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Traditionally, the ocean economy is viewed solely as a mechanism for economic growth. In this business-as-usual approach, large-scale industrial economies have developed the ocean economy by exploiting maritime and marine resources, often without considering how those activities impact the future health or productivity of those same resources. This has led to marine ecosystems being viewed and treated as limitless resources; the marine environment becoming a dumping ground for waste; overfishing diminishing fishing stocks; ocean habi- tats being degraded from coastal developments; sea-level rise impacting coastal communities and infrastructure; increasing ocean acidification; and the marginalisation of poor coastal communities. 

In response, there is a transition underway worldwide towards the blue economy, which views economic development and ocean health as complementary to one another. In the blue economy, the environ- mental risks of and ecological degradation from economic activity are mitigated or significantly reduced. Therefore, economic activity balances the ocean ecosystems’ long-term capacity to support this activity and remain healthy and resilient.1,2 

Despite recognising the benefits of the blue economy, the concept has yet to be mainstreamed worldwide for various reasons. For instance, while our scientific knowledge of the oceans, including coastal processes, fisheries science, marine biology, and so forth, are well developed, there is a lack of understanding on how best to develop and implement tech- nologies, investment strategies, and interdisciplinary partnerships that enhance synergies and reduce trade-offs between sectors in the develop- ment of a blue economy. There are many cases of initiatives worldwide that ignore blue economy concepts, even when they are obvious and proven to be beneficial to humans and nature.3,4,5 

As such, there is a need for innovative policies, technologies, and financing tools to accelerate the transition towards a blue economy that is low-carbon, efficient, and clean with its growth driven by investments that reduce carbon emissions and pollution; protect and restore blue carbon ecosystems; enhance the resilience of vulnerable coastal commu- nities; enhance food security and nutrition; and promote sustainable economic growth opportunities.6,7 

Palgrave macmillan

We developed a non-fish meal diet using plant and/or animal protein materials. Threekinds of non-fish meal diets and a control diet containing 50% fish meal were processed. In the non-fish meal diets, the fish meal was replaced with commercially available plant or animal materialsand supplemented with taurine and materials for maintaining palatability. These diets were fedto one year old yellowtail (BW 753±96g) in net cages. There wasno difference in growth, dailyweight gain, daily feeding rate, feed conversion ratio and protein efficiency ratio among the diets.Non-fish meal diets were processed in a factory and dietary properties were studied such asuptake, stomach evacuation rate, and comparative disease resistance in fish fed the experimentaldiets. In addition, palatability of each substitute protein material for fish was examined andmaterials to enhance palatability of the non-fish meal diets were clarified. Non-fish meal diets havethe potential to support the growth of one year old yellowtail.

Land-based seaweed (Gracilaria) cultivation systems may provide products with high quality and biosafety for human consumption, as well as for other high value applications. However, a limitation for this land based system is high management costs. The objective of this study was to determine if the management costs for Gracilaria cultivation can be reduced without a decrease in productivity by using CO2 injection along with a high stocking density and high photosynthetically active radiation (PAR), and commercially available fertilizers. When Gracilaria tikvahiae was cultivated at a high stocking density and high PAR, coupled with CO2 enhancement, the productivity was significantly higher than that at a lower stocking density, low light without CO2 injection. We also found that G. tikvahiae grown in a medium of commercially available fertilizer (Jack's Special, JS) showed a similar growth rate and productivity to that grown in von Stosch's enriched (VSE) seawater, while the cost for JS media is only 2% of the cost for VSE. These results suggest that CO2 injection and commercial fertilizer may be a potential way to provide sustainability in land-based Gracilaria cultivation systems.

An effective semi-continuous process was developed to grow a locally isolated green microalga Chlorella sp. on acidogenically digested swine wastewater in bench scale for improved algal biomass production and waste nutrient removal using central composite design (CCD). The influences of two key parameters, namely wastewater dilution rate (DR) and hydraulic retention time (HRT), on algal biomass productivity and nutrient removal rates were investigated. The optimal parameters estimated from the significant sec- ond-order quadratic models (p < 0.05) were 8-fold DR and 2.26-d HRT. The cultivating experiment in a bench-scale multi-layer photobioreactor with the optimized conditions achieved stable algal productivity and nutrient removal rates, which fitted the predictive models well. Moreover, relatively high and stable protein and lipid contents (58.78% and 26.09% of the dry weight, respectively) were observed for the col- lected algae sample, indicating the suitability of the algal biomass as ideal feedstock for both biofuel and feed production.