Mankind has the potential to harvest more sustenance from the oceans to support global nutrition while mitigating the adverse effects of mariculture on biodiversity, as indicated by recent studies spearheaded by the University of Michigan.
However, there is a caveat: a strategic approach is essential.
“We can attain sustainable mariculture advancement,” asserted Deqiang Ma, who directed the study during his postdoctoral tenure at the U-M School for Environment and Sustainability. “By planning strategically, we can strive to protect marine species while addressing the global appetite for expanding mariculture.”
Mariculture pertains to the sector of aquaculture dedicated to cultivating saltwater seafood. In 2020, it represented nearly 20% of the food sourced from fisheries, providing a critical source of protein for billions globally.
The demand for seafood is experiencing an upward trend, and mariculture production is escalating swiftly to satisfy that demand, Ma noted. To evaluate the consequences of this expansion, Ma and a global consortium of researchers developed a model designed to gauge mariculture’s effects on the populations of over 20,000 marine species.
This model enabled the team to ascertain a baseline for the current effects of mariculture and predict how these would evolve by 2050 under various scenarios, influenced by factors such as the specific farming locations. It also examined two climate scenarios, referred to as RCP 4.5 and 8.5, which assume different warming and greenhouse gas emission levels.
The optimal scenario—creating the greatest farming capacity in regions with minimal environmental consequences—yielded promising projections for both bivalve shellfish and finfish.
“Bivalve output could increase by 2.36 times, and finfish could rise by 1.82 times in comparison to present output—these figures illustrate what’s necessary to fulfill global demand—but the overall mariculture effects could drop by as much as 30.5% in the best-case scenario,” Ma commented.
Conversely, the worst-case scenario was equally alarming. Should new farms be established in areas with the most harmful repercussions for biodiversity, it would be over four times worse than placing them in random locations.
This highlights the necessity for strategic planning, as emphasized by U-M senior co-author Neil Carter, and collaborating with experts across various fields to evaluate an extensive array of factors.
“It is vital to harness the increasing insights across disciplines, whether it relates to climate change research, economics, or marine production,” stated Carter, associate professor of environment and sustainability. “All these varied aspects had to converge from different sources to develop these forecasts.”
The group comprised researchers from the University of Washington, the University of Freiburg in Germany, Hokkaido University in Japan, and the University of California, Santa Barbara.
The breadth of the analysis and the cooperation needed to conduct it can pose challenges for initiatives like this, remarked study co-author Benjamin Halpern, a professor at UCSB.
“However, I have engaged in similar work multiple times throughout my career, and the rewards can be significant,” said Halpern, who also directs the National Center for Ecological Analysis and Synthesis. “The interdisciplinary nature of the issues addressed and the capacity to evaluate them for every chunk of ocean globally makes this research considerably more relevant and impactful for society and the scientific community.”
Ma and Carter reiterated that this paper serves as an initial step toward establishing the most sustainable future for mariculture. From a scientific perspective, the model can be fine-tuned by incorporating additional and contemporary data as we progress.
The study also revealed that there isn’t a universal solution for sustainably enhancing mariculture. From a research viewpoint, the possibilities for farm development vary significantly in the South Pacific compared to the French coastline.
Moreover, the choices made to aim for the world’s ideal scenario can still entail disadvantages. The advancement of mariculture negatively impacts vital and iconic marine mammals—including whales, seals, and sea lions—in all the scenarios examined by the team.
Yet, comprehending these constraints and trade-offs empowers researchers and policymakers to better anticipate the repercussions of critical decisions before they are enacted.
“With these insights, we can understand that it’s not a guaranteed outcome that the growth of an industry will always adversely affect the environment,” Carter stated. “Thus, the next phase is fostering collaboration between policymakers and communities to identify how we can implement some of these concepts to mitigate those effects and prioritize marine biodiversity.”
The project received funding from the U-M School for Environment and Sustainability and the U-M Institute for Global Change Biology.