The daily egg production method: recent advances, current applications and future challenges

By Y. Stratoudakis, M. Bernal, K. Ganias, A. Uriarte. 2006

184 citations recorded by the source corpus.

More than 120 surveys over 25 years suggest that appropriate use of the daily egg production method (DEPM) provides unbiased but rather imprecise estimates of spawning biomass (coefficient of variation generally above 30%). Knowledge of species reproductive biology and early life history and a survey design adapted to local population dynamics are required to optimize DEPM performance in terms of bias, precision and cost. Clupeoid applications dominate worldwide (mainly for anchovies and sardines) and estimates are often used to tune indirect assessment models or to calibrate other fisheries-independent methods. The method seems better adapted to the life history of anchovies than of sardines, leading to more precise estimates of anchovy spawning biomass and facilitating extensions of the method to estimate total biomass and numbers at age. The continuous underway fish egg sampler is often used as a secondary sampler in the ichthyoplankton survey of the DEPM to reduce the cost and improve the precision of egg production. Multinomial models were recently developed to analyse egg incubation data and used in a Bayesian procedure for egg ageing and delimitation of daily cohorts. These were incorporated in model-based estimators to get spatially explicit estimates of egg production, daily fecundity parameters and spawning biomass that can improve the precision of DEPM. Uncertainty in daily fecundity estimation of clupeoids is mainly because of spawning fraction estimation by the post-ovulatory follicle (POF) method. Exploration of recent histological and molecular techniques for POF characterization and laboratory experiments to test the effect of temperature on POF degradation can help to improve spawning fraction estimation. Available estimates of egg production and mortality, daily fecundity, spawning area and biomass from different populations, species and ecosystems are being used to improve the understanding of clupeoid spawning dynamics, their relation with ecosystem productivity and to build comprehensive population models. Finally, a counter-intuitive finding of this review is that, although the DEPM is almost exclusively applied to clupeoids, recent evidence indicates that it may be easier and cheaper to use in other teleost families, including demersal species.

Subfields: Global and Planetary Change, Nature and Landscape Conservation, Physiology

View Paper: https://www.semanticscholar.org/paper/3e7942145548fecbf9bf31747973766c40e8c2ae

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Citations in the corpus

Reproductive Timing in Marine Fishes: Variability, Temporal Scales, and Methods (2011, methodology): “…spawning (i.e., hours prior to spawning or hours postspawning), and this requires prior knowledge of diel periodicity or spawn times as well as the ability to identify clear histomorphological stages in OM and POF resorption (Hunter and Macewicz 1985; Stratoudakis et al. 2006; Ganias et al. 2007).”
Sardine (Sardina pilchardus) spawning seasonality in European waters of the northeast Atlantic (2007, background): “For an indeterminate spawner with a low daily-spawning fraction (ICES 2004; Stratoudakis et al. 2006) this can refer to a period that is larger than 10 days, but, in the absence of histological data, this is the limit of precision.”