Operational Plan for the Restoration of Diadromous Fishes to the ...

Approximately 600,000 smolts are stocked in the Penobscot basin annually,
accounting for 90% or more of the adult Atlantic returns. Major factors that affect
where and when to stock smolts are: 1) homing to suitable habitat, 2) survival due to
migration through dams, 3) seasonal timing, and, 4) physiological timing. Additional
consideration should be given to smolt “quality”. Alternative rearing and release
strategies may improve survival.
Currently, smolts are stocked at a number of fixed locations. These have been
adjusted over time, with the most recent adjustments based on relative return rates
among stocking locations. The adaptive management decision based on these
findings was to shift smolts from the lowest return rate location to a higher return rate
location.
Major constraints on system flexibility are hatchery rearing requirements and smolt
transportation. Changes to some aspect of smolt rearing may need to be vetted a
year or more in advance. Other aspects of smolt stocking, such as shifting a
stocking location can usually be done with short notice. However, under adaptive
management, all substantive decisions should be planned, following the process
outline in the adaptive management section of this plan. Marking is the primary
means of assessing management changes. Smolts marks are coordinated by an
interagency Marking Group. All marking needs must be vetted through this group to
ensure unique and compatible marking.
Up until 2006, there was no single reference stocking location that could be used to
track temporal changes in return rates. Whole cohort return rates are the only long
term data, and offer not options to compare alternative stocking strategies. In 2006,
the decision was made by TAC to establish a long-term baseline return rate site.
From 2006 to present, 175,000 marked smolts have been stocked at Morin Fuel in
Bradley. This was the location selected to use as the baseline location prior to any
dam removals. The smolts stocked in Bradley have carried three different VIE
marks and were stocked on several dates with equal numbers of all three marks.
This marking strategy provides an estimate of return rate for each cohort with a
variance. The baseline site will change to a location above Milford in anticipation of
the Milford fish lift coming online and Veazie being removed. This plan results in a
long-term baseline return rate site above Milford.
The stocking plan for 2007 and 2008 was:
~ 175,000 tagged PN stocked in Veazie pond (Morin Fuel)
~ 200,000 PN stocked in the Pleasant River (Milo)
~ 200,000 PN stocked at near West Enfield smolt ponds or Passadumkeag boat
launch
~ 25,000 PN stocked into West Enfield smolt ponds
PRFP Page 175