Daily growth rate of juvenile anchovy, Engraulis encrasicolus (Linnaeus, 1758), was estimated in the south-eastern Adriatic Sea. Samples were taken by a commercial beach seine net and the size range ...of 100 sampled individuals was 5.0-6.8 cm total length. Age was estimated by counting growth increments of sagittal otoliths, which are formed with daily periodicity. Estimated ages were 41 - 90 days and hatch date for each age class was back-calculated from the date of capture. The calculated instantaneous growth rate was 0.41 mm day super(-1). Fish size at metamorphosis from late larva to juvenile was estimated to 3.2 cm total length. Parameters of the von Bertalanffy's growth function were L sub( proportional to ) = 10.41 and K = 3.36.Original Abstract: Dnevna stopa rasta juvenilnog incuna, Engraulis encrasicolus (Linnaeus, 1758), procijenjena je u jugoistocnom Jadranu. Uzorci su sakupljani komercijalnom obalnom mrezom potegacom, a raspon velicine kod 100 uzorkovanih jedinki iznosio je 5.0-6.8 cm ukupne duzine. Dob je procijenjena brojenjem dnevnih narastajnih prstenova na sagitalnim otolitima. Procijenjena starost kolebala je izmedu 41-90 dana, a nadnevak izvaljivanja licinke za svaki starosni razred bio je naknadno izracunat prema datumu ulova. Izracunata trenutna stopa rasta iznosila je 0.41 mm dan super(-1). Velicina ribe za vrijeme metarmofoze iz kasnog stadija licinke u juvenilni stadij procijenjena je na 3.2 cm ukupne duzine. Parametri u von Bertalanffy-jevoj jednadzbi rasta bili su L sub( proportional to ) = 10.41 i K = 3.36.
An updated checklist of the monogenoids infecting Italian marine fish is provided, including seven new records (Diplectanum simile on Sciaena umbra; Diplectanum sp. on Scorpaena porcus; Lamellodiscus ...elegans, L. ergensi, L. fraternus on Diplodus vulgaris; L. virgula on Pagellus erythrinus; Pseudanthocotyloides heterocotyle on Engraulis encrasicolus). The number of monogenoidean species recorded in Italian marine ichtyofauna is therefore increased to 141, harboured by 93 host species.
Specimens of twaite shad, Alosa fallax were sampled from commercial purse seiners and trammel netters in Izmir Bay during November and December 2007. A total of 287 prey items from 14 taxa from 208 ...stomachs were recorded. The primary food of twaite shad was found to be fish, especially anchovy Engraulis encrasicolus, which was the most frequent (%F = 66.11) and abundant (%N = 63.64) prey item, and also had the highest percentage by weight (%W = 81.91). Decapoda, Isopoda, Ostracoda and Copepoda (Calanus spp., Candocia armata, Temora stylifera from Calanoida and Corycaeus spp. from Cyclopodia), were recorded occasionally with low values for all indices. The study showed that in the Aegean Sea Alosa fallax is a predator of small pelagic fish, E. encrasicolus, A. boyeri, S. pilchardus, and some crustaceans. Benthopelagic P. acarne and demersal S. hepatus were first recorded in diet of twaite shad.
Similar regimes of selection in different geographical settings can deterministically produce similar adaptive morphologies. We tested the hypothesis that the evolutionary trajectories of fish in ...upwelling zones can be altered by biogeographic contingencies in the biological and physical environment. Eastern Pacific and western Atlantic oceans. We estimated phylogenetic relationships among eastern Pacific temperate anchovies (genus Engraulis) and tropical anchovies (genus Cetengraulis) with neighbour-joining and Bayesian tree analysis of a 521-bp segment of mitochondrial DNA cytochrome b. Available sequences for five additional engraulid taxa were included to establish polarity of the tree. Bayesian estimates (BEAST) of time to most recent common ancestor (TMRCA) for the nodes in the phylogeny were calibrated with divergence between Cetengraulis edentulus and Cetengraulis mysticetus precipitated by the rise of the Panama Isthmus 2.8-3.2 Ma. Neighbour-joining and Bayesian trees indicate that South American Engraulis anchoita (Argentina) and Engraulis ringens (Chile) together are basal sister taxa to the California anchovy (Engraulis mordax) and Old World anchovies (Engraulis japonicas, Engraulis australis, Engraulis capensis and Engraulis encrasicolus). The two tropical species of Cetengraulis are sister-taxa to Californian E. mordax, even though their phenotypes and ecologies differ markedly. A relaxed molecular clock indicates a TMRCA between Californian E. mordax and Cetengraulis at about 4.2 Ma (3.0-6.3 Ma 95% highest probability density). The TMRCA between the California anchovy, E. mordax, and tropical Cetengraulis coincides with the formation of the Gulf of California, which provided opportunities for allopatric isolation during climate oscillations. Mid-Pliocene warming (3.1-2.9 Ma) may have trapped ancestors of Cetengraulis in the Gulf of California, where they evolved digestive tract morphologies to exploit inshore tropical habitats with low plankton productivities. While populations of several other temperate fishes have become isolated in the Gulf of California, few of these derived species show strong adaptive shifts from temperate sister taxa or range expansions into the tropical provinces of the western Atlantic and eastern Pacific.
The growth strategies of pelagic larvae of 3 fish species from the Bay of Biscay belonging to 2 different shape groups, the eel-like anchovyEngraulis encrasicolusand sardineSardina pilchardus, and ...the tadpole-like horse mackerelTrachurus trachurus, are compared in terms of changes in their biochemical composition and energy allocation. In anchovy and sardine, the relative amount of protein increased and relative amounts of carbohydrates and lipids decreased throughout their growth. The biochemical composition in horse mackerel did not change significantly during growth. Differences between the 2 shape groups could be associated with the various energy allocation patterns related to dissimilar growth strategies. Although the patterns of change in biochemical composition during growth are different in the 2 shape groups, they show a very similar biochemical composition at the notochord flexion stage, indicating convergences in life-history patterns of the different species.
A simple two-stage biomass random effects population dynamics model is presented for carrying out fish stock assessments based on survey indices using no commercial catch information. Recruitment and ...biomass growth are modelled as random effects, reducing the number of model parameters while maintaining model flexibility. No assumptions regarding natural mortality rates are required. The performance of the method was evaluated using simulated data with emphasis on identifying parameter redundancy, which showed that the variance of the biomass growth random effect might only be estimable if large (>0.2). The full and two nested models were fitted to European anchovy (
Engraulis encrasicolus
) in the Bay of Biscay using two survey series. The best-fitting model had fixed biomass growth and random recruitment following a lognormal distribution.
Knowledge of the pelagic vertical distribution of fish eggs is central for several aspects of fisheries science including fisheries recruitment and egg production studies. In modelling egg vertical ...distributions, variation in fish egg density is an important issue. Though variation in egg density between individual eggs has been reported, evidence for significant spatial variation in egg density is novel. The present study provides evidence that egg density of anchovy (Engraulis encrasicolus) varies spatially across spawning sites in the Bay of Biscay, depending on the regional scale variation in sea water properties due to river discharge. We measured the density of the eggs using a density gradient column at 17 stations in 2005 and 2006 as well as their diameter. At station, the variability in the individual egg density was statistically distributed according to a Gaussian probability function. Significant variation in the mean egg density was observed across stations. Mean egg density displayed a significant correlation with sea surface salinity. Results are discussed in light of the mechanisms determining the egg density. PUBLICATION ABSTRACT
The otolith (sagitta) measurements of five pelagic fish species - Engraulis encrasicolus (Linnaeus, 1758); Sardina pilchardus (Walbaum, 1792); Scomber scombrus Linnaeus, 1758; Scomber japonicus ...Houttuyn, 1780 and Belone belone (Linnaeus, 1761) - were obtained by image analysis of catch samples retrieved from the Croatian part of the Adriatic Sea. Three dimensionless shape descriptors of form factor (FF), roundness (RD) and aspect ratio (AR) were analysed and revealed statistically significant differences between the otoliths of the stated pelagic fish species. Maximum otolith length (LO) and otolith weight (WO) were linearly correlated to total fish length (TL) for each studied fish species; they were increasing proportionally during fish growth.Original Abstract: U radu se iznose rezultati morfometrijske analize otolita brgljuna Engraulis encrasicolus (Linnaeus, 1758), srdele Sardina pilchardus (Walbaum, 1792), skuse Scomber scombrus Linnaeus, 1758, lokarde Scomber japonicus Houttuyn, 1780 i iglice Belone belone (Linnaeus, 1761). Za svaku je istrazivanu vrstu analizirano po 30 jedinki koje potjecu iz lovina ostvarenih na podrucju istocnog dijela Jadrana tijekom razdoblja sijecanj - prosinac 2005. godine. Na temelju analize triju faktora oblika otolita (FF, RD, AR) je uoceno da postoji statisticki znacajna razlika izmedju otolita promatranih pelagicnih vrsta riba. Znacajna linearna korelacija je utvrdjena izmedju najvece duzine otolita (LO) i ukupne duzine tijela ribe (LT) kao i mase otolita (WO) i ukupne duzine tijela ribe (LT) - s porastom ukupne duzine tijela analizirane pelagicne vrste se proporcionalno povecavala najveca duzina otolita i masa otolita.
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