Journal articles: 'Glass eels'

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Budiharjo, Agung, Tjut Sugandawaty Djohan, Djumanto Djumanto, and Jusup Subagja. "UMUR GLAS EEL (Anguilla spp.) YANG MASUK MUARA SUNGAI PROGO, YOGYAKARTA." Berkala Penelitian Hayati 14, no. 2 (June 30, 2009): 179–83. http://dx.doi.org/10.23869/bphjbr.14.2.200910.

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The leptocephalus drift with sea currents and moving from spawning area into coastal area near mouth of Progo River. In the coastal area, leptocephalus metamorfosed into glass eel, after that glass eel migrated to river. The aims of this research were to estimate glass eels age and predict hatching dates. Glass eels sampled on new moon during Februari 2007–Mei 2009 at mouth of Progo River. Glass eel ages estimated using their otolith microstructure. Hatching dates predicted with back calculation of glass eels age. We collected 1.082 glass eels. The ages of glass eel at recruit ranged from 58 to 190 days, and divided into 5 age groups. Glass eels are migrated to river hatched on new moon from July to January. Glass eels are migrated to river during October–January hatched during July–October. Glass eels are migrated to river during February–Juny hatched during November – January.

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Budiharjo, Agung. "KOMPOSISI JENIS LARVA SIDAT (Anguilla spp.) YANG BERMIGRASI KE MUARA SUNGAI PROGO, YOGYAKARTA." Berkala Penelitian Hayati 15, no. 2 (June 30, 2010): 121–26. http://dx.doi.org/10.23869/bphjbr.15.2.20104.

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Progo River is one of the rivers on the Java Island, which empties into the Indian Ocean, are became the entrance of the glass eels from the ocean. Glass eels were entering the river consists of several species. The aim of this research was to study of the species composition of glass eels that migrated into the estuary of the Progo River. Glass eels collected in the estuary in the year 2007–2009 at the lunar date 28 on at 20:00 until 04:00. In the period of 3 years, was successfully collected as many as 1.110 glass eels, which consisted of 3 species of Anguilla marmorata (31.17%), Anguilla bicolor bicolor (64,32%), and Anguilla nebulosa nebulosa (4.50%). Glass eels migrated into the estuary of Progo River during September to June. Glass eel of A. marmorata migrated to the estuary during September to June, A. bicolor bicolor migrated during October to June, and A. nebulosa nebulosa migrated to the estuary only during February to June.

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Cresci, Alessandro, Caroline M. Durif, Claire B. Paris, Cameron R. S. Thompson, Steven Shema, Anne Berit Skiftesvik, and Howard I. Browman. "The relationship between the moon cycle and the orientation of glass eels ( Anguilla anguilla ) at sea." Royal Society Open Science 6, no. 10 (October 2019): 190812. http://dx.doi.org/10.1098/rsos.190812.

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Links between the lunar cycle and the life cycle (migration patterns, locomotor activity, pulses in recruitment) of the European eel ( Anguilla anguilla ) are well documented. In this study, we hypothesized that the orientation of glass eels at sea is related to the lunar cycle. The European eel hatches in the Sargasso Sea and migrates across the Atlantic Ocean towards Europe. Upon reaching the continental shelf, the larvae metamorphose into glass eels and migrate up the estuaries, where some individuals colonize freshwater habitats. How glass eels navigate pelagic waters is still an open question. We tested the orientation of 203 glass eels in a transparent circular arena that was drifting in situ during the daytime, in the coastal Norwegian North Sea, during different lunar phases. The glass eels swimming at sea oriented towards the azimuth of the moon at new moon, when the moon rose above the horizon and was invisible but not during the other moon phases. These results suggest that glass eels could use the moon position for orientation at sea and that the detection mechanism involved is not visual. We hypothesize a possible detection mechanism based on global-scale lunar disturbances in electrical fields and discuss the implications of lunar-related orientation for the recruitment of glass eels to estuaries. This behaviour could help glass eels to reach the European coasts during their marine migration.

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Dutil, J. D., M. Michaud, and A. Giroux. "Seasonal and diel patterns of stream invasion by American eels (Anguilla rostrata) in the northern Gulf of St. Lawrence." Canadian Journal of Zoology 67, no. 1 (January 1, 1989): 182–88. http://dx.doi.org/10.1139/z89-024.

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Seasonal and diel patterns of stream invasion by American eels (Anguilla rostrata) were monitored in a small stream located on the north shore of the Gulf of St. Lawrence from 1981 to 1985. Glass eels and elvers migrated from the sea in late June and July. Glass eels made up only a small percentage of the migrants. Pigmentation progressed quickly in the estuary, but elvers grew very slowly. Migration from the estuary and through the lower reaches of the stream was slow; no glass eels or elvers occurred at a station located only 4 km from saltwater. Juvenile eels reached that station in their second summer of stream residence. Juvenile eels migrated in July and August. They ranged from 70 to 250 mm in length and included more than one age-class. Those less than 100 mm in length were most numerous. Relative abundance of glass eels and elvers decreased in the estuary from 1981 to 1985. This coincided with a decrease in the proportion of smaller sized eels in the stream migration over the same period. Juvenile eels migrated progressively later in summer as the proportion of smaller sized eels decreased. Stream migration was nocturnal. Movements mainly occurred between 21:00 and 23:00. The relationship between glass eel and elver abundance in the estuary and juvenile eel abundance in the stream 1 and 2 years later was not clear.

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Wibowo, Arif, Nicolas Hubert, Hadi Dahruddin, Dirk Steinke, Rezki Antoni Suhaimi, Samuel, Dwi Atminarso, et al. "Assessing Temporal Patterns and Species Composition of Glass Eel (Anguilla spp.) Cohorts in Sumatra and Java Using DNA Barcodes." Diversity 13, no. 5 (April 29, 2021): 193. http://dx.doi.org/10.3390/d13050193.

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Anguillid eels are widely acknowledged for their ecological and socio-economic value in many countries. Yet, knowledge regarding their biodiversity, distribution and abundance remains superficial—particularly in tropical countries such as Indonesia, where demand for anguillid eels is steadily increasing along with the threat imposed by river infrastructure developments. We investigated the diversity of anguillid eels on the western Indonesian islands of Sumatra and Java using automated molecular classification and genetic species delimitation methods to explore temporal patterns of glass eel cohorts entering inland waters. A total of 278 glass eels were collected from monthly samplings along the west coast of Sumatra and the south coast of Java between March 2017 and February 2018. An automated, DNA-based glass eel identification was performed using a DNA barcode reference library consisting of 64 newly generated DNA barcodes and 117 DNA barcodes retrieved from BOLD for all nine Anguilla species known to occur in Indonesia. Species delimitation methods converged in delineating eight Molecular Operational Taxonomic Units (MOTUs), with A. nebolusa and A. bengalensis being undistinguishable by DNA barcodes. A total of four MOTUs were detected within the glass eel samples, corresponding to Anguilla bicolor, A. interioris, A. marmorata, and A. nebulosa/A. bengalensis. Monthly captures indicated that glass eel recruitment peaks in June, during the onset of the dry season, and that A. bicolor is the most prevalent species. Comparing indices of mitochondrial genetic diversity between yellow/silver eels, originating from several sites across the species range distribution, and glass eels, collected in West Sumatra and Java, indicated a marked difference. Glass eels displayed a much lower diversity than yellow/silver eels. Implications for the management of glass eel fisheries and species conservation are discussed.

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Wilson, Jonathan Mark, José Carlos Antunes, Patricío Duro Bouça, and João Coimbra. "Osmoregulatory plasticity of the glass eel of Anguilla anguilla: freshwater entry and changes in branchial ion-transport protein expression." Canadian Journal of Fisheries and Aquatic Sciences 61, no. 3 (March 1, 2004): 432–42. http://dx.doi.org/10.1139/f04-010.

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The glass-eel stage of the life history of Anguillid eels (Anguilla spp.) makes the important physiological transition from seawater (SW) to freshwater (FW) osmoregulation. Central to successful adaptation to fresh water is the switch from active hypoosmoregulation (ion excretion) to active hyperosmoregulation (ion uptake) to counter passive fluxes imposed by concentration gradients. Anguilla anguilla (L.) glass eels, captured from the lower Minho River estuary and maintained in brackish water (BW; 24), were fully capable of adapting to FW following acute transfer. In a comparison between SW- (34) and FW-adapted glass eels, gill Na+/K+-ATPase and Na+:K+:2Cl cotransporter (NKCC) expression were both markedly reduced in the FW group. Branchial mitochondria-rich chloride cells (MRCs) were also significantly larger in SW-adapted glass eels. Apical CFTR Cl channel immunoreactivity associated with branchial MRCs was also only present in SW-adapted glass eels. The expression of these three ion-transport proteins is strongly associated with active ion excretion in SW teleost fishes. In FW-adapted glass eels, cortisol treatment increased branchial Na+/K+-ATPase expression but was without effect on NKCC expression. Glucocorticoid receptor blockade by RU-486 had no effect on Na+/K+-ATPase or NKCC expression.

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Sukardi, Purnama, Norman Ari Prayogo, Tjahyo Winanto, Asrul Sahri Siregar, and Taufan Harisam. "Nursery I: The effect of stocking density on the performance of glass eels, Anguilla bicolor in the biofloc system." E3S Web of Conferences 47 (2018): 02009. http://dx.doi.org/10.1051/e3sconf/20184702009.

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Glass eels of Anguilla bicolor is an expensive and still abundant commodity in Laguna Segara Anakan, Central Java, Indonesia. However, the growth of glass eels to elver is still a problem because of high mortality in nursery I and II. The objective of the study was to evaluate the result of stocking density on the performance of glass eels in the biofloc system during nursery I. Glass eels were stocked at densities of 54.95, 109.89 and 164.84 fish/m3, respectively, with three replicate ponds for each density. Eels were fed a formulated pasta-diet containing 40% crude protein and , 4% crude lipid, 5% crude fiber, 11.5% ash and 12% moisture, respectively. The water quality were maintained at levels of for fish culture througout the experiements: water temperature was 27.1°C (ranged from 26.3 to 28.2°C), pH (7.6, ranged from 6.8 to 7.8) and DO (7.2 mg.L-1, ranged 6.9 to 7.5 mg.L-1). The results showed that the stocking density did not significantly affect the final weight, weight gain, AGR, SGR, FCR and survival, however this had a significant effect on the yield. The biofloc system was suitable for raising glass eels.

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Hewavitharane, C. A., T. D. Pickering, R. Ciro, and N. Mochioka. "Species composition, abundance and seasonal recruitment patterns of freshwater eels (Anguilla spp.) to Viti Levu, Fiji Islands, in the western South Pacific." Marine and Freshwater Research 69, no. 11 (2018): 1704. http://dx.doi.org/10.1071/mf18105.

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To understand the inshore recruitment mechanisms of tropical eels (Anguilla spp.), we collected 1368 glass eels at the mouth of a small river at Namelimeli, ~2km east of Navua Town, Fiji Islands, between April 2015 and June 2016. Specimens were identified using both morphological characters and DNA barcoding to only three species: one short-finned Anguilla obscura and two long-finned eels A. marmorata and A. megastoma. Anguilla obscura was the most abundant species (55% of glass eels collected) with peak recruitment periods from February to April. Anguilla marmorata was the second most abundant species (41.4% of glass eels collected) with peak recruitment periods in April 2015 and September–October 2015. Anguilla megastoma only comprised 3.9% of glass eels collected, with peak recruitment periods in April 2015 and October 2015. Anguilla obscura and A. marmorata were present in samples almost throughout the year, suggesting that tropical eels recruit to some degree throughout the year. Results suggest that peak recruitment occurs during seasons of heavy rain, from September to October and from February to April commencing 1h after sunset on the day following a new moon.

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ANGELIDIS, P., I. POURNARA, and G. PHOTIS. "Glass eels (Anguilla anguilla) growth in a recirculating system." Mediterranean Marine Science 6, no. 1 (June 1, 2005): 99. http://dx.doi.org/10.12681/mms.196.

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On a commercial eel farm, which uses a recirculation system, 400,000 glass eels were farmed for a period of 328 days at 20o – 23o C. The physicochemical parameters of the farm water were kept at normal conditions during the experiment. The NO 2 was kept between 1.0 and 3.0 mg/l. By the end of the experiment, 4,582 kg of fish feed were consumed and 2,939 kg of eels were produced (177,523 eels with mean final individual body weight of 16.6g and mean food conversion ratio of 1.625). The glass eels showed a high variability in their capacity to grow.

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Krismono, Krismono, and Endi Setiadi Kartamihardja. "OPTIMASI PEMANFAATAN DAN KONSERVASI STOK IKAN SIDAT (Anguilla spp) DI DAS POSO, SULAWESI TENGAH." Jurnal Kebijakan Perikanan Indonesia 4, no. 1 (May 31, 2012): 9. http://dx.doi.org/10.15578/jkpi.4.1.2012.9-16.

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Daerah Aliran Sungai (DAS) Poso yang terdiri atas sungai Poso dan anak sungainya yang mengalir dari Danau Poso sampai muaranya di Teluk Tomini dan sungai-sungai kecil di sekitar muara Poso merupakan kawasan ruaya ikan sidat. Penangkapan ikan sidat dewasa (induk) di Tentena dengan Wayamassapi (perangkap) dan penangkapan glass eel di muara Poso yang sangat intensif akan berpengaruh terhadap penurunan produksi dan potensi ikan sidat di DAS Poso. Pembangunan PLTA Sulewana yang membendung sungai Poso di Sulewana juga akan berpengaruh terhadap penurunan produksi dan potensi ikan sidat karena pembendungan akan memutus ruaya ikan sidat. Selama periode tahun 2010-2012 anakan ikan sidat (glass eel) yang berruaya ke sungai Poso turun sekitar 10 juta ekor per tahun yaitu dari 36 juta ekor per tahun menjadi 35 juta ekor per tahun. Potensi induk sidat turun sekitar 3.000 ekor per tahun, yaitu dari 9.000 ekor menjadi 6.000 ekor per tahun. Dalam rangka konservasi dan optimasi pemanfaatan sumberdaya ikan sidat, upaya yang perlu dilakukan adalah menetapkan sungai Pandiri dan Rawa Pandiri sebagai kawasan konservasi, melakukan restocking elver yang berukuran panjang lebih besar dari 15 cm di Danau Poso, membangun jalur ruaya sidat (eels ladder) di Sulewana, mengatur penangkapan sidat dewasa di Tentena dan menetapkan kuota penangkapan “glass eels” di Muara Sungai Poso.Poso watershed composting of Poso River and its tributaries flowing the waters from Poso Lake to its mouth at Tomini Bay is one of migration habitat of tropical eels (Anguilla spp). Intensive exploitation of adult eels at outlet of the lake Poso at Tentena by using trap and glass eel at mouth of the Poso River has affected on the decreasing of the eels production. Damming of the Poso River at Sulewana has also affected the eels production sustainability due to barrier of the eels migration. During the period 2010-2012, the glass eels migration from the mouth of Poso River to the river decreased about 10 millions, from 36 millions to 35 millions individuals per year. The adult eels also decreased for about 3000 individuals, from 9000 individuals to 6000 individuals per year. In order to conserve and optimize the exploitation of the eels stock, some efforts, i.e., establishment of conservation area at Pandiri river and its swampy area, restocking of the elver with a total length more than 15 cm at Lake Poso, establishment of eels ladder at Sulewana, regulation of fishing for adult eels at Tentena and glass eels at mouth of the Poso River should be implemented.

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Hein, Jennifer L., Isaure de Buron, William A. Roumillat, William C. Post, Allan P. Hazel, and Stephen A. Arnott. "Infection of newly recruited American eels (Anguilla rostrata) by the invasive swimbladder parasite Anguillicoloides crassus in a US Atlantic tidal creek." ICES Journal of Marine Science 73, no. 1 (June 1, 2015): 14–21. http://dx.doi.org/10.1093/icesjms/fsv097.

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Abstract Little is known about the infection status of glass eel and elver stages of the American eel Anguilla rostrata by the invasive swimbladder parasite Anguillicoloides crassus. This study examined infection by adult and larval A. crassus in glass eels (n = 274) and elvers (n = 199) collected during March–December 2013 from an eel ladder at a dammed creek near Charleston, SC, USA. Among all the eels examined [total lengths (TLs), 34–156 mm], the prevalence (±SE), mean abundance, and mean intensity of A. crassus worms was 29.4 ± 2.1%, 0.88 ± 0.12, and 2.98 ± 0.34, respectively. Infection by A. crassus was not detected in the earliest glass eel development stages (pigment stages 1–3), but it was detected in more advanced stages (pigment stages 4–7) and fully pigmented elvers. From March to July, parasite prevalence increased significantly with eel TL, and all eels 125 mm or longer (n = 13) were infected. From August–December, when fewer eels were caught, parasite prevalence was generally lower and less dependent on the eel TL. Our study demonstrates the potential risk of spreading A. crassus to new areas by transporting live glass eels and elvers. This is of particular relevance because our study site was located in the Cooper River drainage, one of the few locations in the USA that permits a glass eel harvest.

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Breteler, J. G. P. Klein, W. Dekker, and E. H. R. R. Lammens. "Growth and Production of Yellow Eels and Glass Eels in Ponds." Internationale Revue der gesamten Hydrobiologie und Hydrographie 75, no. 2 (1990): 189–205. http://dx.doi.org/10.1002/iroh.19900750206.

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Walmsley, Sarah, Julie Bremner, Alan Walker, Jon Barry, and David Maxwell. "Challenges to quantifying glass eel abundance from large and dynamic estuaries." ICES Journal of Marine Science 75, no. 2 (September 23, 2017): 727–37. http://dx.doi.org/10.1093/icesjms/fsx182.

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Abstract European eel Anguilla anguilla recruitment into the rivers of the northeastern Atlantic has declined substantially since the 1980s. Monitoring of recruiting juveniles, or glass eels, is usually undertaken in small estuaries and rivers. Sampling of large-scale estuaries is rare, due to the size of the sampling area and the resources needed to provide adequate sampling levels. Here we describe surveys for glass eels in the UK’s largest estuarine system, the Severn Estuary/Bristol Channel. We sampled across a 20 km-wide stretch of the estuary in 2012 and 2013, using a small-meshed net deployed from a commercial fishing trawler, and the surveys yielded over 2500 glass eels. Eels were more abundant in the surface layer (0–1.4 m depth) than at depth (down to 8.4 m depth), were more abundant close to the south shore than along the north shore or middle of the estuary, and were more abundant in lower salinity water. Numbers were higher in the second year than in the first and eels were more abundant in February than April. The difficulties and logistics of sampling in such a large estuary are discussed, along with the level of resources required to provide robust estimates of glass eel abundance.

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Warshafsky, Zoemma T., Troy D. Tuckey, Wolfgang K. Vogelbein, Robert J. Latour, and Andrew R. Wargo. "Temporal, spatial, and biological variation of nematode epidemiology in American eels." Canadian Journal of Fisheries and Aquatic Sciences 76, no. 10 (October 2019): 1808–18. http://dx.doi.org/10.1139/cjfas-2018-0136.

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American eels (Anguilla rostrata) are infected by the non-native parasitic nematode Anguillicoloides crassus, which can cause severe swim bladder damage. We investigated epidemiology of A. crassus to better understand its population-level effects on American eels. Nematode prevalence, abundance, and intensity and swim bladder damage were quantified in glass eels, elvers, and yellow eels from the lower Chesapeake Bay and related to season of capture, river system, and total length. Age-variant force-of-infection and disease-associated mortality were estimated using a three-state irreversible disease model, which assumes recovery is not possible. Results showed glass eels have very low infection prevalence and severity compared with elvers and yellow eels. Nematode abundance varied by season, river, and eel length, whereas swim bladder damage varied by season and eel length. Nematode abundance and swim bladder damage were weakly positively correlated. Force-of-infection, based on swim bladder damage, peaked at age 2, and disease-positive eels had an estimated lower annual survival probability of 0.76 compared with disease-negative eels. Full understanding of American eel population dynamics will require broader knowledge of cryptic disease-associated mortality throughout North America.

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Wippelhauser, Gail S., and James D. McCleave. "Rhythmic activity of migrating juvenile American eels Anguilla rostrata." Journal of the Marine Biological Association of the United Kingdom 68, no. 1 (February 1988): 81–91. http://dx.doi.org/10.1017/s0025315400050116.

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Glass eels of the American eel Anguilla rostrata (Lesueur) utilize selective tidal stream transport, a series of semidiurnal vertical migrations in phase with the tide, to migrate up the Penobscot River estuary, Maine, U.S.A., in the spring. Glass eels, freshly collected during their migration, exhibited rhythmic activity with circatidal periodicities when tested in groups in the presence of a water current under constant conditions in the laboratory. Freshly collected groups of eels which had already completed their migration through tidal water did not exhibit circatidal activity rhythms under the same conditions. The activity rhythms of groups of eels freshly caught in tidal water appeared to be entrained by a 12.5 h cycle of water current reversals, but not by a 10.0 h cycle of current reversals. In other entrainment experiments water collected on flood and ebb tides was alternately added to the experimental tanks every 5.0 h. Under these conditions groups of eels freshly caught in tidal water did not display any rhythmic activity. Only 2 of 100 glass eels, freshly collected from tidal and non-tidal water, which were tested individually in static tanks, exhibited rhythmic activity. The activity rhythms would allow an eel to time its vertical migrations in the estuary despite varying environmental conditions.

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Tapie, Nathalie, Karyn Le Menach, Stéphanie Pasquaud, Pierre Elie, Marie Hélène Devier, and Hélène Budzinski. "PBDE and PCB contamination of eels from the Gironde estuary: From glass eels to silver eels." Chemosphere 83, no. 2 (March 2011): 175–85. http://dx.doi.org/10.1016/j.chemosphere.2010.12.044.

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Han, Yu-San, Kuan-Mei Hsiung, Heng Zhang, Lai-Yin Chow, Wann-Nian Tzeng, Akira Shinoda, Tatsuki Yoshinaga, et al. "Dispersal Characteristics and Pathways of Japanese Glass Eel in the East Asian Continental Shelf." Sustainability 11, no. 9 (May 4, 2019): 2572. http://dx.doi.org/10.3390/su11092572.

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The Japanese eel Anguilla japonica is an important aquaculture fish species in the East Asian countries of Japan, China, Korea, and Taiwan. All glass eel fry are captured from the wild and understanding the recruitment patterns of the glass eel is important. The larvae of A. japonica are passively transported to the East Asian Continental Shelf by the North Equatorial Current, the Kuroshio, the Kuroshio intrusion currents, and coastal currents. In each location, recruitment time is diverse: It is November in Taiwan and April in the Yalu River. How the glass eels reach recruitment areas remains poorly understood. Here, we combine information from larval ages based on otolith increments, simulated drifting paths on the East Asian Continental Shelf, and main fishing seasons in each location of East Asia. We identify five main recruitment blocks: (1) The main Kuroshio, (2) The Taiwan Strait Warm Current, (3) The Taiwan Warm Current, (4) The Yellow Sea Warm Current and (5) The branch of Yellow Sea Warm Current. The counted age of the glass eels is significantly underestimated for the later recruits, possibly due to the cessation of the otolith edge growth under low water temperatures. This study clarifies the eel’s larval characteristics and transport mechanisms in the East Asia Continental Shelf, providing important information for its recruitment dynamics in the marine stage.

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NIMETH, K., P. ZWERGER, J. WÜRTZ, W. SALVENMOSER, and B. PELSTER. "Infection of the glass-eel swimbladder with the nematode Anguillicola crassus." Parasitology 121, no. 1 (July 2000): 75–83. http://dx.doi.org/10.1017/s003118209900606x.

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The ability of the nematode Anguillicola crassus to infect eel larvae (glass-eel stage) was tested. The results show that glass-eels fed on infected copepods, the natural intermediate host of the nematode, can be infected. Light microscopical examination of the infected developing swimbladder tissue revealed that the infection results in a significant thickening of the connective tissue. The basolateral labyrinth of gas gland cells is very much reduced in infected swimbladders, and the distance of gas gland cells to blood capillaries is enlarged. Critical swimming speed, defined as the speed where the larvae were no longer able to swim against the current, was similar in infected and uninfected animals. At intermediate speeds (about 60–80% of critical swimming speed) infected eels showed a slightly higher swimming activity than control animals. Resting oxygen consumption, measured as an index of metabolic activity, within the first 2 months of infection was higher in control animals, which may be due to a reduced rate of activity in infected glass-eels. By 4–5 months after the infection, however, it was significantly higher in infected animals. This may indicate that at this stage a higher activity of the animals is required to compensate for the increase in body density, but swimming performance of infected and non-infected glass-eels was not significantly different. Oxygen consumption during swimming activity, measured in a swim tunnel at 50% of maximal swimming speed, also was not affected. The results thus show that even glass-eels can be infected with A. crassus, and this probably contributes to the rapid spread of the nematode in Europe. While aerobic metabolism during swimming activity is not affected at this stage of infection, the swimbladder tissue shows severe histological changes, which most likely will impair swimbladder function.

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Westerberg, Håkan, and Håkan Wickström. "Stock assessment of eels in the Baltic: reconciling survey estimates to achieve quantitative analysis." ICES Journal of Marine Science 73, no. 1 (March 29, 2015): 75–83. http://dx.doi.org/10.1093/icesjms/fsv049.

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Abstract The data from two scientific surveys, where eel is part of the catch, have been studied to assess trends in recruitment and escapement to and from the Baltic. Abundance of juvenile eel was monitored in the Sound, between Sweden and Denmark, from 1992 to 2002. The total natural recruitment of new eels was estimated under the assumption that the number of juvenile eels observed in the surveys represented an accumulation of eels migrating into the Baltic. To assess the total recruitment, the stocking by imported glass eels, or transplanted juveniles from outside the Baltic, was added. Fish larvae monitoring at a nuclear power plant in the Kattegat gave an index of glass eel abundance which was well correlated with glass eel monitoring in the Sound. This was used to extrapolate the recruitment time-series to the full period from 1981 to the present. The main conclusions from the analysis were: (i) the recruitment to the Baltic region, including the contribution from stocking, has declined by 95% between 1981 and 2012. (ii) The stocking of glass eel and bootlace eel has been of the same order of magnitude as natural recruitment, averaging 25–30% of the total supply of glass eel to the Baltic, with a decreasing trend with time. (iii) The total landings in the Baltic countries have ranged from 5 to 15% of the estimated survival without anthropogenic mortality. This proportion has been stable and independent of a large decrease in potential escapement.

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Bult, Tammo P., and Willem Dekker. "Experimental field study on the migratory behaviour of glass eels (Anguilla anguilla) at the interface of fresh and salt water." ICES Journal of Marine Science 64, no. 7 (August 22, 2007): 1396–401. http://dx.doi.org/10.1093/icesjms/fsm105.

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Abstract Bult, T. P., and Dekker, W. 2007. Experimental field study on the migratory behaviour of glass eels (Anguilla anguilla) at the interface of fresh and salt water. – ICES Journal of Marine Science, 64: 1396–1401. European eels (Anguilla anguilla) in the glass eel phase migrate using ocean currents and selective tidal stream transport. Conventional fish ladders installed at the interface of marine and fresh water, however, require the fish to swim upstream actively. We question the efficiency of these fish ladders for glass eel immigration, and propose a simple siphon over migration barriers, restoring the original selective tidal stream transport. A conventional trap and our siphon were tested concurrently at two sluice complexes in The Netherlands (Tholen, Nieuwe Statenzijl) in spring 2005. In all but one case, the siphon caught more glass eels than the trap, as well as more sticklebacks and other species. Clearly, the natural immigration process can be restored fairly easily and at low cost and with low intrusion levels of salt. Follow-up studies should focus on optimization, and the effect of a passage on the hinterland stock.

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Sola, C., and L. Tosi. "Freshwater odorants and glass-eels (Angtiilla angnitla) ascent." Ethology Ecology & Evolution 5, no. 3 (September 1993): 414. http://dx.doi.org/10.1080/08927014.1993.9523083.

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Honda, Satoshi, Dina Muthmainnah, Ni Komang Suryati, Dian Oktaviani, Somboon Siriraksophon, Taweekiet Amornpiyakrit, and Budi Iskandar Prisantoso. "CURRENT STATUS AND PROBLEMS OF THE CATCH STATISTICS ON ANGUILLID EEL FISHERY IN INDONESIA." Marine Research in Indonesia 41, no. 1 (May 31, 2016): 1–14. http://dx.doi.org/10.14203/mri.v41i1.94.

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To compensate the decline of the populations of temperate anguillid eels, tropical anguillid eels become getting attention of East Asian eel market in recent years. Many eel farms have been established in Java Island to culture tropical anguillid eels intending to export the products to East Asia. Since eel farming is reliant on wild-caught anguillid eels such as glass eels, elvers and yellow eels, these eel seeds have been captured in various places in Indonesia. However, it is still unknown that how much of tropical anguillid eels are caught as seeds for eel farming. This study showed two different patterns of the commodity chains of eel seeds from both Sukabumi Regency and Bengkulu Province to the eel farms in Java Island. Official catch statistics on anguillid eels found in both Sukabumi Regency and Bengkulu Province were also analyzed on their features and problems underlied. Considering the sustainable use of anguillid eel resources and critical stances on exploitation of eel seeds from all over the world, the Indonesian government should take an immediate action for developing the national catch statistics on anguillid eel fishery as soon as possible.

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Watupongoh, Navy Novy Jefry, and Krismono Krismono. "KEBIJAKAN TENTANG INTEGRASI AKTIVITAS PENANGKAPAN DENGAN PEMBUDIDAYAAN UNTUK KEBERLANJUTAN SUMBERDAYA IKAN SIDAT (Anguilla spp) DI DAS POSO." Jurnal Kebijakan Perikanan Indonesia 7, no. 1 (May 1, 2015): 37. http://dx.doi.org/10.15578/jkpi.7.1.2015.37-44.

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Daerah Aliran Sungai (DAS) Poso merupakan salah satu daerah penangkapan ikan sidat, memiliki luas 1.101,87 km2 dan panjang ± 68,70 km. Ikan sidat di perairan Poso merupakan komoditas perikanan yang memiliki nilai ekonomis tinggi (harga Rp.100.000,-/kg) dan menjadi primadona hasil tangkapan. Ikan sidat yang hidup di DAS Poso terdapat 5 jenis, yaitu A. marmorata, A. bicolor pasific, A. celebensis, A. borneensis dan A. interioris. Saat ini telah terjadi penurunan produksi induk maupun glass eel ikan sidat di DAS Poso disebabkan oleh penangkapan yang belum memperhatikan faktor kelestarian dan keberlajutannya seperti penangkapan yang berlangsung tidak hanya pada saat induk ikan sidat yang beruaya ke laut tapi juga glas eel yang menuju ke danau. Pembangunan PLTA pada alur Sungai Poso mengganggu ruaya ikan sidat yang mengakibatkan terputusnya ruaya ikan sidat dari dan ke Danau Poso yang berakibat hilangnya ikan sidat di Danau Poso. Berkaitan dengan permasalahan ini maka populasi sumberdaya ikan sidat perlu dijaga keberlanjutannya dengan cara mengintegrasikan aktivitas penangkapan dengan pembudidayaan, oleh karena itu diperlukan kebijakan yang menetapkan peraturan terkait dengan penangkapan yang menggunakan alat tangkap ramah lingkungan serta diintegrasikan dengan pembudidayaan. Kajian kebijakan ini bertujuan untuk merumuskan kebijakan tentang integrasi aktivitas penagkapan dengan pembudidayaan untuk berkelanjutan ikan sidat di DAS Poso. The watershed of Poso River is one of anguillid eel fishing areas. This watershed has an area of 1,101.87 km2 and length ± 68.70 miles. The anguillid eel is a commodity that has a high economic value (IDR 100,000 / kg) and has an excellent catches. There are 5 types of eels that live in the watershed of Poso, they are: A. marmorata, A. bicolor pacific, A. celebensis, A. borneensis and A. interioris. The decreased production of anguillid parent and glass eels in the watershed of Poso is a result from the capture that had not yet noticed the preservation and sustainability factors, such as the capture that took place not only at the time of sea migration phase (the parents), but also on the lake migration phase (the glass eels), as well as Poso river damming for hydropower purpose. The decrease in the production of glass eel and parent eels in the watershed of Poso is also caused by fishing activities that have not been integrated with cultivation. There is a need of a regulation for fishing by using environmentally friendly fishing gears as well as the integration with cultivation. This paper aims to formulate policy on integration of capture and cultivation for sustainable catch of anguillid eels in the watershed of Poso.

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Pedersen, Michael I., and Gorm H. Rasmussen. "Yield per recruit from stocking two different sizes of eel (Anguilla anguilla) in the brackish Roskilde Fjord." ICES Journal of Marine Science 73, no. 1 (September 28, 2015): 158–64. http://dx.doi.org/10.1093/icesjms/fsv167.

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Abstract Stocking of young eel is widely practised, as a measure, to meet the management target of the EU eel recovery plan. The target of the recovery plan is to increase the escapement to 40% silver eel biomass, relative to pristine conditions. The scientific information to predict the outcome in silver eel biomass from stocking is limited and may depend on whether translocation of wild glass eel or yellow eel is used, or if the stocked eels used are yellow eel from aquaculture. We evaluated the yield from stocking two different sizes, 3 and 9 g eels from aquaculture. A professional fishery recaptured 12.7% of the 3 g and 9.4% of the 9 g eels, originally stocked. Growth rate and mortality rate were different for the two stocked sizes, favouring the small eels. Brutto yield per recruit (YPR) was 13 and 9.2 g and netto YPR was 9.8 and 0.31 g for 3 and 9 g eel, respectively. We conclude that there seems to be no advantage in using larger 9 g eels compared with small 3 g eels for stocking.

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Borges, Francisco O., Catarina P. Santos, Eduardo Sampaio, Cátia Figueiredo, José Ricardo Paula, Carlos Antunes, Rui Rosa, and Tiago F. Grilo. "Ocean warming and acidification may challenge the riverward migration of glass eels." Biology Letters 15, no. 1 (January 2019): 20180627. http://dx.doi.org/10.1098/rsbl.2018.0627.

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The dramatic decline of European eel ( Anguilla anguilla ) populations over recent decades has attracted considerable attention and concern. Furthermore, little is known about the sensitivity of the early stages of eels to projected future environmental change. Here, we investigated, for the first time, the potential combined effects of ocean warming (OW; Δ + 4°C; 18°C) and acidification (OA; Δ − 0.4 pH units) on the survival and migratory behaviour of A. anguilla glass eels, namely their preference towards riverine cues (freshwater and geosmin). Recently arrived individuals were exposed to isolated and combined OW and OA conditions for 100 days, adjusting for the salinity gradients associated with upstream migration. A two-choice test was used to investigate migratory activity and shifts in preference towards freshwater environments. While OW decreased survival and increased migratory activity, OA appears to hinder migratory response, reducing the preference for riverine cues. Our results suggest that future conditions could potentially favour an early settlement of glass eels, reducing the proportion of fully migratory individuals. Further research into the effects of climate change on eel migration and habitat selection is needed to implement efficient conservation plans for this critically endangered species.

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Schmucker, Andrew K., Nicholas S. Johnson, Heather S. Galbraith, and Weiming Li. "Glass-Eel-Stage American Eels Respond to Conspecific Odor as a Function of Concentration." Transactions of the American Fisheries Society 145, no. 4 (June 15, 2016): 712–22. http://dx.doi.org/10.1080/00028487.2016.1146164.

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Okamura, Akihiro, Noriyuki Horie, Naomi Mikawa, Yoshiaki Yamada, and Katsumi Tsukamoto. "Recent advances in artificial production of glass eels for conservation of anguillid eel populations." Ecology of Freshwater Fish 23, no. 1 (August 5, 2013): 95–110. http://dx.doi.org/10.1111/eff.12086.

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28

Bureau Du Colombier, S., V. Bolliet, P. Lambert, and A. Bardonnet. "Energy and migratory behavior in glass eels (Anguilla anguilla)." Physiology & Behavior 92, no. 4 (November 2007): 684–90. http://dx.doi.org/10.1016/j.physbeh.2007.05.013.

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Blakeslee, Carrie J., Heather S. Galbraith, and Robert M. Deems. "The Effects of Rearing Temperature on American Glass Eels." Agricultural Sciences 09, no. 08 (2018): 1070–84. http://dx.doi.org/10.4236/as.2018.98074.

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De Meyer, J., C. Ide, C. Belpaire, G. Goemans, and D. Adriaens. "Head shape dimorphism in European glass eels ( Anguilla anguilla )." Zoology 118, no. 6 (December 2015): 413–23. http://dx.doi.org/10.1016/j.zool.2015.07.002.

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31

Yang, Guang, Günter Möbus, and Russell Hand. "Fine structure EELS analysis of glasses and glass composites." Journal of Physics: Conference Series 26 (February 22, 2006): 73–76. http://dx.doi.org/10.1088/1742-6596/26/1/017.

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32

Birrell, L., G. Cramb, and N. Hazon. "Osmoregulation during the development of glass eels and elvers." Journal of Fish Biology 56, no. 6 (June 2000): 1450–59. http://dx.doi.org/10.1111/j.1095-8649.2000.tb02156.x.

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33

Munk, Peter, Michael M. Hansen, Gregory E. Maes, Torkel G. Nielsen, Martin Castonguay, Lasse Riemann, Henrik Sparholt, et al. "Oceanic fronts in the Sargasso Sea control the early life and drift of Atlantic eels." Proceedings of the Royal Society B: Biological Sciences 277, no. 1700 (June 23, 2010): 3593–99. http://dx.doi.org/10.1098/rspb.2010.0900.

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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.

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34

Beaulaton, Laurent, and Cédric Briand. "Effect of management measures on glass eel escapement." ICES Journal of Marine Science 64, no. 7 (June 23, 2007): 1402–13. http://dx.doi.org/10.1093/icesjms/fsm071.

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Abstract Stocks of European eel (Anguilla anguilla) have declined continuously and steadily, since 1980. A model, GEMAC, namely Glass Eel Model to Assess Compliance, has been developed with the objective of assessing anthropogenic impacts on glass eels in estuaries and evaluating the effects of management measures, to support initiatives aimed at helping the eel stocks recover. The model is described and applied to two estuaries with contrasting anthropogenic pressures: the Vilaine and the Garonne. It assesses the proportion of settled glass eels relative to a non-impacted situation with current (%S/R) or pristine recruitment (%S/R0). The estimated %S/R (%S/R0) is 5.5% (1.1%) for the Vilaine and 78% (19%) for the Garonne, in accord with the different levels of anthropogenic pressure in these two estuaries. A sensitivity analysis shows that the assessment of %S/R is accurate, and that in a data-poor context, the %S/R is under-assessed, as required by the precautionary approach. Seven management scenarios are explored all aiming to halve the anthropogenic pressure, but in fact leading to different levels of glass eel escapement, from almost zero to a 13-fold increase. This variation emphasizes the need for the estuarine context of eel stock management to be carefully evaluated for effectiveness when implementing management measures.

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Jiang, N., and J. Silcox. "Segregation of Ba to Cr Thin Film and Glass Interfaces." Microscopy and Microanalysis 5, S2 (August 1999): 802–3. http://dx.doi.org/10.1017/s1431927600017335.

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The knowledge of interface properties is important in understanding the adhesion of metal films to glasses. To simplify the analysis, silicate glasses are usually regarded as amorphous SiO2. Comparing the measured energy loss functions of Code 7059 (BaO-B2O3-SiO2) and Code 1737 (Al2O3-B2O3-Si2) glasses by EELS with the calculated result of a-Si02 from optical data, this is a fairly good assumption in bulk materials. Depositing metals, which have strong affinity for oxygen on glasses, however, may result in minor elements, such as Ba in both 7059 and 1737 glasses, segregating to interfaces, and breaking down the chemical balance.Figs. 1 and 2 show the EELS spectra acquired with a 2Å electron probe in Cr film, interface and bulk glass respectively. The Cr film in Fig. 1 was sputtered on 7059 glass at room temperature, and annealed at 450°C in compressed Ar gas for 10 min. The preparation of Cr thin film in Fig. 2 is mentioned elsewhere.

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van Utrecht, W. L., and M. A. Holleboom. "Notes on Eel Larvae (Anguilla Anguilla Linnaeus, 1758) from the Central and Eastern North Atlantic and on Glass Eels from the European Continental Shelf." Bijdragen tot de Dierkunde 55, no. 2 (1985): 249–62. http://dx.doi.org/10.1163/26660644-05502004.

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Eel larvae caught in the mid North Atlantic and along the continental slope off the Portuguese coast are studied together with samples of glass eels caught just before entering fresh water along the Dutch and French coasts.

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Krsmanović, R., Giovanni Bertoni, and Gustaaf Van Tendeloo. "Structural Characterization of Erbium doped LAS Glass Ceramic Obtained by Glass Melting Technique." Materials Science Forum 555 (September 2007): 377–81. http://dx.doi.org/10.4028/www.scientific.net/msf.555.377.

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Samples of transparent glass-ceramics in the ternary system Li2O-Al2O3-SiO2 (LAS), with Er2O3 as a luminescent dopant, are investigated. The initial glass is obtained by the classical melting technique. In order to induce ceramization of the glass, TiO2 and ZrO2 are added in small amount as nucleating agents. The thermal treatments at 730 and 770°C are carried out to promote formation of titanium zirconate solid solution precipitates. The spatial distribution of the precipitates in the material, their morphology, and their composition are investigated with TEM, HRTEM, HAADF-STEM, EELS and EFTEM. The results demonstrate that with the glass-melting preparation technique it is possible to achieve small nanoparticles with uniform distribution and higher number density than with the sol-gel glass preparation.

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38

Podgorniak, T., S. Blanchet, E. De Oliveira, F. Daverat, and F. Pierron. "To boldly climb: behavioural and cognitive differences in migrating European glass eels." Royal Society Open Science 3, no. 1 (January 2016): 150665. http://dx.doi.org/10.1098/rsos.150665.

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European eel ( Anguilla anguilla ) is a catadromous fish species that received substantial attention as its population has markedly declined in the last three decades. The possible causes of this decline include habitat fragmentation factors such as dams and weirs. In some cases, these obstacles are equipped with fish friendly passage devices that may select young eels according to their climbing behaviour. We tested how individual climbing tendency was related to the event of fishway passage experienced in the field and classified fish climbing profiles as climbing ‘leaders’, ‘followers’, ‘finishers’ and ‘no climbers’. Moreover, we analysed the brain transcription level of genes related to neurogenesis and synaptic plasticity and compared it to climbing profiles. We found that fish from the upstream segments of an impounded river had a higher climbing propensity. Their behaviour was also more repeatable throughout the whole test than the obstacle-naive fish from the downstream segment. Moreover, we found that boldly climbing ‘leaders’ had lower levels of transcription of synapse-related genes than the climbing ‘followers’. These differences could be related to coping styles of fish, where proactive ‘leaders’ express a routine and risky behaviour, whereas reactive fish need an environmental assessment before exploratory behaviour. Our study showed that differences in climbing propensity exist in glass eels separated by water obstacles. Moreover, eels could adopt climbing different strategies according to the way they deal with environmental stress and to the cognitive abilities they possess.

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Miyake, Yoichi, Aigo Takeshige, Hikaru Itakura, Hajime Itoh, Hiroaki Onda, Akira Yamaguchi, Akihito Yoneta, Kohma Arai, Yulina V. Hane, and Shingo Kimura. "Predation on glass eels of Japanese eel Anguilla japonica in the Tone River Estuary, Japan." Fisheries Science 84, no. 6 (July 30, 2018): 1009–14. http://dx.doi.org/10.1007/s12562-018-1238-x.

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40

Jiang, Nan. "Spatially Resolved EELS-an Alternative Approach for Characterizing Glass Structure." Microscopy and Microanalysis 10, S02 (August 2004): 794–95. http://dx.doi.org/10.1017/s1431927604884642.

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41

Gascuel, Didier, Eric Feunteun, and Guy Fontenelle. "Seasonal dynamics of estuarine migration in glass eels(Anguilla anguilla)." Aquatic Living Resources 8, no. 2 (April 1995): 123–33. http://dx.doi.org/10.1051/alr:1995009.

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42

Yu, Z., and J. Silcox. "Observation of Non-uniformities in Calcium Aluminosilicate Glass using EELS." Microscopy and Microanalysis 8, S02 (August 2002): 604–5. http://dx.doi.org/10.1017/s1431927602105964.

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43

Williamson, G. R. "Vertical drifting position of glass eels, Anguilla rostrata, off Newfoundland." Journal of Fish Biology 31, no. 4 (October 1987): 587–88. http://dx.doi.org/10.1111/j.1095-8649.1987.tb05261.x.

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44

Sola, C., A. Spampanato, and L. Tosi. "Behavioural responses of glass eels (Anguilla anguilla) towards amino acids." Journal of Fish Biology 42, no. 5 (May 1993): 683–91. http://dx.doi.org/10.1111/j.1095-8649.1993.tb00377.x.

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45

Yamamoto, Toshihiro, Noritaka Mochioka, and Akinobu Nakazono. "Seasonal occurrence of anguillid glass eels at Yakushima Island, Japan." Fisheries Science 67, no. 3 (June 2001): 530–32. http://dx.doi.org/10.1046/j.1444-2906.2001.00285.x.

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46

Leapman, R. D., and D. E. Newbury. "Trace analysis of transition elements and rare earths by parallel EELS." Proceedings, annual meeting, Electron Microscopy Society of America 50, no. 2 (August 1992): 1250–51. http://dx.doi.org/10.1017/s0424820100130882.

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It has been realized for some years that electron energy loss spectroscopy (EELS) offers the potential for a highly sensitive microanalytical technique. Here, we present measurements from some NIST glass standard reference materials showing that EELS provides both high spatial resolution and trace sensitivity for a wide range of elements including the 3-d transition metals and the lanthanides.Specimens were prepared by grinding the glass and depositing the powder on to thin carbon support films. The energy loss spectra were collected by means of a Gatan 666 parallel-detection spectrometer attached to a VG Microscopes HB501 scanning transmission electron microscope (STEM) operating at 100 keV beam energy. This arrangement gave an energy resolution of approximately 0.4 eV limited by the spread of the field-emission source. Large spectral intensities were obtained by setting the probe current to about 8 nA and the collection semi-angle to 20 mrad. In order to eliminate possible hydrocarbon contamination the specimens were cooled to -160 C.

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Salanggon, Alismi M., Alimudin Laapo, and Fadly Y. Tantu. "ANALISIS FAKTOR LINGKUNGAN INTERNAL DAN EKSTERNAL PENGEMBANGAN USAHA IKAN SIDAT (Anguilla sp.) DI KOTA PALU." KAUDERNI : Journal of Fisheries, Marine and Aquatic Science 1, no. 1 (September 30, 2016): 1–7. http://dx.doi.org/10.47384/kauderni.v1i1.3.

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This study aims to analyzed Internal Factor Evaluation, External Factor Evaluation, SWOT and Grand Strategy Matrices. The results showed that the strengths of eel business development in Palu were experience in the eel business, regular customers and suppliers as well strategic business location. The weaknesses were that the collectors/traders/middlemen don’t yet know how to grow out glass eels and captive breeding is not yet possible, business management is still family-oriented and production capacity is still limited. Opportunity factors for eel business development in Palu were high market demand (domestic and foreign), eel resources are still abundant and eel prices remain high. While threat factors were weaknesses in legislation/regulation on eels, environmentally damaging capture methods, and changes in climate that affect the availability of eels. The strategy for eel business development in Palu City was in quadrant I, which is a Strength-Opportunity (S-O) or aggressive strategy

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Nzau Matondo, Billy, Jean-Philippe Benitez, Arnaud Dierckx, Xavier Rollin, and Michaël Ovidio. "An Evaluation of Restocking Practice and Demographic Stock Assessment Methods for Cryptic Juvenile European Eel in Upland Rivers." Sustainability 12, no. 3 (February 5, 2020): 1124. http://dx.doi.org/10.3390/su12031124.

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Restocking of the critically endangered European eel Anguilla anguilla is widespread, but it is rarely scientifically evaluated. Methods used to assess its associated performance by estimating the survival rate and implement restocking for maximum recruitment in rivers have not yet been investigated. Based on two glass eel restocking events using a single release site/point and multiple sites per river performed in upland rivers (>340 km from the North Sea), the recruitment success of stocked eels was scientifically evaluated during a 3-year study using multiple capture-mark-recapture methods and mobile telemetry. We compared the observed data with the data estimated from the Telemetry, De Lury and Jolly-Seber stock assessment methods. For recruitment data, Telemetry was very close to Jolly-Seber, an appropriate stock assessment method for open populations. Using the best model of Jolly-Seber, survival probability was higher (>95%) in both restocking practices, but recruitment yields were higher and densities of stocked eels were lower in multiple sites compared to a single site. Our results suggest that Telemetry can help to rapidly assess cryptic juvenile eel stocks with good accuracy under a limited number of capture-mark-recapture sessions. Artificial dispersal of glass eels on several productive habitats/sites per river appears to be the better-suited practice for restocking.

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Zhang, Zhi Li, Rik Brydson, Aidan Westwood, and B. Rand. "Nanostructure of a Glass-Like Carbon Characterized by X-Ray Diffraction and Electron Energy Loss Spectroscopy." Advanced Materials Research 177 (December 2010): 58–61. http://dx.doi.org/10.4028/www.scientific.net/amr.177.58.

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In our present study, phenolic resins heated at different temperatures from 600 oC to 3000 oC were analysised in terms of phase structure and chemical structure using X-ray diffraction and high resolution transmission electron microscopy equipped with an electron energy loss spectrometer (EELS). It is shown that materials appear to be amorphous with many micro-pores surrounded by crystalline graphite layers; the formation of the pore is due to the gas evolution reaction. Using the intensities of peaks in EELS CK-ionization edge which arise from transition of an atomic 1s electron to the π* and σ* antibonding band-like states, the percentage of sp2-bonded carbon have been analyzed and the results reveal notable differences with heat treatment temperature.

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Holmgren, K., H. Wickström, and P. Clevestam. "Sex-related growth of European eel, Anguilla anguilla, with focus on median silver eel age." Canadian Journal of Fisheries and Aquatic Sciences 54, no. 12 (December 1, 1997): 2775–81. http://dx.doi.org/10.1139/f97-193.

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Silver eels, Anguilla anguilla, migrating downstream were monitored for 15 years since being stocked in 1980 as cultured fingerlings in a Swedish lake. Females were larger than males in each separate year, but mean growth rate was higher in males than in females. This discrepancy was due to different age distributions, with 64.5% of the males migrating after four or five growing seasons, while 86.3% of the females grew for 10-15 seasons before migration. Otolith length in the glass eel stage was independent of sex, and it was not correlated with year of migration. With focus on median year of migration, otolith lengths after one, two, and three growing seasons were significantly larger in males than in females. This was mainly due to a higher otolith length increase during the first growing season, i.e., before the eels were stocked in the lake. These results are inconsistent with the view that female eels generally grow faster than males.

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Journal articles on the topic 'Glass eels'

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