Sources of Variation in Growth of the European Eel (Anguilla anguilla) Estimated from Otoliths

1994 ◽  
Vol 51 (3) ◽  
pp. 506-515 ◽  
Author(s):  
Jacques Panfili ◽  
Marie-Claude Ximénès ◽  
Alain J. Crivelli
Keyword(s):  
Somatic Growth ◽  
Growth Period ◽  
Anguilla Anguilla ◽  
Individual Variability ◽  
Fish Length ◽  
European Eel ◽  
Otolith Growth ◽  
Absolute Growth ◽  
Sources Of Variation ◽  
Natural Pond

Tetracycline labelling of otoliths was used for studying the growth of the European eel (Anguilla anguilla), which has strong individual variability. Two groups of eels were injected with tetracycline and released into a natural pond (Camargue, south of France) in spring 1989 and in autumn 1989. The marginal growth of otoliths between marking (tetracycline mark) and capture (otolith margin) was measured for all fish sampled until spring 1990. Comparisons of otolith growth rates were made according to fish size, age, sex, and growth period (ANCOVA). The results showed a great variability. After 15 mo of growth, the mean growth in length (back-calculated) was 6.6 cm. The three main factors tested, age, sex, and seasonal growth period, had a significant effect on otolith growth and therefore on somatic growth, since the relation between fish length and that of the otolith is highly significant (r2 = 0.802). There was also a very significant effect of size at marking on otolith growth. It is difficult to rank qualitative importance of these various factors, even though there are no interactions among them. The best absolute growth in Mediterranean lagoons could be attained by 2-yr-old female fish growing in the summer months.

scholarly journals Relationships of Otolith Dimension with Body Length of European Eel Anguilla anguilla (Linnaeus, 1758) from Adriatic catchment of Montenegro

2018 ◽  
Vol 59 (1) ◽  
pp. 91-96 ◽  
Author(s):  
Tamara Kanjuh ◽  
Danilo Mrdak
Keyword(s):  
Linear Function ◽  
Body Length ◽  
Somatic Growth ◽  
Anguilla Anguilla ◽  
Body Growth ◽  
The Body ◽  
European Eel ◽  
Fish Size ◽  
Sagittal Otolith ◽  
The Relationship

This study examined the relationship between the sagittal otolith morphometric variables (length, height and weight) and body growth of the European eel. Eels that were studied ranged in total length from 11.2 to 79.5 cm. The relationships between the sagittal otolith variables and fish somatic growth were described with a non-linear function. The resulting coefficients of determination \((r^2)\) ranged from 0.782 to 0.914. The variable most strongly related to fish size was found to be the sagittal otolith length (OL) with 91.4 % of the variability. The results of this study provide the first comprehensive data regarding the relationship between the sagittal otolith morphometric variables with the body length of Anguilla anguilla.

scholarly journals Is the continental life of the European eel Anguilla anguilla affected by the parasitic invader Anguillicoloides crassus ?

2013 ◽  
Vol 280 (1754) ◽  
pp. 20122916 ◽  
Author(s):  
François Lefebvre ◽  
Géraldine Fazio ◽  
Béatrice Mounaix ◽  
Alain J. Crivelli
Keyword(s):  
Reproductive Potential ◽  
Adaptive Immune Response ◽  
Anguilla Anguilla ◽  
Individual Variability ◽  
Growth Potential ◽  
Size Increase ◽  
European Eel ◽  
History Of ◽  
Internal Marker ◽  
Anguillicoloides Crassus

Quantifying the fitness cost that parasites impose on wild hosts is a challenging task, because the epidemiological history of field-sampled hosts is often unknown. In this study, we used an internal marker of the parasite pressure on individual hosts to evaluate the costs of parasitism with respect to host body condition, size increase and reproductive potential of field-collected animals for which we also determined individual age. In our investigated system, the European eel Anguilla anguilla and the parasitic invader Anguillicoloides crassus , high virulence and severe impacts are expected because the host lacks an adaptive immune response. We demonstrated a nonlinear relationship between the severity of damage to the affected organ (i.e. the swimbladder, our internal marker) and parasite abundance and biomass, thus showing that the use of classical epidemiological parameters was not relevant here. Surprisingly, we found that the most severely affected eels (with damaged swimbladder) had greater body length and mass (+11% and +41%, respectively), than unaffected eels of same age. We discuss mechanisms that could explain this finding and other counterintuitive results in this host–parasite system, and highlight the likely importance of host panmixia in generating great inter-individual variability in growth potential and infection risk. Under that scenario, the most active foragers would not only have the greatest size increase, but also the highest probability of becoming repeatedly infected—via trophic parasite transmission—during their continental life.

scholarly journals Unsupervised Bayesian reconstruction of individual life histories from otolith signatures: case study of Sr:Ca transects of European eel (Anguilla anguilla) otoliths

2007 ◽  
Vol 64 (1) ◽  
pp. 152-165 ◽  
Author(s):  
Ronan Fablet ◽  
Françoise Daverat ◽  
Hélène De Pontual
Keyword(s):  
Habitat Use ◽  
Life Histories ◽  
Habitat Type ◽  
River Estuary ◽  
Anguilla Anguilla ◽  
Unsupervised Classification ◽  
European Eel ◽  
Otolith Growth ◽  
Individual Life ◽  
Growth Axis

The reconstruction of individual life histories from chemical otolith measures is stated as an unsupervised signal-processing issue embedded in a Bayesian framework. This computational methodology was applied to a set of 192 European eel (Anguilla anguilla) otoliths. It provided a robust and unsupervised analysis of the individual chronologies of habitat use (either river, estuary, or coastal) from Sr:Ca measures acquired along an otolith growth axis. Links between Sr:Ca values and habitat, age, and season and the likelihood of the transitions from one habitat type to another were modelled. Major movement characteristics such as age at transition between habitats and time spent in each habitat were estimated. As a straightforward output, an unsupervised classification of habitat use patterns showed great variability. Using a hidden Markov model, 37 patterns of habitat use were found, with 20 different patterns accounting for 90% of the sample. In accordance with literature, residence behaviour was observed (28% of the eels). However, about 72% changed habitat once or several times, mainly before age 4. The potential application of this method to any other measures taken along an otolith growth axis to reconstruct individual chronologies gives a new insight in life history tactics analysis.

Interpretation of Otolith Microstructure in Juvenile Winter Flounder (Pseudopleuronectes americanus): Ontogenetic Development, Daily Increment Validation, and Somatic Growth Relationships

1991 ◽  
Vol 48 (10) ◽  
pp. 1862-1871 ◽  
Author(s):  
Susan M. Sogard
Keyword(s):  
Growth Rates ◽  
Somatic Growth ◽  
Winter Flounder ◽  
Pseudopleuronectes Americanus ◽  
Otolith Growth ◽  
Morphological Asymmetry ◽  
Daily Increments ◽  
Absolute Growth ◽  
Left And Right ◽  
Calcium Carbonate Deposition

In winter flounder (Pseudopleuronectes americanus), sagittae developed secondary origins of calcium carbonate deposition during metamorphosis just prior to completion of eye migration. Sagittae and lapilli of larvae were bilaterally symmetrical, but those of postmetamorphic individuals showed increasing morphological asymmetry between the left and right side. In juveniles marked with oxytetracycline and maintained in field enclosures for 10 d, increment deposition on sagittae was daily if somatic growth following marking was good (> 0.25 mm∙d−1), but less than daily in individuals with poor or negative somatic growth (< 0.25 mm∙d−1). Narrowly spaced increments or divergence of otolith growth from the main rostral–postrostral growth axis, where counts were made, may have limited detection of daily deposition. Lack of detectable daily increments occurred primarily in larger juveniles (> 50 mm total length), which had lower absolute growth rates than newly settled juveniles. In oxytetracycline-marked fish there was a significant correspondence between otolith growth and somatic growth in both length and weight. The strength of this relationship, which varied with the specific radius used, was highest (r = 0.854) for the rostral radius of the left sagitta; increment widths along this radius are reliable estimators of prior somatic growth rates.

Metazoan Parasites and Health State of European Eel, Anguilla Anguilla (Anguilliformes, Anguillidae), From Tonga Lake and El Mellah Lagoon in the Northeast of Algeria

2018 ◽  
Vol 52 (4) ◽  
pp. 279-288 ◽  
Author(s):  
F. Bakaria ◽  
S. Belhaoues ◽  
N. Djebbari ◽  
M. Tahri ◽  
I. Ladjama ◽  
...  
Keyword(s):  
Brackish Water ◽  
Parasite Species ◽  
Anguilla Anguilla ◽  
European Eel ◽  
Health State ◽  
Component Community ◽  
Metazoan Parasites ◽  
Parasite Communities ◽  
High Dominance ◽  
Argulus Foliaceus

Abstract The aim of the study was to examine metazoans parasite communities of European eels (Anguilla anguilla) in freshwater (Tonga Lake) and brackish water (El Mellah lagoon) in the northeast of Algeria. Six parasite taxa were collected: one monogenean, Pseudodactylogyrus sp.; two crustaceans, Ergasilus sp. and Argulus foliaceus; two nematodes, Cucullanus sp. and Anguillicola crassus; one cestode, Bothriocephalus claviceps. Th e most prevalent parasite taxa in freshwater were Pseudodactylogyrus sp., A. crassus and Bothriocephalus claviceps; whereas in the brackish water, eels were infected mainly with A. crassus. Th e characteristics of the parasite component community structure revealed low parasite species diversity and high dominance values in eels from the two localities. Both communities were dominated by a single parasite species: Tonga eels by the monogenean Pseudodactylogyrus sp. and El Mellah lagoon eels by the nematode A. crassus, verified by high Berger-Parker dominance values of 0.76 and 0.87 respectively.

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