scholarly journals Oceanic Environmental Effects on American Eel Recruitment to the East River, Chester, Nova Scotia

2020 ◽  
Vol 12 (4) ◽  
pp. 222-237
Author(s):  
Brian M. Jessop
Keyword(s):  
Nova Scotia ◽  
Environmental Effects ◽  
American Eel ◽  
East River

Geographic and seasonal variation in biological characteristics of American eel elvers in the Bay of Fundy area and on the Atlantic coast of Nova Scotia

1998 ◽  
Vol 76 (12) ◽  
pp. 2172-2185 ◽  
Author(s):  
B M Jessop
Keyword(s):  
Nova Scotia ◽  
Atlantic Coast ◽  
Bay Of Fundy ◽  
Biological Traits ◽  
American Eel ◽  
East River ◽  
Commercially Important ◽  
The Mean ◽  
Seasonal Decline ◽  
Collection Date

Seasonal (April-July) patterns in the decline of length, mass, and condition and an increase in pigmentation stage of American eel (Anguilla rostrata) elvers collected during the estuarine commercial fishery and during entrance into fresh water varied among rivers in the Bay of Fundy and on the Atlantic coast of Nova Scotia. Elver mean length, adjusted to a mean collection date, varied among commercially fished rivers by up to 9%; mean mass varied by up to 27%. Within commercially fished rivers, mean length declined seasonally by 2-5%, mass by 0-60%, and condition by 0-44%. Elver condition declined 7-9% by the time 50% of the run (number of elvers) had entered the East River, Chester, and East River, Sheet Harbour, and by 21% at 95% of the run, while the mean pigmentation stage increased to 4.1-4.8 and 5.7-6.5, respectively, on a scale of 1-7. Such geographic variability in biological traits may result from the effect of varying annual and seasonal environmental conditions on the coastal distribution of elvers and on their run timing and physiological development in estuarine and stream habitats. The biological importance of the seasonal decline in elver length, mass, and condition is uncertain, but a seasonal decline in mass of 35% may be commercially important when elvers are sold by weight rather than count.

Rheotaxis of Elvers of the American Eel (Anguilla rostrata) in the Laboratory to Water from Different Streams in Nova Scotia

1968 ◽  
Vol 25 (8) ◽  
pp. 1591-1602 ◽  
Author(s):  
S. G. Miles
Keyword(s):  
Organic Matter ◽  
Nova Scotia ◽  
Fresh Water ◽  
Stream Water ◽  
Salt Water ◽  
The Other ◽  
Anguilla Rostrata ◽  
American Eel ◽  
Heat Stable ◽  
Experimental Apparatus

In an experimental apparatus, elvers of the American eel (Anguilla rostrata) showed a stronger positive rheotaxis to fresh water than to salt water. The attractiveness of the fresh water was due to dissolved and particulate organic matter; these components were bio-degradable, heat stable, and nonvolatile. Four streams near Halifax, Nova Scotia, were tested, and were found to differ greatly in their attraction of elvers. Elvers were collected from each of three of these streams, and were not found to be attracted to their own stream water; elvers from one stream gave a greater rheotactic response than elvers from the other streams. The presence of adult eels in the water rendered it more attractive, whereas the presence of elvers made it less so.

scholarly journals Productivity of riverine habitats may be changing for American eel

2018 ◽  
Vol 75 (11) ◽  
pp. 1773-1777 ◽  
Author(s):  
Heather Dawn Bowlby
Keyword(s):  
Nova Scotia ◽  
Atlantic Coast ◽  
American Eel ◽  
Regional Productivity ◽  
Glass Eel ◽  
Watershed Characteristics ◽  
High Productivity ◽  
Enhanced Production ◽  
Juvenile Abundance ◽  
Riverine Habitats

The panmictic population of American eel (Anguilla rostrata) is at risk, making any region that supports enhanced production important from a recovery perspective. Strong glass eel runs to a small number of rivers along the Atlantic coast of Nova Scotia are thought to indicate high productivity, partially buffering declines occurring in other regions. However, contrary to glass eel indices of recruitment, an index representing older juveniles has strongly declined in riverine habitats throughout Nova Scotia from 1995 to 2005, with evidence of substantial differences in relative abundance among watersheds. This suggests that glass eel indices may not reflect trends of older juveniles and consequently that the contribution of Atlantic coast rivers to population persistence may be overstated. More recent monitoring from two rivers shows divergent trends in juvenile eel abundance, underscoring the importance of widespread surveys to assess changes in regional productivity. Further evaluation of the watershed characteristics associated with higher juvenile abundance would aid in understanding differences in productivity among watersheds and possibly in facilitating increased spawning escapement for American eel.

Stage loading of a highway embankment on tidal flats

1981 ◽  
Vol 18 (4) ◽  
pp. 535-542
Author(s):  
W. J. Burwash ◽  
M. A. J. Matich
Keyword(s):  
Nova Scotia ◽  
Case History ◽  
Tidal Flats ◽  
Economic Advantage ◽  
The Other ◽  
Sufficient Time ◽  
East River ◽  
History Of ◽  
Porewater Pressure ◽  
Predicted Values

The approach embankment to the eastern extremity of a bridge across the East River near Trenton, Nova Scotia involved construction of a 6.4 m high embankment on tidal flats. Very soft to soft slightly organic marine silts were found to underlie the tidal flats to a depth of 6–9 m where bedrock was encountered. Construction of an embankment of this height on the tidal flats would require very flat sideslopes to ensure stability. Alternatively, all or part of the silt could be removed or the embankment could be built slowly using the stage loading technique and allow the silt to consolidate and gain strength during construction of the embankment. Stage loading had a considerable economic advantage over the other alternatives and since sufficient time was available, this method was adopted.The case history of this project is presented including results of the settlement performance of the embankment and porewater pressure response in the silt. These results are compared with predicted values and conclusions are drawn regarding the stage loading technique for this particular type of application.

Total Mercury and Methylmercury Content of the American Eel (Anguilla rostrata)

1973 ◽  
Vol 30 (3) ◽  
pp. 454-456 ◽  
Author(s):  
H. C. Freeman ◽  
D. A. Horne
Keyword(s):  
Nova Scotia ◽  
Total Mercury ◽  
Mercury Content ◽  
Human Consumption ◽  
Anguilla Rostrata ◽  
American Eel ◽  
The Mean ◽  
American Eels

In American eels (Anguilla rostrata) caught in Nova Scotia, the total mercury content was found to be 0.72 ± 0.05 ppm and the methylmercury content was 0.40 ± 0.06 ppm (mean ± SE for 23 fish). Since the mean total mercury content was less than 1 ppm and the toxic methylmercury content was 50% of this, or less than the 0.5 ppm guideline, such eels may be acceptable for human consumption.

Behavior of Atlantic salmon (Salmo salar) During Suspended Migration in an Estuary, Sheet Harbour, Nova Scotia, Observed Visually and By Ultrasonic Tracking

1982 ◽  
Vol 39 (2) ◽  
pp. 248-256 ◽  
Author(s):  
Vivien M. Brawn
Keyword(s):  
Nova Scotia ◽  
Atlantic Salmon ◽  
Salmo Salar ◽  
Small Area ◽  
Migration Behavior ◽  
Ground Speed ◽  
Atlantic Salmon Salmo Salar ◽  
East River ◽  
Constant Distance ◽  
Ultrasonic Tracking

The movements of adult Atlantic salmon (Salmo salar) were followed in an estuary from August to November 1978 and in July and August 1979 by ultrasonic tracking. During these periods, the proportion of time spent by salmon in apparent random movement inside a small area steadily increased, reaching 97 or 98% in September and October, and then declined. This behavior was observed visually in schools of 17 to 75 salmon which showed no preference for sun or shade, were not easily disturbed, kept a constant distance from the surface associated with the halocline, and were in currents too low to measure. As the frequency of this behavior increased, average ground speed of moving fish decreased. Suspended migrations of up to [Formula: see text] mo were recorded. Salmon planted as smolts in East River and returning as adults remained almost exclusively in the East River arm of the Y-shaped estuary. Salmon favored areas having water deeper than 3 m, but showed no preference for areas deeper than 5 m inside the 3-m contour. Moving fish showed a tendency to move upstream on a rising tide and downstream on a falling tide, but these movements could be reversed by high turbine flows at the mouth of East River. A means of removing ultrasonic tags from live salmon without injury was developed.Key words: Atlantic salmon, estuary, migration, behavior, ultrasonic tracking

An Application of Louver Deflectors for Guiding Atlantic Salmon (Salmo salar) Smolts From Power Turbines

1972 ◽  
Vol 29 (10) ◽  
pp. 1397-1404 ◽  
Author(s):  
L. J. A. Ducharme
Keyword(s):  
Nova Scotia ◽  
Atlantic Salmon ◽  
Salmo Salar ◽  
Velocity Ratio ◽  
Atlantic Salmon Salmo Salar ◽  
East River ◽  
Approach Velocity ◽  
Flow Turbulence ◽  
Guiding System ◽  
Reduced Flow

Louver deflectors for guiding Atlantic salmon (Salmo salar) away from destructive power turbines were installed in a canal leading to the powerhouse at East River, Sheet Harbour, Nova Scotia, in 1966. Guiding efficiency studies, using hatchery-reared smolts, showed that a minimum approach:bypass velocity ratio of 1.0:1.5 was a prerequisite to high guiding efficiency. From 1967 to 1971, average guiding efficiency was increased from 57% to 80% through modifications which increased velocity and reduced flow turbulence in the bypass. A significant correlation existed between approach velocity and guiding efficiency within the range tested after bypass hydraulics had been modified. Tests conducted with varying louver bar spacing ranging from 5.1 to 30.5 cm (2–12 inches) showed that the wider spacings did not impair guiding efficiency.Vertical distribution of smolt migrants in the power canal indicated that over 80% of the fish remained above depth 1.3 m. This was borne out by the fact that the bypass was effective when operating to a depth of only 0.91 m. An appraisal of the practicality of the louver guiding system is presented.

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