Report of the 2005 ICES/NASCO Symposium on Interactions ...

NINA SPECIAL REPORT 34
native species was also found to increase as a result <strong>of</strong>
escapees predating on native species and an increase in
marine birds near farms. The use <strong>of</strong> a <strong>the</strong>oretical model
comparing populations exposed to salmon farming to
those not exposed identified a reduction in productive
capacity <strong>of</strong> up to 1% per tonne <strong>of</strong> production in <strong>the</strong> areas
studied. An increase in predation on salmon as a result <strong>of</strong>
a successful restoration programme for ano<strong>the</strong>r
anadromous species emphasized <strong>the</strong> importance <strong>of</strong>
thinking <strong>of</strong> <strong>the</strong> entire ecosystem.
Management <strong>of</strong> Interactions
Increased reporting <strong>of</strong> escapees was identified as a
positive development. <strong>Report</strong>ing <strong>of</strong> all escapees and
causes is required in Norway and o<strong>the</strong>r countries.
Interactions between vessels and cages were identified as
a significant cause <strong>of</strong> escapees and <strong>the</strong> simple solution <strong>of</strong>
requiring radar reflectors and updating navigational charts
was identified. The National Action Plan in Norway is
designed to prevent escapees (staff competence,
information and education, environmental management
systems). In addition, new certification requirements in
Norway require capability assessments to ensure that <strong>the</strong>
equipment at a farm is matched to <strong>the</strong> site conditions.
Solutions to freshwater escapement may be inexpensive
and relatively easy (redundant screening).
One <strong>of</strong> <strong>the</strong> tools that has been identified for management
is better information on when, where, and how escapes
occur. Mandatory reporting is one source <strong>of</strong> such
information. If farmed fish were marked in a way to
indicate farm <strong>of</strong> origin this could prove useful in being
able to trace escapees back to a farm to learn more
about <strong>the</strong> cause <strong>of</strong> that escape. Using genetic markers,
escaped farmed salmon may be assigned with a high
degree <strong>of</strong> certainty to strain (which may be somewhat
indicative <strong>of</strong> farm <strong>of</strong> origin). Both biological and physical
methods <strong>of</strong> containment were reviewed and discussed. In
considering triploidy, it was emphasized that it is
important to be explicit about <strong>the</strong> purpose <strong>of</strong> sterility.
Fur<strong>the</strong>r research into cage design was encouraged and it
was suggested that cage design should focus on reducing
<strong>the</strong> probability and consequences <strong>of</strong> accidents as well as
minimizing potential for incorrect use. Ano<strong>the</strong>r
management tool presented was <strong>the</strong> decision to move to
native strains for intentional enhancement programmes.
Recommendations for Future Research
Although much has been learned since <strong>the</strong> Bath
symposium, many more questions remain unanswered.
The following research needs were identified during <strong>the</strong>
discussion:
• Environmental effects <strong>of</strong> farming <strong>of</strong> salmon in Chile;
• Information on spawning success <strong>of</strong> escapees;
• <strong>NASCO</strong> and <strong>ICES</strong> have suggested a joint experiment
to track escapees;
• Need fur<strong>the</strong>r genetic work to determine if precision
can be increased to provide enough information to
assign an escapee to farm <strong>of</strong> origin;
• Pros and cons <strong>of</strong> triploids warrants fur<strong>the</strong>r
investigation and discussion - effects on immunity,
stress response;
• Development <strong>of</strong> a high-performing triploid strain
requires a deliberate selective process.
Recommendations and Challenges for Management
The fact that <strong>the</strong> causes <strong>of</strong> escapees are diverse and
highly variable on an annual basis (technical difficulties,
boat propellers, predators, floating objects) means that
<strong>the</strong>re must be multiple management actions targeting
<strong>the</strong>se various sources. The question was raised as to
whe<strong>the</strong>r management should change seasonally and/or
depending on age <strong>of</strong> fish in recognition <strong>of</strong> <strong>the</strong> anticipated
differences in survival <strong>of</strong> <strong>the</strong> escapees. Storms were
identified as major source <strong>of</strong> escapees and <strong>the</strong> question
was raised as to whe<strong>the</strong>r climate change would increase
storm events and lead to more escapees. The aquaculture
industry appears to be moving toward larger and larger
cages which pose significant management challenges as
<strong>the</strong> loss <strong>of</strong> one <strong>of</strong> <strong>the</strong>se cages could release more fish
than an entire site using older, smaller cages. Also, sites
are moving fur<strong>the</strong>r away from salmon rivers and to more
exposed areas which may also increase <strong>the</strong>ir vulnerability
to storms. Managers were cautioned to consider <strong>the</strong>
effects <strong>of</strong> farmed fish on catch advice as <strong>the</strong>y can inflate
catch-based spawning escapement (which may increase
risk to wild fish). There was a strong emphasis on <strong>the</strong>
application <strong>of</strong> an ecosystem approach to fully understand
all <strong>of</strong> <strong>the</strong> effects <strong>of</strong> aquaculture.
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