Guidelines for In-Stream Placement Of Hatchery Salmon
Carcasses For Nutrient Enrichment

Introduction

Historically, large numbers of salmonid carcasses provided entire watersheds with
abundant nutrients and organic matter derived from the ocean. Recent research strongly
supports the hypothesis that salmon carcasses play a key role in maintaining the
productivity of salmonid systems and benefiting the aquatic and terrestrial ecosystem as a
whole. Rearing juveniles consume salmon eggs, feed directly on spawned-out carcasses,
and benefit from increased abundance of invertebrates and algal growth. The presence of
carcasses in streams has been related to increased juvenile density, growth rate, body
size, improved fish condition, improved overwintering survival and ultimately increased
marine survival.

These guidelines have been developed to regulate the in-stream placement of hatchery
salmon carcasses from Fisheries and Oceans Canada enhancement facilities where there
is a desire and the capacity to distribute carcasses. The guidelines are not intended to
enforce the distribution of carcasses, nor to replace harvest under an Excess Salmon to
Spawning Requirements (ESSR ) authorization.
These guidelines are meant to increase the overall benefits from carcass placement by
minimizing disease risks and other concerns, providing general management strategies
for carcass placement, and highlighting the interagency process to avoid conflicts with
potentially affected groups and agencies. Numerous factors affect the benefits of carcass
placement in streams. These include ambient nutrient content in treatment streams,
abundance of native salmon spawners, presence of fish disease agents in carcasses,
retention and distribution of carcasses in waterways, water temperatures, flow levels,
light penetration, and predator / scavenger activity on carcasses by insects, fish, birds and
mammals. These factors have been considered in the development of the guidelines
The guidelines were developed utilizing current relevant literature (Appendix 1), input
from DFO fish health specialists and ecological research scientists, and guidelines
prepared by thhe Washington Department of Fish and Wildlife.
Planning, Review, And Awareness
• Carcass placement plans must be reviewed by a DFO member of the Introductions
and Transfers committee. Projects that meet the terms of the carcass placement
guidelines will be issued a letter from the Department allowing the transport and
deposition of carcasses. This letter must accompany all carcass movements.
• Carcass placement plans should be discussed with all relevant groups and agencies.
These groups will include DFO local area staff in stock assessment, habitat, resource
management, and Conservation and Protection (Fishery Officers), as well as local
First Nations, stewardship groups, affected landowners or any other affected groups.
It is also important to contact the regional Ministry of Water, Land and Air Protection
(MWLAP) office to ensure that carcass placement is coordinated with MWLAP
inorganic nutrient enrichment projects. MWLAP should also be contacted if
placement is considered in non-anadromous waters.
• Under the Water Act, downstream water users (primarily local municipalities), must
be advised of activities that may potentially impact water quality of their withdrawals.
Accordingly, Water Licensees on treatment streams should be advised prior to
placement programs. Carcasses should be distributed in such a way so as to avoid or
minimize impacts on domestic and other types of intakes or water supplies.
• Background material and signage may be provided to advise members of the public
of carcass placement activity and its benefits.
Carcass Management and Condition
The placement of salmon carcasses in streams may pose a risk of disease transmission if
carcasses of infected fish are used, if carcasses are moved to areas within the watershed
that are normally not accessible to salmon, or if carcasses are moved to streams outside
the watershed.
• Streams that receive carcasses are referred to as “treatment” streams and those that
provide carcasses are referred to as “donor” streams. In general, no carcasses may be
moved outside their natal stream because of concerns regarding disease transmission.
However, in specific circumstances, movement of carcasses from the watershed to
nearby streams may be considered if all of the following conditions are met:
• donor and treatment streams are geographically proximate and,
• treatment stream is within the zone of influence of the donor stock (i.e. adults may be
straying from donor to treatment stream), and
• current disease history is available.
If sufficient information is not available, health testing of fish in the donor stream and
treatment stream may need to be undertaken. Historical information can be obtained
by searching the Pacific Biological Station (PBS) Fish Health Database; the Fish
Pathology Program may be contacted at (250) 756-7057. Please note that wild fish
surveys have not been conducted in many locations in recent years so that
information contained in the database does not include current disease status for many
salmon stocks.
• Only those fish killed with CO2 or blunt trauma that show no visible evidence of
serious disease should be used for carcass placement. Carcasses of recently dead
salmon from managed spawning channels may also be considered for placement.
• Because of drug clearance times, and the length of holding, fish previously treated
with an antibiotic or anaesthetic must not be used for carcass placement. However,
fish treated with external chemicals that do not require a withdrawal period (e.g.
Parasite S or Chloramine T) are considered safe for placement. If in doubt, contact
the Fish Pathology Program.
• Carcasses may be frozen for later use. However, as freezing will not significantly
reduce disease organism loads, it should not be considered a disease management
tool.
Carcass Loading Density
• All salmonid carcasses are considered equal from a nutrient content basis. That is,
required placement load may be calculated as biomass and then converted to fish
numbers of the available species. For example, chinook carcasses may be substituted
for coho, and vice versa. Where system-specific weight data are not available, the
following average weights for returning B.C. salmon are provided for weight
conversion.
Suggested Average Weghts for B.C. salmon *
Pink 1.5 kg Steelhead 4.0 kg
Sockeye 2.5 kg Chum 4.5 kg
Coho 3.0 kg Chinook 8.5 kg
* Data sources: mean weights from B.C. catch statistics (J. Bateman, pers. comm.)
• The maximum carcass placement within a stream segment (including the areas into
which carcasses drift from the distribution point), over the course of a spawning
season should be 1.9 kg/m² based on Wipfli et al. (2003) and WDFW (in prep). In
treatment streams with continuous escapement records, the carcass numbers may be
reduced by the recent 10 year average for natural escapement to the treatment reach.
For determining total carcass deposition maximums for streams used by more than
one salmon species, the area historically available to each salmon species should be
used to calculate the loading rate. Spawning timing should be factored into
distribution schedules.
• Maximum loading densities may be adjusted to reflect the stream’s carcass retention
properties. Carcass retention in streams is affected by predator / scavenger activity,
carcass transport during high flows, and abundance of in-stream structures to catch
and retain carcasses. Accordingly, for streams with expected good carcass retention,
maximum carcass densities may be reduced by the current spawner densities. For
streams with expected poor carcass retention (high gradient, high flows, few pools
and few in-stream structures), carcass loading densities need not be adjusted for
current spawner densities.
Carcass Distribution
• The temporal and spatial distribution of carcasses should reflect the historic spawn
timing and abundance of salmon in the treatment reach,.
• Carcasses should be placed in stream areas that are normally (or recently historically)
accessible to salmon, (i.e., not above barriers). Carcass placement into inaccessible
stream segments may be permitted where juvenile salmon of the same stock and
species have been previously outplanted (e.g., colonized upper areas above
impassable barriers) but consultation with regional MWLAP staff is necessary.
• Placement in the riparian zone is not necessary and often results in increased numbers
of blowflies. (Reimchen et al, 2003.). Natural predators will remove carcasses from
the treatment stream and distribute them in riparian zones.
• For streams with poor access (and low public use), a few accessible sites may be used
for regular carcass placement. These sites should be inspected periodically to ensure
adequate natural dispersion of carcasses. Where dispersal is poor, carcass loading
should be reduced.
• Carcasses should be distributed in stable stream areas, where possible. This will help
avoid rapid downstream transport of carcasses. Optimal sites include shallow
backwater pools, side-channels, small headwater tributaries, areas with abundant
woody debris and beaver-dam complexes. However, note that placing excessive
numbers of carcasses in side pools with sluggish or intermittent water exchange may
cause de-oxygenation (E.A. MacIsaac, pers. comm.).
• Carcass placement should be avoided or delayed during high flow events, especially
where anchoring and/or riparian placement is not feasible.
• Timing of carcass placement is also important as nutrients should be made available
to young salmon upon their emergence from the gravel. Placement timing may be
early, mid or late, and may be used to influence the ecological response to loading
within watersheds. For example, the use of carcasses from later runs of native salmon
(fall and winter) may benefit the next growing season, provided that some nutrients
are stored through the winter (Wipfli et al. 1999). Also, the use of carcasses from
several species, each with a different run timing (e.g., early sockeye, mid-chum, late
coho), will provide a longer nutrient pulse in the treatment stream than if only one or
two species were used, each with a brief spawning period.
• If a treatment stream has a late natural spawning timing, carcasses from earlier runs to
the treatment stream may be frozen and stored for later placement. The use of frozen
carcasses is also convenient for long-distance transport.
• Carcass distribution schedule should consider anticipated problems of poor stream
accessibility due to snow, high water, and other constraints.
Carcass Anchoring/Mutilation
• Carcasses may be tethered or anchored in place, especially in unstable, higher-flow
areas in order to improve carcass retention.
• Where carcass anchoring is desirable, natural anchors (e.g., large woody debris, logjams,
beaver-dams) or bio-degradable tethers such as natural-weave ropes, should be
used where possible. External identification tags should be removed from carcasses
prior to their placement.
• Non-bio-degradable tethers should be collected and removed from the stream after
carcass decomposition.
• Where frozen carcasses are used, they should be tethered in place (frozen carcasses
float and may be readily transported downstream). Where tethering is not possible, it
is preferred to thaw out at least one fourth of the frozen carcasses before distributing
them in order to enhance carcass retention at the point of access.
• Where escapement enumeration programs will be conducted on treatment streams,
carcasses should be cut in half or otherwise mutilated at placement, as directed by
area stock assessment staff. This is crucial in order to avoid double-counting and
ensure that enumeration programs are not affected.
Records of Carcass Placement
• Records of numbers and species of carcasses placed in treatment streams should be
maintained in annual data summaries, including areas and dates of placement.
• Summaries should be provided to the contact member of the Introductions and
Transfers Committee.
Appendix 1. References and Background Literature
Ashley, K.I. and P.A. Slaney. 1997. Accelerating recovery of stream, river and pond
productivity by low-level nutrient replacement (Chapter 13). In: Fish Habitat
Rehabilitation Procedures. P.A. Slaney and D. Zaldokas (eds.). Province of B.C.,
Ministry of Environment, Lands and Parks, and Ministry of Forests. Watershed
Restoration Technical Circular No. 9: 341 p.
B.C. Ministry of Fisheries. Feb. 2000. Proposal re International conference on the role of
marine derived nutrients and salmonids in the Pacific Northwest.
Bilby, R.E., B.R. Fransen, P.A. Bisson and J.K. Walter. 1998. Response of juvenile coho
salmon (Oncorhynchus kisutch) and steelhead (O. mykiss) to the addition of salmon
carcasses to two streams in southwestern Washington, U.S.A. Can. J. Fish. Aquat. Sci.
55: 1909-1919.
Bilby, R.E., B.R. Fransen, J.K. Walter, C.J Cederholm and W.J. Scarlett. 2001.
Preliminary evaluation of the use of nitrogen stable isotope ratios to establish escapement
levels for Pacific Salmon. Fisheries. 26(1): 6-14.
Cederholm, C.J., M.D. Kunze, T. Murota and A Sibatani. 1999. Pacific salmon carcasses:
essential contributions of nutrient and energy for aquatic and terrestrial ecosystems.
Fisheries 24 (10): 6-15.
Gresh, T., J. Lichatowich and P. Schoonmaker. 2000. An estimation of historic and
currrent levels of salmon production in the northeast Pacific ecosystem: Evidence of a
nutrient deficit in the freshwater systems of the Pacific Northwest. Fisheries 25(1): 15-21.
Groot and Margolis.(eds),1991. Pacific Salmon Life Histories. UBC Press, 564 p,
Johnston N.T. E.A. MacIsaac, P.J. Tschaplinski, and K.J. Hall 2004. Effects of the
abundance of spawning sockeye salmon (Oncorhynchus nerka) on nutrients and algal
biomass in forested streams. Can. J. Fish. Aquat. Sci.. In Press.
Reimchen, T.E., D.D. Mathewson, M.D. Hocking and J. Moran. 2003. Isotopic Evidence
for Enrichment of Salmon-Derived Nutrients in Vegetation, Soil, and Insects in Riparian
Zones in Coastal British Columbia. In: J.Stockner (ed.) Nutrients in Salmonid
Ecosystems: Sustaining Production and Biodiversity, Am. Fish. Soc. Symposium 34,
Bethesda. Pp. 59-69.
Oregon Department of Fish and Wildlife. Nov 2000. ODFW fish health guidelines for
use of salmon and steelhead carcasses for nutrient enrichment. 2 p.
Shively, D. 2001. The role and benefits of salmon carcass supplementation – selected
research findings and quotes. Nov. 2001. 6 p.
Washington Department of Fish and Wildlife (WDFW). Protocols and guidelines for
distributing salmonid carcasses, salmon carcass analogs, and delayed release fertilizers to
enhance stream productivity in Washington State. 11 p. (In prep.)
Wipfli, M.S., J.P. Hudson, D.T. Chaloner and J.P. Caouette. 1999. Influence of salmon
spawner densities on stream productivity in Southeast Alaska. Can. J. Aquat. Sci. 56:
1600-1611.
Wipfli, M. S., J. P. Hudson, J. P. Caouette, ad D. T. Chaloner. 2003. Marine subsidies in
freshwater ecosystems: salmon carcasses increase growth rates of stream-resident
salmonids. Trans. Am. Fish. Soc. 132:371-381.
Placement of Hatchery Carcasses In Streams for Nutrient
Enrichment
Historically, large numbers of salmon returned to spawn in their natal streams. After
providing fertilized eggs for the next generation, the adults died leaving behind nutrientrich
carcasses. These replenished the entire watersheds with organic nutrients on an
annual basis. A large variety of organisms (insects, fish, birds, mammals) fed on the
carcasses, while aquatic and terrestrial invertebrates and plants thrived on the released
nutrients.
Recent studies show that spawned-out salmon carcasses provide direct food to salmon
juveniles and play a key role in maintaining the productivity of salmonid ecosystems.
Rearing juveniles consume salmon eggs, feed directly on spawned-out carcasses, and
benefit from increased abundance of aquatic invertebrates and algal growth. The presence
of carcasses in streams is related to increased juvenile density, growth rate and body size;
larger size of juveniles means improved overwintering survival and ultimately increased
marine survival to maturity.
During the last century, numbers of salmon carcasses in streams and rivers have
decreased. However, a portion of the spent salmon carcasses from several hatchery
facilities in B.C are being used to replenish the nutrients in the ecosystem to help future
generations of salmon. These carcasses are distributed in their stream of origin for
nutrient enrichment.
Numerous factors affect the ultimate benefits of carcass placement in streams. These
include original nutrient content in treatment streams, abundance of native salmon
spawners, retention and distribution of carcasses in waterways, water temperatures,
stream discharge levels, light penetration, and predator and scavenger activity on the
carcasses. Proper timing of carcass placement is also important as nutrients should be
made available to young salmon upon their emergence from the gravel and to older
salmon juveniles inhabiting the stream. For example, the use of carcasses from several
species native to the stream, each with a different run timing (e.g., early-run sockeye and
late-run coho), will provide a longer nutrient pulse in the stream than if only one species
were used.
Fisheries and Oceans Canada has developed guidelines to maximize the benefits from
carcass placement, and address concerns over such issues as disease transfer and user
conflict. For example, carcasses will be distributed in such a way as to minimize impacts
on public-use areas and private property. No diseased or medicated fish will be used, and
there will be restrictions on the placement of carcasses outside the watershed in order to
minimize the risk of disease transfer. As well, carcass loading densities will reflect the
historic spawning abundance and distribution in the treatment stream. Bio-degradable
anchors may be used to tether carcasses in place, to improve their retention in streams.
By providing direct benefits to the future generations of salmon, the regulated placement
of hatchery carcasses in streams will facilitate salmon stock rebuilding in British
Columbia in a manner that is natural, environmentally friendly and effective.