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.

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 Fecundity of silver-phase eels (Anguilla anguilla) from different habitat types and geographic locations

2015 ◽  
Vol 73 (1) ◽  
pp. 135-141 ◽  
Author(s):  
Ruairí MacNamara ◽  
T. Kieran McCarthy ◽  
Håkan Wickström ◽  
Patrik D. Clevestam
Keyword(s):  
Life History ◽  
Body Size ◽  
Baltic Sea ◽  
Life History Traits ◽  
Geographic Origin ◽  
Habitat Type ◽  
Anguilla Anguilla ◽  
European Eel ◽  
Habitat Types ◽  
Geographic Locations

Abstract The reproductive ecology of European eel (Anguilla anguilla) is poorly understood, though information on life-history traits such as fecundity is necessary for appropriate management of this critically endangered species. During the growth period of the life cycle, yellow-phase eels can be resident in different habitat types (e.g. salinity ranging from freshwater to marine) over a wide geographic distribution. Consequently, maturing silver-phase eels migrating back to the oceanic spawning grounds can display considerable variation in certain life-history traits depending on their habitat and/or geographic origin. Few fecundity estimates are available from wild A. anguilla, and no investigation of the effects of habitat type (i.e. salinity) or geographic location on variation in fecundity has been undertaken. To assess the former, we examined silver-phase eels which had predominantly been resident in freshwater (Lake Mälaren, Sweden) or brackish (Baltic Sea) habitats. Despite Lake Mälaren eels generally being larger, there was no difference in the fecundity–body size relationship between these salinity zones. Second, we determined if fecundity differed between silver-phase eels sampled from different geographic locations: Lake Mälaren and the Baltic Sea outlet in Sweden, the River Shannon in Ireland (northwest Europe) and Vistonis Lake in Greece (eastern Mediterranean). Our results showed that silver-phase eels from Sweden (Lake Mälaren and Baltic Sea outlet) and Greece were significantly more fecund at a given body size than those from Ireland. Spawner models and conservation policies should therefore take account of eel geographic origin in particular when incorporating this life-history parameter.

Habitat use by the European eel Anguilla anguilla in Irish waters

2006 ◽  
Vol 67 (4) ◽  
pp. 569-578 ◽  
Author(s):  
T. Arai ◽  
A. Kotake ◽  
T.K. McCarthy
Keyword(s):  
Habitat Use ◽  
Anguilla Anguilla ◽  
European Eel

scholarly journals Phenotypic plasticity in habitat use and growth of the European eel (Anguilla anguilla) in transitional waters in the Mediterranean area

2013 ◽  
Vol 23 (1) ◽  
pp. 65-76 ◽  
Author(s):  
Fabrizio Capoccioni ◽  
Dai-Yu Lin ◽  
Yoshiyuki Iizuka ◽  
Wann-Nian Tzeng ◽  
Eleonora Ciccotti
Keyword(s):  
Phenotypic Plasticity ◽  
Habitat Use ◽  
Anguilla Anguilla ◽  
Mediterranean Area ◽  
European Eel ◽  
Transitional Waters ◽  
The Mediterranean

scholarly journals Oceanic fronts in the Sargasso Sea control the early life and drift of Atlantic eels

2010 ◽  
Vol 277 (1700) ◽  
pp. 3593-3599 ◽  
Author(s):  
Peter Munk ◽  
Michael M. Hansen ◽  
Gregory E. Maes ◽  
Torkel G. Nielsen ◽  
Martin Castonguay ◽  
...  
Keyword(s):  
Life Cycle ◽  
Life Histories ◽  
Anguilla Anguilla ◽  
European Eel ◽  
Sargasso Sea ◽  
American Eel ◽  
Wide Range ◽  
Frontal Processes ◽  
Glass Eels ◽  
Atlantic Eels

Anguillid freshwater eels show remarkable life histories. In the Atlantic, the European eel ( Anguilla anguilla ) and American eel ( Anguilla rostrata ) undertake extensive migrations to spawn in the oceanic Sargasso Sea, and subsequently the offspring drift to foraging areas in Europe and North America, first as leaf-like leptocephali larvae that later metamorphose into glass eels. Since recruitment of European and American glass eels has declined drastically during past decades, there is a strong demand for further understanding of the early, oceanic phase of their life cycle. Consequently, during a field expedition to the eel spawning sites in the Sargasso Sea, we carried out a wide range of dedicated bio-physical studies across areas of eel larval distribution. Our findings suggest a key role of oceanic frontal processes, retaining eel larvae within a zone of enhanced feeding conditions and steering their drift. The majority of the more westerly distributed American eel larvae are likely to follow a westerly/northerly drift route entrained in the Antilles/Florida Currents. European eel larvae are generally believed to initially follow the same route, but their more easterly distribution close to the eastward flowing Subtropical Counter Current indicates that these larvae could follow a shorter, eastward route towards the Azores and Europe. The findings emphasize the significance of oceanic physical–biological linkages in the life-cycle completion of Atlantic eels.

scholarly journals Occurrence and habitat use of European eel (Anguilla anguilla) in running waters: lessons for improved monitoring, habitat restoration and stocking

2019 ◽  
Vol 53 (4) ◽  
pp. 639-650 ◽  
Author(s):  
Erik Degerman ◽  
Carl Tamario ◽  
Johan Watz ◽  
P. Anders Nilsson ◽  
Olle Calles
Keyword(s):  
Habitat Use ◽  
Habitat Restoration ◽  
Anguilla Anguilla ◽  
European Eel ◽  
Running Waters

Advances in Fish Tagging and Marking Technology

2012 ◽  
Keyword(s):  
Growth Rates ◽  
Life Histories ◽  
River Mouth ◽  
Anguilla Anguilla ◽  
European Eel ◽  
Coastal Site ◽  
Otolith Sr:Ca Ratios ◽  
Sr:Ca Ratios ◽  
The Mean ◽  
Fish Tagging

<i>Abstract</i>.—Restocking programs of the European eel <i>Anguilla anguilla </i>have been conducted for nearly one century in Latvia. To evaluate the efficiency of the eel restocking program and reveal the migratory life histories of European eels in Latvian waters, a total of 75 individuals was collected from the mouth of River Daugava (Daugavgrīva, brackish), a nearby lake (Lake Ķīšezers, freshwater), and a coastal site (Mērsrags, brackish). The naturally-recruited eels consisted of two saltwater types: eels that lived in saltwater and did not enter freshwater (SW, 0–7%) and eels that experienced both freshwater and saltwater, referred to as inter-habitat-shifter (IHS, 60–85%). Restocked eels consisted of purely freshwater types (FW, 7–36.7%)without any exposure to saltwater. Average Sr:Ca ratios at the edge of otoliths were different among sites and origins, and corresponded to the salinities of sampling sites. The mean age at first freshwater entry of IHS was 4.8 ± 2.3 years and was similar to previous studies in Lithuania. The growth rates of FW eels in the river mouth and coast were significantly slower than that of IHS eels (<i>p </i>< 0.001 and 0.012). The use of otolith Sr:Ca ratios as a natural mark to distinguish restocked eels here enabled the assessment of restocking efficiency.

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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