32 Fish as feed inputs for aquaculture – Practices, sustainability and implications
- Sustainable purchasing strategies: Fishmeal purchasers should develop a purchasing
strategy that minimizes and, where possible, eliminates the use of those species of
those fisheries considered unsustainable. This strategy could be prepared with a
number of different timescales:
o short term: reduce the purchase of less sustainable species such as blue whiting
or jack mackerel, where possible;
o medium term: develop approaches to halting purchases of less sustainable
species through a detailed analysis of alternatives; and
o long term: develop alternative protein and oil substitutes for fishmeal and fish
oil; set a date for and establish an approach to purchasing all fishmeal and
fish oils from sources that have been independently verified as “responsibly
managed” and that originate from sustainable fisheries.
The purchasing strategy could be updated regularly to reflect changes in different
fishing practices and the latest “sustainability assessments”, together with emerging
trends in fish nutrition and alternative feed materials. The use by procurement
departments of environmental management systems such as the International
Organization Stadarization (ISO), ISO 14001 to ensure that procurement strategies
minimize the environmental implications of purchasing should also be considered. - Substitution with non-fish protein and oil sources: Greater knowledge should be
developed about the options for substituting different species at different times of
year to obtain a required fishmeal quality and specification. - Premium branding: Aquaculture, in partnership with its customers, should seek
to develop its premium brand image by encouraging feed suppliers to move
towards targets for achieving sustainable supplies.
- ENVIRONMENTAL IMPACTS OF FEEDFISH-BASED AQUACULTURE
The nature of aquaculture feeds and feeding regimes plays a major role in determining
the degree of environmental impact resulting from semi-intensive and intensive finfish
and crustacean farming operations (Tacon and Forster, 2003; Mente et al., 2006). This
is particularly true for those intensive farming operations employing open aquaculture
production systems (e.g. net cages/pen enclosures placed in rivers, estuaries and open
waterbodies, and land-based flow-through tank, raceway and pond production systems)
(Black, 2001; Goldburg, Elliot and Naylor, 2001; Brooks, Mahnken and Nash, 2002;
Lin and Yi, 2003; Piedrahita, 2003; Muñoz, 2006). The bulk of dissolved and suspended
inorganic and organic matter contained within the effluents of intensively managed
open aquaculture production systems is derived from feed inputs, either directly in the
form of the end-products of feed digestion and metabolism or from uneaten/wasted
feed (Cho and Bureau, 2001), or indirectly through eutrophication and increased
natural productivity (Tacon, Philips and Barg, 1995).
It follows from the above that the rate of supply and assimilation of aquaculture
feeds in fish-fed aquaculture operations (which include the use of fishmeal, fish oil and/
or trash fish-based feeds) will play a major role in dictating the nutrient and/or waste
outputs from the aquaculture production facility. Moreover, it also follows that these
outputs and their environmental impacts will vary depending upon the farming system
employed (open or closed systems), on-farm feed/nutrient and water management,
and the assimilative capacity of the surrounding aquatic and terrestrial environments
(Tacon, 2009). In general, the greater the intensity and scale of production, the
greater the nutrient inputs required and the consequent risk of potential negative
environmental impacts emerging from the aquaculture facility through water use and
effluent discharge.