Halley E. Froehlich

Fishing amplifies forage fish population collapses

Significance Forage fish provide substantial benefits to both humans and ocean food webs, but these benefits may be in conflict unless there are effective policies governing human activities, such as fishing. Collapses of forage fish induce widespread ecological effects on dependent predators, but attributing collapses to fishing has been difficult because of natural fluctuations of these stocks. We implicate fishing in forage fish stock collapses by showing that high fishing rates are maintained when stock productivity is in rapid decline. As a consequence, the magnitude and frequency but not duration of stock collapses are far greater than expected from natural fluctuations. Risk-based management policies would provide substantial ecological benefits with little effect on fishery catches. Forage fish support the largest fisheries in the world but also play key roles in marine food webs by transferring energy from plankton to upper trophic-level predators, such as large fish, seabirds, and marine mammals. Fishing can, thereby, have far reaching consequences on marine food webs unless safeguards are in place to avoid depleting forage fish to dangerously low levels, where dependent predators are most vulnerable. However, disentangling the contributions of fishing vs. natural processes on population dynamics has been difficult because of the sensitivity of these stocks to environmental conditions. Here, we overcome this difficulty by collating population time series for forage fish populations that account for nearly two-thirds of global catch of forage fish to identify the fingerprint of fisheries on their population dynamics. Forage fish population collapses shared a set of common and unique characteristics: high fishing pressure for several years before collapse, a sharp drop in natural population productivity, and a lagged response to reduce fishing pressure. Lagged response to natural productivity declines can sharply amplify the magnitude of naturally occurring population fluctuations. Finally, we show that the magnitude and frequency of collapses are greater than expected from natural productivity characteristics and therefore, likely attributed to fishing. The durations of collapses, however, were not different from those expected based on natural productivity shifts. A risk-based management scheme that reduces fishing when populations become scarce would protect forage fish and their predators from collapse with little effect on long-term average catches.

Mapping the global potential for marine aquaculture

Marine aquaculture presents an opportunity for increasing seafood production in the face of growing demand for marine protein and limited scope for expanding wild fishery harvests. However, the global capacity for increased aquaculture production from the ocean and the relative productivity potential across countries are unknown. Here, we map the biological production potential for marine aquaculture across the globe using an innovative approach that draws from physiology, allometry and growth theory. Even after applying substantial constraints based on existing ocean uses and limitations, we find vast areas in nearly every coastal country that are suitable for aquaculture. The development potential far exceeds the space required to meet foreseeable seafood demand; indeed, the current total landings of all wild-capture fisheries could be produced using less than 0.015% of the global ocean area. This analysis demonstrates that suitable space is unlikely to limit marine aquaculture development and highlights the role that other factors, such as economics and governance, play in shaping growth trajectories. We suggest that the vast amount of space suitable for marine aquaculture presents an opportunity for countries to develop aquaculture in a way that aligns with their economic, environmental and social objectives.Marine aquaculture has the potential to improve food security. A global analysis shows that space in coastal areas is unlikely to limit the potential for aquaculture.

Public Perceptions of Aquaculture: Evaluating Spatiotemporal Patterns of Sentiment around the World

Aquaculture is developing rapidly at a global scale and sustainable practices are an essential part of meeting the protein requirements of the ballooning human population. Locating aquaculture offshore is one strategy that may help address some issues related to nearshore development. However, offshore production is nascent and distinctions between the types of aquatic farming may not be fully understood by the public–important for collaboration, research, and development. Here we evaluate and report, to our knowledge, the first multinational quantification of the relative sentiments and opinions of the public around distinct forms of aquaculture. Using thousands of newspaper headlines (Ntotal = 1,596) from developed (no. countries = 26) and developing (42) nations, ranging over periods of 1984 to 2015, we found an expanding positive trend of general ‘aquaculture’ coverage, while ‘marine’ and ‘offshore’ appeared more negative. Overall, developing regions published proportionally more positive than negative headlines than developed countries. As case studies, government collected public comments (Ntotal = 1,585) from the United States of America (USA) and New Zealand mirrored the media sentiments; offshore perception being particularly negative in the USA. We also found public sentiment may be influenced by local environmental disasters not directly related to aquaculture (e.g., oil spills). Both countries voiced concern over environmental impacts, but the concerns tended to be more generalized, rather than targeted issues. Two factors that could be inhibiting informed discussion and decisions about offshore aquaculture are lack of applicable knowledge and actual local development issues. Better communication and investigation of the real versus perceived impacts of aquaculture could aid in clarifying the debate about aquaculture, and help support future sustainable growth.

Offshore Aquaculture: I Know It When I See It

Offshore aquaculture is increasingly viewed as a mechanism to meet growing protein demand for seafood, while minimizing adverse consequences on the environment and other uses in the oceans. However, despite growing interest in offshore aquaculture, there appears to be no consensus as to what measures commonly define an offshore site or how effects of offshore aquaculture – relative to more nearshore practices – are assessed. This lack of agreement on what constitutes offshore aquaculture has the potential to convolute communication, create uncertainty in regulatory processes, and impede understanding of the ecological implications of offshore farming. To begin addressing these issues, we reviewed and analyzed biologically-focused primary and gray literature (Ntotal = 70) that categorize and quantify characteristics of offshore aquaculture from around the world. We found that many ‘offshore’ descriptions are relatively close to shore (< 3 nm) and significantly shallower (minimum depth ≤ 30 m) than may be assumed. We also uncovered an overall lack of consistent reporting of even the most common location-focused metrics (distance from shore, depth, current), a dearth of impact related studies (n = 17), and narrow scope of the studies themselves (i.e., 82% nutrient pollution). Of the finite subset of articles that investigated negative ecological impacts of offshore aquaculture, we found the probability of any measurable impact from an offshore farm appears to significantly decrease with distance from the farm (probability of measurable response at 90 m ± SE = 0.01 ± 0.03). Such general, but informative points of reference could be more robustly quantified with better systematic and standardized reporting of physical farm characteristics and a broader scope of ecological investigation into the effects of marine aquaculture. With offshore aquaculture still in its infancy, consistent metrics are needed for a comparable framework to guide sustainable offshore aquaculture research and development globally.

Comparative terrestrial feed and land use of an aquaculture-dominant world

Significance Studies are revealing the potential benefits of shifting human diets away from meat and toward other protein sources, including seafood. The majority of seafood is now, and for the foreseeable future, farmed (i.e., aquaculture). As the fastest-growing food sector, fed aquaculture species increasingly rely on terrestrial-sourced feed crops, but the comparative impact of aquaculture versus livestock on associated feed and land use is unclear––especially if human diets shift. Based on global production data, feed use trends, and human consumption patterns, we simulate how feed-crop and land use may increase by midcentury, but demonstrate that millions of tonnes of crops and hectares could be spared for most, but not all, countries worldwide in an aquaculture-dominant future. Reducing food production pressures on the environment while feeding an ever-growing human population is one of the grand challenges facing humanity. The magnitude of environmental impacts from food production, largely around land use, has motivated evaluation of the environmental and health benefits of shifting diets, typically away from meat toward other sources, including seafood. However, total global catch of wild seafood has remained relatively unchanged for the last two decades, suggesting increased demand for seafood will mostly have to rely on aquaculture (i.e., aquatic farming). Increasingly, cultivated aquatic species depend on feed inputs from agricultural sources, raising concerns around further straining crops and land use for feed. However, the relative impact and potential of aquaculture remains unclear. Here we simulate how different forms of aquaculture contribute and compare with feed and land use of terrestrial meat production and how spatial patterns might change by midcentury if diets move toward more cultured seafood and less meat. Using country-level aquatic and terrestrial data, we show that aquaculture requires less feed crops and land, even if over one-third of protein production comes from aquaculture by 2050. However, feed and land-sparing benefits are spatially heterogeneous, driven by differing patterns of production, trade, and feed composition. Ultimately, our study highlights the future potential and uncertainties of considering aquaculture in the portfolio of sustainability solutions around one of the largest anthropogenic impacts on the planet.

Avoiding the ecological limits of forage fish for fed aquaculture

Aquaculture is supporting demand and surpassing wild-caught seafood. Yet, most fed aquaculture species (finfish and crustacea) rely on wild-captured forage fish for essential fatty acids and micronutrients, an important but limited resource. As the fastest growing food sector in the world, fed aquaculture demand will eventually surpass ecological supply of forage fish, but when and how best to avoid this ecological boundary is unclear. Using global production data, feed use trends, and human consumption patterns, we show how combined actions of fisheries reform, reduced feed use by non-carnivorous aquaculture and agricultural species, and greater consistent inclusion of fish by-products in China-based production can circumvent forage fish limits by mid-century. However, we also demonstrate that the efficacies of such actions are diminished if global diets shift to more seafood-heavy (that is, pescatarian) diets and are further constrained by possible ecosystem-based fisheries regulations in the future. Long-term, nutrient-equivalent alternative feed sources are essential for more rapid and certain aquaculture sustainability.Aquaculture is surpassing wild-caught seafood, but we feed aquaculture with wild forage fish for key nutrients. This study finds removing such forage fish from diets of livestock and non-carnivorous aquaculture species and moderating its use in China will help sustain forage fish populations in the future.

Global change in marine aquaculture production potential under climate change

Climate change is an immediate and future threat to food security globally. The consequences for fisheries and agriculture production potential are well studied, yet the possible outcomes for aquaculture (that is, aquatic farming)—one of the fastest growing food sectors on the planet—remain a major gap in scientific understanding. With over one-third of aquaculture produced in marine waters and this proportion increasing, it is critical to anticipate new opportunities and challenges in marine production under climate change. Here, we model and map the effect of warming ocean conditions (Representative Concentration Pathway scenario 8.5) on marine aquaculture production potential over the next century, based on thermal tolerance and growth data of 180 cultured finfish and bivalve species. We find heterogeneous patterns of gains and losses, but an overall greater probability of declines worldwide. Accounting for multiple drivers of species growth, including shifts in temperature, chlorophyll and ocean acidification, reveals potentially greater declines in bivalve aquaculture compared with finfish production. This study addresses a missing component in food security research and sustainable development planning by identifying regions that will face potentially greater climate change challenges and resilience with regards to marine aquaculture in the coming decades. Understanding the scale and magnitude of future increases and reductions in aquaculture potential is critical for designing effective and efficient use and protection of the oceans, and ultimately for feeding the planet sustainably.Marine aquaculture is a rapidly growing global source of food, but is likely to be affected by climate change. Here, the effect of warming oceans on the production potential of 180 cultured finfish and bivalve species is mapped over the next century.

Predator in the Pool? A Quantitative Evaluation of Non-indexed Open Access Journals in Aquaculture Research

Predatory open access (OA) journals can be defined as non-indexed journals that exploit the gold OA model for profit, often spamming academics with questionable e-mails promising rapid OA publication for a fee. In aquaculture – a rapidly growing and highly scrutinized field – the issue of such journals remains undocumented. We employed a quantitative approach to determine whether attributes of scientific quality and rigor differed between OA aquaculture journals not indexed in reputable databases and well-established, indexed journals. Using a Google search, we identified several non-indexed OA journals, gathered data on attributes of these journals and articles therein, and compared these data to well-established aquaculture journals indexed in quality-controlled bibliometric databases. We then used these data to determine if non-indexed journals were likely predatory OA journals and if they pose a potential threat to aquaculture research. On average, non-indexed OA journals published significantly fewer papers per year, had cheaper fees, and were more recently established than indexed journals. Articles in non-indexed journals were, on average, shorter, had fewer authors and references, and spent significantly less time in peer review than their indexed counterparts; the proportion of articles employing rigorous statistical analyses was also lower for non-indexed journals. Additionally, articles in non-indexed journals were more likely to be published by scientists from developing nations. Worryingly, non-indexed journals were more likely to be found using a Google search, and their articles superficially resembled those in indexed journals. These results suggest that the non-indexed aquaculture journals identified herein are likely predatory OA journals and pose a threat to aquaculture research and the public education and perception of aquaculture. There are several points of reference from this study that, in combination, may help scientists and the public more easily identify these possibly predatory journals typically were established after 2010, publishing <20 papers per year, had fees <

Synthesis and comparative analysis of physiological tolerance and life-history growth traits of marine aquaculture species

1000, and published articles <80 days after submission. Subsequently checking reputable and quality-controlled databases such as the Directory of Open Access Journals, Web of Science, Scopus, and Thompson Reuters can aid in confirming the legitimacy of non-indexed OA journals and can facilitate avoidance of these aquaculture journals.