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Testing assumptions associated with farm-escaped Atlantic salmon in British Columbia. Dr. John Volpe Biological Sciences University of Alberta jvolpe@ualberta.ca. Issues. Visual pollution (ecotourism) Site contamination (organic & pharmacological) Anti predator methods

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Presentation Transcript
slide1

Testing assumptions associated with

farm-escaped Atlantic salmon in British

Columbia

Dr. John Volpe

Biological Sciences

University of Alberta

jvolpe@ualberta.ca

slide2

Issues

  • Visual pollution (ecotourism)
  • Site contamination (organic & pharmacological)
  • Anti predator methods
  • Disease transfer to / from wild salmonids
  • Ecological consequences of escapees
slide3

1905

5.5 - 13.2 M eggs + alevins released in B.C.

Interspecific agonism (ST) 10 resistance factor

1934

Import of S. salar eggs for aquaculture

1984

1987

First capture of S. salar in B.C. waters

1991

First reported escape of S. salar

1995 SAR initiated

1997

SAR

released

First Atlantic salmon research

on Pacific coast initiated

Phase I research complete

2001

slide4

The Explanation Cascade

  • Escapes of Atlantic salmon are rare
  • Escapes of Atlantic salmon are inevitable but they

won't survive in the wild

  • Some Atlantic salmon may survive but will not ascend

freshwater rivers

  • Some adult Atlantic salmon are likely to be found in

freshwater rivers but can't spawn

  • Spawning is likely to occur but progeny will not be

competitively viable

And finally, the current position,

  • There is no scientific evidence to show that the

presence of feral juvenile Atlantic salmon in some

rivers pose a threat to native populations.

slide6

According to DFO’s ASWP 396,552 Atlantic salmon

have been reported as escaped 1991-2001

slide7

The Explanation Cascade

  • Escapes of Atlantic salmon are rare
  • Escapes of Atlantic salmon are inevitable but

they won't survive in the wild

  • Some Atlantic salmon may survive but will not ascend

freshwater rivers

  • Some adult Atlantic salmon are likely to be found in

freshwater rivers but can't spawn

  • Spawning is likely to occur but progeny will not be

competitively viable

And finally, the current position,

  • There is no scientific evidence to show that the

presence of feral juvenile Atlantic salmon in some

rivers pose a threat to native populations.

slide8

Atlantic salmon are commonly part of commercial

salmon catches from Alaska to Washington

No data are available regarding the source of these fish

(physical or DNA tags) or period since escape and

performance in the interim (otolith microstructure / stable

isotope analyses)

slide10

Atlantic salmon have been

reported in 77 BC streams

and rivers

Atlantic salmon are

now part of the

terrestrial food web

via predation

slide13

58 m channel

  • Heterogeneous habitat
  • 30 females; 20 males
  • transplanted without
  • acclimatization
slide14

1/3 females spawned

  • Spawning initiated
  • in mid January
slide15

Spawning Chronology

Little Qualicum

Atlantic Salmon

Chum

Sockeye

Steelhead

Sept Oct Nov Dec Jan Feb Mar Apr May

Pink

Coho

Chinook

Wild Atlantic salmon in native range

slide16

0+

1+

  • Natural reproduction
  • Two year classes present (0+ & 1+)
  • ~50 juveniles identified to date
  • Sympatric with strong steelhead population
slide17

0+ AS 0+ ST 1+ AS 1+ ST

Mean Fork

Length (mm)

63.75 ±3.3 55.42 ±5.81 119.25±5.52 92.59±10.46

Mean Weight

(g)

2.94±0.60 1.91±0.5419.61±4.01 8.67±2.75

Mean CF

(g x 100)/cm3

n

1.12 1.16 1.12 1.10

4 33 8 33

slide18

Feral Atlantic Salmon populations in Vancouver

Island Rivers

N

100 km

Port Hardy

Tsitika R.

Amor de Cosmos Cr.

Eve R.

Campbell R.

<1% potential spawning

and rearing habitat has

been surveyed on

Vancouver

Island. Coastal

mainland systems

remain entirely

uninvestigated.......?

Port

Alberni

Nanaimo

Tofino

Victoria

slide20

Wetted area:

2.2m x 0.6m x 0.9 m

Coarse river cobble

(19.4  5.6cm)

~ 10% replacement per

hour

Flow 0.85 ms-s

(4542.5 L min-1)

10 hp centrifugal pump

Water temp maintained

by a 240V, 60amp chiller

Clear Lexan viewing

windows

Natural prey provided by

a unique “upweller”

feeding system

slide21

Treatments

  • High / low forage
  • Density
  • Intra- / interspecies comp.
  • Assembly of “community”

Response Variables

  • Growth
  • Foraging
  • Agonism (action + result)
  • Territory size

High Forage

4 AS

4 AS

4 ST

4 ST

4 ST

4 AS

4 AS

4 AS

4 ST

4 ST

aAA

aSA

assembly

Low Forage

4 AS

4 AS

4 ST

4 ST

4 ST

4 AS

a = comp. coefficient (Δ g)

A = Atlantic salmon

S = Native Steelhead

4 AS

4 AS

4 ST

4 ST

aAS

aSS

slide22

ST on average engage in agonism 5:1 over AS

ST show agonistic bias towards other steelhead 2 : 1

AS show bias towards steelhead

2.2 : 1

Therefore, steelhead are agonism targets, Atlantic salmon are not

slide23

Of all treatment combinations the only

consistent and significant predictor of

performance is assembly order

Residents with 3 days prior residency

performed better than challengers under

all conditions - regardless of all other

parameters

slide26

Atlantic salmon

- residency

+ residency

Perform well

relative to steelhead

Perform poorly

relative to steelhead

1905-1934: Very low likelihood of establishing prior

residency in Vancouver Island rivers

Today: Vancouver Island steelhead populations are at

~ 10 - 20% of historical abundance

Potential for successful colonization is likely much

higher today than during historical intentional introductions

slide27

At present YES

Are production fish capable of spawning?

YES

Are juvenile Atlantic salmon competitively viable?

YES (qualified)

Are such conditions present in coastal B.C.?

Historically NO

Sufficient spawner densities for natural reproduction?

YES

Presence of feral populations?

YES (3)

Feral individuals perform as predicted?

YES

Prognosis?

slide30

Sea lice are native however the density of farms may act

as bio-magnifiers of parasites and disease such that the

migratory habitat becomes saturated ie. pink smolt run

slide32

There is no scientific evidence to show that the

presence of feral juvenile Atlantic salmon in

some rivers pose a threat to native populations.

There is no evidence that salmon aquaculture as currently

practiced in BC will not result in serious harm to native

salmon populations or their environment.

slide33

1) all reasonable actions must be taken to protect the

environment

2) inherent to this statement is the understanding of

“reverse onus” - the burden of proof lies with industry

to satisfactorily demonstrate their activity is not detrimental

to the environment. The burden is not on the public to

demonstrate the opposite