Population density, growth and diet of eels, Anguilla anguilla L., in two rivers in eastern England

Barak, Nir; Mason, C. F.

doi:10.1111/j.1365-2109.1992.tb00596.x

Cited by 36 publications

(50 citation statements)

References 12 publications

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“…This supports the hypothesis that the parasite is not restricted to freshwater and can potentially be transferred to new locations through all salinity regimes and through many paratenic hosts (reviewed by Taraschewski 2006). The vast array of potential hosts and the eel's generalist feeding behavior (Helfman et al 1987, Barak & Mason 1992 ensure that the parasite's distribution will not be limited by host availability. Yellow American eels exhibit homing, home site fidelity, and limited home ranges (Parker 1995, Oliveira 1997, Morrison & Secor 2003, and thus their movements are unlikely to contribute to the parasite's spread between river systems.…”

Section: Discussionsupporting

confidence: 59%

Distribution, prevalence, and intensity of the swim bladder parasite Anguillicola crassus in New England and eastern Canada

Aieta

Oliveira

2009

Dis. Aquat. Org.

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In the summer of 2005, yellow phase American eels Anguilla rostrata were examined for the swim bladder parasite Anguillicola crassus from 26 locations in New England, USA, ranging from the Pawcatuck River, Rhode Island, to the East Machias River, Maine. An additional 12 sites were sampled within Canada during the summers of 2006 and 2007: 7 sites in southern Nova Scotia and 5 sites within the St. Lawrence River system. In 2007, eels were also obtained from New Brunswick, northern Nova Scotia, Prince Edward Island, and Newfoundland through the commercial eel fishery. All locations in Rhode Island (n = 3) and Massachusetts (n = 10) and 7 in Maine (n = 13) had infected eels, with parasite prevalence ranging from 7 to 76%. No eels sampled from southern Nova Scotia or the St. Lawrence River system were infected with the parasite. New Brunswick and northern Nova Scotia had infected eels ranging from 3 to 30% parasite prevalence, with Cape Breton, Nova Scotia, being the furthest north the parasite has been reported in American eels. There was no significant relationship between parasite prevalence and latitude. The present study supports the hypothesis that the parasite is capable of expanding its range further into the Maritimes and could potentially reach the St. Lawrence River system.

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Section: Discussionsupporting

confidence: 59%

Distribution, prevalence, and intensity of the swim bladder parasite Anguillicola crassus in New England and eastern Canada

Aieta

Oliveira

2009

Dis. Aquat. Org.

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“…From 1998, watershed saturation would have increased mortality of young eels entering the downstream-saturated rivers because of competition and cannibalism behaviours (SINHA and JONES, 1967;KNIGHTS, 1987;LAMOTHE et al, 2000). A replacement by larger eels would not be apparent in the shallow sectors, because the foraging area might not coincide with the resting place located in deeper sectors of the tributary (LAFFAILLE et al, 2004), as niche breadth expands with increasing size of eels (BARAK and MASON, 1992). These observations would indicate that downstream and middle stream sectors reached carrying capacity in 1998 and 2000.…”

Section: Density Dependent Effectsmentioning

confidence: 81%

“…Eel habitat partitioning varied according to habitat and the resulting variability explains the lack of significance in temporal trend . Seasonal fluctuations in eel densities probably occurred (RASMUSSEN, 1983;MORIARTY, 1986;BARAK and MASON, 1992;LOBÓN-CERVIÁ et al, 1995) but had a limited effect when compared to habitat variability, as the sampling period remained in late summer.…”

Section: Density Dependent Effectsmentioning

confidence: 99%

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Effect of Re-Opening of a Migratory Pathway for Eel (Anguilla Anguilla, L.) at a Watershed Scale

Briand

Fatin

Fontenelle

et al. 2005

Bull. Fr. Pêche Piscic.

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The construction of the Arzal dam eel ladder in 1996 allowed enhancing fluvial recruitment from a negligible level, limited to yellow eels crossing sluice and dam overflow, to a level ranging from 0.2 to 2.4 million glass eels per year. The effect of such recruitment on the eel population (Anguilla anguilla) of the Vilaine watershed was analysed at 19 electrofishing sampling stations. From 1998 to 2003, average densities of eel varied from 0.34 to 0.72 eels.m -2 , with a maximum reached in 1999 of 0.82 eels.m -2 . Fluvial recruitment failure, together with density dependent mortalities, explains the drop in yellow eel densities observed from 1998 in the downstream area (< 50 rkm) and from 2000 in the middle stream area (50-100 rkm). The largest densities consisted of a large proportion eels classified as age 1 and the increased density in middle stream sectors was interpreted as the consequence of density-dependent migration at the periphery of a saturated area. The construction of 13 eel ladders on the Vilaine waterway in 1999 and 2000 was followed by increased densities in the upstream area (> 100 rkm) in 2001. The comparison to an electrofishing survey performed at 17 stations in 1981, ten years after dam construction, confirmed that ladder installation increased densities by a factor 6 and modified the population structure, with densities of eels age 0 and 1 multiplied 29 fold. This change corresponded to reduced escapement rates to the glass eel fishery (1% to 5%). Considering this result, a preliminary escapement target of 240 glass eel per km 2 of watershed area or 1 500 glass eel per ha of water surface, is proposed and discussed for glass eel fisheries.

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“…eels exploiting more efficiently an environment which they have already experienced. The attachment to precise loci may proportionally be higher in densely populated environments, such as the Awirs stream, where the population density is sensibly higher than in most European waters (Tesch, 1977;Lobon-Cervia et al, 1990;Barak & Mason, 1992).…”

Section: Discussionmentioning

confidence: 99%

Seasonal variations in time and space utilization by radio-tagged yellow eels Anguilla anguilla (L.) in a small stream

Baras

Jeandrain

Serouge

et al. 1998

Advances in Invertebrates and Fish Telemetry

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Seven yellow eels (572-643 mm, 318-592 g) Anguilla anguilla (L.) were tagged with surgically implanted radio transmitters (activity circuit, 1.6-1.7 g) and tracked in the Awirs stream, a small (width < 5 m, depth from 0.1 to 1.2 m), densely populated (ca. 250 kg of eel ha −1 ) tributary of the Belgian River Meuse. The eels were positioned daily from late April to mid-August, and their diel activity was studied during twenty four 24-h cycles. During day-time, the eels were resting in rootwads or in crevices inside stone walls or in crevices in between rocks. They became more active in the late afternoon but generally did not leave their residence before sunset, except under overcast weather. Activity peaked during the first part of the night then progressively vanished, and always ended before sunrise. The area exploited during night-time never extended over more than 40 m 2 , except when the eel changed its residence. The intensity and timing of nocturnal activity and the extent of the daily activity area were dependent on water temperature (respectively P < 0.0001, P < 0.05 and P < 0.0005), with eels showing little or no activity when the diurnal temperature did not exceed 13 • C. Eels showed higher agitation under full moon and maintained their activity later in the night (P < 0.05). The eels showed restricted mobility, and occupied small stream areas (from 0.01 to 0.10 ha) in a non sequential mode, except for two fish which were displaced to the River Meuse by a spate in early June and were never recovered. The length and frequency of net daily journeys were higher (P = 0.005) at water temperatures above 16 • C in late May and June, which also corresponded to the period of immigration of eels from the River Meuse. This study thus shows that large yellow eels may adopt a highly sedentary lifestyle in a continental, fast flowing and densely populated environment, even at periods of the year when these stages usually show upstream migrations.

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Population density, growth and diet of eels, Anguilla anguilla L., in two rivers in eastern England

Cited by 36 publications

References 12 publications

Distribution, prevalence, and intensity of the swim bladder parasite Anguillicola crassus in New England and eastern Canada

Distribution, prevalence, and intensity of the swim bladder parasite Anguillicola crassus in New England and eastern Canada

Effect of Re-Opening of a Migratory Pathway for Eel (Anguilla Anguilla, L.) at a Watershed Scale

Seasonal variations in time and space utilization by radio-tagged yellow eels Anguilla anguilla (L.) in a small stream

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