Reduction Fisheries Research Articles

Food supplementation increases reproductive performance of ospreys in the lower Chesapeake Bay

The Atlantic States Marine Fisheries Commission (ASMFC), the governing body responsible for managing fisheries on the U.S. East Coast, formally adopted the use of Ecological Reference Points (ERPs) for Atlantic menhaden, Brevoortia tyrannus. Scientists and stakeholders have long recognized the importance of menhaden and predators such as ospreys, Pandion haliaetus, that support the valuable ecotourism industry and hold cultural significance. Landings in the reduction fishery are at their lowest levels and menhaden is facing potential localized depletion. Mobjack Bay, located within the lower Chesapeake Bay, has been a focus of osprey research since 1970 and represents a barometer for the relationship between osprey breeding performance and the availability of their main prey, menhaden. Since local levels of menhaden abundance were not available, we conducted a supplemental menhaden feeding experiment on osprey pairs during the 2021 breeding season. Our main objective was to determine if the delivery rate of menhaden had an influence on nest success and productivity. Nest success (χ2 = 5.5, df = 1, P = 0.02) and productivity (β = 0.88, SE = 0.45, CI = 0.049, 1.825, P = 0.048) were significantly higher within the treatment group. Reproductive rates within the control group were low and unsustainable suggesting that current menhaden availability is too low to support a demographically stable osprey population. Menhaden populations should be maintained at levels that will sustain a stable osprey population in which they are able to produce 1.15 young/active nest to offset mortality.

Concerns about illegal, unreported and unregulated fishing, carbon footprint, and the impact of fuel subsidy - An economic analysis of the Black Sea anchovy fishery

Among the unresolved problems of fisheries, illegal, unreported and unregulated (IUU) fishing, high carbon footprint, overfishing, and overcapitalization of the fleet are at the forefront. Supporting fishers through fuel subsidy is commonly practiced but eventually led to overcapitalization of the sector. Moreover, the reported catch weights were insufficient to meet fleet operational costs and investments, and therefore there must be some degree of IUU fishing in Black Sea. Therefore, the study examined the economic performance of the purse seiners engaged in anchovy fishery in the Black Sea coast of Turkey and Georgia. The results revealed that economic performance and revenue in the Black Sea anchovy fishery segments evaluated were sufficient to cover expenses and be profitable, even in years when the catch was insufficient. Economic analysis also showed that fuel constitutes a significant part of operational cost in all fleet segments and, in return, 0.17–0.59 tons of CO2 was produced to catch one ton of fish. Under these circumstances, the segment displaying the best fuel utilization efficiency would not survive if the remedy suggested by the UN's sustainable development goal-14, which advocates eliminating fuel subsidy to curb IUU and overfishing, were enforced. In light of the study findings, a series of remedies are suggested to discourage a trend towards IUU fishing, control the fleet's carbon footprint, and ensure sustainability. Among the proposed remedies, the removal of least effective medium-sized boats from the fleet, enforcing more efficient harvest control measures, and limiting the catch used for anchovy reduction fishery were emphasized.

A spatial simulation approach to hydroacoustic survey design: A case study for Atlantic menhaden

Patchily distributed pelagic fish species present a challenge to classical approaches to hydroacoustic survey designs. We propose a spatial simulation approach to designing acoustic surveys and provide a case study in the northern resident stock of Atlantic menhaden Brevoortia tyrannus during winter. The structure and abundance of this stock is poorly characterized due to a paucity of fishery-independent surveys and the geographically limited range of the reduction fishery. In order to develop new fishery-independent information for this stock, we conducted a simulation study to estimate the accuracy and precision of an offshore hydroacoustic survey. We simulated a spatial super-population based on fishery-dependent data, and randomly re-sampled the population with various types of hydroacoustic survey equipment. Our results suggest that a combination of down-viewing echosounder and omni-directional sonar can generate biomass estimates with a coefficient of variation around 25%. The use of down-viewing echosounder alone, however, generated biomass estimates with poor precision. Our approach accounts for the patchy spatial distributions of the survey populations, which leads to more realistic estimates of precision than classical approaches implicitly assuming independence. The approach also evaluates several types of hydro-acoustic survey equipment in deriving absolute biomass estimates, and the survey, once implemented, may contribute to improved spatially explicit management of the stock.

Ex-vessel Fish Price Database: Disaggregating Prices for Low-Priced Species from Reduction Fisheries

Ex-vessel fish prices are essential for comprehensive fisheries management and socioeconomic analyses for fisheries science. In this paper, we reconstructed a global ex-vessel price database with the following areas of improvement: 1) compiling reported prices explicitly listed as ‘for reduction to fishmeal and fish oil’ to estimate prices separately for catches destined for fishmeal and fish oil production, and other non-direct human consumption purposes; 2) including 95% confidence limit estimates for each price estimation; and 3) increasing the number of input data and the number of price estimates to match the reconstructed Sea Around Us catch database. Our primary focus was to address this first area of improvement as ex-vessel prices for catches destined for non-direct human consumption purposes were substantially overestimated, notably in countries with large reduction fisheries. For example in Peru, 2010 landed values were estimated as 3.8 billion real 2010 USD when using separate prices for reduction fisheries, compared with 5.8 billion using previous methods with only one price for all end-products. This update of the price database has significant global and country-specific impacts on fisheries price and landed value trends over time.

Global reduction fisheries and their products in the context of sustainable limits

AbstractGlobally, one‐sixth of landings from marine capture fisheries are destined for the production of fishmeal and fish oil (FMFO), which are currently overwhelming utilized by fed aquaculture. Many different species are used globally for the production of FMFO, but little concern has been given to the divergent environmental and ecological impacts of FMFO products based on species, ecosystem and fishing gear used in their capture. We evaluated the variable environmental performance of FMFO products from a wide range of fisheries whose products are either primarily intended for reduction or whose by‐products are redirected to reduction. Assessed fisheries accounted for 44% of global reduction fishery landings in 2014. Analysis was conducted on the basis of two measures: the carbon footprint (i.e., greenhouse gas [GHG] emissions) and the marine footprint (i.e., primary production required [PPR]). We found large differences between the impacts of FMFO products across the 18 reduction fisheries examined. Cumulatively, we estimate that reduction fisheries emitted 4.6 million tonnes of CO2‐e GHGs in 2014, and appropriated over 4% of primary production in some ecosystems, demonstrating a non‐trivial impact. As demand for aquafeeds grow, the sustainable sourcing of raw material inputs will be of great importance. Results here suggest that the source of FMFO inputs can have dramatic effects on the environmental performance of fish feeds and fed aquaculture. We recommend further research on the environmental and ecological impacts of food production systems, and specifically to understand these results in relation to global production and sustainable boundaries.

To What Extent Is Aquaculture Socially Beneficial? A Theoretical Analysis

This article offers a theoretical analysis of the impact that the introduction of aquaculture has on wild fish stocks and consumer utility, taking into account three key components: (1) the dependence of aquaculture on reduction fisheries for the feeding of the farmed species; (2) biological interactions between the wild edible species—the predator—and the wild feed species—the prey; and (3) consumer preferences for wild and farmed fish. Fisheries are in open access, while the aquaculture sector is competitive. We show that when biological interactions are moderate, the introduction of aquaculture is beneficial in the long run: it improves consumer utility and alleviates the pressure on the edible fish stock. Results are deeply modified when biological interactions are strong: the stock of edible wild fish is reduced and the introduction of aquaculture may even cause a decrease in consumer utility. We then explore the consequences of improving aquaculture efficiency and the sensitivity of consumer preferences to the farmed fish characteristics, in the case where biological interactions are absent. Lastly, we analyze how our outcomes on the entry of aquaculture are affected when the wild edible fishery is optimally regulated, in combination with different assumptions on the regulation of the feed fishery. Results are again conditional on the intensity of biological interactions.

Evaluation of fish meal and fish oil replacement by soybean protein and algal meal from Schizochytrium limacinum in diets for giant grouper Epinephelus lanceolatus

Sparing marine-origin protein and lipid was investigated in diets for giant grouper (Epinephelus lanceolatus), using various combinations of soybean meal (SBM), soy protein concentrate (SPC), and an algal meal derived from Schizochytrium limacinum (ALG) to replace fish meal (FM), squid meal (SQM) and fish oil (FO). Diets were formulated to contain 45% protein (dry weight) and 10% lipid. Three diets were derived from this formulation, using combinations of SBM, SPC, and ALG to replace 20% (FM80), 40% (FM60), or 80% (FM20) of the marine-origin protein sources; additionally, incorporation of the lipid-dense ALG resulted in complete FO replacement in the FM60 and FM20 diets. A feeding experiment was carried out in a seawater recirculating system with 12, 90-L tanks initially stocked with 6 fish each (individual weight=45.9±7.1g) and maintained at 25°C. Diets were assigned to tanks in triplicate, fish were fed to apparent satiation twice daily for 12weeks, and growth rate, body composition, nutrient retention, survival, hepatosomatic index and intestinal integrity were subsequently evaluated. With the exception of retained lipid, the FM100, FM80, and FM60 diets all yielded equivalent (P>0.05) growth and feed utilization. In comparison, weight gain, specific growth rate, feed intake, retained nitrogen and retained lipid were significantly reduced in fish fed the FM20 feed, whereas FCR was significantly elevated. Amino acid analysis of the diets indicated that methionine was limiting in the FM20 feed. Hepatosomatic index did not vary among treatments, but other aspects of body composition were affected. Carcass lipid and ash significantly decreased with marine ingredient inclusion; carcass protein also varied, though less appreciably and without a clear pattern. Fillet fatty acid profile reflected dietary composition. The FM100 diet yielded the highest fillet EPA content, whereas DHA content, DHA:EPA and n−3:n−6 ratios, and total long-chain polyunsaturated fatty acids increased with dietary inclusion of ALG. Histological analysis revealed progressive morphological changes to the distal intestine with higher levels of FM replacement, suggesting enteritis among fish fed the FM20 feed. It is concluded that a blend of SBM, SPC, and ALG can replace at least 40% of marine protein sources, and ALG can be used as the main lipid source in diets for E. lanceolatus without significantly affecting fish performance or condition. Statement of relevanceThe results of this work contribute to decrease the dependence on protein and lipids from reduction fisheries traditionally used in commercial feeds for carnivorous fish, potentially improving the sustainability of aquaculture production of marine fish.

Dietary supplements: health from the ocean?

Dietary supplements: health from the ocean?

Successful fish oil sparing in White Seabass feeds using saturated fatty acid-rich soybean oil and 22:6n-3 (DHA) supplementation

Like other carnivorous species, White Seabass typically demand a nutrient-dense feed. Research is ongoing to develop formulations that contain minimal amounts of marine-origin protein and lipid, i.e., fish meal and fish oil, as a mean of reducing production costs and pressure on reduction fisheries. Previous research has shown that a greater level of fish oil-sparing is possible with saturated fatty acid-rich, hydrogenated soybean oil than with C18 polyunsaturated fatty acid-rich standard soybean oil. To confirm this observation and to assess whether docosahexaenoic acid (DHA) is a limiting factor in fish oil sparing with soy-derived lipids, we evaluated the performance and tissue fatty composition of juvenile White Seabass fed diets containing fish oil, or standard or hydrogenated soybean oil with or without the addition of an algal DHA supplement. In addition, a low temperature stress challenge was done after the feeding trial. Fish fed the hydrogenated soybean oil feeds exhibited growth performance equivalent to those fed the fish oil feed, regardless of DHA supplementation. Growth performance was impaired among fish fed the standard soybean oil feed compared to those fed the fish oil control feed, but the addition of DHA corrected this effect. Dietary treatments significantly affected fatty acid composition of fillet, liver, eye, and brain tissues. In terms of long-chain polyunsaturated fatty acids and n-3 fatty acids, the tissues of fish fed the hydrogenated soybean oil feeds were equivalent to those of fish fed the fish oil feed. Tissues of fish fed the standard soybean oil feeds exhibited significantly lower levels of these beneficial fatty acids; however, this effect was corrected by dietary DHA supplementation. The low temperature stress challenge induced elevated plasma cortisol, and reduced glucose, osmolality and hematocrit; though dietary inclusion of soybean oils did not appear to negatively affect stress tolerance. Results suggest that fish oil sparing in White Seabass feeds is limited by DHA, and that DHA bioavailability may be greater in the presence of hydrogenated soybean oil than standard soybean oil.

Neoliberal and neo-communal herring fisheries in Southeast Alaska: Reframing sustainability in marine ecosystems

The transformation of Pacific herring (Clupea pallasii) fisheries from communal to commons to neoliberal regulation has had significant impacts on the health and sustainability of marine ecosystems on the Northwest Coast of North America. Due to their abundance, seasonality, and sensitivity in disturbance, herring were carefully cultivated and protected by coastal Tlingit, Haida, and Tsimshian communities. The early industrial fishing era undermined this communalist approach in favor of an unregulated commons for bait and reduction fisheries, attracting non-local fleets and leading to conflicts with local Natives and tragedy of the commons style overexploitation of herring stocks by the mid-twentieth century. Since the 1970s, a re-regulated neoliberal sac roe fishery for Japanese markets has provided new opportunities for limited commercial permit holders, but with further depredations on local spawning populations. This paper uses frame theory and historical and political ecology to show how this transformation was justified by three critical but dubious (re)framings of Southeast herring populations under modern scientific management: (1) a reductionist framing of single species productivity models, expressed as herring “biomass,” within space and time (baseline scale framing); (2) the selective framing and privileging of human industrial predation under maximum sustainable yield (MSY) within a dynamic ecosystem of multiple predator populations (actor relations framing); and (3) the strategic framing of spawning failure events and policy responses to those events by professional fisheries managers (event–response framing). Finally, the paper argues for a new social–ecological systems approach, based on aboriginal models of herring cultivation, to sustain a commercial, subsistence, and restoration economy for the fishery.

Life Cycle Environmental Impacts of Three Products Derived from Wild-Caught Antarctic Krill (Euphausia superba)

Concern has been voiced in recent years regarding the environmental implications of the Antarctic krill fishery. Attention has focused primarily on ecological concerns, whereas other environmental aspects, including potentially globally problematic emissions and material and energy demands, have not been examined in detail. Here we apply life cycle assessment to measure the contributions of krill meal, oil, and omega-3 capsules to global warming, ozone depletion, acidification, eutrophication, energy use, and biotic resource use. Supply chains of one krill fishing and processing company, Aker BioMarine of Norway, were assessed. Impacts of krill products were found to be driven primarily by the combustion of fossil fuels onboard the fishing vessel and a transport/resupply vessel. Approximately 190 L of fuel are burned per tonne of raw krill landed, markedly higher than fuel inputs to reduction fisheries targeting other species. In contrast, the biotic resource use associated with extracting krill is relatively low compared to that of other reduction fisheries. Results of this study provide insight into the broader environmental implications of the krill fishery, comparisons between products derived from krill and other species targeted for reduction, opportunities for improving the fishery's performance, and a baseline against which to measure future performance.

World War II and the “Great Acceleration” of North Atlantic Fisheries

Abstract World War II impacted both the marine and the terrestrial environment of the North Atlantic, triggered major political and economic decisions with profound cultural implications, and eventually induced a change in ocean management. The War helped develop technologies and state responses to immediate post-war market problems and impacted the Great Acceleration of fisheries between 1945 and 1975. During the war, fisheries were closed completely only in certain parts of the most fished waters, such as the central North Sea and the English Channel. Even in the most affected Northern European waters some fishing continued throughout the war. Fishing was carried on in the waters off Iceland and the Arctic, but extractions were much reduced. Previously unfished stocks in the Baltic were targeted for the first time ever. The effect of the closure of certain fisheries was an overall increase of survival rates of marine animals. Technological advances made during the War increased the fishing efficiency of vessels when the technology was put to commercial use soon after the War. The immediate benefit of better catch-per-unit effort after the War was concealed by the slump in the international fish market. The wartime ‘dividend’ of marine resources was largely spent by the mid-1950s in the North Sea and by 1960 in the wider North Atlantic. The war disrupted market allegiances, effectively ended old fishing patterns and introduced a forced modernisation in the High North. Among North Sea countries, Denmark in particular responded to the disruption of the market for fresh fish by introducing reduction fishery, which led to severe environmental stress and eventually a collapse of the North Sea herring stock. Before WWII, the oceans had largely been regulated according to the international law of open access to all ocean resources. North Sea countries resumed negotiations over fishing rights after 1945, expecting to revert to old principles. However, U.S. President Harry Truman’s declaration against Japan came to impact fishing negotiations in the North Atlantic and changed post-war fishing management forever.

Uncertainty and natural variability in the ecological footprint of fisheries: A case study of reduction fisheries for meal and oil

It is well understood that measurements of ecological footprint and many other ecological indicators are associated with varying degrees of uncertainty, yet imprecision in ecological footprint results is rarely assessed or communicated. We calculated the marine portion of the ecological footprint of products derived from five reduction fisheries: Peruvian anchovy ( Engraulis ringens), Atlantic herring ( Clupea harengus), Gulf menhaden ( Brevoortia patronus), blue whiting ( Micromesistius poutassou) and Antarctic krill ( Euphausia superba). Monte Carlo analysis was used to measure the imprecision in marine footprint measurements resulting from multiple sources of uncertainty and natural variability in input parameters, and to determine the degree to which imprecision affects our ability to draw meaningful conclusions when comparing products sourced from different fisheries on the basis of ecological footprint. Gulf menhaden and Antarctic krill were found to have the smallest marine footprints, while blue whiting was found to have the largest. Results show that there is much uncertainty associated with marine footprint calculations and that the most significant drivers of this imprecision are uncertainty and natural variability regarding measurements of trophic level and trophic interactions. Marine footprint is highly correlated with trophic level, and clear differences can be seen when comparing species of very different trophic levels. However, comparisons of products derived from species’ with similar trophic levels are less likely to provide conclusive results. The choice of mass, protein or energy content as the basis of comparison was also considered and was found to influence the results, particularly when comparing species with similar trophic levels. While it is likely that imprecision of marine footprint measurements of fishery-derived products will remain high, technological improvements and a better understanding of marine ecosystem dynamics may make future studies more precise.

Replacement of Fish Meal with Ethanol Yeast in the Diets of Sunshine Bass

AbstractIncreasing demand and rising costs of fish meal (FM) coupled with static landings of reduction fisheries have made continued use of FM‐rich aquaculture feeds environmentally and economically unsustainable. Animal‐ and plant‐derived proteins have been investigated as alternatives to FM, with variable success. Observed limitations of commonly used alternative proteins have led nutritionists to investigate new alternatives to FM. Ethanol yeast, a co‐product of bioethanol production and potential new alternative protein source, was evaluated as a FM replacement in the diets of sunshine bass (female white bass Morone chrysops × male striped bass M. saxatilis). Five diets were evaluated, including a control diet containing 30% FM and four experimental diets (22.5, 15, 7.5, and 0% FM) in which 25, 50, 75, or 100% of the FM content was replaced with ethanol yeast. Juvenile sunshine bass (∼16 g) were fed twice daily to apparent satiation for 45 d. Production performance of sunshine bass was not impaired by partial FM replacement and in some cases was marginally improved by dietary inclusion of ethanol yeast. Feed conversion ratio, specific growth rate, and feed intake were equivalent among fish fed the control, 22.5% FM, 15% FM, and 7.5% FM feeds; weight gain was significantly increased in the 15% FM group compared with the control. However, complete replacement (0% FM) resulted in significantly impaired growth performance and conversion efficiency. Whole‐body composition did not differ with respect to moisture, ash, or protein content; however, crude lipid content was significantly elevated in the 7.5% FM treatment, suggesting a protein–energy imbalance in this formulation. Although our study was a short‐term screening trial, based on our results we suggest that an optimal level of FM in ethanol‐yeast‐based feeds for sunshine bass would be between 7.5% and 15%.Received March 15, 2010; accepted June 5, 2010

Simulated Short‐Term Impacts of the Atlantic Menhaden Reduction Fishery on Chesapeake Bay Water Quality

AbstractAtlantic menhaden Brevoortia tyrannus support an intense fishery in Chesapeake Bay, an estuary that is impaired by eutrophication and excess phytoplankton biomass. Since Atlantic menhaden are filter‐feeding fish that consume plankton, including phytoplankton, fishery removals may negatively affect water quality and may therefore hinder bay restoration efforts. We performed a simulation to estimate the short‐term (monthly and annual) water quality impacts caused by the reduction fishery harvesting its current total allowable catch of Atlantic menhaden in Chesapeake Bay (109,020 metric tons/year). A theoretical loss in net nitrogen removal (Nt) due to the fishery was estimated for each month, and the simulation was repeated for several scenarios to account for uncertainties associated with Atlantic menhaden feeding behavior. The largest potential impact of the fishery (i.e., absolute value of Nt) occurred in August for all scenarios, but depending on the value assumed for average feeding rate the fishery was estimated to have either a positive impact or a negative impact on water quality. The sum of Nt across months ranged from −5.78 × 105 to 1.85 × 107 kg of N/year, indicating that the harvested Atlantic menhaden could have contributed up to 0.38% or removed up to 12.19% of the estimated total nitrogen load for Chesapeake Bay. This large range probably captures all possible scenarios of Atlantic menhaden feeding intensity; however, the current understanding of their feeding rates as related to phytoplankton composition in Chesapeake Bay suggests that average feeding rates are relatively low and that the probable impact of the fishery on water quality is negligible.Received July 13, 2010; accepted December 24, 2010

The rebuilding imperative in fisheries: Clumsy solutions for a wicked problem?

There is mounting evidence that global fisheries are in crisis and about 25–30% of fish stocks are over exploited, depleted or recovering. Fish landings are increasingly coming from fully-exploited and over-exploited fisheries, and from intensive aquaculture that often relies indirectly on reduction fisheries. This poses severe challenges for marine ecosystems as well as food security and the livelihoods of resource-dependent coastal communities. Growing awareness of these social, economic and ecological consequences of overfishing is reflected in an expanding literature which shows that reducing fishing effort to allow fish stocks to recover has been the main focus of management efforts, but successful examples of stock recovery are few. An alternative, less explored social-ecological approach focuses on rebuilding entire ‘fish chains’ from oceans to plate. This paper supports this alternative approach. A review and synthesis of stock rebuilding initiatives worldwide suggests effective governance is central to rebuilding, and fisheries governance is a wicked problem. Wicked problems are complex, persistent or reoccurring and hard to fix because they are linked to broader social, economic and policy issues. This review and analysis implies that, due to socioeconomic and sociopolitical concerns, fisheries governance challenges are particularly wicked when dealing with collapsed fisheries and rebuilding efforts. The paper concludes that rebuilding might benefit from experimenting with clumsy solutions. Clumsy solutions are exploratory, include inputs from a broad range of stakeholders along the fish chain, and require information sharing, knowledge synthesis, and trust building. Moreover, clumsy solutions that address power relations, collective action dilemmas, and the fundamental question of ‘rebuilding for whom’ are essential for stewardship, equity and long-term resource sustainability.

A review of factors limiting recovery of Pacific herring stocks in Canada

AbstractSchweigert, J. F., Boldt, J. L., Flostrand, L., and Cleary, J. S. 2010. A review of factors limiting recovery of Pacific herring stocks in Canada. – ICES Journal of Marine Science, 67: 1903–1913. On the west coast of Canada, Pacific herring (Clupea pallasi) supported an intensive reduction fishery from the early 1930s until the collapse of all five major stocks in the late 1960s, which then recovered rapidly following a fishery closure. Despite conservative harvests, abundance has declined again recently, with little evidence of recovery. We investigated the effect of bottom-up forcing by zooplankton abundance, top-down forcing by fish and mammal predators, and the effects of sardine abundance as potential competitors on the natural mortality of the herring stock on the west coast of Vancouver Island. Herring mortality was positively related to Thysanoessa spinifera and southern chaetognaths and negatively to pteropod abundance. Estimated predation on herring decreased significantly during the years 1973–2008, with the main consumers changing from fish to mammals. However, the correlation with herring mortality was negative, whereas there was a significant positive relationship with sardine abundance. Population recovery is expected to be facilitated by a combination of factors, including adequate food supply, limited or reduced predation (including fishing), and limited competition particularly for wasp–waist systems, where different forage species may occupy similar niches.

Impacts of global environmental change and aquaculture expansion on marine ecosystems

The stability of world's reduction fisheries and the global fishmeal market they support is explored through a geographically-specific, global bio-economic model, driven by three interactive forcing factors: climate-driven changes in the biological production of regional fish stocks, the potential global expansion of aquaculture demand for fishmeal and differential management schemes. The model captures approximately 85% of the world's fishmeal and fish oil data and is driven by trade data from the period 1997–2004. Twenty-year model simulations are conducted considering, on the production side, a random recruitment variability of the fish stocks supporting all regional production systems, plus an El Niño-type perturbation altering the productivity of Peruvian and Chilean stocks. The production systems are confronted with two alternative aquaculture expansion scenarios, allowing for the quantification of the synergism between regional climate-driven fluctuations and economic globalization of marine commodities in determining sustainable and unsustainable pathways for the world's reduction fisheries. The simulation results are compared to trends in regional climate indices, trade information from international markets and aquaculture and small pelagic fisheries data. The work pioneers the quantification of the double exposure created by climate variability and change and economic globalization on particular natural resources and explains the stakes involved in the development of fishmeal trade for global aquaculture expansion for marine fish populations. The results demonstrate that regional stocks can recover from climate-driven fluctuations unless these act simultaneously to an expansion in international market demand, and are subject to sub-optimal management schemes. It is argued that the dynamics of the fishmeal price since the early 1990 already responds to the balance between climatic variability in production and market developments, as mimicked by the model. Furthermore, under sub-optimal management scenarios, a sequential pattern of overexploitation emerges as an endogenous property of the interaction between regional climatic disturbances and a globalized trade system. It is concluded that the way we manage climate impacts, both at regional and global level, will determine the sustainability of the world's reduction fisheries, a conclusion that could be extended to other, similarly affected, natural resources.

Potential, Implications and Solutions Regarding the Use of Rendered Animal Fats in Aquafeeds

Problem statement: In the past, aquafeeds were comprised largely of fish meal and fish oil derived from marine reduction fisheries. In addition to being highly palatable and readily digested by cultured fishes, these feedstuffs were historically inexpensive sources of protein, energy and essential nutrients. However, increasing cost and concerns over safety and sustainability have greatly incentivized the transition from fish meal and oil to alternative sources of protein and lipid for aquafeed formulation. Fish oil replacement is proving more difficult than originally anticipated, particularly for marine carnivorous species. Approach: If complete fish oil replacement is not a viable goal for fish nutritionists and aquafeed manufacturers, at a minimum, we must strive for judicious use of limited marine-derived resources. In the present review, we explore the opportunities of using rendered fats as alternatives to marine-derived fish oils in aquaculture feeds, beginning with a discussion of the products themselves before reviewing the most recent literature and concluding with a discussion of the future of these products in aquafeed formulations. Results: Rendered fats have not been as intensively evaluated in aquaculture nutrition as grain and oilseed-derived lipids, although a number of recent publications on the subject suggest increasing interest in the use of rendered products in aquafeeds. Conclusion: Poultry fat, beef tallow, pork lard and to a lesser extent, yellow/restaurant grease and catfish oil, have been investigated individually or in combination with other lipids in feeds for a broad range of cultured taxa with generally acceptable results.

Feeding farmed salmon: Is organic better?

Feed provision accounts for the majority of material and energetic inputs and emissions associated with net-pen salmon farming. Understanding and reducing the environmental impacts of feed production is therefore central to improving the biophysical sustainability of salmon farming as a whole. We used life cycle assessment (with co-product allocation by gross energy content) to compare the cradle-to-mill gate life cycle energy use, biotic resource use, and global warming, acidifying, eutrophying and aquatic ecotoxiticy impacts associated with producing ingredients for four hypothetical feeds for conventional and organic salmon aquaculture in order to assess the benefits, if any, associated with a transition to organic feed use. Fish and poultry-derived ingredients generated substantially greater impacts than crop-derived ingredients. Despite the fact that organic crop ingredients had markedly lower life cycle impacts compared to equivalent conventional ingredients, substituting organic for conventional crop ingredients therefore resulted in only minor reductions to the total impacts of feed production because the benefits of this substitution were effectively overwhelmed by the much larger impacts associated with animal-derived ingredients. Replacing fish meals/oils from dedicated reduction fisheries with fisheries by-product meals/oils markedly increased the environmental impacts of feed production, largely due to the higher energy intensity of fisheries for human consumption, and low meal/oil yield rates of fisheries by-products. Environmental impacts were considerably lower when feeds contained reduced proportions of fish and poultry-derived ingredients. These results indicate that current standards for organic salmon aquaculture, which stipulate the use of organic crop ingredients and fisheries by-product meals and oils, fail to reduce the environmental impacts of feed production for the suite of impact categories considered in this study. This information should be of interest to feed producers and aquaculturists concerned with improving the biophysical sustainability of their products, and bodies responsible for aquaculture certification, eco-labeling, and consumer awareness programs.