At present, millions of tonnes of marine materials are processed into fishmeal and fish oil. These products are used as sources of protein and lipids in aquaculture and pet feed. The production of fishmeal and fish oil, and their subsequent processing into pet and aquaculture feed, requires thermal treatment that degrades DNA quality. As a result, it can be difficult to trace back the original species used as raw material. Several studies have shown that endangered shark species can be found in pet food. In addition, Rotterdam Zoo “Blijdorp” strongly suspects that shark species are present in their aquaculture feed, based on DNA testing. Although research is being conducted into alternative protein sources that do not rely on marine materials, it cannot yet fully be replaced. Fish rests will also remain available as long as fish is consumed. The aim of the study, therefore, is to investigate, and develop, a system to transform fish rest materials into traceable aquaculture and pet feeds.

Designing of this “Fish Rest Processing system” (FRP-system) was split in two steps. The first was at Blijdorp, where fish rest material of known origin could be used to replace dry aquaculture feeds. The aim of the second step was to adapt the FRP-system to one of producing pet feeds out of fish rest material on Bonaire, while ensuring traceability. First, system requirements were established for both Blijdorp and Bonaire to guide the design process. This was done through a combination of literature research and on-site research at Blijdorp. Based on these system requirements and laboratory experiments, a system prototype was built to produce aquaculture feeds. This was further developed into a concept design for producing pet feeds on Bonaire.

At Blijdorp, a manual process was used to bind rest material with agar in order to produce fish feed. This process was translated into a mechanized process in a laboratory setting. Using this FRP-system prototype, several types of conventional aquaculture feed could be replicated. Based on the underlying processes, a concept design was developed for Bonaire that processed 10 kg of residual waste per hour into ready-to-use dog food portions. The core process for both systems consists of inductively cooking agar, followed by automatic cooling of the agar to 50 °C. This temperature was then maintained using hysteresis control. Subsequently, fish residues were mechanically mixed into the agar. The material was then poured into moulds and allowed to solidify in a refrigerator, after which it was processed into the required final size.

This research into traceable feed has identified key requirements that a system for aquaculture and pet food production must meet. The initial technical challenges associated with achieving the desired feed properties were addressed through the development of a laboratory prototype. This resulted in a process that can be further developed for the production of aquaculture feed. In addition, the process could be scaled up, a concept design has been developed to serve as a guideline for this.

This study addresses the research question “How can zoos be enabled to define and position their role in nature conservation and explore different strategic scenarios while gaining insight into their operational and stakeholder implications?”. Diergaarde Blijdorp (hereafter ‘Rotterdam Zoo’) serves as the primary case organisation. The study employed a mixed-methods approach combining literature review, historical and trend analysis, case study research, stakeholder interviews, and participatory design.

Zoo transformation: The study investigated how the role of zoos has historically developed, Rotterdam Zoo’s current positioning, and emerging trends creating both pressures and opportunities that necessitate a transformation away from the traditional entertainment-based zoo model. This transformation is driven by changing public perceptions, financial sustainability challenges, and evolving nature conservation expectations. Zoo transformation is inevitable rather than optional, with zoos facing a fundamental choice between nature conservation leadership or risking a decline in relevance. The ‘One Plan Approach’ (coordinated conservation across captive and wild populations) offers a proven framework for transformation, but requires fundamental organisational change. Long-term legitimacy and relevance depend on zoos’ ability to redefine their institutional purpose and align all operations with clear nature conservation goals.

Masterplan 2050: Rotterdam Zoo’s strategic response to these transformation pressures is outlined in their Masterplan 2050, which aims to transform the zoo into a nature conservation and restoration organisation. The analysis explored what the strategic challenges and trade-offs would be that complicate its implementation. It became apparent that the zoo has clear nature conservation intentions, but their main challenge is to translate these ambitions into concrete strategic choices. Operational frameworks need to be developed to support this transformation across areas including animal collection strategy implementation, revenue diversification, and practical approaches to in situ nature conservation work. Rather than expanding further, the challenge now lies in narrowing focus and a wider need for structured decision-making.

Case study: A key question is how nature conservation or restoration commitments translate into effective in situ practice. A case study was performed to learn from the approach taken by the Rotterdam Zoo-led coral reef restoration programme called RoffaReefs on Bonaire, and to identify what factors are important for successful nature conservation initiatives and partnerships. This case study reveals that successful nature conservation requires designing for socio-ecological ecosystems; it must simultaneously address natural processes, scientific understanding, and human social dynamics. This finding fundamentally challenges approaches that prioritise technical solutions only. Moreover, authentic nature conservation requires genuine partnership development with local stakeholders (community co-ownership) and commitments to be aligned with organisational capabilities.

Decision support tool: Results of the research have been translated into the design of a strategic decision-support tool (“Zoo Nature Conservation Choice Compass”) that supports zoos in defining and positioning their role in nature conservation by exploring different transformation scenarios, gaining insight into operational and stakeholder implications. Through iterative co-creation sessions involving Rotterdam Zoo and RoffaReefs stakeholders, the choice compass concept was refined and validated, with development of testing protocols, integration methods, and recommendations for continued validation and implementation.

The resulting choice compass successfully bridges the gap between nature conservation aspirations and operational reality, providing zoos with concrete frameworks for strategic decision-making, and supporting Rotterdam Zoo's transformation towards its 2050 conservation objectives.