Daily egg production of anchovy in European waters

Abstract Since the late 1980s, the Daily Egg Production Method (DEPM) has been applied to several anchovy stocks in European waters. DEPM surveys in the Bay of Biscay were well standardized and focused on providing fisheries-independent information for stock assessment purposes. Those targeting Mediterranean stocks were largely experimental and often opportunistic, with the main aim of developing and testing the method, rather than providing estimates of spawning stock biomass (SSB) for stock assessment. Consequently, the DEPM has been applied once, twice, or a maximum of three times in certain Mediterranean areas with no among-area standardization. Different techniques for several aspects of the method have been used in the Mediterranean, and the parameters estimated vary greatly among stocks and year of application. Evidence is provided that variability in biological production among sub-basins and/or years, a characteristic of Mediterranean Sea, may directly affect anchovy egg production. The daily specific fecundity of anchovy stocks can vary greatly among years, areas, or seasons in response to changing environmental and trophic regimes. When the correlation between regression-derived estimates of daily egg production and associated estimates of daily specific fecundity for anchovy in the Mediterranean, the Bay of Biscay, and upwelling areas are compared, a significant isometric relationship emerges for the Mediterranean and the Bay of Biscay, implying density-dependent use of spawning habitat. In upwelling areas, estimates of daily egg production are relatively high for a narrow range of generally low daily specific fecundities. There is a strong linear relationship between anchovy SSB and spawning area in European waters that does not differ significantly between the Bay of Biscay and the Mediterranean Sea.

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A reanalysis of North Sea plaice spawning-stock biomass using the annual egg production method

ICES Journal of Marine Science ◽

10.1093/icesjms/fsp169 ◽

2009 ◽

Vol 66 (9) ◽

pp. 1999-2011 ◽

Cited By ~ 13

Author(s):

Cindy J. G. van Damme ◽

Loes J. Bolle ◽

Clive J. Fox ◽

Petter Fossum ◽

Gerd Kraus ◽

...

Keyword(s):

North Sea ◽

Egg Production ◽

Stock Assessment ◽

Population Analysis ◽

Spatial Dynamics ◽

Production Method ◽

Southern Bight ◽

The North ◽

Stock Biomass ◽

Spawning Stock

Abstract van Damme, C. J. G., Bolle, L. J., Fox, C. J., Fossum, P., Kraus, G., Munk, P., Rohlf, N., Witthames, P. R., and Dickey-Collas, M. 2009. A reanalysis of North Sea plaice spawning-stock biomass using the annual egg production method. – ICES Journal of Marine Science, 66: 1999–2011. Uncertainty about the quality of current virtual population analysis-based stock assessment for North Sea plaice (Pleuronectes platessa) has led to various abundance indices. We compared biomass estimates from the annual egg production (AEP) method with current stock assessments based on catch-at-age to validate the current and historical perception of exploitation. The AEP method was also used to investigate the dynamics of the spatial components of plaice in the North Sea. We corrected for fecundity down-regulation and changes in sex ratio. Estimates from both methods were similar in trend and absolute biomass. On the Dogger Bank, there was a dramatic decline in biomass from 1948 and 1950 to 2004, and in the Southern Bight, the stock appeared to increase from 1987 and 1988 to 2004, although not reaching the historically high levels of 1948 or 1950. The timing of spawning of North Sea plaice does not appear to have changed throughout the period of high exploitation. We conclude that the AEP method is a useful way to hindcast the spatial dynamics of heavily exploited flatfish stocks.

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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 ◽

10.1093/icesjms/fsp066 ◽

2009 ◽

Vol 66 (4) ◽

pp. 617-622 ◽

Cited By ~ 13

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.

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

ICES Journal of Marine Science ◽

10.1016/j.icesjms.2005.07.006 ◽

2006 ◽

Vol 63 (1) ◽

pp. 25-35 ◽

Cited By ~ 21

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.

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Distribution and abundance of eggs and estimation of spawning stock biomass of anchovy, Engraulis encrasicolus (Linnaeus, 1758), in the south-eastern Adriatic Sea

Journal of the Marine Biological Association of the United Kingdom ◽

10.1017/s002531541400215x ◽

2015 ◽

Vol 95 (5) ◽

pp. 1051-1059 ◽

Cited By ~ 2

Author(s):

Milica Mandić ◽

Slobodan Regner ◽

Mirko Đurović ◽

Aleksandar Joksimović ◽

Ana Pešić ◽

...

Keyword(s):

Egg Production ◽

Adriatic Sea ◽

Production Method ◽

Seasonal Distribution ◽

The South ◽

South Eastern ◽

Stock Biomass ◽

Spawning Stock ◽

First Time ◽

Egg Abundance

Seasonal distribution and abundance of anchovy eggs were analysed during three scientific cruises carried out from summer 2006 to summer 2007 in the Boka Kotorska Bay, and one cruise in July 2008 in the open waters of the south-eastern Adriatic Sea. Daily egg production method (DEPM) was applied for the first time for estimation of the anchovy spawning stock biomass in the south-eastern Adriatic Sea. The daily egg production was 13–581 eggs day−1 within the bay, and 42–110 eggs day−1 in the open waters. Anchovy egg abundance was highest in spring inside the Bay of Kotor (one of the innermost and eutrophic sub-bays of the Boka Kotorska Bay), which indicates that the conditions for anchovy spawning are very favourable in this part of the Adriatic Sea, even when temperatures are below the optimum. This study has shown that the Boka Kotorska Bay is an area of very intensive spawning of anchovy, and that small-size anchovies live and spawn in the bay, and after spawning migrate towards open waters. The length at which 50% of anchovy were mature (L50) was calculated as 9.28 for females and 9.02 for males. Spawning stock biomass was at a stable level during the period of investigation.

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Estimation of the spawning stock biomass of blue grenadier (Macruronus novaezelandiae) off western Tasmania based upon the annual egg production method

Marine and Freshwater Research ◽

10.1071/mf98104 ◽

1999 ◽

Vol 50 (3) ◽

pp. 197 ◽

Cited By ~ 8

Author(s):

C. M. Bulman ◽

J. A. Koslow ◽

K. A. Haskard

Keyword(s):

Egg Production ◽

Production Method ◽

Confidence Limits ◽

A Value ◽

Stock Biomass ◽

Spawning Stock ◽

Egg Density ◽

Spawning Periods ◽

Total Stock ◽

Spawning Biomass

Egg production of the blue grenadier, Macruronus novaezelandiae, spawning stock off western Tasmania was surveyed from June through September in 1994 and 1995. In each year, daily egg production rates were calculated for each of three surveys and a normal curve was fitted to estimate annual egg production. The CV for the egg production estimate for the survey at the peak of the 1995 season was 14%. Daily egg mortality was not significant in any survey, but a value of 5% was assumed. The spawning biomass of blue grenadier on the west coast of Tasmania was estimated to be between 83 660 and 100 073 t in 1994 and between 59 727 and 71 376 t in 1995. Confidence limits of the estimates were obtained by a bootstrap where the highly skewed egg density data were resampled. Biomass was approximately inversely proportional to incubation time. Increases or decreases in mortality resulted in slightly smaller increases or decreases of biomass respectively. Uncertainty of the sex ratio between spawning and non-spawning periods caused the largest variation in biomass estimate (~30%). The proportion of the population that spawns each year remains a further uncertainty in the estimate of total stock biomass.

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First thorough assessment of de novo oocyte recruitment in a teleost serial spawner, the Northeast Atlantic mackerel (Scomber scombrus) case

Scientific Reports ◽

10.1038/s41598-021-01234-1 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Thassya C. dos Santos Schmidt ◽

Anders Thorsen ◽

Aril Slotte ◽

Leif Nøttestad ◽

Olav S. Kjesbu

Keyword(s):

Egg Production ◽

De Novo ◽

Seasonal Pattern ◽

Production Method ◽

Spawning Period ◽

Northeast Atlantic ◽

Atlantic Mackerel ◽

Scomber Scombrus ◽

Stock Biomass ◽

Spawning Stock

AbstractThe understanding of teleost fecundity type (determinate or indeterminate) is essential when deciding which egg production method should be applied to ultimately estimate spawning stock biomass. The fecundity type is, however, unknown or controversial for several commercial stocks, including the Northeast Atlantic mackerel (Scomber scombrus). Aiming at solving this problem, we applied state-of-the-art laboratory methods to document the mackerel fecundity type, including any de novo oocyte recruitment during spawning. Initially, active mackerel spawning females were precisely classified according to their spawning status. The number and size of all phasei-specific oocytes (12 phases), with a special attention to previtellogenic oocytes phases (PVO [PVO2 to PVO4a–c]), were also thoroughly investigated. Examinations of relative fecundity (RFi) clarified that the latest phase of PVOs (PVO4c) are de novo recruited to the cortical alveoli–vitellogenic pool during the spawning period, resulting in a dome-shaped seasonal pattern in RFi. Hence, we unequivocally classify mackerel as a true indeterminate spawner. As PVO4c oocytes were currently identified around 230 µm, mackerel fecundity counts should rather use this diameter as the lower threshold instead of historically 185 µm. Any use of a too low threshold value in this context will inevitably lead to an overestimation of RFi and thereby underestimated spawning stock biomass.

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Spatiotemporal modelling for the annual egg production method of stock assessment using generalized additive models

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f98-143 ◽

1998 ◽

Vol 55 (12) ◽

pp. 2608-2621 ◽

Cited By ~ 23

Author(s):

N H Augustin ◽

D L Borchers ◽

E D Clarke ◽

S T Buckland ◽

M Walsh

Keyword(s):

Environmental Variables ◽

Egg Production ◽

Survey Design ◽

Stock Assessment ◽

Generalized Additive Models ◽

Production Method ◽

Additive Models ◽

Atlantic Mackerel ◽

Egg Density ◽

Survey Designs

Generalized additive models (GAMs) are used to model the spatiotemporal distribution of egg density as a function of locational and environmental variables. The main aim of using GAMs is to improve precision of egg abundance estimates needed for the annual egg production method. The application of GAMs requires a survey design with good coverage in space and time. If the only results available are from less optimal survey designs, they can be improved by using historical data for spawning boundaries. The method is applied to plankton egg survey data of Atlantic mackerel (Scomber scombrus) in 1995. The GAM-based method improves the precision of estimates substantially and is also useful in explaining complex space-time trends using environmental variables.

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New insights in the biogeographical distributions of two Spionidae (Annelida) from the NE Atlantic and Mediterranean French coasts

Zoosymposia ◽

10.11646/zoosymposia.19.1.18 ◽

2020 ◽

Vol 19 (1) ◽

pp. 173-184

Author(s):

JÉRÔME JOURDE ◽

NICOLAS LAVESQUE ◽

CÉLINE LABRUNE ◽

JEAN-MICHEL AMOUROUX ◽

PAULO BONIFÁCIO ◽

...

Keyword(s):

Mediterranean Sea ◽

Morphological Characters ◽

Bay Of Biscay ◽

Ne Atlantic ◽

Marine Waters ◽

Gulf Of Lion ◽

The Mediterranean ◽

Brown Pigmentation

We report the first occurrences of Spiophanes afer Meißner, 2005 and Prionospio cristaventralis Delgado-Blas, Díaz-Díaz & Viéitez, 2018 from French marine waters (from the southern part of the Bay of Biscay in NE Atlantic, and the Gulf of Lion in the Mediterranean Sea). Morphological characters of S. afer include the presence of an occipital antenna, dorsal ciliated organs extending to chaetigers 13–15, neuropodial hooks from chaetiger 15, ventrolateral intersegmental pouches from chaetigers 14–15, chaetal spreaders of “2+3 type”, and conspicuous dark brown pigmentation on parapodia of chaetigers 9–13. Prionospio cristaventralis has four pairs of branchiae (1st and 4th pinnate, 2nd and 3rd apinnate), ventral crests from chaetigers 11–12, high dorsal crests on chaetigers 10–11, and very large notopodial prechaetal lamellae on anterior chaetigers. Both records represent northern extensions of their known distributions. However, the presence of S. afer on French coasts may have been overlooked for several decades. The validity of the recently proposed Spiophanes adriaticus is questioned.

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CCAMLR’s precautionary approach to management focusing on Ross Sea toothfish fishery

Antarctic Science ◽

10.1017/s095410201400087x ◽

2015 ◽

Vol 27 (4) ◽

pp. 333-340 ◽

Cited By ~ 12

Author(s):

Stuart Hanchet ◽

Keith Sainsbury ◽

Doug Butterworth ◽

Chris Darby ◽

Viacheslav Bizikov ◽

...

Keyword(s):

Fisheries Management ◽

Management System ◽

Ross Sea ◽

Stock Assessment ◽

Precautionary Approach ◽

Adaptive Feedback ◽

Stock Biomass ◽

Stock Assessments ◽

Antarctic Marine ◽

Spawning Stock

AbstractSeveral recent papers have criticized the scientific robustness of the fisheries management system used by the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR), including that for Ross Sea toothfish. Here we present a response from the wider CCAMLR community to address concerns and to correct some apparent misconceptions about how CCAMLR acts to promote conservation whilst allowing safe exploitation in all of its fisheries. A key aspect of CCAMLR’s approach is its adaptive feedback nature; regular monitoring and analysis allows for adjustments to be made, as necessary, to provide a robust management system despite the statistical uncertainties inherent in any single assessment. Within the Ross Sea, application of CCAMLR’s precautionary approach has allowed the toothfish fishery to develop in a steady fashion with an associated accumulation of data and greater scientific understanding. Regular stock assessments of the fishery have been carried out since 2005, and the 2013 stock assessment estimated current spawning stock biomass to be at 75% of the pre-exploitation level. There will always be additional uncertainties which need to be addressed, but where information is lacking the CCAMLR approach to management ensures exploitation rates are at a level commensurate with a precautionary approach.

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Recruitment variation in abalone: Its importance to fisheries management

Marine and Freshwater Research ◽

10.1071/mf9950555 ◽

1995 ◽

Vol 46 (3) ◽

pp. 555 ◽

Cited By ~ 32

Author(s):

PE McShane

Keyword(s):

Egg Production ◽

Field Experiments ◽

Stock Assessment ◽

Reference Points ◽

High Fecundity ◽

Spatial And Temporal Scales ◽

Recruitment Failure ◽

Spawning Stock ◽

Stock Recruitment ◽

Many Sources

Recruitment failure has been implicated in the decline of several abalone fisheries. Traditionally, fisheries scientists invoke theoretical stock-recruitment relationships to predict trends in abundance of an exploited stock under various harvest regimes. The empirical evidence in support of a positive relationship between spawning stock and recruits is not strong. A further problem in interpretation of such relationships is that both 'stock' and 'recruitment' have various definitions in fisheries and ecological literature. The definition of a stock for abalone is not clear. As emphasized in this review, which considers each stage in the life history of abalone, the abundance of spawners is one of many sources of variation in recruitment. The evidence for invertebrates, particularly those with high fecundity, is that recruitment varies independently of the abundance of spawners. This is also the case for abalone, where recruits have been measured as the density of immediate post-settlement individuals, juveniles, or as adults entering the exploitable stock. A problem with stock-recruitment hypotheses is that they have intuitive appeal. It is considered 'dangerous' to manage fisheries under the assumption that a reduction in the number of spawners by fishing will not affect recruitment. Such danger to abalone stocks has been more recently assessed by egg-per-recruit analyses, whereby various harvest strategies are examined relative to reference points for egg production. These studies are reviewed and assessed relative to the often conflicting aims of managers and scientists. This review of studies of recruitment variation in abalone emphasizes the need for a more rigorous, autecological approach to stock assessment in which field experiments are conducted over realistic spatial and temporal scales, permitting robust testing of hypotheses.

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