Canada. Fisheries Service Maritimes Reg1on. Resource Development Branch MANUSCRIPT REPORT
1+ Environment Canada Environnement Canada RESOURCE DEVELOPMENT BRANCH
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. . """' No . . 71-3 2 .. -· ..
The Effect of Causeway construction on Atlantic Salmon (Salmo sal ar) Populations in Middle River And West River, Pictou County, Nova Scotia
by
C.L. McLeod
Fisheries Service =111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111 11111111111111 Halifax, N.S. /J.,_06
THE EFFECT OF CAUSEWAY CONSTRUCTION ON ATLANTIC SALMON (Salmo salar) POPULATIONS IN MIDDLE RIVER AND WEST RIVER, PICTOU COUNTY, NOVA SCOTIA.
C.L. McLEOD
Environmental Protection Section Resource Development Branch Fisheries Service Department of the Environment Halifax, Nova Scotia
NOVEMBER, 1971 (i)
TABLE OF CONTENTS
Page INTRODUCTION l
DESCRIPTION OF THE STUDY AREA 1 General physical features 1 Fish Fauna 2 Causeway dams 3
METHODS 3
RESULTS 4
Movement of fish through fishways 4 Juvenile salmon relative abundance & growth 4 Smolt migration delay in the reservoirs 5
DISCUSSION 7
LITERATURE CITED 10
FIGURES 11 12
TABLES 13 17 A. INTRODUCTION
In recent years, causeway dams have been constructed across the lower reaches of numerous Maritime streams. These causeways are utilized for transportation routes, protect agricultural lands from tidal flood water and provide fresh water for recreation, domestic and industrial use. Unfor tunately, many of these causeway dams are formidable barriers to the migration of anadromous fish species. In 1966 and 1967, the construction of causeways on Middle River and West River, Pictou County, Nova Scotia, initiated a biological assessment to determine the effects of such physical barriers on the fish stocks of the rivers.
Studies were begun by T.G. Carey in 1968 and included a survey of the fish fauna, invertebrate life, and physical and chemical characteristics of Middle River and West River. Examination of the fish fauna was continued by C.L. Dominy in 1969-70 and by the author in 1971. In 1970, a third stream, River John, was included in the study as a control stream. The biological evaluation has concentrated on one anadromous fish species, the Atlantic salmon (Salmo s a lar). Results of this evaluation are presented in this report and inlcude data on migration of adults and smolts; juvenile abundance, age, growth and distribution.
B. DESCRIPTION OF THE STUDY AREA
1. General Physical Features
Figure 1 shows the location and drainage basins of West River, Middle River and River John. All three rivers are characterized by wooded banks of coniferous and deciduous trees. However, the lower reaches of the streams are relatively open and streamside vegetation provides only a small amount of shade coverage. Dominy (1970) found mid-summer water temperatures as high as 80°F in the lower reaches, with temperatures 4-5° lower in the shaded upper portions of the river.
Bottom materials of all the streams consists mainly of cobble (2-10 inches in diameter), gravel and some boulders. Riffles, runs and pools alternate throughout most of the lenght of the streams. Areas of sand, silt and reduced flow are found in the lower reaches of the streams.
2. Fish fauna
Species of anad:r;omous fish using t ''.lese rivers in clude Atlantic salmon, speckled trout, striped bass, shad, alewives and smelt . The catadromous eel is also found in each river. Other fish found in the river systems include common suckers, chubs, nine-spine sticklebacks , three-spine sticklebacks, shiners, banded killifish and mummichogs.
No salmon catch statistics are available for Middle River or West River. Carey (1968) reported angling pressure on Middle River to be very light, while West River yielded a considerable number of black salmon in the spring of each year.
Speckled trout are stocked yearly in West and Middle Rivers. Carey (1968) found that anglers took approximately 1,200 trout per year from the West River drainage and 400 per year from Middle River . - 3 -
3. Causeway Dams
In 1966, construction was begun on a causeway dam across the mouth of Middle River. In 1967, a second causeway was constructed about 1 1/2 miles below this, across the upper portion of Pictou Harbour (See Fig 2). The Pictou Harbour causeway, while blocking the mouth of the West River, also creates a double barrier for the movement of fish into Middle River. The causeways were constructed to provide water for the Scott Maritime Pulp Mill, located on the east shore of Pictou Harbour, and to supplement supplies to the nearby Towns of Trenton, Stellarton, New Glasgow and Westville, for industrial and municipal expansion. The Pictou Harbour cause way now serves as a Trans-Canada Highway link and the Middle River causeway as a crossing for Canadian National Railways. The Middle River reservoir is now used to provide the Scott Mari time Pulp Mill with 25 MGD of fresh water, while no dernand for water is currently placed on the Pictou Harbour reservoir.
At the tirne of construction, pool and weir type fishways were installed in both causeway structures. Auto rnàtically adjusting baffles were fitted to rnaintain a constant flow of water through the fishways. Although there seerns to be an adequate supply of water to operate both fishways, additional dernands by Scott Maritime and other industrial development could result in a lack of water for the Middle River Fishway (Jansen, 1970) .
C. METHODS
During the fall of 1969 and spring of 1970, fish counting traps were operated at bath causeway fishways. All fish passing upstream through the fishways were counted and released above the causeways. - 4 -
Small mesh gill nets (1.0, 1.5, 2.0 inch stretched mesh) were used to sample salmon smolt in Middle River and Pictou Harbour reservoirs each summer from 1968 to 1971.
Juvenile salmon and other stream dwelling fish were sampled throughout West River, Mi ddle River and River John from 1968-1971, by using an electric f ish shocker.
D. RESULTS
1. Movement of fish through fishway s
Table 1 gives the complete count of fish movement through the causeway fishways from Sept ember 11 to December 9, 1969. During this time, only 8 s almon moved through the Pictou Harbour fishway; none move d through the Middle River Fishway. Normal water levels of betwee n 3.0 - 3.8 feet were maintained in the Pictou Harbour reservoir during this time. However, water levels at the Middle River reservoir dropped to a -low of 6.0 feet on the first of October and rose to only 8.6 feet by November. No fish used the fishway until November 12, at which time the water level had risen to 10.8 feet. Jansen (1970) reported that water levels less than 6.4 feet would render the Middle River fishway inoperable.
The fishways were monitored during the spring of 1970, (May 20-June 5) and these records are also presented in Table 1.
2. Juvenile salm:on - re·lative abundance and growth
Electroseining operations were carried out during July-August of each year. No samples were taken from River John in 1968 and 1969. The number of sites seined varied each - 5 - year from about six to twelve sites per river. Barrier nets were used at selected locations, the remainder were sampled roughly by single sweep spot checks. For the purpose of this analysis, all data has been cornbined. The results, in terms of abundance per 100 square yards, are presented in Table 2.
These results show an almost cornplete absence of juvenile salmon in the Middle River drainage by 1971 and indicate a significant reduction, in the population of juvenile salmon in the West River. Although not really comparable, the abundance of juveniles in West River is lower than the abundance in River John, (the control stream).
Good spawning success was noted in 1968; presurn ably the last year adult salmon could pass unhindered into Middle and West Rivers. The success of the 1968 spawning can be seen, with the increas ed juvenile abundance in 1969 and 1970. The complete lack of salrnon fry in Middle River from 1969 to 1970 indicates the blocking effect of the cause way upon the spawning migration. The nurnbers of fry observed in West River from 1969-1971 are very low and the possibility of many juveniles reaching the smolt stage seems rernote.
Growth-weight data for juveniles is given in Table 3. Considerable variations in size and weight are evident be tween the juveniles from different streams. The best growth seems to be exhibited by individuals from the Middle River drainage.
3. Smolt migration delay in the reservoirs
Test netting for smolts was carried out in Middle River and Pictou Harbour reservoirs each summer from 1968 to 1971. The results (nurnber of fish per hour fishing effort) are shown in Table 4. An extremely large nurnber of smolts 6 -
were taken from the Middle River reservoir in 1969. At the same time, only a few smolts were captured in the Pictou Harbour impoundment.
Approximately 80% of the smolts captured in the Middle River reservoir were 3+ years of age, 10-15% were 4+ years and the remainder 2 + years. Table 5 gives the size and wéight of the smolt age classes.
Middle River parr averaged 97 mm in length at the start of their second season in fresh water (l+) as compared with 89 mm for l+ individuals from the Petitcodiac River, New Brunswick (Dominy, 1970). Yet, Dominy found most Petit- codiac River smolts to be 2 + years of age (142 mm) while most Middle River smolts captured were 3+ years (approx. 189 mm). Three year smolts are not uncommon, but it is suggested that the Middle River causeway provided more than just a casual influence; as many salmon parr seemed to spend at least one extra year in fresh water.
In 1971, the only juvenile salmon captured by electroseining in Middle River were 5 extremely large parr (165.4 mm average, 3 + years) which were of smolt size but were still in freshwater.
No age-size data is available for smolts from Pic tou Harbour reservoir. 7 -
E. DISCUSSION
Construction of the Middle River causeway has virtually eliminated this river as a spawning and rearing area for Atlantic salmon and other anadromous fish species.
Water levels in the Middle River reservoir are instrumental in controlling the operation of the causeway f ish way. Poor management of reservoir water levels in 1969 rendered the f ishway inoperable for a period of time during the fall salmon run. Future demands by industrial development will contribute to an even further draw down in the reservoir and may make it difficult to provide water to operate the fishway (Jansen, 1970).
Industrial demands on the Middle River reservoir are met by storage during the months of increased water flow and there is a subsequent draw down during months of low water flow. Significant volumes of water are not released until the reservoir is filled in late fall. Few water releases during the summer of 1969 resulted in a considerable delay to the seaward migration of smolts. Development and use of the reservoir waters in the future will further reduce spillage.
Considerable volumes of water appear to be needed in order to attract fish to the fishway entrance at the Middle River Causeway. Upon entering the Pictou Harbour reservoir it is only logical that migrating fish will be attracted to the main source of inflow; in this case, West River. It can be seen that any attempt to provide increased attraction water from Middle River reservoir during fall spawning migrations is impossible because of present and future industrial demands.
As a ~esult of the above conditions, the fish passage facilities at the Middle River causeway are not fully utilized and serve no useful purpose for most anadromous fish. Demands on the
U044#WPW W'i:J!f - 8
Middle River are not compatible with the perpetuation of a salmon fishery. In view of existing observations, stocking of juvenile salmon or transfer of adult spawning stock is not recommended. Speckled trout have been successfully stocked in t he upper reaches of the river; any future stocking program should concentrate on trout species or some other species which are not necessarily anadromous.
The Pictou Harbour causeway has not had such a visible effect on anadromous fish populations in West River. Fishway counts during 1969 indicated that many species of fish were able to move through the causeway fishway. Water levels in the reservoir are relatively stable and the fishway experiences no lack of water for operation. However, the very low count of adult salmon in 1969 and the low abundance of juvenile salmon from 1969 to 1971 (compared with 1968) suggests that the causeway does constitute a barrier to the migration of salmon. No evidence was found for smolt delay during the seaward migration, but more sampling is needed before reaching a conclusion. The size and shape of the reservoir would necessitate a large concentration of smolts before they could be detected. Because of the low juvenile abundance in the river, the numbers of smolts captured by occasional test netting has been understandably low. Since little or no water is spilled from the reservoir during the period from June to September (Jansen, 1970), it is quite likely that smolts attempting to leave the river at this time experience some delay.
Several possibilities exist for improving fish movement past the Pictou Harbour causeway. Because of the low head between tidal and reservoir levels, some fish likely move through the causeway gates when they are opened. Mani pulation of the gates could be carried out so that suitable - 9 - hydraulic conditions exist for movement of fish, i.e. opening
the gates when the reservoir-tide height dif ference was
approximately 1 foot, would likely give suitable flows. Also,
additional attraction water for the fishway would be desirable.
Water spilled from one of the causeway gates on a more regulated basis is needed. Providing water for smolt migration during the
summer would be more difficult. Some improvement could be made
if the reservoir level was held as high as possible during· runoff in April, thus providing water for a regulated spillage which may last until early July. The above operations do not entail large expenditures of money nor are they complicated.
Most of the requirements could be handled by a better regulation
and scheduling of présent water releases from the impoundment.
Stocking juvenile salmon in West River should be
considered as it may supplement natural reproduction and help rebuild the population in a shorter time. However, without
some attempt to increase the successful migration of adults and smolt past the causeway, stocking of salmon in West River would be futile.
It is also recommended that the present study be continued for another year in order to obtain further data for confirmation of population trends of anadromous fish in Middle
River, West River and River John. - 10 -
LITERATURE CITED
Carey, T.G., 1968. Unpub. Rept. Resource Developrnent Branch Departrnent of Fisheries and Forestry (Halifax) .
Dorniny, C.L., 1970. Progress Rept. Petitcodiac River Causeway - Fishway evaluation studies. Environrnental Protection Section, Resource Developrnent Branch, Departrnent of Fisheries and Forestry (Halifax) 16 p.
Jansen, H., 1970. An investigation into a possible inadequate water supply to operate the Middle River and Pictou Harbour fishways. Report, Environrnental Protection Section, Resource Developrnent Branch, Departrnent of Fisheries and Forestry (Halifax). 20p. N !
' 112 ' \ \ , __ ...... ' ...... 1
West I , I River / / Middle ' River ----
Figure 1
Map of Middle River, West River and River John Drainage Areas (nurnerals refer to square miles). - 12-
PIC TOU HARBOUR CAUSEWAY __/
MIDDLE RIVER CAUSEWAY
Figure 2
Middle River and Pictou Harbour Causeway sites. Table 1
Fishway counts, Middle River and Pictou Harbour reservoirs, Nova Scotia.
Pictou Harbour Fishway
1969 1970 (Sept 11-De c 9) (May 20-June 5) Atlantic Salmon 8 0
Speckled Trout 10 0
Shad 605 approx.* 0
Gaspereau 1635 approx.* 0
Arnerican Eel 1437 19
Striped Bass 75 0
Cornrnon sucker 112 0
Perch 0 32
Srnelt 0 300
Middle River Fishway
Striped Bass 9 0
Cornrnon Sucker 51 0
* juvenile fish, rnoving into salt water Table 2. Abundance of juvenile salrnon in Middle River, West River, and River John, Nova Scotia, frorn 1968-1971 (nurnbers / 100 square yards).
* = less than 1/100 sq. yd.
1968 1969 1970 1971 0+ l+ 2+ 3+ O+ l+ 2+ 3+ O+ l+ 2+ 3+ o+ l+ 2+ 3+ MIDDLE RIVER 18 * 1 * 0 3 7 * 0 0 1 0 0 0 0 *
WEST RIVER 67 3 * 0 0 19 4 * 1 2 5 0 5 2 1 0
RIVER JOHN ------9 8 5 0 6 27 3 0
Age Size Eg:uivalent
0+ - f ry l+ - small parr 2+ - large parr 3+ - large parr - 15 -
Table 3.
Length-weight of juvenile Atlantic salmon in Middle River, West River and River· John, Nova Scotia.
MEAN FORK LENGTH MEAN WEIGHT (gm) (mm) AGE l+ 2+ 3+ l+ 2+ 3+
Middle River 97.0 110.0 145.0 11. 2 17.3 39.4 (50) (20) ( 1) ( 50) (20) (1)
West River 88.0 103.0 120.0 7.4 14.7 21. 4 ( 32 0) (46) (1) (320) (46) (1) River John 77.6 99.4 - 6.4 13.2 - ( 10 3) ( 61) ( 10 3) ( 61)
Numbers of fish sampled indicated within brackets
River John 1970 data
Middle River & West River 1969 data - 16 -
Table 4.
Nurnber of Atlantic salmon smolts captured (per hour fishing effort) in Middle River and Pictou Harbour Reservoirs.
1968 1969 1970 1971
Middle River 1.9 28.6 O* 0 Impoundment (17) ( 3. 5) (2) ( 6)
Pictou Harbour 0 . 4 O* 0 Impoundme n t (17) ( 7) ( 2. 5) ( 6)
Hours fished indicated within brackets
* personal communication with O. Barrett (Technician) - 17 -
Table 5.
Mean length-weight of Atlantic salrnon smolt age classes in Middle River, Nova Scotia.
Fork Length (in mm) 2+ 3+ 4+ 5+ 6+
1968 187.9 247.0 360.0 (15) ( 4) (1)
1969 165.7 189.6 253.8 ( 4) ( 41) ( 5)
Weight (in grn) 2+ 3+ 4+ 5+ 6+
1968 64.2 171. 5 314.0 (15) ( 4) (1)
1969 46.9 68.8 142.6 ( 4) ( 41) (5)
Nurnbers of f ish sarnpled indicated within brackets