Low Commercial Value Research Articles

The Flash Vacuum Expansion Process Increases the Bioaccessibility and Stability of Antioxidant Compounds in Papaya Puree During Digestion

Among all fruits, the papaya ranks among the most significant, occupying fourth place in terms of marketing volumes. The papaya encounters various deterioration issues throughout the marketing chain, which results in the loss of bioactive phytochemicals in the fruit’s pulp. Making puree is the best way to make papaya pulp last longer, but processing can break down antioxidants like phenolic compounds (which are mostly stored in cell vacuoles) and carotenoids (which are stored in chromoplasts). The flash vacuum expansion process (FVE) promotes an expansion of the water present in the vacuoles, which generates cell rupture and consequently, the release of intracellular components. Because cell rupture is promoted from within the cell, the expulsion of bioactive compounds is more efficient and can therefore increase their bioaccessibility. Our results show that the FVE process increased the antioxidant capacity of the purees (measured by TEAC, FRAP, and DPPH assays) before and during digestion. Our results show that the FVE process significantly enhances the bioaccessibility and stability of antioxidant compounds, providing a clear advantage over the conventional method. Fruit purees generated by FVE can be an ingredient that increases the functionality of foods (juices, nectars, purees, ice creams, and yogurt) aimed at people with digestive problems, baby food, or the use of fruits with low commercial value.

Appearance, Tastiness, and Healthiness Perception of University Students Towards Sustainable Cereal Snack Bar Enriched With Pumpkin

Pumpkin (Cucurbita maxima) is an endogenous product of low commercial value. Cereal bars are used as a snack, mainly in intermediate meals. The development of new food products with low commercial value contributes to endogenous products’ valorisation and sustainability. This study aimed to develop a cereal bar using pumpkin and pumpkin seed flour and analyse appearance, tastiness, and healthiness perception related to it by university students from different areas. The nutrition students’ group was constituted of 33 students and the hospitality group was constituted of 26 students, both rated the bar in terms of appearance, tastiness and healthiness perception using a Likert scale from 1 (lower value) to 5 (higher value). Based on the global appearance was notorious the higher value rate of the nutrition students (32.2%) compared to the hospitality students (3.4%). The developed cereal-pumpkin bar seems to be an interesting alternative to other snack bars available on the market.

Biological Aspects of Sphyraena sphyraena (L., 1758) in the Central Mediterranean (E. Ionian Sea)

S. sphyraena is a widely distributed species with low commercial value and no sufficient scientific knowledge of its biology. In the present study, the age, growth, weight–length relationship, otolith morphometry, and reproduction of the species were investigated in the Eastern Ionian Sea for the first time. The von Bertalanffy growth function parameters were L∞ = 63.65 cm, k = 0.14 year−1 and t0 = −2.01 years and Φ′ = 2.75. The negative allometric growth in weight was found. Slope b of the weight–length relationship was 2.634. For the otolith moprhometry, the variables radius, length, width, area, perimeter, roundness, circularity, form factor, rectangularity, and ellipticity were examined, which showed that the otolith shape is elongated with an elliptical and rectangular form. Six otolith variables (radius, length, width, area, perimeter, and ellipticity) showed a significant relationship with size. The sex ratio (females/males) was 1:0.74 (no statistically significant difference from 1:1), and the spawning season extended from April to June with peak values of GSI in May for females and April for males. The results of this work improve our knowledge of the species life cycle and provide basic information for species stock identification and fisheries management.

Predicting Chemical Body Composition Using Body Part Composition in Boer × Saanen Goats

Two experiments were conducted to determine which part of the empty body of Boer × Saanen intact male kids can be used to predict the chemical composition of the whole body. In the first experiment, kids were fed ad libitum and slaughtered at 5, 10, and 15 kg body weight (BW). Eighteen animals were group-fed at three intake levels (ad libitum or restricted to 30% and 60% of the ad libitum level). When the ad libitum animal in the group reached 15 kg BW, all animals in the group were slaughtered. In the second experiment, kids were fed ad libitum and slaughtered at 15, 20, and 25 kg BW. Twenty-one animals were group-fed at three intake levels and slaughtered when the ad libitum animal within the group reached 25 kg BW. Analyzed body parts included head + feet, hide, organs, neck, shoulder, ribs, loin, leg, 9–11th ribs, and half carcass. Principal component and cluster analyses showed that the neck, 9–11th ribs, and loin had the highest frequency of grouping with the empty body. These body parts were used to develop prediction models for estimating body composition. The neck, loin, and 9–11th ribs accurately and precisely predicted the dry matter, ash, fat, protein, and energy body composition of goats, with most models also incorporating BW as a predictor variable. The equations showed root mean squared error (RMSE) lower than 13.5% and a concordance correlation coefficient (CCC) greater than 0.84. Fat and protein concentrations in the loin and neck were also reliable predictors of empty body energy composition (RMSE = 2.9% of mean and concordance correlation coefficient = 0.93). Removing the loin and 9–11th ribs could reduce the carcass retail price. Using the neck to estimate body composition in growing Boer × Saanen goats provides a valuable alternative for nutrition studies, given its low commercial value.

Microbiological and Chemical Characteristics of Yoghurt Incorporated with Watermelon Rind Powder

Watermelon rind accounts for approximately one-third of the overall fruit mass. It is usually discarded due to its low commercial value. However, it is reported to contain valuable nutrients and is an effective source of pectin that can act as a potential prebiotic. This study aimed to study the effects of watermelon rind powder (WRP) on the growth of probiotic bacteria in yoghurt and its chemical characteristics. Watermelon rind was dried by using a dehydrator and ground into powder form before being incorporated into fresh yoghurt at 2% and 4% w/v. A sample with 0% w/v WRP was prepared as control. The effect of WRP on the growth of probiotic bacteria was determined by MRS plate count. Chemical analyses including titratable acidity, pH and Brix were conducted during the fermentation process. The results showed that the increase in WRP percentage resulted in a significant increase in bacterial growth with 7.20 ± 0.22 log CFU/mL for the control sample as compared to 8.42 ± 0.23 log CFU/mL for sample with 4% WRP after 30 hr of incubation. The fermentation time was also improved with the presence of WRP with a 0.22 h-1 increase in growth rate observed for the sample with 4% WRP as compared to the control sample. Furthermore, samples containing 4% WRP showed the highest increment in titratable acidity (12.47) and the highest percentage in Brix value reduction (51.04%) during the fermentation period as compared to the control sample. Biochemical analysis showed negative values for oxidase and catalase test while positive values were obtained for gram-staining indicating the presence of Lactic acid bacteria from the gram-positive group. This study demonstrates the high potential of WRP in promoting bacterial growth for yoghurt production which is beneficial to the food industry other than promoting the ongoing effort of food waste reduction.

Classification of Open and Closed Pistachio Shells Using Machine Vision Approach

Pistachio nuts are a type of nut that is widely consumed around the world due to their high nutritional value and pleasant taste. Pistachios are usually sold in their shells, either open or closed. However, closed-shell pistachios are not well received by consumers, resulting in a lower commercial value. It is essential to be able to distinguish between open and closed pistachio shells in order to ensure quality control during production processes and processing. This can be done manually or by using mechanical devices. Manual inspection and categorization of pistachio nuts have traditionally been done by workers, but this process is inefficient in terms of time and money. Mechanical separation of open and closed-shell pistachio can damage the kernels of open-shell nuts due to the needle mechanism used in the sorting process. This study aims to classify pistachio nuts using a machine vision-based system and evaluate its applicability in terms of classification accuracy. The system is evaluated on the Antep pistachio species, which can be distinguished from other pistachio varieties, such as Siirt and Urfa pistachios, based on their shape, size, and taste properties. The machine vision system in this study classifies pistachio nuts into closed and open shell classes in a completely automated manner. In this study, 1,000 Antep pistachio nuts images were obtained and examined, including 500 open and 500 closed nuts. The images were pre-processed and prepared for feature extraction. From the images, a total of 14 color features were extracted. Although the single feature was used, promising classification accuracy rates of 95.6%, 94.8%, and 93.6% from the Random Forest, Support Vector Machine (SVM), and Logistic Regression were achieved, respectively. The performances of classifiers were compared to each other. Almost similar performances were detected. These results demonstrate that the Random Forest classifier is the most effective algorithm for classifying open and closed Antep pistachio nuts.

Fish of Low Commercial Value in Lakes of Different Trophic Status (Poland)

In a commercial fishery, some fish are classified as low-value, but their classification varies in different countries. The aim of this study was to determine the abundance, contribution, and dominance of low-value fish species, such as Abramis brama < 1000 g, Alburnus alburnus, Blicca bjoerkna, Gymnocephalus cernua, Perca fluviatilis < 100 g, Rutilus rutilus < 200 g, and Scardinius erythrophthalmus < 200 g, in 145 Polish lakes of different areas, depths, and trophic statuses situated in the northern and central parts of Poland in 2021. Perca fluviatilis and R. rutilus were the most frequent low-value species (100% and 99%, respectively). The contribution of all low-value fish to the total biomass of caught fish was relatively high, ranging from 37% in the mesotrophic lake to 100% in the eutrophic lake (mean of 77 ± 14%). Lakes in which the contribution of low-value species exceeded 90% were relatively numerous (24 lakes, 17% of the studied lakes). Among a total of about 437.5 thousand low-value fish, 261 thousand specimens (60%) had a body weight of below 10 g. All low-value fish species, except for P. fluviatilis and S. erythrophthalmus, were related to the studied environmental variables. The relative biomass of these species increased with increasing lake productivity, while it decreased with the increasing maximum and mean depth of the studied lakes. The high contribution of low-value fish to the total biomass in many lakes indicates the need for the constant monitoring of the abundance and structure of fish communities and the use of appropriate actions (biomanipulation and stocking with piscivorous fish species) to improve the ecological condition of lakes.

Population parameters of golden ponyfish, Photopectoralis aureus and goldstripe ponyfish, Karalla daura from Saint Martin Island, Bay of Bengal

Golden ponyfish Photopectoralis aureus and Goldstripe ponyfish Karalla daura are small fish with less economic value. Many marine fish population parameters were not investigated because of their low commercial value. Therefore, the primary goals of this study were to determine the size frequency, length-weight relationship (LWR), length-length relationship (LLR), and Fulton’s condition factor (Kn) of two tropical ponyfishes from Saint Martin’s Island. From March to April 2022, specimens were caught using fixed purse nets. A total of 409 specimens of P. aureus and K. daura were measured to determine size frequency, LWRs, LLRs, and Fulton's condition factor. For P. aureus, the maximum total length (TL) of 12.9 cm sets a new record. The LWRs for P. aureus and K. daura were highly significant (p<0.001), where the coefficient of determination (r2) was 0.985 and 0.869 for P. aureus and K. daura, respectively. The estimated slope (b) for P. aureus and K. daura were 3.147 and 2.986, respectively. The LLR equations were TL = 1.1089 SL + 0.2689 for P. aureus and TL = 0.6792 SL + 3.3309 for K. daura. The Kn value had no significant difference between the species of different length classes for P. aureus (0.97-1.40) and K. daura (1.19-1.26). There has never been any prior reporting of LWRs or length-length relationships (LLRs) for P. aureus in literature or FishBase. The study's findings may benefit the management and conservation of these ponyfishes. Res. Agric. Livest. Fish. Vol. 11, No. 1, April 2024: 105-114

Moringa oleifera Seed Cake: A Review on the Current Status of Green Nanoparticle Synthesis

Growing demands for sustainable and ecological nanoparticle synthesis methods have incentivized the scientific community to develop new approaches to counteract these challenges. Green synthesis resorts to biocomponents obtained from plants, bacteria, fungi, and other organisms to synthesize nanostructures, with beneficial gains in the economic and ecological cost associated with the process, simplicity of the process, and resource efficiency. Moringa oleifera, a native plant originally from India with immense nutritive value, has long been used by researchers in the biosynthesis of nanoparticles. Leaves, flowers, bark, and seeds are among the “miracle tree” parts that can be used in nanoparticle green synthesis. Moringa oleifera seed cake, a by-product obtained from defatted seeds, is often overlooked due to its apparent low commercial value. The main objective of this review is to highlight the recent findings reported in the literature on nanoparticles/nanocomposites synthesized with seed cake biocompounds acting as reducing/capping agents. Furthermore, we analyzed the methods currently employed for the extraction of bioactive compounds. Moringa oleifera seed for industrial applications was also addressed.

Age, Growth, and Otolith Morphometrics of Trachinus draco (L., 1758) and Trachinus radiatus (Cuvier, 1829) in the Eastern Mediterranean

Trachinus draco and Trachinus radiatus are two bycatch species of low commercial value and no sufficient knowledge on their biological features. In the present study, the weight–length relationship, age, growth, and ten otolith morphometric variables of these species were investigated in the southwestern Aegean Sea for the first time. Positive allometric and isometric growth in the weight were defined in T. draco and T. radiatus. The weight–length relationship was described by the parameters α = 0.002415 and b = 3.35745 in T. draco and α = 0.007582 and b = 3.09452 in T. radiatus. The von Bertalanffy growth function parameters were L∞ = 44.51 cm, k = 0.15 year−1, and t0 = −1.31 years for T. draco and L∞ = 58.47 cm, k = 0.16 year−1, and t0 = −0.78 years for T. radiatus. Ten otolith variables (radius, length, width, area, perimeter, roundness, circularity, form factor, rectangularity, and ellipticity) showed a significant relationship with size for both species, except the ellipticity in T. radiatus. The mean values of all the otolith variables were higher in T. radiatus than in T. draco. The otolith of T. radiatus was found to become more rectangular with size as compared to the otolith of T. radiatus. The results of this work can support further research on the behavioral and ecological features of the two species.

Proposal for preparing pasta based on petiole and turnip leaves

Brazilian food production is one of the largest in the world, with fruit and vegetables being the highlight. Despite this position, it is also a country of contrasts, since a considerable part of this production does not fulfill its food function, due to post-harvest losses, which reach rates of up to 40%. Thus, the transformation of discards or vegetables of low commercial value into flour or the creation of new foods has proven efficient in recent years, so this study aimed to develop vegetable-based flours of low commercial value to be inserted into pasta. A fresh pasta was prepared with the incorporation of the “non-noble” part of the turnip and its physical-chemical characteristics were evaluated: moisture content, dry matter, lipids, crude protein, total fiber, ash, total carbohydrates by difference, total titratable acidity and hydrogen potential (pH). When carrying out the process of producing fresh pasta with the leaves and stems of the nado, it proved to be simple, as it used low-cost techniques, being a process easily accessible to the population, demonstrating a new way of consuming such waste in a more nutritionally qualitative way.

Detection of Adulterated Oregano Samples Using Untargeted Headspace-Gas Chromatography-Ion Mobility Spectrometry Analysis.

Oregano is often adulterated for economic reasons. This fraud mainly consists of adding other species with lower commercial value, such as olive leaves. To ensure the authenticity of oregano, an analytical method based on the analysis of the volatile organic compound (VOC) profile obtained by headspace gas chromatography coupled to ion mobility spectrometry (HS-GC-IMS) was developed and validated. Samples of ecological Mediterranean oregano adulterated with different percentages of two types of olive leaves (cornicabra and manzanilla) were studied using a non-targeted analysis. Moreover, a total of 30 VOCs were identified in the analyzed samples, and 24 compounds could be quantified using calibration curves based on Boltzmann's equation. A chemometric model based on orthogonal partial least squares discriminant analysis (OPLS-DA) was used to detect the adulterated oregano samples, obtaining a 100% validation success rate, and partial least squares (PLS) analysis was used to quantify the percentage of adulterant. Finally, the proposed methodology was applied to 15 commercial oregano samples, resulting in two of them being classified as adulterated with 31 and 43% of olive leaves, respectively.

Efficient recovery and regeneration of FePO4 from lithium extraction slag: Towards sustainable LiFePO4 battery recycling

The recovery and regeneration of FePO4 from lithium extraction slag (LES) are crucial steps in the closed-loop recycling of waste LiFePO4 batteries. This necessity arises despite the low commercial value of LES, as conventional recovery methods are cost-prohibitive, leading to insufficient attention to LES recovery. The recent surge in retired batteries has resulted in a significant accumulation of LES, posing serious environmental concerns, however, the high content of Fe and P resources in LES presents a potential value. The study begins with a theoretical analysis, concluding that the reduction leaching of LES is a feasible approach. By integrating this with the Fe powder synthesis route for FePO4, it is found that efficient leaching of LES can be achieved using a low concentration of H2SO4, thereby significantly reducing the recovery cost. This method not only efficiently utilize LES but also alleviates environmental pressure. The thermodynamic analysis sheds light on the mechanism of LES leaching and FePO4 synthesis, confirming the feasibility of each reaction. Optimal leaching conditions (1.4 times the stoichiometric amount of H2SO4, 1.5 times the amount of Fe powder, an L/S ratio of 5 mL/g, and a reaction duration of 150 min at 60 °C), under which the leaching rates of Fe and P reached 94.66% and 98.23%, respectively. Additionally, the study introduces a method to remove the main impurity Al in LES, achieving a removal rate of over 99%, reducing its concentration to below 100 ppm. Other impurities, such as Ti, Mn, and Zn, also meet the Chinese Chemical Industry Standard (HG/T 4701-2021). Comparative analyses were conducted between regenerated R-FePO4, commercial C–FePO4, and untreated LES (r-FePO4). LiFePO4 materials derived from these sources were synthesized, followed by an evaluation of their electrochemical performance. The regenerated R-FePO4 matched the quality of commercial FePO4 and significantly outperformed r-FePO4. Additionally, the process proposed in this study yields significant economic benefits, estimating a profit of 719.6 $/t of recycled LES. This research proposes a cost-effective and efficient method for regenerating high-quality battery-grade FePO4 from LES, offering a significant contribution to the closed-loop recycling of waste LiFePO4 batteries.

Termo–mekanik yoğunlaştırma işleminin ahşap malzemenin fiziksel özellikleri üzerine etkisi

It can be made into high strength, and valuable products by compacting low density, and low commercial value wood species. In this study, black pine (Pinus nigra) and Uludağ fir (Abies nordmanniana subsp. bornmulleriana) tree species were densified by using Thermo-mechanical (TM) method, which is an environmental modification method, at 140 oC and two different ratios of 25% and 50% (in the radial direction). Compression ratio in air-dry moisture, spring-back ratio after densification, and physical properties of air-dry densities were determined. The obtained data were subjected to statistical analysis in the MSTAT-C program. According to the results, wood type, densification type, and all their interactions were found to be effective on the compression ratio, and spring-back ratio in air dry moisture. The compression ratio in air-dried moisture was lower in Uludağ fir (Uludağ fir: 0.40 gr/cm³, black pine: 0.49 gr/cm³) compared to black pine due to the spring-back effect. While the volumetric recovery (spring-back) rates were 15.44% in Uludağ fir, it was determined as 19.40% in black pine. After the condensation process, the air-dry density value increase was lower in black pine compared to Uludağ fir, and it was determined as 35.94% in Uludağ fir and 34.53% in Black Pine

Effects of electric arc furnace slag powder and fly ash within ternary waste blend on performance of concrete

Recently, research on utilising industrial and natural waste has advanced owing to their environmental concerns, including soil and groundwater contamination. Most such waste possess zero or low commercial value, yet it is stored, occupying large storage yards. Iron and steel factories and quarries worldwide produce large amounts of waste annually. This study used three types of steel mill waste (electric arc furnace slag powder, fly ash and steel sludge and natural waste from quarries limestone dust, marble dust, and recycled glass powder) as supplementary cementitious materials with the aim of producing an economical and environmentally friendly ternary waste binder. To determine the appropriate waste blend compounds of mixes, the study was conducted in three stages. First, waste mortars were used to mix, tests of mortars properties were conducted, and the properties of the mix were compared with those of a control mortar mix. Second, concrete was mixed from the waste blend with the most suitable properties. Finally, durability tests on the concrete were performed. Ternary residue having 4.5% SP, 10% FA, and 4.5% SS with 18% replacement of cement and that having 3.75% SP, 7.5% FA, and 3.75% LD with 15% replacement of cement achieved the requirements of concrete and improved the compressive strength and durability towards sulfate and chloride attack, including impermeability and resistance.

Fish waste silage, a green process for low feedstock availability. A Review

Introduction. Different fishing activities generate a waste volume related to the processing species (viscera, heads and bones), the discards of the companion fauna, species of low commercial value and the losses related to handling problems. Fish meal production is the most common process for recovery nutrients from these fish processing byproducts. However, those places with reduced infrastructure or where the volume of wastes produced do not justified the economic equation for conversion into fish meal or oil, the biological silage could be the technology of choice to promote a sustainable waste management. Objective. To compilate, organize and summarize literature related to biological fermentation of fish waste and its applications. Development. A bibliographic review was carried out (January 1994 - December 2020) referring to the comprehensive use of fishing residues mainly focused on the use of lactic acid bacteria in fish waste fermentation. The information was organized in different sections: fish silage, lactic acid bacteria and carbohydrate sources for biological silage. Conclusions. The studies analyzed in this review highlight the possibility of using a wide variety of carbohydrate sources, biological starters and fish waste fermentation conditions. The satisfactory results show the potential use of fish waste in different applications. This work could contribute to the fisheries that decide to adopt this kind technology in order to provide an innovative and viable recycling bioeconomy.

Vulnerability of elasmobranchs caught as bycatch in the grouper longline fishery in the Gulf of Gabès, Tunisia

The present study aims to quantify the effect of the grouper demersal longline fishery to elasmobranchs in the Gulf of Gabès to support future conservation actions for the most vulnerable species. Data from 162 demersal longline sets carried out during the grouper fishing seasons in 2016 and 2017 were analyzed. At least 17 elasmobranch species were caught, representing about 50% of the total catch in number which exceeded the target catch of groupers Epinephelus spp. (44.15%). Elasmobranchs were present in 139 (85.80%) out of the 162 examined sets, while the frequency of occurrence per set varied greatly depending on the species. The nominal Catches Per Unit Effort of all species combined was 3.07 specimens per 1,000 hooks/hour of fishing. Sharks and batoids contributed equally to the total elasmobranch catch, comprising 51.84% and 48.16% in terms of number, respectively. Mustelus mustelus, Carcharhinus plumbeus and Squalus spp. were the most abundant species, representing 45.65% of the total elasmobranch catch, whereas the remaining shark species were rarely caught (6.19%). Batoids were dominated by Glaucostegus cemiculus, which represented 19.07% of the total elasmobranch catch in number, followed by Dasyatis spp. (8.91%), Raja clavata (7.1%) and Taeniura grabata (4.59%). The elasmobranchs discarded due to their low commercial value and/or small size represented 11.34% of the total catch in number. According to the results of the Productivity and Susceptibility Analysis, the coastal viviparous elasmobranch species in the study area are highly vulnerable to the grouper longline fishery activity and should be carefully managed to reduce the likelihood of overfishing.

Selection of fish resources for consumption and sale by artisanal fishers and implications to fisheries sustainability

Artisanal fishing may be directed at a diversity of target species. Understanding the factors that influencing the choice of fishing resources for sale or consumption helps us comprehend the pattern of use of natural resources and the pressures on the species caught. The commercial value of the species fished influences the fishing effort. Still, other attributes may interfere with the choice of species to be sold or consumed, such as biomass, trophic level, species habitat, and individual preferences. We analyzed the variables that interfere with the choice of fishing resources for consumption or sale (commercial value, trophic level, and habitat) among artisanal fishers in a subtropical estuarine system. We also explored the relationship between the commercial value and the species' trophic level. We conducted 80 interviews with artisanal fishers from five municipalities around Babitonga Bay, located on the southern coast of Brazil, who fish both invertebrates (crustaceans and mollusks) and fish. We found an overlap between the number of species sold (92) and consumed (79). Fishing resources with higher commercial value, and trophic level tend to be sold, while species with low commercial value, and trophic level are the most consumed by fishers. Furthermore, some species used for consumption and sale are classified with different degrees of threat regarding their conservation status as Critically Endangered (CR), Endangered (EN), and Vulnerable (VU), both at local and international assessments. We suggest future directions to support sustainable fisheries management in Babitonga Bay based on these data.

Drawing on local knowledge and attitudes for the conservation of critically endangered rhino rays in Goa, India

Abstract In the context of marine species declines in data‐limited regions, local ecological knowledge (LEK) is a valuable source of information on species ecology and historical trends. LEK can also help understand how threatened species exist within a local culture, in terms of their uses and values, and reveal attitudes towards their conservation. Rhino rays (guitarfish and wedgefish) are highly threatened by overfishing with most species critically endangered, yet poorly studied in countries like India that fish them the most. We drew on LEK to understand the socio‐ecological status of rhino rays in Goa, on the west coast of India. We investigated their habitat use and seasonality, interaction with fisheries, socio‐economic uses and relational values. We also explored attitudes of fishers towards rhino rays and their conservation. A combination of semistructured interviews and key informant interviews (88 in total) was conducted with fishers at multiple sites. Local knowledge suggests that nearshore habitats around river mouths form important nursery grounds for some rhino rays, and provided insights on their seasonality and breeding. Rhino rays appeared to be targeted historically but are entirely bycaught at present, with highest catches in gillnets and in the South Goa district, during September and October. LEK indicated that taxa like sawfish (Pristis spp.) and wedgefish (Rhynchobatus spp.) have severely declined or disappeared from this region. We coded different relational values, from recreation (rhino rays are consumed and enjoyed with alcohol) to symbolic values (rhino rays are considered lucky). All key informants expressed positive attitudes towards rhino ray conservation and stated that a ban on landing these species would have little to no impact on fisher earnings. The usefulness of LEK suggests it should be brought into the scientific mainstream to support development of more equitable and socially appropriate management plans. Fostering relational values can reinforce fishers' positive attitudes, thereby enhancing rhino ray conservation. Their low commercial value and potentially high post‐capture survival suggest that using norm‐based approaches to promote live release may be successful. Further research on rhino ray ecology and human dimensions can support the development of appropriate conservation interventions. Read the free Plain Language Summary for this article on the Journal blog.

Changes in catch efficiency and selectivity in the beam trawl fishery for sole when mechanical stimulation is replaced by electrical stimulation

Beam trawl fisheries for sole are characterised by large amounts of unwanted bycatch (i.e. discards) consisting of fish below the Minimum Conservation Reference Size, unwanted fish due to low commercial value or lack of quota, and benthic invertebrates. In order to reduce the quantity of discards, a substantial part of the Dutch beam trawl fleet was allowed to replace the conventional tickler chain beam trawl (BT) with the pulse trawl (PT) on an experimental basis. The PT used electrical stimulation to immobilise and capture fish. Here we study whether pulse trawling reduced the amount of discards by comparing catch rates of landings and discards of BT and PT in the period 2009–2018 for a wide range of species. The PT caught (kg.km-2) significantly more marketable sized sole (Solea solea, 48 %), turbot (Psetta maxima, 8 %), brill (Scophthalmus rhombus, 28 %) and whiting (Merlangius merlangus, 95 %), and significantly less marketable sized plaice (Pleuronectes platessa, −16 %), cod (Gadus morhua, −32 %) and gurnards (−12 %). No significant difference was found for dab (Limanda limanda), gadoids, or rays and sharks. Among discards, the PT caught more undersized sole (27 %) and whiting (42 %) but less undersized plaice (−21 %), dab (−19 %) and grey gurnard (Eutrigla gurnardus, −31 %). The observed differences in species selectivity are discussed in relation to the response of fish to bottom trawl gear and the effects of pulse stimulation. For the benthic invertebrates Ophiuroidae, bivalves and crabs the PT caught fewer individuals (between −38 % and −57 %). No significant difference was observed in sea urchins and sea stars. Overall, this study shows that the transition from the BT to PT resulted in a 36 % decrease (95 % prediction interval: 31–42 %) in discards (kg.hour-1).