Pelagic Fisheries Research Articles

Nutritional characterization of Trachurus lathami discarded by the Argentine fishing industry: first step towards the sustainable valorization of the species

In the Argentine Continental Shelf pelagic fisheries, rough scad (Trachurus lathami) is incidentally caught, being discarded by the commercial fleet despite its high abundances. With the aim of promoting the sustainable use of this species, the nutritional characterization of T. lathami is reported here for the first time. High protein (16%) and lipid (5.4%) content in whole individuals indicated that this is a moderately fat species. In the edible portion, within total lipids (4.8%), the n-3 polyunsaturated fraction was represented by docosahexaenoic (16.8%) and eicosapentaenoic (5.6%) acids. Results encourage potential strategies towards the developing of restructured products for human consumption.

The role of certification standards in supporting improved fisheries management for small pelagics in mauritania: An example to follow in the North West African zone?

This study presents an assessment of the role of fisheries certification programmes in the management of fisheries in Mauritania, with the example of the small pelagic fishery. We show how the industry and authorities in Mauritania are taking advantage of the pressure for certification in the international supply chain to mobilise resources to make improvements in fisheries management and science on the ground, via the medium of a Fisheries Improvement Project (FIP) and through collaboration with a fisheries certification organisation (MSC). We consider the recent expansion of the fishmeal industry and the management needs of the fishery in this context (for example, controlling capacity, rationalising management measures by fleet, moving fishing grounds away from sensitive areas, reducing wastage etc.). We evaluate the role of these projects, driven by certification objectives, in contributing to progress. We consider how a similar private-sector driven model might be applied in neighbouring West African countries (Senegal, Gambia and others) and what barriers might exist in these countries in comparison to Mauritania.

Dietary metabarcoding of keystone sardine species reveals the importance of their ichthyoplankton prey in food webs of the Southern Brazilian Bight fisheries

AbstractClupeiform fishes are ecologically and economically important species contributing to industrial and artisanal fisheries worldwide. They represent key links in food webs, influencing the dynamic between trophic levels. The dietary interactions of these species are poorly studied in many regions, yet essential for fisheries management. To elucidate the role of these species in food webs of the Southern Brazilian Bight pelagic fisheries, we used metabarcoding analysis of fish stomach contents of Clupeiformes and possible predators. Onboard sampling from March to September 2016 allowed for processing of 87 stomach samples representing 31 species (including 12 samples representing three species of Clupeiformes). Links between trophic levels showed the predominance of Sardinella brasiliensis and Engraulis anchoita as important dietary items of a large range of fishes (28 species belonging to 18 families) and representing the majority of the total prey read abundance assigned to clupeiform fishes (~46% and ~32%, respectively). Opisthonema oglinum contributed to the diet of 16 species in 13 families and ~18% of total read abundance of clupeiform fishes as prey. The appearance of multiple clupeiform taxa in the diet of predators that are not commonly associated with pelagic prey indicates that ecosystem‐based fisheries management should not be separated between pelagic and demersal fisheries. The diet of Clupeiformes revealed an unexpectedly large diversity of fish species and a low proportion of invertebrates (<5% of clupeiform prey reads). This was likely due to a combination of both a limitation of the metabarcoding method (primer bias and low success of invertebrate taxonomic identification) as well as a contribution of early life stages (ichthyoplankton) to the diet of these fishes. The potential role of clupeiform fish populations as a constraint to the recruitment from the ichthyoplanktonic phase of other ecologically or commercially important fishes should be considered as an important direction for future studies.

A comparative economic analysis of industrial fisheries targeting small pelagic fish in Mauritanian waters: Free license versus charter regime

AbstractIndustrial fisheries targeting small pelagic fish have significant socio‐economic implications for North West African countries. This study examines the economic performance of fleets operating in Mauritania's exclusive economic zone under the free license and chartering systems. Using national production data from 1989 to 2010 and economic indicator ratios from European pelagic fishing vessels, we assess the economic performance of pelagic fisheries over one decade. Our findings show that vessel characteristics have rapidly evolved, with free‐licenced vessels having a higher average fishing capacity than chartered vessels. The nominal number of free licenses increased from under 8% in 1995; the year of free licencing began in Mauritania, to over 80% in 2010. The estimated average economic output for 2000–2010 was US$ 231 million, with free licenses contributing over 80% of the total turnover (US$ 187 million). Vessels operating under free licenses made a greater contribution to wealth creation than the chartering regime. Foreign ship owners generated US$ 40.7 million (22%) in income, while chartering yielded US$ 3.6 million (8%). However, the chartering regime was more fiscally advantageous, contributing over 68% of pelagic fisheries tax revenues (estimated at over US$ 29 million). The small pelagic fishery has been subject to a system of total allowable catches and fishing quotas since 2015. This study provides insights into the economic dynamics of the small pelagic fishery, informing decision‐making and potential strategies to enhance the sector's performance and overall economic impact.

EDNA based bycatch assessment in pelagic fish catches

Pelagic fish like herring, sardines, and mackerel constitute an essential and nutritious human food source globally. Their sustainable harvest is promoted by the application of precise, accurate, and cost-effective methods for estimating bycatch. Here, we experimentally test the new concept of using eDNA for quantitative bycatch assessment on the illustrative example of the Baltic Sea sprat fisheries with herring bycatch. We investigate the full pipeline from sampling of production water on vessels and in processing factories to the estimation of species weight fractions. Using a series of controlled mixture experiments, we demonstrate that the eDNA signal from production water shows a strong, seasonally consistent linear relationship with herring weight fractions, however, the relationship is influenced by the molecular method used (qPCR or metabarcoding). In four large sprat landings analyzed, despite examples of remarkable consistency between eDNA and visual reporting, estimates of herring bycatch biomass varied between the methods applied, with the eDNA-based estimates having the highest precision for all landings analyzed. The eDNA-based bycatch assessment method has the potential to improve the quality and cost effectiveness of bycatch assessment in large pelagic fisheries catches and in the long run lead to more sustainable management of pelagic fish as a precious marine resource.

Global shark fishing mortality still rising despite widespread regulatory change.

Over the past two decades, sharks have been increasingly recognized among the world's most threatened wildlife and hence have received heightened scientific and regulatory scrutiny. Yet, the effect of protective regulations on shark fishing mortality has not been evaluated at a global scale. Here we estimate that total fishing mortality increased from at least 76 to 80 million sharks between 2012 and 2019, ~25 million of which were threatened species. Mortality increased by 4% in coastal waters but decreased by 7% in pelagic fisheries, especially across the Atlantic and Western Pacific. By linking fishing mortality data to the global regulatory landscape, we show that widespread legislation designed to prevent shark finning did not reduce mortality but that regional shark fishing or retention bans had some success. These analyses, combined with expert interviews, highlight evidence-based solutions to reverse the continued overexploitation of sharks.

Anchovy (Engraulis ringens) and Pacific sardine (Sardinops sagax) variability changes in northern Chile associated with the environment and inter species synchronicity: GARCH model with exogenous variable and hybrid Bayesian deep learning estimation approach

Small pelagic fish species, such as anchovy (Engraulis ringens) and Pacific sardine (Sardinops sagax), play a crucial role in marine ecosystems worldwide as they serve as an important food source for higher-order predators, such as seabirds, marine mammals, and larger fish species; also from their high productivity in terms of fishery landings, they help with maintaining food security. However, small pelagic populations are known for their variability, with fluctuations in their distribution and abundance influenced by interactions with environmental and human-related factors in different spatio-temporal scales. This study aims to investigate the variability in anchovy and sardine populations in northern Chile and their potential environmental drivers by using a class of models that address the changes in variability (i.e. variance) over time, namely Generalized autoregressive conditional heteroskedasticity (GARCH) models. In particular, this work considers a GARCH model that includes an additional term in the variance, that could help to better model the variability fluctuations of both anchovy and sardine, explained by environmental factors. Since there is no estimation procedures for those type of models, we propose a hybrid Approximate Bayesian Computation (ABC) procedure that involves the use of Deep Learning structures for estimating the parameters of the model and obtain posterior distributions. The results are two-fold: First, the proposal of a new time series model that better explain conditional variance with exogenous variables and a novel estimation procedure, and second, a novel approach for establishing explicit models that address the variability of small pelagic fisheries and their interaction with the environment.

Shelf oceanography and small pelagic fishes in the Java Sea

The optimization of small pelagic fisheries in the Java Sea could be enhanced by providing oceanographic information for analysis and determining potential fishing grounds. This study aims to investigate shelf oceanographic factors influencing small pelagic fisheries using multidatasets of sea surface temperature and surface salinity CROCO ocean model output (2010 – 2020), distribution of light-fishing vessel position of VIIRS satellite, and small pelagic fish catches landing data (round scads Decapterus spp. and the spotted sardinella Amblygaster sirm) at Pekalongan Fishing Port, Central Java. The results showed that the peak of fishing season for the spotted sardinella occurs during northwest monsoon, in which the eastward monsoon current and Sunda shelf throughflow brings fresher (±32.4 psu) and warmer (±28.5 oC) water into the Java Sea. In contrast, the peak of fishing season for round scads. is associated with saltier (>33.0 psu) and cooler (<28.5 °C) water supplied by the westward monsoon current and Makassar ITF during the southeast monsoon. Alternating intensification of monsoonal current along the northern Java and the southern Kalimantan coast during different monsoon periods is associated with a higher abundance of neritic and oceanic small pelagic fishes, respectively.

Longline pelagic fishery assemblage in Kenya’s exclusive economic zone marine waters

Fisheries catch data is important for monitoring and assessing anthropogenic and natural impacts on fish communities. Information on fish assemblages and diversity in the Western Indian Ocean region is limited complicating management of the fisheries. In this study, we determined longline catch rates, species diversity indices, species richness, and species evenness for fish assemblages of Kenya’s exclusive economic zone (EEZ) through experimental surveys conducted using a commercial Fishing Vessel (FV) between April and October 2020. A total of 110 sets were conducted where 4217 specimens of 50 species and 23 families were caught. The catches were mainly composed of Xiphias gladius (70.2%), Prionace glauca (7.8%), and Thunnus obesus (4.4%). About 15.0% of the catches were discarded of which 11.3% comprised of fish no commercial value. High levels of endangered, threatened and protected species forming 5.5% of the catches were observed. Catch rates were high for the dominant species in the three zones and differed significantly between months. Species abundance, richness, Shannon-Weiner diversity, and Simpson’s diversity indices were highest at the nearshore zone and during August. However, the diversity indices were not statistically different both for the zones and months. The nearshore zone exhibited higher species assemblages and greater species richness compared to other zones. This suggests the importance of prioritizing conservation efforts in the nearshore zone, as it serves as a critical habitat for diverse fish populations. Implementing protective measures can help preserve the biodiversity and sustainability of fish assemblages in the nearshore zone.

Influence of migrant Western Regional shark fishers on shark fishing practices along the eastern coastline of Ghana

Sharks have formed an integral part of Ghana’s fisheries for many years, although in many areas outside the Western Region, they are often captured as bycatch. The shark fishery in the Dangme communities along the eastern coastline of Ghana has, however, over the last decade, acquired a commercial character that is believed to have been influenced by migrant fishers from the Western Region. This study thus sought to characterise the influence of the migrant fishers in the development of the thriving shark fishery in Dangme communities. Data collection was through key informant interviews, questionnaire administration to 180 randomly selected native and migrant fishers from the selected communities, and observations of fishing practices. Until the mid-2000 s, only the migrant fishers carried out targeted shark fishing along the Dangme coastline. Presently, however, a significant number of native fishers have redirected their fishing efforts towards shark fishing in the face of dwindling catches from the small pelagic fisheries, which were the primary target of the fisheries. Accounts 75 % of native fishers indicated that the declines in small pelagic fish stocks coupled with the influence of the migrant shark fishers have acted synergistically to influence the shark fisheries dynamics along the Dangme coastline. Despite the average ages of the native and migrant fishers being fairly the same (∼36 years), the migrants possessed a more profound understanding of the marine ecosystem where they operated based on historical antecedents and their longer interactions with the shark fishing zones. Presently, this new fishery, like shark fishing in other shark fishing hotspots in Ghana, is unregulated, but it will be imperative for national fisheries authorities to implement some management measures to reduce fishing pressure on the most vulnerable species.

Dynamic energy budget model for the complete life cycle of chub mackerel in the Northwest Pacific

Chub mackerel (Scomber japonicus) in the Northwest Pacific is an important pelagic fishery resource and a significant target species in purse seine fisheries. However, the catch of chub mackerel fluctuates greatly from year to year, and recent studies have shown that the Tsushima stock may be overfished. Therefore, research on the biology and population dynamics of this species is required to provide sufficient scientific support for the development of reasonable management and recovery plans and for the increased sustainable use of resource fisheries. In this study, a dynamic energy budget (DEB) model was constructed based on DEB theory for the complete life cycle of chub mackerel in the Northwest Pacific by using biological data to simulate processes, including growth, reproduction, and death. The key results were as follows. 1) The DEB model accurately simulated the complete life cycle of chub mackerel, with a good fit for the relationships between age and length as well as length and weight, while accurately estimating annual absolute fecundity, aging, and death and predicting the metamorphosis time of larval fish. 2) The DEB model can incorporate the effects of temperature and food to describe the effects of marine environmental conditions on chub mackerel growth. 3) The DEB model involved multiple interrelated parameters; however, owing to a lack of observational data, there was a certain degree of uncertainty in estimated parameter values. The DEB model provides a basis for establishing correlations and intrinsically unifying biological processes, including growth, sexual maturation, reproduction, aging, and death, thereby guiding studies of growth, reproduction, and population dynamics of chub mackerel in the Northwest Pacific.

Fish aggregating devices could enhance the effectiveness of blue water marine protected areas

AbstractIn the past two decades, drifting fish aggregation devices (FADs) have revolutionized pelagic fisheries, and are now responsible for the majority of tuna purse seine catches. Here, we argue that by taking advantage of the same proven aggregative properties, FADs could be used to enhance the benefits provided by blue water marine protected areas (MPAs). Using models of commercially targeted fish populations, we explore the potential benefits that could be achieved if unfished conservation FADs—designed as self‐powered devices capable of remaining semi‐stationary—were deployed within blue water MPAs. By increasing the residence time of exploited species in MPAs, conservation FADs will reduce average mortality rates. By increasing the local density of exploited species, they may also improve the function of ecosystems in blue water MPAs. Conservation FADs could, therefore, amplify the benefits of blue water MPAs. We find this amplification is largest in those contexts where blue water MPAs have attracted the most criticism—when their area is small compared to both the open ocean and the distribution of fish stocks that move through them.

Multiple lines of evidence highlight the dire straits of yellowfin tuna in the Indian Ocean.

Yellowfin tuna (Thunnus albacares) are highly valued pelagic fisheries target species. Regional fisheries management organizations (RFMOs) are the principal mechanism that manage yellowfin tuna fisheries. Determining changes in population abundances is crucial for effective conservation and management. We use multiple methods for monitoring biomass trends and evaluating the status of yellowfin tuna in each ocean basin and show how additional, multiple lines of evidence can enhance our understanding of the conservation and exploitation status of this species. Our analysis of regional biomass trajectories and Catch-MSY++ assessments corroborate the findings of the most recent RFMO stock assessments suggesting yellowfin tuna in the Indian Ocean are in critical condition, while the Eastern Pacific yellowfin tuna population shows the lowest levels of exploitation. These results are supported by fisheries-independent data from baited remote underwater video systems (BRUVS), showing that the Indian Ocean yellowfin tuna population is the least common, least abundant, and smallest across all oceans. Our findings support previous claims of systematic and widespread overfishing of yellowfin tuna in the Indian Ocean and thus confirm calls to reduce current fishing levels to ensure the long-term viability of the species.

Shifts in the pelagic fishery dynamics in response to regional sea warming and fishing in the Northeastern Mediterranean

Shifts in the pelagic fishery dynamics in response to regional sea warming and fishing in the Northeastern Mediterranean

Faroe Islands Fisheries in the Northeast Atlantic: Brexit, Russia, and economic incoherence

Among major fishing nations, the Faroe Islands is an exemplar of what should not be tried in the way of fisheries governance and management. Governance is not management, and the Faroes reinforces that point. The government has managed to degrade its demersal sector (cod, haddock, saithe), while undermining its pelagic sector (mackerel, herring, blue whiting) by alluring gifts of free quota for firms that have little interest in using a significant share of that quota. Not all free gifts are valuable. In this paper we document Faroese fisheries performance over the past 24 years to illustrate how things can go badly wrong. We develop econometric models of the demersal and pelagic fisheries to provide empirical support for a general account of incoherence and disarray. Pelagic quota has been given (for free) to demersal vessels unable to fish for pelagic stocks. This has maintained the number of demersal vessels at a higher level than is justified—only because such vessels serve as a destination for mackerel quota (that is then transferred to pelagic vessels). Such policies bring economic incoherence to both sectors. Faroese policies continue to undermine economic rationality in this crowded pelagic fisheries complex.

Multiple stable isotopes (C, N & S) provide evidence for fin whale (Balaenoptera physalus) trophic ecology and movements in the Humboldt Current System of northern Chile

Reflecting the intense coastal upwelling and high primary productivity characteristic of the Humboldt Current System (HCS), the northern coast of Chile supports a diverse and productive community of marine consumers, including worldwide important pelagic fisheries resources. Although marine mammals are relatively understudied in the region, recent studies have demonstrated that fin whale (Balaenoptera physalus) is the most frequently encountered whale species, and forages in these waters year-round. However, a current lack of information limits our understanding of whether fin whales actively feed and/or remain resident in these waters or whether whales are observed feeding as they migrate along this part of the Pacific. Here, we use stable isotope ratios of carbon, nitrogen and sulphur of fin whale skin samples collected in early summer 2020 (n = 18) and in late winter 2021 (n = 22) to examine evidence of temporal isotopic shifts that could provide information on potential migratory movements and to estimate likely consumption patterns of putative prey (i.e. zooplankton, krill, pelagic fishes and Pleuroncodes sp.). We also analysed prey items in fin whale faecal plumes (n = 8) collected during the study period. Stable isotope data showed significant differences in the isotopic values of fin whales from summer and winter. On average, summer individuals were depleted in 15N and 34S relative to those sampled during winter. Whales sampled in summer showed greater isotopic variance than winter individuals, with several showing values that were atypical for consumers from the HCS. During winter, fin whales showed far less inter-individual variation in stable isotope values, and all individuals had values indicative of prey consumption in the region. Analysis of both stable isotopes and faeces indicated that fin whales sighted off the Mejillones Peninsula fed primarily on krill (SIA median contribution = 32%; IRI = 65%) and, to a lesser extent, zooplankton (SIA zooplankton = 29%; IRI copepod = 33%). These are the first isotopic-based data regarding the trophic ecology of fin whales in the north of Chile. They provide evidence that fin whales are seasonally resident in the area, including individuals with values that likely originated outside the study area. The information presented here serves as a baseline for future work. It highlights that many aspects of the ecology of fin whales in the Humboldt Current and wider SE Pacific still need to be clarified.

User rights in the fisheries and salmon-farming of the Faroe Islands

This paper focuses on the user rights regimes that have governed access to the marine resources of the Faroe Islands, which in the case of the fisheries are primarily fish stocks, and, in the case of salmon farming, primarily clean and healthy water masses. Examining the application of different user rights arrangements, we were able to observe a gradual improvement in the economic efficiency of the production activity for salmon farming, where strong operating exclusivity played a pivotal role in strengthening user rights. Similarly, the pelagic fisheries and the distant-waters demersal fisheries governed by ITQs have witnessed improved economic efficiency, although the strength of their user rights weakened over the last decade because of diminishing exclusivity and security of their rights. At the same time, the coastal demersal fisheries governed by ITEs continued to be marked by overcapacity and low fish stock levels despite the presence of strong exclusivity. These findings indicate that the design of user rights must also relate to specific management differences in marine resource exploitation under consideration.

Dynamic human, oceanographic, and ecological factors mediate transboundary fishery overlap across the Pacific high seas

AbstractThe management and conservation of tuna and other transboundary marine species have to date been limited by an incomplete understanding of the oceanographic, ecological and socioeconomic factors mediating fishery overlap and interactions, and how these factors vary across expansive, open ocean habitats. Despite advances in fisheries monitoring and biologging technology, few attempts have been made to conduct integrated ecological analyses at basin scales relevant to pelagic fisheries and the highly migratory species they target. Here, we use vessel tracking data, archival tags, observer records, and machine learning to examine inter‐ and intra‐annual variability in fisheries overlap (2013–2020) of five pelagic longline fishing fleets with North Pacific albacore tuna (Thunnus alalunga, Scombridae). Although progressive declines in catch and biomass have been observed over the past several decades, the North Pacific albacore is one of the only Pacific tuna stocks primarily targeted by pelagic longlines not currently listed as overfished or experiencing overfishing. We find that fishery overlap varies significantly across time and space as mediated by (1) differences in habitat preferences between juvenile and adult albacore; (2) variation of oceanographic features known to aggregate pelagic biomass; and (3) the different spatial niches targeted by shallow‐set and deep‐set longline fishing gear. These findings may have significant implications for stock assessment in this and other transboundary fishery systems, particularly the reliance on fishery‐dependent data to index abundance. Indeed, we argue that additional consideration of how overlap, catchability, and size selectivity parameters vary over time and space may be required to ensure the development of robust, equitable, and climate‐resilient harvest control rules.

Isotopic and biochemical trophic markers reveal the complexity of interactions at the base of pelagic food webs (Mediterranean sea)

To gain insight into the impact of bottom-up changes in the plankton community on planktivorous fish in the context of the decline of small pelagic fisheries in the Northwestern Mediterranean Sea, we have conducted an extensive year-long study. The investigation combined biochemical analyses (proteins, carbohydrates, and lipids) with C and N stable isotope analyses (SIA) to simultaneously study phytoplankton, zooplankton, and eight planktivorous fish species (Engraulis encrasicolus, Sardina pilchardus, Sardinella aurita, Sprattus sprattus, Cepola macrophthalma, Chromis chromis, Boops boops, and Spicara maena). This study is the first to analyze both stable isotope and biochemical compositions in coastal particulate organic matter (POM) size classes (0.7–2.7 μm, 2.7–20 μm, and 20–200 μm), zooplankton size classes (200–300 μm, 300–500 μm, 500–1000 μm, 1000–2000 μm, and >2000 μm), and taxonomic groups.We demonstrated that: (1) POM stable isotope compositions varied based on its spatial origin, the taxonomic composition of its biota, and its biochemical content; (2) δ15N values increased with zooplankton size classes and groups, indicating different trophic levels; (3) Phytoplankton exhibited a lipid-rich composition (∼55%), while zooplankton and fish muscles were protein-rich (∼61% and ∼66%, respectively).Bayesian stable isotope mixing models revealed that, on average: (1) POM from oceanic waters contributed the most to the POM in the bay (>51%), with a dominance of pico-POM (∼43%); (2) The 200–1000 μm zooplankton primarily consumed nano-POM, the 1000–2000 μm zooplankton mostly consumed micro-POM (∼64%), and the >2000 μm zooplankton also mostly consumed micro-POM; (3) Mesozooplankton (200–2000 μm) constituted the main portion (∼42%) of the diet for planktivorous fish species, while macrozooplankton organisms (>2000 μm) were the primary food resource (∼43%) for both B. boops and S. sprattus.Our study underscores the complexity of the pelagic food web and highlights the bottom-up transfer of organic matter from the smallest phytoplankton size fractions to planktivorous fish.

Effect of feed supplementation with seaweed wracks on performance, muscle lipid composition, antioxidant status, digestive enzyme activities, and plasma biochemistry of gilthead seabream (Sparus aurata) juveniles

Macroalgal wracks are frequently considered as waste products. However, macroalgae are a rich source of protein and bioactive compounds with antioxidant and antimicrobial activities whose inclusion in aquafeeds is receiving growing attention. The aim of this study was to assess the use of beach-cast macroalgae as dietary supplement for gilthead seabream (Sparus aurata) juveniles. Fish were fed for 93 days with an extruded commercial diet (CD); a CD supplemented with 7% of a dried-powder from a multispecific macroalgal wrack (30.9% Lobophora sp., 21.9% Dictyota sp., 19.6% Asparagopsis taxiformis, 17.5% Cymopolia sp., 1.8% Hypnea sp., 0.2% Laurencia sp., 0.1% Stypocaulon sp., and 8% not determined) (CD+MU7); a CD supplemented with a monospecific macroalgal wrack of 85% Lobophora sp. (CD+MOL7); and a CD supplemented with a monospecific macroalgal wrack of 85% Dictyota sp. (CD+MOD7). Macroalgae were extracted with n-hexanes, ethyl acetate and ethanol, and the antioxidant capacity of extracts was assessed, with ethyl acetate leading to the most active extracts (p < 0.05). The dietary inclusions of a 7% macroalgal wrack did not negatively affect S. aurata survival, growth, body indexes, proximate composition, oxidative status and plasma parameters. Contrarily, fish fed on CD+MU7 and CD+MOD7 showed the highest monoacylglycerols content, while both monospecific diets led to the highest total saturated fatty acids content in muscle (p < 0.05). The digestive enzymes profile was slightly modified (p < 0.05), but without compromising fish performance. Finally, muscle from fish fed on CD+MOL7 seemed to display a better capacity to modulate the glutathione metabolism (p < 0.05). In conclusion, a 7% of macroalgal wracks can be used as a dietary supplement for S. aurata juveniles, depicting an attractive alternative for the effective harnessing of this usually discarded biomass. Macroalgal inclusion may also reduce the use of fish-based ingredients for aquafeeds, diminishing the pressure on pelagic fisheries, and contributing to the blue bioeconomy strategy.