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Canada. Fisheries Service Maritimes Reg1on. Resource Development Branch MANUSCRIPT REPORT 1+ Environment Canada Environnement Canada RESOURCE DEVELOPMENT BRANCH , m~ i1liii1inliili1Îlil1ii\ilil1i1i1tïi11 09093281 MANUSCRIPT REPORT . """' 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.

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