Transcript Atlantic Salmon

Atlantic Salmon
Salmo salar
A species indicator?
Atlantic salmon Life Cycle
Wild Atlantic Salmon migration routes
Source: “The Wild Atlantic Salmon-State of the Population in North America 2000 (www.asf.ca)
•Salmon spawn any
time between mid
October to mid or late
November.
•Each female can
produce between
1500-1800
eggs/kg/body weight
•Once the female has
located a site, she
prepares a redd (nest).
Introduction
The Atlantic salmon is born in
fresh water & remains there
until it undergoes a
physiological transformation
allowing it to tolerate salt water.
•The ALEVINS (hatchlings or fry) & PARR
(yolk sac is gone & actively feeding & free
swimming) will stay in the freshwater system
for usually 2-3 years before reaching the
SMOLT stage.
It is during the
smolt stage that
the salmon will
leave the fresh
water river &
migrate to the
salt water sea.
The smolt stage
would be the
equivalent of our
“adolescent”
stage of
development.
After 1-3 years at sea, the
salmon returns to its river
of origin (where it was
born!) to spawn
(reproduce). They are now
called grilse. Others will
remain in salt water to
overwinter another season
& will return to fresh water
to spawn as adult salmon.
(>63 cm)
The soils & vegetation along the streams & rivers play an
important role in protecting & maintaining salmon habitat.
The vegetation both
nourishes the river
ecosystem & protects
it by stabilizing the
riverbanks,
preventing them
from collapsing &
silting the river.
A good spawning site will have coarse, loose gravel 3-7 cm
thick, a moderately strong current to prevent eggs from being
smothered by settling silt, & well-oxygenated water.
# of
Fish
Time (year – 19??)
Atlantic salmon situation in Nova
Scotia??
2002 FINAL Cumulative
counts of MSW salmon on
rivers of the Nova Scotia
portion of the Maritimes
Region, as of November 15,
2002 (Click here to learn
more)
Reasons for Species Loss
Siltation
Altering/diverting
Water Flow
Erecting Dams or
Barriers
Altering/destroying
Riverside Vegetation
Altering/destroying
Riverbanks
Harvesting
Illegal
Harvesting
Logging
Aquaculture
At-Sea mortality
General Facts about
Aquaculture
In 1999, 70 000 tons of
domestic salmon were
raised in Canada
Presently approx 30
companies operating
more than 200 salmon
farms on both coasts.
(salmon & rainbow trout
are preferred choice)
Slightly more than 33%
of Canada’s domestic
salmon output comes
from the Maritimes.
90% of Maritime production
comes from Passamaquoddy
Bay & Grand Manan areas
10% from NS & NFLD
Aquaculture now accounts
for more than 25% of all fish
consumed by humans
worldwide.
Salmon farming is the fastest
growing sector in world
aquaculture.
Dangers Presented by
Aquaculture
In 1997 approx. 300 000 Atlantic salmon were
accidently released into Puget Sound, BC.
In Norway, approx. 1.3 million salmon escape
from farms every year (~33% of the salmon
spawning in coastal rivers in Norway are
ESCAPED domestic salmon!)
There are areas in Norway where escaped
domestic salmon have completely engulfed the
historic range of wild salmon.
Domestic vs. Wild
Selectively bred
to grow faster
(10X faster); tend
to be larger &
more aggressive
Scientists claim
that a genetically
engineered
salmon could be
grown up to 4 m
in length & weigh
>80kg!
Atlantic salmon
fare better in
captivity than
Pacific salmon
Domestic salmon
now outnumber
wild salmon by a
factor of 10 to 1
Do domestic
salmon fall under
the category of
GM foods?
Current salmon farming practices involve
open netcages like these that allow fish to
escape & pollution to flow freely into the
surrounding water.
Problems associated with
salmon farming…
Sewage
Drugs
Escapees
Net loss
Waste accumulates beneath salmon
farms, smothering the ocean bottom
and choking out life.
Salmon farm pollution…
Organic
Chemical
Main source is fish
excrement &
uneaten food
The accumulated
waste can smother
the organisms and
set up anoxic
(oxygen depleted)
conditions in the
seabed sediment.
Nutrient-loading (N
& P)
Antibiotics
Pesticides
feed additives
paints used on
netcages and boats
to prevent marine
growth (antifouling
paints)
disinfectants.
Drugs used in the salmon
farming industry…
A variety of chemicals, including antibiotics,
pesticides and fungicides are used on salmon
farms to treat disease outbreaks.
These drugs are often administered to the fish
through their feed.
Since salmon are mostly raised in open marine
netcages, most of the drug, or its metabolic
byproducts, end up in the marine environment
through uneaten feed or the salmon's
excrements.
The distribution and environmental impact of
these chemicals is a cause of great concern.
Escaping farmed salmon pose
risks…
Escaped salmon can be carriers of disease and
parasites, which pose a threat to wild salmon
populations.
When the species farmed is native to an area
there may still be an impact from escaped farmed
salmon breeding with populations of wild salmon
that are genetically adapted to specific streams.
In British Columbia there is a greater danger
arising from the fact that most of the salmon
farmed are Atlantic salmon. Evidence exists that
escaped Atlantic salmon can breed in BC's wild
streams. The potential negative consequences of
this could be dramatic.
average “escapees” in BC is ~90,000 per year for
the period 1990-2000.
Net loss of wild fish to produce
farmed salmon…
Salmon farming proponents often point out that, since the wild
fisheries are collapsing, farming the oceans is necessary to feed
a hungry world
They claim that their industry can supply food while taking
pressure off ocean resources. But it isn't that straightforward.
The impact of aquaculture (farming of a seafood species) varies,
depending on what species is farmed and what method is used.
With regard to taking pressure off ocean resources, a key factor
is whether the species being farmed is carnivorous or not.
A total of 2.7-3.5 tonnes of wild fish are used to make 1 tonne of
farmed salmon!
The consumption of 6.2 tonnes of wild fish for each tonne of
salmon produced not only means less food for humans, but also
for the many ocean species that rely on these fish as part of their
food chain. Currently, the continued expansion of salmon farming
is not sustainable.
Possible Remedies?
Commitment on the part of Federal & Provincial
Governments
It has been suggested that salmon farms be located
entirely within land-based pens fed by salt water to
create a closed containment system (aquaculture
industry opposed this measure because of the costs
associated with creating the pens)
Sterile, all-female strains of domestic salmon could
reduce threats to wild salmon from cross- breeding with
farm escapees.
“it is only a matter of time before a suitable seed-based
food concentrate can be used to replace marine protein
for feeding domestic salmon” (DFO)
Sources…
A number of
images in this
presentation are
from the Atlantic
Salmon
Federation
website…
David Suzuki
Foundation
News & Issues
concerning
Aquaculture
Facts are located
at the Nova
Scotia Salmon
Association
Siltation
Occurs when a riverbed is covered with fine
particles.
Destroys spawning areas & smothers
salmon eggs.
Can cause gill abrasion
Makes feeding more difficult because the
fish can’t see their food.
Caused by…
poor or improper road construction
Irresponsible logging practices
All-terrain vehicles (ATV’s) in riverbeds
Altering/diverting Water Flow
Water flow is either too high or too
low for the salmon
Affects spawning & survival rates
Erecting Dams or Barriers
Creates barriers for migrating
salmon
Destroys spawning beds
Example: Kejimkujik National Park
(dam erected in the 1940’s which
affected the rivers that drained this
park)
Altering/destroying Riverside
Vegetation
Reduces food supply to the river
ecosystem
Causes siltation
Altering/destroying
Riverbanks
Causes flooding…which leads to..
SILTATION!
Harvesting
Native bands that use salmon for
food
The importance of fishing to
Aboriginal communities is
recognized by DFO & given first
priority AFTER conservation.
Conne River Mi’kmaq are the only
band in NFLD with a recognized
food fishery.
Innu Nation & Labrador Inuit
Association have a food fishery in
Labrador.
Illegal Harvesting
Loss of fish stock due to poaching.
Logging
Aggravates flooding & causes
flash floods & siltation of water
bodies.
Really impacts on eggs &
juveniles.
Use of insecticides & herbicides
can also be a problem
Aquaculture
Declining commercial salmon industry has placed
an emphasis on raising Atlantic salmon in
artificial environments.
A salmonid is a member of the salmon family
which includes salmon, trout, and char.
New Brunswick, Newfoundland & Labrador are
BIG players on the East coast.
If farmed salmon (domestic salmon) escape they
can introduce new disease & new genes into a
watershed producing offspring that are less
suitable for survival.
“Escapees” may also compete for same food
resources.
At-Sea mortality
A result of ….
by-catch
Global climate change (salinity &
temperature)
Seal predation (suspected but
unproven)