Fish Discards Research Articles

Partial Replacement of Fishmeal with Seafood Discards for Juvenile Penaeus japonicus: Effects on Growth, Flesh Quality, Chemical and Fatty Acid Composition

The present study was designed to assess the influence of fishmeal replacement with increasing percentages of fresh seafood discards (0, 25, 50 and 75%) in diets for Penaeus japonicus on growth performance, physical characteristics and the chemical and fatty acid composition of shrimp flesh. Each diet was administered for 108 days, and the trial was assayed in triplicate. The final body weight and the specific growth rate were significantly higher (p < 0.05) in shrimps fed with 75% fishmeal replacement as compared to 25%, while the abdomen weight and the total length were the highest (p < 0.01). Moreover, 75% replacement showed a significantly (p < 0.05) lower value of hardness and a greater crude protein and lipid content as compared to the 0% replacement. The shrimps fed with high levels of seafood discards (50 and 75%) showed a lower saturated fatty acid concentration and, in turn, a greater amount of polyunsaturated fatty acids in shrimp meat significantly (p < 0.05) affected the lower atherogenic and thrombogenic indices. In conclusion, replacing 75% of fishmeal with seafood discards provided satisfactory results. An economic analysis based on ESG indicators and PESTLE methodology is provided in order to show the socio-economic and governance impacts affecting the replacement of shrimps’ diet with fish discard.

The Revalorization of Fishery By-Products: Types, Bioactive Compounds, and Food Applications.

Recently, fish consumption has been increasing; subsequently, the number of by-products has also increased. However, generated residues are frequently discarded, and an appropriate management is necessary to properly use all fish by-products. Fishery by-products are well known for their content of bioactive compounds, such as unsaturated fatty acids, amino acids, minerals, peptides, enzymes, gelatin, collagen, and chitin. Several studies have reported that fishery by-products could provide significant properties, including antioxidant, antihypertensive, antimicrobial, anti-inflammatory, and antiobesity. Consequently, fish discards are of considerable interest to different industrial sectors, including food, nutraceuticals, medical, and pharmacology. In the food industry, the interest in using fishery by-products is focused on hydrolysates as food additives, collagen and gelatin as protein sources, chitin and chitosan to form edible films to protect food during storage, and oils as a source of Omega-3 and useful as antioxidants. Although different studies reported good results with the use of these by-products, identifying new applications in the food sector, as well as industrial applications, remains necessary.

Deepening in the understanding of the role of collagen subunits on the differential molecular arrangement of P. glauca and M. merluccius marine collagens

Decades of extensive efforts on marine collagen extraction and characterization allowed to recognize the unique and excellent characteristics of marine collagen offering advantages over that obtained from terrestrial sources. However, not all marine collagens have the same biochemical characteristics; understanding those at molecular and supramolecular level, is crucial for optimal design of applications. One relevant aspect of collagen characterization is the analysis of its different subunits (α-chains) and their intermolecular cross-links (β- and γ-components), which ultimately determine the specific functions of a particular collagen. Collagens from a teleost and an elasmobranch species were analyzed to understand the influence of their subunit composition and intermolecular crosslinking pattern on their different physicochemical behaviour. For comparative purposes a commercial mammal collagen was included in the study. Although electrophoretic profiles showed the typical composition of type I collagen for hake, blue shark and calf collagen, molar ratios of their α-chains were different indicating a different degree of dimerization of their α2-chains with implications in the presence of a different crosslinking degree pattern. Electrophoresis, amino acid composition, hydrophobicity (RP-HPLC) and molecular weight analysis (GPC-HPLC) results, besides a peptide mapping and an antioxidant activity study of the resultant peptides, would help to understand the role of different subunit collagen composition and different crosslinking pattern in the conformation of a differential quaternary supramolecular structure within different species and its biofunctional implications. The experiments developed would allow to progress in the valorization potential of fish discards and byproducts to explore commercial uses of collagens from marine origin.

Fish processing discards: A plausible resource for valorization to renewable fuels production, optimization, byproducts and challenges

Considering the petroleum and fuel prices in India for the past ten years, it can be concluded that there is a huge need for alternative sources of energy. The fuels that are currently used are obtained from fossil fuels, which is on the verge of depletion because of its continuous exploitation. In addition, these fossil fuels emit toxic elements, polluting the atmosphere and causes health ailments, affecting both land and living beings. Production of eco-friendly sources of energy has increasingly gained importance because of the problems involving fossil fuels (nonrenewable sources), such as cost, global warming, and energy crises. Every year, almost millions of tons of lipid-rich fish wastes are dumped by the domestic markets. A part of these wastes is used in the production of animal feed and fertilizers, whereas a majority is discarded in the environment, causing pollution. Recently, research has found out that fish discards are promising alternatives for the production of biogas and biodiesel. This review focusses on the potential benefits of using fish waste in the manufacture of biofuels, as well as the advantages over other methods. In addition, other key factors that play a major role, such as the quality of fish waste that is being dumped, biofuel preparation method, and its utilization, will also be reviewed. Thus, this present study is useful for those who work in industries that process fish, manage fishery waste, and produce biofuel, making it beneficial for them to utilize these high organic wastes in an efficient manner, thereby introducing an alternate renewable biodiesel feedstock.

Teaching fisheries bycatch: Exploring economic and behavioral drivers of bycatch through a classroom game

AbstractThis paper presents a pedagogical exercise to explore the economics of price-based fisheries bycatch. In the exercise students experience the economic incentives that lead to bycatch due to highgrading; the discarding of low-value fish. We first discuss existing fisheries economics pedagogical activities and how our exercise is distinct. We then identify over forty economics, environmental studies, geography, management, and philosophy courses where the exercise could be played. Next, we describe the game and share results and student feedback. Finally, we provide discussion prompts and extensions to illustrate how incentives and policies can change fishing behavior to lead to sustainable fisheries.

Seasonal study of the nutritional composition of unexploited and low commercial value fish species from the Portuguese coast.

Target species diversification is essential for fisheries sustainability and fish market revitalization. Fish discards are a widely recognized problem resulting from fisheries worldwide, and are of major concern for all sector players, from administrations, to fishermen, and scientists. However, non‐target species are seldom studied, and information on nutritional profiles and seasonal changes in nutritional properties is generally lacking. This study assessed the seasonal nutritional composition of two unexploited (Serranus cabrilla, Capros aper) and three low commercial value fish species (Trachurus picturatus, Spondyliosoma cantharus, and Trigla lyra), captured on the Portuguese coast over 1 year. Significant seasonal variations were observed in the nutritional composition of all the species studied. Moisture and ash contents varied from 70% to 81% and from 5% to 13%, respectively. The maximum fat contents were 5% for C. aper and 4% for T. picturatus, allowing to classify all studied fishes as lean. The highest protein contents were recorded for C. aper (25%) and S. cantharus (20%). The unexploited and low commercial value fish species studied were shown to be good fat and protein sources, comparable to commonly consumed species, such as cod and salmon, having a great potential to become commonly consumed fish in Portugal.

Improving the Lipid Profile of Black Soldier Fly (Hermetia illucens) Larvae for Marine Aquafeeds: Current State of Knowledge

The replacement of fish meal and fish oil by insect-based ingredients in the formulation of marine aquafeeds can be an important step towards sustainability. To pursue this goal, the modulation of the lipid profile of black soldier fly larvae (Hermetia illucens) has received great attention. While its nutritional profile can shift with diet, the ability to modulate its lipidome is yet to be understood. The present work provides an overview of the lipid modulation of H. illucens larvae through its diet, aiming to produce a more suitable ingredient for marine aquafeeds. Marine-based substrates significantly improve the lipid profile of H. illucens larvae, namely its omega-3 fatty acids profile. An improvement of approximately 40% can be achieved using fish discards. Substantial levels of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), two essential fatty acids for marine fish and shrimp species, were recorded in H. illucens larvae fed on fish discards and coffee silverskin with Schyzochytrium sp. Unfortunately, these improvements are still deeply connected to marine-based bioresources, some still being too costly for use at an industrial scale (e.g., microalgae). New approaches using solutions from the biotechnology toolbox will be decisive to make H. illucens larvae a feasible alternative ingredient for marine aquafeeds without having to rely on marine bioresources.

Pre-Treatment of Fish By-Products to Optimize Feeding of Tenebrio molitor L. Larvae.

Simple SummaryThe rapid population growth and the consequent increase in demand for protein-rich foods pose a challenge for the food industry. On the other hand, resources are limited and production must be sustainable. Currently, insects are accepted by the European Union as sustainable and nutritive food for humans, consequently allowing the use of seven insect species, including Tenebrio molitor (Linnaeus, 1758). From a nutritional point of view, T. molitor is rich in protein (42.2–67.7%) with a good ratio of essential amino acids. However, their lipidic fraction lacks n−3 long chain polyunsaturated fatty acids (LCPUFAs), while it is rich in n−6 polyunsaturated fatty acids. This poses a problem for human intake, since the beneficial effect of n−3 polyunsaturated fatty acids and a low n−6/n−3 ratio on the prevention of cardiovascular inflammation and heart disease is well known. The present study is focused on the improvement of the fatty acid profile and proximal composition of T. molitor larvae through fish discard-based diets subjected to different pre-treatments to increase the fish-based diet intake.Fish discards are organic waste with high and good-quality protein levels, as well as a fatty acid profile rich in n−3 LCPUFAs, mainly eicosapentaenoic acid and docosahexaenoic acid. These discards can be used as food for Tenebrio molitor (Linnaeus, 1758) larvae, thus increasing the nutritional value of this insect. This study focused on increasing larval acceptance of fish through different pre-treatments of the diets provided, as well as increasing the accumulation of EPA and DHA in fish-fed larvae. Four different diets were prepared: control (broiler feed), DGF50: 50% dried ground fish (Pagellus bogaraveo, Brünnich, 1768) + 50% broiler feed, for different periods, FGF100: 100% fresh ground P. bogaraveo and DUF100: 100% dried whole unground P. bogaraveo. Growth, mortality, proximate composition, fatty acid profile and lipid nutritional indices were determined. Larvae fed with FGF100 displayed better results among treatments, doubling the initial weight, as well as increasing their protein level and decreasing fat levels. Regarding fatty acids, eicosapentaenoic acid and docosahexaenoic acid were only detected in larvae fed with a fish-based diet for a period longer than 5 days. These results show that pre-treatment of fish-based diets causes changes in the growth and compositional parameters of T. molitor larvae.

A Review on Biphasic Calcium Phosphate Materials Derived from Fish Discards.

This review summarizes the results reported on the production of biphasic calcium phosphate (BCP) materials derived from fish wastes (i.e., heads, bones, skins, and viscera), known as fish discards, and offers an in-depth discussion on their promising potential for various applications in many fields, especially the biomedical one. Thus, considerable scientific and technological efforts were recently focused on the capability of these sustainable materials to be transformed into economically attractive and highly valuable by-products. As a consequence of using these wastes, plenty of beneficial social effects, with both economic and environmental impact, will arise. In the biomedical field, there is a strong and continuous interest for the development of innovative solutions for healthcare improvement using alternative materials of biogenic origin. Thus, the orthopedic field has witnessed a significant development due to an increased demand for a large variety of implants, grafts, and/or scaffolds. This is mainly due to the increase of life expectancy and higher frequency of bone-associated injuries and diseases. As a consequence, the domain of bone-tissue engineering has expanded to be able to address a plethora of bone-related traumas and to deliver a viable and efficient substitute to allografts or autografts by combining bioactive materials and cells for bone-tissue ingrowth. Among biomaterials, calcium phosphate (CaP)-based bio-ceramics are widely used in medicine, in particular in orthopedics and dentistry, due to their excellent bioactive, osteoconductive, and osteointegrative characteristics. Recently, BCP materials (synthetic or natural), a class of CaP, which consist of a mixture of two phases, hydroxyapatite (HA) and beta tricalcium phosphate (β-TCP), in different concentrations, gained increased attention due to their superior overall performances as compared to single-phase formulations. Moreover, the exploitation of BCP materials from by-products of fish industry was reported to be a safe, cheap, and simple procedure. In the dedicated literature, there are many reviews on synthetic HA, β-TCP, or BCP materials, but to the best of our knowledge, this is the first collection of results on the effects of processing conditions on the morphological, compositional, structural, mechanical, and biological properties of the fish discard-derived BCPs along with the tailoring of their features for various applications.

Valorization of toxic discarded fish skin for biomedical application

Fish discards are dumped into the sea and sea shore during fishing and segregation by fishing sectors. Fish of no or low economic value, or damaged and of a reduced value are thrown away. The discards adversely affect the marine habitats and huge number of proteins, essential fatty acids, collagen, enzymes are lost. The retrieval of the value-added components from these discards will be a better approach for waste utilization and for a cleaner ecosystem. The purpose of this study is to maximize the output and minimize the waste. As pollution generation is related to an inefficiency of resource use, the present study describes the state-of-the-art to make use of a discarded fish, Trachicephalus uranoscopus, for extracting collagen. High yield of 58.3% collagen was obtained through pepsin extraction and sodium dodecyl sulfate polyacrylamide gel electrophoresis revealed that the isolated collagen was type I. The collagen was crosslinked with chemical crosslinkers and formed as a scaffold. The scaffold exhibited a maximum crosslinking efficiency of 60.92% and was stable for about 72 h with 50% enzymatic degradation rate. The whole blood clotting experiment and RBC attachment indicated hemocompatibility of the scaffolds. In vitro cytotoxic study in 3T3 fibroblast cells exhibited cell viability of 100% showing biocompatibility of the prepared scaffolds. From the results it can be concluded that the extracted collagen could be used for biomedical applications as an alternate for bovine collagen. The value-added product from the discarded fish skin has a positive impact on the marine ecosystem, human health, and the development of fishing industries.

Characterization of Protein Hydrolysates from Fish Discards and By-Products from the North-West Spain Fishing Fleet as Potential Sources of Bioactive Peptides.

Fish discards and by-products can be transformed into high value-added products such as fish protein hydrolysates (FPH) containing bioactive peptides. Protein hydrolysates were prepared from different parts (whole fish, skin and head) of several discarded species of the North-West Spain fishing fleet using Alcalase. All hydrolysates had moisture and ash contents lower than 10% and 15%, respectively. The fat content of FPH varied between 1.5% and 9.4% and had high protein content (69.8–76.6%). The amino acids profiles of FPH are quite similar and the most abundant amino acids were glutamic and aspartic acids. All FPH exhibited antioxidant activity and those obtained from Atlantic horse mackerel heads presented the highest 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity, reducing power and Cu2+ chelating activity. On the other hand, hydrolysates from gurnard heads showed the highest ABTS radical scavenging activity and Fe2+ chelating activity. In what concerns the α-amylase inhibitory activity, the IC50 values recorded for FPH ranged between 5.70 and 84.37 mg/mL for blue whiting heads and whole Atlantic horse mackerel, respectively. α-Glucosidase inhibitory activity of FPH was relatively low but all FPH had high Angiotensin Converting Enzyme (ACE) inhibitory activity. Considering the biological activities, these FPH are potential natural additives for functional foods or nutraceuticals.

Amino Acid δ15N Can Detect Diet Effects on Pollution Risks for Yellow-Legged Gulls Overlooked by Trophic Position

The use of top-consumers as bioindicators of the health of food webs is hampered by uncertainties in their effective use of resources. In this study, the abundance of stable nitrogen isotopes in amino acids from homogenised eggs of the Yellow-legged Gull (Larus michahellis) allowed to identify variations in trophic resource exploitation between geographically adjacent nesting colonies in the Ria de Vigo (NW Spain) that exhibited marked differences in pollutants. Eggs from nests in the Cíes Islands (located in a National Park) showed a large variability in stable carbon and nitrogen isotopes in bulk egg content encompassing that of eggs from Vigo city (a major fishing harbour). However, both colonies differed in the relative concentration and abundance of nitrogen isotopes of lysine, an essential amino acid present in marine prey, but also extensively used in feed stocks for poultry and swine. Notwithstanding the similarity in trophic position for both colonies, gulls from Cíes Islands may have acquired a substantial fraction of lysine from garbage dump sites, while those of the urban colony relied on fish discards. This unexpected conclusion is partly supported by the large variability reported for gull’s diet in this region and calls for detailed estimations of diet when assessing the conservation status and pollution risks of marine ecosystems.

Biogenic Calcium Phosphate from Fish Discards and By-Products

Every year, millions of tons of fish waste are generated from fishing activities, and a similar amount is discarded and returned to the sea as unwanted catches. This material can be used as a biological source for many potential new added-value products, such asobtaining hyaluronic acid from fish eyeballs or extracting collagen from fish skin, but there are not many utilities for fish bones yet. This work tackles the transformation of fish discards into calcium phosphates. Discards from scorpionfish (Scorpaena scrofa) and Atlantic horse mackerel (Trachurus trachurus), as well as by-products generated from aquaculture activities (heads and trimmings frames) of salmon (Salmon salar), were used to obtain calcium phosphate. Biphasic carbonated hydroxyapatite (HA) /beta-tricalcium phosphate (TCP) material was obtained. The biphasic HA-TCP material has a promising range of applications in the biomedical field based on its similarity to calcium phosphates found in human bones in terms of crystallite size and carbonate content. The presence of Na, Mg, Sr, and K ions in the HA-TCP material is very beneficial, since they contribute to bone metabolism and cell adhesion.

First molecular detection of the parasites Molicola uncinatus and Hepatoxylon trichiuri (Cestoda: Trypanorhyncha) infecting the silver scabbardfish Lepidopus caudatus from the Central Mediterranean Sea: Implications for the seafood quality and safety

Trypanorhynch tapeworms are marine heteroxenous parasites, involving sharks and rays as definitive hosts, invertebrates (i.e. crustaceans) as first intermediate hosts, and various teleost fishes as intermediate/paratenic ones. The massive presence of Trypanorhyncha larval forms in the flesh or body cavity of the fish hosts reduces their market value, making them unappealing to consumers, or causing discards of fish products.The identification of merocercoids (N = 100) of Molicola uncinatus and plerocercoids (N = 46) of Hepatoxylon trichiuri parasitizing the silver scabbardfish, Lepidopus caudatus, from the Central Mediterranean Sea (off Malta coast), was obtained, for the first time, by using sequences analysis of the complete small subunit (ssrDNA) and the partial large subunit (lsrDNA) ribosomal RNA gene loci. The Bayesian Inference from the concatenated sequences obtained at the two gene loci showed that the individuals of M. uncinatus and H. trichiuri clustered, respectively, in two well distinct and supported phylogenetic lineages, corresponding to the two cestode species. High prevalence (P) and mean abundance (MA) values were observed in the infection with merocercoids of M. uncinatus (P = 100%, A = 28.81), with the ventral musculature of the silver scabbardfish as the most parasitized site. Plerocercoids of H. trichiuri were found to infect only the mesenteries, attached to various fish tissues, with a mean abundance rate of 1.28.Even if harmless to humans, a heavy parasitic load with larval stages of Trypanorhyncha, particularly in the edible part of the silver scabbardfish (as here reported for merocercoids of M. uncinatus), can compromise the appearance of the fish-food, making it repugnant and unappealing for the final consumer. It has been also discussed that when managing the risk related to parasites affecting the fish quality and safety of fisheries products, the fishing ground where the life cycle of those parasites takes place should be also taken into account, as it would include the ecological drivers of the infection with those parasites. This wider ecological approach would be of help to the Food Business Operators (FBOs), gathering knowledge useful to manage fisheries in a wide “One-Health” perspective, aware of sustainability, quality and consumer safety aspects of sea-food production.

Production and identification of dipeptidyl peptidase IV (DPP-IV) inhibitory peptides from discarded Sardine pilchardus protein

Production of bioactive peptides via enzymatic hydrolysis is a sustainable way to take advantage of proteinaceous by-products from food industry, such as fish discards. Sardine pilchardus protein was subjected to different enzymatic treatments using two endopeptidases of different selectivity and one exopeptidase in order to produce hydrolysates with antidiabetic activity. The highest dipeptidyl peptidase IV inhibitory activity was obtained by the combination of three enzymes (subtilisin, trypsin and flavourzyme) employed sequentially. This hydrolysate was subsequently purified by size exclusion chromatography to obtain fractions sorted by size (hydrodynamic volume). Peptides below 1400 Dalton had the highest activity, and these pools were analysed by mass spectrometry in order to identify the peptides responsible for that activity. Numerous peptides with adequate molecular features, it is, owning an alanine (A) as their penultimate N-terminal residue (e.g. NAPNPR, YACSVR) were identified and are proposed to be antidiabetic peptides from Sardine pilchardus muscle.

Survival of undersized plaice (Pleuronectes platessa) discarded in the bottom otter trawl and Danish seine mixed fisheries in Skagerrak

The landing obligation of the new Common Fisheries Policy includes a “high survival”-exemption, which allows to continue discarding of fish with scientifically proven high chances to survive the process of capture, handling and release. This study presents survival rates of undersized plaice (Pleuronectes platessa) caught by two commercial fishing vessels targeting plaice in Skagerrak during the summer, a bottom otter trawler and a Danish anchor seiner. Instead of being discarded, the fish were assessed and monitored in on-land observation tanks for 14 days. For each gear, a Weibull mixture model was fitted to the data to estimate survival probabilities, including the uncertainties from the haul selection and conditions of the captivity experiment, and to determine which biological, environmental and operational factors influence survival. Generally, fish caught by the trawler showed lower survival (44%, 95%-confidence interval: 37–52%) than those caught by the seiner (78%, 95%-confidence interval: 67–87%). Air exposure was found to be the most important factor in determining survivability of fish discarded from the trawler. For the seiner, bottom temperature was identified as an additional important determinant.

Evaluating the effect of distance to different food subsidies on the trophic ecology of an opportunistic seabird species

AbstractThe availability of food subsidies of anthropogenic origin has strong consequences on the trophic ecology and population dynamics of several opportunistic species. However, evidence suggests that the use of certain feeding sources is very local, and hence, potentially important food subsidies may have a relatively small area of influence, resulting in only limited impact from the large geographic‐scale perspective. In the south‐eastern part of the Bay of Biscay, the Yellow‐legged Gull Larus michahellis population is distributed across several colonies, which are located close to each other but have variable dependence on the landfills and fishing harbours in the area. This population is therefore a good model to test the influence of anthropogenic food subsidies on the trophic ecology of an opportunistic species at the local scale. Distance to the nearest fishing harbour showed a stronger effect on the diet of Yellow‐legged Gull chicks than distance to the nearest landfill site. Gulls notably reduced their consumption of marine prey (mostly comprised of fishing discards) in relation to decreasing distance of their colony to the nearest fishing harbour. This result has direct implications from a management standpoint, since fish discards were also found to have only a limited effect on diet at regional scales, but a very high impact at the local scale. Moreover, those colonies that consumed a higher proportion of marine prey showed better population trends. In line with European Union policies, a reduction in the availability of fish discards, together with the closure of landfill sites, will occur in the coming years, probably leading to a change in the trophic ecology and dynamics of Yellow‐legged Gull populations.

Optimising mesh size with escape gaps in a dual-species portunid-trap fishery

In south-eastern Australia, the same baited, round traps (comprising 50–57-mm mesh netting) are used to target giant mud, Scylla serrata and blue swimmer crabs, Portunus armatus in spatially separated fisheries. Both fisheries are characterised by the common, problematic discarding of undersized portunids (<85 and 65 mm carapace length; CL for S. serrata and P. armatus) and fish (yellowfin bream, Acanthopagrus australis). This poor selectivity was addressed here in two experiments assessing the utility of (1) traps partially or completely covered in larger mesh (91 mm to match the minimum legal size of the smaller P. armatus), and then (2) any cumulative benefits of fitting species-specific escape gaps. In experiment 1, there were no differences among catches of legal-sized portunids associated with either partial, or complete trap coverage with larger mesh. Irrespective of mesh coverage, both designs of 91-mm traps also retained significantly fewer (by up to 42%) undersized P. armatus and A. australis. In experiment 2, replicate traps completely covered in 91-mm mesh were tested against conventional traps comprising 56-mm mesh, and traps with the same mesh sizes, but also three escape gaps configured for either S. serrata (46 × 120 mm) or P. armatus (36 × 120 mm) (i.e. four treatments in total). All modified traps maintained catches of legal-sized S. serrata, and only the 91-mm traps with escape gaps caught fewer legal-sized P. armatus. Fewer undersized S. serrata, P. armatus and A. australis (mean catches reduced by up to 49%) were retained in all larger-meshed than small-meshed traps, and in all of those traps with escape gaps (by up to 95%) than without. While there were no significant cumulative benefits of escape gaps in larger-meshed traps (measured by a statistical interaction), there was a trend of fewer unwanted catches overall. These data support configuring portunid traps with mesh sizes matching the morphology of the smallest legal-sized target species. But, simply retroactively fitting escape gaps in existing, smaller-meshed traps will also realize positive selectivity benefits.

Reducing discards of demersal species using a 100 mm square mesh cylinder: Size selectivity and catch comparison analysis

We assessed the impact of an additional 100 mm square mesh cylinder (SMC) on the selective property of the demersal whitefish trawl in the Celtic Sea. Sea trials were conducted on board a French trawler using twin trawl rigging. We tested the effects of the position of the SMC (in front of and behind the mandatory 100 mm square mesh panel) and of the insertion of a dispersive float. Selectivity analysis revealed the 50% retention length (L50) to be greater than the Minimum Conservation Reference Sizes regardless of species (haddock, whiting or megrim) or rigging configuration. Results did not reveal a clear effect of the SMC position. However, the insertion of the float led to a decrease in selection ranges suggesting enhanced contact probabilities with the square meshes. With the largest L50 values, the SMC placed in the front position (and without the float) proved to be the most selective rigging configuration and was then tested under commercial conditions. Catch comparisons revealed that the test gear retained less fish across all size classes than the commercial gear. For haddock, the test gear retained less fish below 50 cm in length. Catch comparisons also indicated significant discards of fish above the MCRS, i.e. “high-grading” practices. Under the requirements of the landing obligation (LO), unwanted catches must be stored on-board and landed regardless of economic value. The SMC is thus a valuable tool to mitigate the impact of the LO on the demersal whitefish fishing fleets operating in the Celtic Sea.

Aquaculture and by-products: Challenges and opportunities in the use of alternative protein sources and bioactive compounds.

There is a growing concern about chronic diseases such as obesity, diabetes, hypertension, hypercholesterolemia, cancer and cardiovascular diseases resulting from profound changes in the western lifestyle. Aquaculture by-products are generated in large quantities and they can be profitably recycled through their bioactive compounds used for health or food supplements. Improving waste utilization in the field of aquaculture is essential for a sustainable industry to prevent or minimize the environmental impact. In this sense fish by-products are a great source of protein and omega-3 polyunsaturated fatty acids which are particularly studied on Atlantic salmon or rainbow trout. Fish protein hydrolysate (FPH) obtained from chemical, enzymatical and microbial hydrolysis of processing by-products are being used as a source of amino acids and peptides with high digestibility, fast absorption and important biological activities. Omega-3 polyunsaturated fatty acids, eicosapentaenoic (EPA) and docosahexaenoic (DHA) from fish discards have been reported to decrease postprandial triacylglycerol levels, reduction of blood pressure, platelet aggregation and the inflammatory response. Crustacean by-products can also be used to produce chitosan with antioxidant and antimicrobial activity for food and pharmaceutical industries and carotenoids with important biological activity. Seaweeds are rich in bioactive compounds such as alginate, carrageenan, agar, carotenoids and polyphenols with different biological activities such as antioxidant, anticancer, antidiabetic, antimicrobial or anti-inflammatory activity. Finally, regarding harvest microalgae, during the past decades, they were mainly used in the healthy food market, with >75% of the annual microalgal biomass production, used for the manufacture of powders, tablets, capsules or pills. We will report and discuss the present and future role of aquaculture by-products as sources of biomolecules for the design and development of functional foods/beverages. This chapter will focus on the main bioactive compounds from aquaculture by-products as functional compounds in food and their applications in biomedicine for the prevention and treatment of diseases.