scholarly journals Glass eel (Anguilla anguilla) predation risk byEuropean sea bass (Dicentrarchus labrax) in the lab. : Have VIE-tagged glass eels an increased predation risk? : how long can glass eels be detected in the stomach of a Sea bass?

2020 ◽  
Author(s):  
A.B. Griffioen ◽  
◽  
T. Wilkes ◽  
W. Janssen ◽  
T. Menke
Keyword(s):  
Predation Risk ◽  
Dicentrarchus Labrax ◽  
Anguilla Anguilla ◽  
Sea Bass ◽  
Glass Eel ◽  
Glass Eels

Challenges to quantifying glass eel abundance from large and dynamic estuaries

2017 ◽  
Vol 75 (2) ◽  
pp. 727-737 ◽  
Author(s):  
Sarah Walmsley ◽  
Julie Bremner ◽  
Alan Walker ◽  
Jon Barry ◽  
David Maxwell
Keyword(s):  
Large Scale ◽  
Anguilla Anguilla ◽  
Commercial Fishing ◽  
European Eel ◽  
Estuarine System ◽  
Glass Eel ◽  
The North ◽  
Adequate Sampling ◽  
South Shore ◽  
Glass Eels

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.

Selective pressure of fishways upon morphological and muscle enzymatic traits of migrating glass eels

2017 ◽  
Vol 74 (4) ◽  
pp. 445-451 ◽  
Author(s):  
T. Podgorniak ◽  
M. Angelini ◽  
E. De Oliveira ◽  
F. Daverat ◽  
F. Pierron
Keyword(s):  
Energy Metabolism ◽  
Selective Pressure ◽  
Condition Factor ◽  
Anguilla Anguilla ◽  
Aquatic Habitats ◽  
Size Selectivity ◽  
Glass Eel ◽  
Glass Eels ◽  
Species Specific

Fishways are built on obstacles to restore the connectivity between aquatic habitats. Our study investigated how species-specific fishways interact with interindividual trait differences among fish. We compared several groups of glass eels (Anguilla anguilla) climbing two types of fishways with those remaining below the water impoundments. We analyzed relative body condition factor, body length, mass, and in vitro activities and gene transcription levels of several enzymes involved in the energy metabolism (LDH, CS, CCO, PK). Differences among groups indicated that glass eel fish ladders can be size-specific, according to the type of substrate covering the surface of apparatus. Moreover, we found that climbing specific glass eel ladders can require higher endurance-related metabolic traits, triggering increased aerobic capacities. Increased aerobic efforts together with potential size selectivity of fishways should be taken into account when designing such devices and choosing appropriate location on eel migratory pathways.

Osmoregulatory plasticity of the glass eel of Anguilla anguilla: freshwater entry and changes in branchial ion-transport protein expression

2004 ◽  
Vol 61 (3) ◽  
pp. 432-442 ◽  
Author(s):  
Jonathan Mark Wilson ◽  
José Carlos Antunes ◽  
Patricío Duro Bouça ◽  
João Coimbra
Keyword(s):  
Ion Transport ◽  
River Estuary ◽  
Anguilla Anguilla ◽  
Chloride Cells ◽  
Concentration Gradients ◽  
Glass Eel ◽  
Ru 486 ◽  
Minho River ◽  
History Of ◽  
Glass Eels

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.

scholarly journals Experimental field study on the migratory behaviour of glass eels (Anguilla anguilla) at the interface of fresh and salt water

2007 ◽  
Vol 64 (7) ◽  
pp. 1396-1401 ◽  
Author(s):  
Tammo P. Bult ◽  
Willem Dekker
Keyword(s):  
Field Study ◽  
Salt Water ◽  
Anguilla Anguilla ◽  
Migratory Behaviour ◽  
Glass Eel ◽  
Experimental Field ◽  
Tidal Stream ◽  
Glass Eels ◽  
Selective Tidal Stream Transport ◽  
Stream Transport

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.

Studies on Prevailing Parasitic Fish Diseases in Pre-mature Cultured Sea bass, Dicentrarchus labrax, Sea bream and Mugil cephalus at Ismailia, Province with Special References to Control

2020 ◽  
Keyword(s):  
Parasitic Infection ◽  
Dicentrarchus Labrax ◽  
Sea Bass ◽  
Mugil Cephalus ◽  
Sea Bream ◽  
Fish Diseases ◽  
Total Prevalence ◽  
Dark Colour ◽  
Gill Filaments ◽  
Mature Fish

This study concentrated on the assessment of the prevailing parasitic fish diseases in some marine fishes at Ismailia province and how to control the infestation using microalgae. This study was carried out on 1080 pre-mature fish (360 D. labrax (225±25 g) and 360 S aurata (150±25 g) and 360 M. cephalus (125±25 g) collected from similar ponds of studies to be examined at the end of treatment. In addition to that we followed non-treated fish (1080 premature). The infested fish showed dark colour and respiratory signs. Post mortem lesions were a presence of congestion or paleness and destruction of gill filaments. The total prevalence of infestation was the total prevalence of parasitic infection of non-treated fishes was 45.83 %. The highest percentage was in D. labrax 56.94 % followed by S. aurata 47.22%, the lowest percentage in M. cephalus 33.33. The total prevalence of parasitic infection in premature treated with 2 g algae was 28.79%, followed by 3 g algae was 23.60 %, while the lowest percentage with 5 g algae was 20.37 % respectively. The detected species of parasites were protozoal parasites, Amyloodinium ocellatum and Riboscyphidia in additions of marine monogenea, Lamellodiscus diplodicus isolated from D Labrex, Mugil Cephalus and S aurata. The present study concluded that, the use of microalgae instead of fish meal decreased parasitic infestation in marine fish. The histopathological alteration of natural infested examined fishes was also recorded.

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