from a letter to the Orland Dam Committee from Claire Enterline, Maine Department of Marine Resources, 2013
RE: Orland Village Dam
Alternatives Feasibility Study
To the members of the Orland Dam Committee:
The Maine Dept. of Marine Resouces (DMR) would like to commend the
Committee for its efforts to identify alternatives to the current management of
the Orland Village Dam, and offer comments and DMR data that may be helpful to
the Committee moving forward.
DMR has documented Atlantic salmon, alewife, blueback herring, and
American eel using habitat above the Orland Village Dam. Data from the
University of Maine (G. Zydlewski, personal communication), and informal
reports from town residents indicate that shortnose and Atlantic sturgeon are making
use of the area below the dam and may be present above the dam on occasion.
Additionally, town residents have informally noted that Atlantic gray seals are
also seen below the dam and may be present above the dam on occasion. Of these
species, Atlantic salmon, shortnose sturgeon, and Atlantic gray seals are
currently listed as “Endangered” under the Endangered Species Act (ESA),
Atlantic sturgeon are listed at “Threatened”, and alewife, blueback herring,
and American eel are currently being considered for listing under the ESA.
Because of the status of these species, the ability of each to move efficiently
and without harm between marine, estuary, and spawning locations is an
important concern.
The June 2013 report, “Orland Village Dam Alternatives Feasibility
Study”, prepared for the Committee by Stantec Consulting describes the
potential impacts of four different alternatives on various resources including
fisheries resources. The report indicates that two options (no action, dam and
fishway rehabilitation) would have negligible beneficial impacts on the
fisheries resource, and major adverse impacts on the fisheries resource. The
DMR agrees with these conclusions. Current fish passage facilities in the form
of two Alaskan steeppass sections that are not accessible for fish passage at
all tides are inefficiently passing Atlantic salmon and river herring, and the
American eel, specifically during the elver (juvenile) stage, do not pass
Alaskan steeppass sections efficiently. Further, these structures are not large
enough to pass other species that are in the Orland River (shortnose and
Atlantic sturgeon, Atlantic gray seal). While these larger species may get
above the dam only on the highest high tides, they will not be able to descend
through the fishway or over the dam without injury. As the report indicates,
the Maine Geologic
Survey (MGS) for the Maine Coastal Program indicate that the State of Maine is planning
for a predicted 2-ft rise in sea level over the next 100 years, which would
increase the frequency of occurrences of the tide over topping the dam, and
possibly also increase the number of Endangered marine species stranded behind
the dam.
The report indicates that the third option, dam and fishway modification,
would result in moderate beneficial
and adverse impacts to fisheries resources. Again, DMR agrees with this
conclusion. Fishway modification that would increase the passage efficiency and
capacity would be moderately beneficial for river herring and Atlantic salmon,
but as the report states there are “inherent limitations of technical
fishpasses” and 100% upstream and downstream passage efficiency would likely
not be achieved. Further, fishway modifications would not provide any benefit
to the larger marine species that are also present in the area. Additionally,
if the fishway modifications suggested in the report (Denil-style fishway) are
used, passage for the elver stage of American eel would need to be built
separately as Denil-style fishways do not effectively pass elvers (the
estimated cost associated with the option does not include additional elver
passage construction/maintenance).
The report indicates
that the fourth option, dam removal, would result in major beneficial and minor
adverse impacts to fisheries resources. The DMR again agrees with the
conclusion that there would be major beneficial impacts to the fisheries
resources. This alternative would provide unobstructed access to the species
currently found within the area, and would likely result in increased spawning
habitat for blueback herring, American shad, rainbow smelt, and Atlantic
tomcod, all which spawn within freshwater mainstem habitat where water is quick
moving. Improving the populations of these species within this river stretch
could lead to increased recreational fishing opportunities, especially for
American shad and rainbow smelt which support popular recreational fishing in
other areas of the state.
The report also
indicates that this option would have “moderate
beneficial and moderate adverse impacts to river herring harvesting facilities
located immediately downstream from the Orland Village Dam. The moderate
beneficial impact … based on the potential for increased alewife production and
associated increased revenue for facilities operation and maintenance. [The]
adverse intensity level … based on the assumption that the existing facility
could still be used at low tide. A higher adverse intensity level would be appropriate
if it was determined that alewife harvesting operations would need to be moved upstream
to the vicinity of the Alamoosook Lake Dam.” The DMR recommends that the Orland
Dam Committee consider these statement together with other information
regarding the harvest and its current location, presented below.
The DMR provides
the following information about the river herring harvest for the Orland Dam
Committee to consider in addition to the report prepared by Stantec Consulting,
and with the hope of providing insight into DMR’s management of the river
herring fishery as well as biological considerations.
...All commercial river herring harvests in Maine are approved jointly
by the DMR and the Atlantic States Marine Fisheries Commission (ASMFC), a
multi-state group that collaboratively forms management decisions about
fisheries for species that cross state boundaries, based on sustainability
criteria that were adopted in 2009. Fisheries that were allowed to remain open
had to meet the following criteria: the run could not be stocked with river
herring from an outside source, average 20-year escapement during closed days had
to exceed 35 fish per acre of spawning habitat, and the spawning population had
to be considered biologically stable (as evidenced by age distribution and
repeat spawning rates). The Orland fishery was approved to remain open because
the escapement target (35 fish/acre) was based only on the acreage of
Alamoosook Lake, not all available habitat, based on the assumption that other
available habitat was not productive for alewives because of the high number of
non-native predator gamefish species (largemouth bass, chain pickerel). If all
available habitat were to be considered (4968 acres), the watershed could
potentially support 1,167,385 alewives without a harvest (based on a production
capacity of 235 fish/acre), and with a harvest would require escapement of
173,865 alewives (35 fish/acre). If the harvest
location were to move to a location targeting fewer spawning lakes, only the acreage
of the spawning lakes above that new location would be considered when
calculating the target escapement.
The commercial harvest is currently encountering immature
blueback herring and alewife (age 1-2). The harvest of immature river herring
does not meet the sustainability standards identified by the DMR and the ASMFC
because the origin of these fish cannot be determined and because the fish have
not yet been able to spawn. Blueback herring and alewife reach maturation at sometimes
3-years-old, but more typically 4-years old. At this point, the fish ascend
freshwater rivers to spawn, and then return to coastal waters. Because the
adult spawning fish return to the same location every year, we are able to define
these adult spawning fish as unique “stocks” according to their spawning
locations, and track the status of that population stock over time. It is not possible at this time, however, to
determine the “birth place” of immature fish. Immature fish, under the age of 3
or 4-years-old, from the entire Atlantic Coast, from Florida to Labrador,
likely school together spending winters off of Cape Hatteras, NC, and migrating
upwards along the coast annually as part of feeding. Because of these migration
patterns, the immature fish in near-shore coastal Maine likely belong to a “mixed
stock” that is not managed by Maine, but originated from multiple states, each
returning to the original spawning location once they are mature. Because there
are serious river herring population declines to the south, Maine has entered
into agreement with all other Atlantic states to not allow fisheries to target
these immature fish of unknown origin. While some bycatch of immature fish may
occur, continued catches of immature will become a problem. Tables showing the
age distribution at the Orland harvest location by year and compared to other
harvest locations are attached.
The term “repeat spawning rate” is used to describe the
number of alewives or blueback herring that have spawned in one or more
previous years. Unlike some anadromous species, both alewife and blueback
herring typically do not die after spawning, but return to the ocean and will
return to the same location annually. The migration into freshwater for
spawning leaves a mark on the fish’s scales that we use to identify how many
times each fish spawned in years prior. A run with a high repeat spawning rate
indicates that many fish are successfully spawning in multiple years, so have
high survival and is likely a more stable run over time. Tables attached to
this letter show the repeat spawning rates for the current harvest location,
for alewives taken from the fishway leading into Toddy Pond, and for all other
harvest locations. Combining 2008-2012, the current harvest location has, on
average, a lower repeat spawning rate than the fish taken from the Toddy Pond
fishway. Further, the Toddy Pond fishway samples were composed entirely of
alewife, while both alewife and blueback herring are caught at the current harvest
site.
