The journey into offshore aquaculture is underway. Systematic net-pen farming has laid the groundwork, while integrating shipbuilding and marine engineering technologies enables larger facilities capable of venturing further out. The proven success of large-scale pen structures in enhancing quality and efficiency is turning heads and steadily pushing deep-sea aquaculture into reality. However, this expansion brings to light significant hurdles in both technology and management.
(1) Facility Safety: The Foremost Concern
Typhoons pose a massive threat to offshore operations. One incident saw a marine pen severely damaged, primarily on the side facing the waves, while the rest remained largely intact. This highlights a common oversight: the failure in initial design and construction to tailor structural strength specifications for different parts of the facility based on their exposure. Conversely, it also demonstrates that properly engineered equipment can withstand harsh sea conditions. The damaged pen, after repairs and design improvements, continues to operate successfully today.
(2) Marine Biofouling: A Small Problem with Big Consequences
Often underestimated, biofouling – organisms attaching to structures – is a critical safety issue. It particularly impacts rigid net supports and can lead to three serious outcomes: 1) torn nets and fish escapes; 2) reduced water flow through clogged nets; and 3) massively increased drag. This added strain can collapse the entire facility, causing irreversible losses. While the problem might seem minor, the damage it can inflict is substantial, making it a decisive factor for the safety of aquaculture installations.
(3) Imperfect Data, Costly Trials, and a Slow-Moving Market
Practical experience has revealed other challenges. Firstly, environmental data is often imprecise. While historical data might exist for a general area, specific, localized information for a planned net-pen site—like detailed currents or seabed composition—is frequently lacking. Secondly, real-world testing is incredibly expensive. The complexity of combining marine engineering with aquaculture equipment is underestimated, and the development of large-scale gear requires more model testing and mid-scale trials before full deployment. The high investment means any failure after launch is devastating. Factors like materials, structure, and assembly of underwater net systems also need thorough consideration. Thirdly, market development is a long game. Marketing fish from offshore farms must account for existing consumer preferences for fresh/live seafood and purchasing power, requiring a gradual build-out of the entire supply chain. Determining the scale of farming equipment must also consider the challenge of aligning large, concentrated harvests with market absorption—a process that will take time.
(4) The Urgent Need for Applied Research
Currently, many companies are eager to deploy designs based on experience and ideals, but foundational and applied research lags far behind, failing to provide adequate support. A case in point: the assumption from coastal farming that larger pen spaces always benefit the growth and quality of species like large yellow croaker. However, underwater sonar studies of fish behavior revealed that currents and conditions often cause schools to cluster in just 20-30% of the available space. This high density can lead to localized oxygen depletion, ironically hindering growth. To address this, compartmentalized designs were later introduced to provide more suitable swimming space. Yet, determining the optimal space for specific stocking densities requires more research. In one tracking study, a single fish spent 90% of its time in one specific area of the pen, returning there even after brief departures for feeding. Therefore, to design the most efficient farming scale, we need deeper, systematic research into the relationships between stocking density, school behavior, spatial needs, and how space ultimately influences fish quality.
(5) Economic Viability: The Ultimate Deciding Factor
Research can explore an industry’s potential, but its survival hinges on economics. An economic model from NOAA analyzing different aquaculture methods (nearshore, offshore, deep-sea) shows little variation in fry and feed costs. The key differentiators in overall cost are management and infrastructure. The model suggests offshore aquaculture is high-investment, high-output. If the farmed fish cannot command a premium price, it risks falling below the market equilibrium price—the point where supply meets demand—resulting in losses. Consequently, deep-sea aquaculture must compete on several fronts: 1) against the same species farmed using cheaper methods; 2) against imported aquaculture products of similar type and quality; and 3) against wild-caught counterparts. For it to be economically feasible, it likely needs a significant price advantage over cheaper farming methods, a lower comprehensive cost compared to similar imports, and an absence of direct competition from wild fisheries.
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