proportion of generally old ISPH around 2004 and 2013 occurred simultaneously with the reappearances of NSSH in the feeding areas east and north of Iceland, respectively. Altogether, it supports earlier suggestions that ISPH might require immigration from NSSH to recover, as these were considered closely related stocks. This is consistent with the source-sink theoretical model of stock size regulation.

EINE CHEMISCHE METHODE ZUR BESTIMMUNG VON 16-EPI-ÖSTRIOL IM URIN DES MENSCHEN

1963 ◽  
Vol 44 (1) ◽  
pp. 47-66 ◽  
Author(s):  
W. Nocke ◽  
H. Breuer
Keyword(s):  
Melting Point ◽  
Phosphoric Acid ◽  
Aqueous Alkali ◽  
Percentage Error ◽  
Organic Layer ◽  
Maximum Percentage ◽  
Chemical Determination ◽  
Routine Assay ◽  
Hydrolysis Of

ABSTRACT A method for the chemical determination of 16-epi-oestriol in the urine of nonpregnant women with a qualitative sensitivity of less than 0.5 μg/24 h is described. The separation of 16-epi-oestriol and oestriol is accomplished by converting 16-epi-oestriol into its acetonide, a reaction which is stereoselective for cis-glycols and therefore not undergone by oestriol as a trans-glycol. Following partition between chloroform and aqueous alkali, the acetonide of 16-epi-oestriol is completely separated with the organic layer whereas oestriol as a strong phenol remains in the alkaline phase. 16-epi-oestriol is chromatographed on alumina as the acetonide and determined as a Kober chromogen. This procedure can easily be incorporated into the method of Brown et al. (1957 b) thus making possible the simultaneous routine assay of oestradiol-17β, oestrone, oestriol and 16-epi-oestriol from one sample of urine. The specificity of the method was established by separation of 16-epi-oestriol from nonpregnancy urine as the acetonide, hydrolysis of the acetonide by phosphoric acid, isolation of the free compound by microsublimation and identification by micro melting point, colour reactions and chromatography. The accuracy of the method is given by a mean recovery of 64% for pure crystalline 16-epi-oestriol when added to hydrolysed urine in 5–10 μg amounts. The precision is given by s = 0.24 μg/24 h. For the duplicate determination of 16-epi-oestriol the qualitative sensitivity is 0.44 μg/24 h, the maximum percentage error being ± 100% The quantitative sensitivity (±25% error) is 1.7 μg/24 h.

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