Background

  • Before the plan can take effect, there will need to be consultation with FSC agencies, stakeholder groups including tribal interests on both sides of the border, and the public. The current bar on alewife access at Grand Falls Dam under Maine State law would also need to be lifted.
     

  • When the plan is implemented, the fishway at Grand Falls Dam would be reopened to allow the alewife population to grow without restrictions until it reaches six per acre, or 146,316 alewife in the portion of the basin to be reopened, from a current level of 10,450 fish. Milltown and Woodland Dams would remain open as before, but Vanceboro and West Grand Dams would be closed to alewife, to exclude them from Spednic and West Grand Lakes and points upstream.
     

  • Once alewife reach the six per acre level, the plan sets conditions for their further population increase, addressing concerns that alewife presence may have negatively affected the bass population in Spednic Lake in the 1980’s. Implementing agencies will monitor the smallmouth bass young of year (YOY) in Grand Falls Flowage and Big Lake, which would be open to alewives, but also in three control lakes; including West Grand Lake, which will not be opened to alewives. Table 5 on p. 11 shows the bass criteria, based on historical YOY catches.
     

  • After each spawning season, biologists will use electrofishing to assess the YOY bass abundance and compare it with historical YOY catch data for each monitored lake. They will assign;traffic light; indicators to their findings: green for good reproductive success, yellow for acceptable reproductive success that may be cause for concern, and red for low reproductive success. Data from control lakes (no alewife) would reveal years when weather limited reproductive success.
     

  • Besides the smallmouth bass population data, the other data input to the decision process is the number of alewife ascending the fishway at Milltown Dam at Calais. Sample data on alewife passage above Grand Falls Dam would be needed as well, as the most recent passage data for that fishway date from 1986, before passage was blocked. The decision process will rebuild the alewife while ensuring that any negative effects on bass are detected and acted upon rapidly.
     

  • The green, yellow or red "traffic lights" for bass in Big Lake and Grand Falls Flowage over each of the most recent three years will be translated into numbers: +1 = green/good conditions, 0 = yellow/cautionary zone, -1 = red/unacceptable conditions. The six resulting numbers (3 numbers for 2 lakes) will be summed into an index of smallmouth bass spawning (recruitment).
     

  • Alewife passing Milltown will only be increased (by a factor of 1.5) if the bass recruitment index is positive and the alewife met their current escapement target. If the index is zero, the alewife escapement remains unchanged. If the index is negative – or, as a further safeguard, if the same lake has a red traffic light two years in a row – alewife escapement is reduced to the previous level that produced a corresponding positive smallmouth bass recruitment score.
     

  • The bass population may vary year by year due to factors other than alewife recovery. Since the plan’s precautionary approach limits alewife access according to bass reproductive success, even chance occurrences can slow the rate of alewife recovery. Computer simulations demonstrate.