Lepidopus Caudatus Research Articles

Using information-based methods to model age and growth of the silver scabbardfish, Lepidopus caudatus, from the mid-Atlantic Ocean

The traditional species targeted by the Azorean demersal mixed hook-and-line commercial fisheries are presently facing a decline in captures, and the demand for new demersal resources is growing. The silver scabbardfish, Lepidopus caudatus, is a potential new resource to be exploited in the region; however, reports on its vulnerability and stock status are contradictory, which highlights the importance of arriving at accurate age and growth parameter estimates for this species. The 808 individuals used in the present study were acquired from commercial landings in the Azorean islands of São Miguel and Faial, collected monthly between 2004 and 2010. Ages were determined by counting growth increments in whole sagittal otoliths. Four different growth models were fitted to the data: von Bertalanffy growth function, the Gompertz model, the logistic model and the power function. Akaike's Information Criterion was used to evaluate the models and finally a multi-model inference was employed to arrive at model-averaged estimates of L∞. The von Bertalanffy function performed as well as the other candidates, although the parameter estimates for this model were usually higher than for the Gompertz and logistic models. The analysis suggests that L. caudatus is a relatively fast-growing species that could constitute a sustainable resource for commercial fisheries in the region, pending further research into the unbalanced sex ratios observed here.

Exposure Assessment of Pregnant Portuguese Women to Methylmercury Through the Ingestion of Fish: Cross-Sectional Survey and Biomarker Validation

Methylmercury (MeHg) contamination is a critical public health problem in Portugal, where fish is an important component of the daily diet. The Portuguese are the third largest consumers in the world (after Japan and Iceland) but first in Europe. Prenatal exposure to MeHg is believed to be linked to fetal/child neurodevelopment and behavioral impairments due to the neurotoxicity of the compound. The objective of this study was to assess the exposure of pregnant Portuguese women to mercury (Hg) due to fish consumption, calculating the indices of risk and confirming exposure through analyses of a biomarker of exposure. The study consisted of a cross-sectional evaluation of 343 pregnant women recruited at their visit to two antenatal care units in Lisbon, Portugal. A food frequency questionnaire was used to estimate prenatal exposure. Total Hg levels in hair were analyzed by atomic absorption, in samples from 186 women. The average fish consumption was 3.1 meals per week. Median Hg level in the hair was 1.26 μg/g (range: 0.07–5.3 μg/g). The mean calculated risk index was 0.81; however, 28% of the pregnant women ingested levels above the provisional tolerable weekly intake (PTWI) level recommended by the World Health Organization (WHO; 1.6 mg/kg per body weight), indicating the possibility of risk due to MeHg exposure. Multiple linear regression analysis showed the risk index was reliably predicted from predatory fish species and number of fish meals consumed per week. Ingestion of black and silver scabbard fish as well as mixed predatory fish cooked in traditional dishes enhanced the toxicity risk. In conclusion, some exposure levels exceeded the reference value; therefore, nutritional counseling needs to be provided to populations at risk.

Seafood consumption health concerns: The assessment of methylmercury, selenium, and eicosapentaenoic + docosahexaenoic fatty acids intake

For hake, ray, and silver scabbard fish, the intake of methylmercury (methyl-Hg), selenium (Se), and eicosapentaenoic + docosahexaenoic fatty acids (EPA + DHA) through their consumption in Portugal and the associated probability of exceeding the provisional tolerable weekly intake (PTWI), the recommended daily allowance (RDA), and the recommended daily intake (RDI), respectively, were estimated. For this, the methyl-Hg, Se, and EPA + DHA concentrations in the studied fish species were combined with constructed consumption scenarios for the elaboration of consumption recommendations or with a hypothesized Portuguese consumption distribution with the purpose of estimating the risk-benefit situation in Portugal.It was calculated that the probabilities of the methyl-Hg intakes exceeding the PTWI were always higher than the probabilities of the Se and EPA + DHA intakes surpassing the recommended thresholds, RDA and RDI, respectively, regardless of the species. The consumption of the three fish species should be limited to less than one meal per week, since this consumption frequency entailed a probability of exceeding the methyl-Hg PTWI ranging from 1:213 in hake to 1:4 in silver scabbard fish. For the Portuguese population, hake consumption −48.3 g/(week.person) — may be excessive, since a probability of 1:310 (meaning 320 persons at risk in 100,000) of the methyl-Hg intake exceeding the PTWI through this species consumption was calculated. Particularly, this applies to that fraction of the population whose hake consumption frequency is two or more weekly meals (which may reach 19.7%) and to more vulnerable groups such as pregnant women and small children, which should choose alternative fish species with lower methyl-Hg contents, such as, small pelagic fish (sardine, scad, or mackerel).

From fish chemical characterisation to the benefit-risk assessment – Part A

Proximate composition, fatty acid profile, cholesterol, α-tocoferol content and essential (K, Na, Cl, S, Mg, Ca, Zn, Cu, Fe, Mn, and Se) and contaminant element (Hg/MeHg, Cd, Pb, and As) levels in silver scabbardfish (Lepidopus caudatus), hake (Merluccius merluccius), and ray (Raja spp.) were investigated.Results showed that these species contain high protein, low cholesterol and energy levels, being its consumption recommended. Polyunsaturated fatty acids (PUFA) were the dominant group of the fatty acids, being 80% of the n-3 family. Attending to the dietary reference intakes (DRIs), these fish species are a good source of Se and the other minerals can give a relevant contribution to the DRIs in a balanced diet. More than one weekly meal of silver scabbardfish has to be avoided due to the organic mercury concentration. More accurate dietary recommendations require a probabilistic assessment, which will be the focus of this study’s Part B.

Occurrence of Hyperostotic Pterygiophores in the Silver Scabbardfish, <I>Lepidopus Caudatus</I> (Actinopterygii: Perciformes: Trichiuridae)

Background. Hyperostosis is a productive change characterized by an increase of the periosteal ossification combined to resorption of the bony tissue. It is common in several fish species. Its presence has been reported in the silver scabbardfish, Lepidopus caudatus (Euphrasen, 1788). The aim of the presently reported study is to improve the knowledge on the presence of hyperostotic pterygiophores in L. caudatus. Materials and methods. In total, 50 specimens of Lepidopus caudatus, captured off the coast of Messina (Sicily, Italy) were examined by radiography. Deformed pterygiophores were decalcified and processed for histopathological examination, and the sections obtained were stained with haematoxylin and eosin. Results. Forty (80%) of the 50 specimens examined showed skeletal deformities exclusively on the pterygiophores of the dorsal fin. In total, 433 deformities were observed. Histological examination showed slight expansion of the bone tissue, which was poor in cells and characterised by thin layers of compact bone tissue. Macroscopic, radiographic, and histological findings were consistent with diagnosis of hyperostosis. Conclusion. Hyperostosis of L. caudatus does not affect its consumption. However, it may be a complication for filleting techniques as the presence of hyperostosis along the longitudinal axis of teleosts does not allow a complete and repeatable filleting technique. This could increase the possibility of bacterial contamination, loss of muscle tissue, and imperfections in cutting and trimming.

Heavy metals content by ICP-OES in Sarda sarda, Sardinella aurita and Lepidopus caudatus from the Strait of Messina (Sicily, Italy)

In this study copper, nickel, lead, cadmium, arsenic, chromium and vanadium content was measured in the muscles and gills of 24 fishes (Sarda sarda, Sardinella aurita and Lepidopus caudatus) caught in the Strait of Messina, by inductively coupled plasma-optical emission spectroscopy with microwave digestion techniques. In general, it was found that arsenic was higher than other analytes in all fish species, particularly its content was much higher in S. aurita than in the other two exemplary species. Lead and cadmium were always detected with values below the legal limits (CE no. 1881/2006 and subsequent modification CE no. 629/2008).

Molecular identification of Anisakis spp. from fishes collected in the Tyrrhenian Sea (NW Mediterranean)

The accurate identification of anisakid nematodes at any life cycle stage is important both to deepen the knowledge on their taxonomy, ecology, epidemiology and for diagnosis and control, as larval stages cause a clinical disease in humans known as anisakidosis. With the aim to investigate the presence of anisakid larvae, specimens of horse mackerel, Trachurus trachurus (Linnaeus, 1758), silver scabbardfish, Lepidopus caudatus (Euphrasen, 1788), European anchovy, Engraulis encrasicolus (Linnaeus, 1758) and opah fish, Lampris guttatus (Brunnich, 1788), were collected by trawling at depths ranging from 50 to 400m. A molecular approach based on restriction profiles obtained after digestion of the nuclear ribosomal ITS region was used to identify Anisakis spp. larvae recovered in fish samples. Restriction profiles showed three banding patterns, corresponding to Anisakis pegreffii, Anisakis physeteris and to heterozygote pattern between A. pegreffii and Anisakis simplex s.s. Specimens showing the heterozygote restriction pattern were also analyzed by sequencing of the entire ITS region, to confirm the heterozygote status.

Anisakis pegreffii experimental challenge in Dicentrarchus labrax: An endoscopic study

To validate the use of imaging techniques to evaluate tissue damage in vivo, ten European sea bass (Dicentrarchus labrax) were anesthetized with MS-222 and experimentally infected with nematode larvae collected from three Lepidopus caudatus. Live nematode larvae were introduced by gastroscopy into the stomach of ten fish. Another challenge was performed 15days later. After a 60day period, an explorative celioscopy was carried out. Fish were examined for Anisakis larvae and biopsy samples were collected. Parasites sampled from L. caudatus and D. labrax were morphologically identified at genus level. Biopsy samples were routinely processed for histopathology. Some larvae were sampled for PCR. At gastroscopic exam 15days after the first challenge some live nematode larvae were found within the lumen of the stomach in four fish. Two months later, at celioscopy, four sea bass showed hemorrhages and/or irregular neoformations within the celomic cavity. Within each of these changes a single nematode larva was detected. Histopathology showed hemorrhagic lesions with a cystic aspect. Parasite larvae were identified as L3 stages Anisakis Type I. PCR-RFLP analysis has allowed the identification of larvae isolated as Anisakis pegreffii. Endoscopy is a suitable noninvasive procedure for evaluation of experimental challenges in sea bass using live Anisakis larvae. The evidence of tissue change is an unusual occurrence in fish parasitized by Anisakis. The paper sets out to assess the damage anisakid nematodes induce in infected fish by imaging techniques.

Evaluation of sorting grids for deepwater rose shrimp (Parapenaeus longirostris) in the Eastern Mediterranean demersal trawl fishery

Summary The study aimed to evaluate sorting grids of 10 and 15 mm bar spacing specifically for separation of deep water rose shrimp, but including other species, in a Mediterranean multispecies demersal trawl fishery. Data were collected 15–25 October 2008 in Sigacik Bay, Eastern Aegean Sea with the commercial trawler, ‘Hapuloglu’, using a modified bottom trawl net. A total of 22 valid hauls (12 with 10 mm, ten with 15 mm grids) were obtained. The separation rate of anglerfish was highest, with 100% for weight and number in both codends among all species. Grid elimination of broadtail short-fin squid showed differences between 95.3 and 80.3% in terms of weight, and 89.7 and 66.2% in terms of number for 10 and 15 mm, respectively. Separation ratios for hake, silver scabbard fish, and horse mackerel were between 96.3 and 100% in terms of weight, and 92.2 and 100% in terms of number in both codends. Shrimp separation was in total calculated as 60.8 and 37.0% by number, and 70.7 and 44.4% by weight in 10 and 15 mm bar spacing trawl grids, respectively, demonstrating that substantial improvement in species selectivity (deep water rose shrimp from others) is possible to achieve by adding sorting grids in the Mediterranean demersal trawl fishery. To optimize the overall selection performance in such fisheries, a variety of grid systems, bar spacings and materials as well as the economic consequences need to be evaluated.

PLEROCERCOID GYMNORHYNCHUS (CESTODA: TRYPANORHYNCHA) IN LEPIDOPUS CAUDATUS: INTERFERENCE ON TMA-N AND TVB-N DETERMINATION

Total Volatile Basic Nitrogen (TVB-N) and Trimethylamine Nitrogen (TMA-N) are the most important freshness indicators in fish. The present report demonstrates that the Gymnorhynchus gigas plerocercoid may interfere on TVBN and TMA-N determination. The study was carried-out on 101 samples: 37 Mp (muscle portions around the parasite), 32 P (larvae of Gymnorynchus gigas extracted from muscle) and 32 Mnp (muscle portions parasite-free), obtained from 10 specimens of Lepidopus caudatus kept at several temperature for different time. The TVB-N and TMA-N contents of each sample were measured using the Conway microdiffusion method. Statistically significant differences (p < 0.05) between Mp and Mnp for TMA-N were found from 24h of storage at 4 and 15°C. No significant differences (p < 0.05) between Mp and Mnp for TVB-N were observed from 48h of storage at 4 and 15°C. TVB-N and TMA-N content was variable in larvae.

Species selectivity in the Eastern Mediterranean demersal trawl fishery using grids to reduce non-target species

Summary Scientific studies have been conducted on size selectivity of trawls with grids in the Mediterranean; however, none has focused on species selectivity. The aim of the present study was to analyze the value of sorting grids with 20 mm bar spacing for species separation, in a demersal trawl fishery mainly targeting deep water rose shrimp (Parapenaeus longirostris) in the Eastern Mediterranean. Fishing trials were carried out 17–24 August 2008 onboard the commercial trawler ‘Hapuloglu’, using a modified bottom trawl net. The separation rate for silver scabbard fish (Lepidopus caudatus) was highest among all species with 98% by weight and 97% by number in 44 mm diamond (44D) and 40 mm square mesh (40S) codends, respectively. The exclusion of European hake (Merluccius merluccius) by the grid shows differences between 85 and 93%, in weight and 64 and 83% in number for codends of 44D and 40S, respectively. Excluding the ratio for greater forkbeard (Phycis blennoides), the angler fish (Lophius piscatorius) and broadtail short fin squid (Illex coindetii) varied between 93 and 97% in weight, and 81 and 86% in number in both codends. Losses of legal sized rose shrimp were determined as 23 and 25% in 44D and 40S, respectively. The results obtained in the present study demonstrate that substantial separation of fish and shrimp can be achieved in this Mediterranean demersal trawl fishery. However, further developments should be explored; for this purpose the behaviour of species has to be studied in relation to trawl and grid design and where commercial consequences of changes in gear technology need to be considered.

10.1007/s11489-008-1010-7

Results of observations from the underwater inhabited device “Sever-2” of the behavior and distribution of fish on seamounts of the Azores region up to a depth of 1200 m are provided. In the natural habitat, 52 species of fish of 46 genera belonging to 36 families were recorded. In the ichthyofauna of the studied region, bottom (37.0%) and near-bottom (29.2%) species dominate; the proportion of off-bottom and off-bottom-pelagic species is 18.0 and 12.4%, respectively, and pelagic species account for only 3.4%. Pelagic species Scomber japonicus and Trachurus picturatus; off-bottom-pelagic Beryx splendens, Lepidopus caudatus, and Aphanopus carbo; and near-bottom species Zenopsis conchifer, Macrorhamphosus scolapax, Antigonia capros, Capros aper, Anthias anthias, and Callanthias ruber dominate by numbers and the amount of biomass.

Selenium Content of Raw and Cooked Marine Species Consumed in Portugal

The present study evaluates the effects of different cooking methods (grilling, frying and boiling) on selenium contents of six marine species commonly consumed in Portugal. Forty-two composite samples of sardine, horse mackerel, gilthead seabream, silver scabbardfish, hake and octopus were digested in a microwave system and analysed by electrothermal atomic absorption spectrometry. The described method is adequate for the analysis of selenium in marine species and meets the requirements of validation and quality control. Mean selenium contents in raw species ranged from 0.35 mg kg−1 to 1.24 mg kg−1. Cooked samples presented mean selenium contents from 0.38 mg kg−1 to 1.85 mg kg−1 in grilled fish, from 1.22 mg kg−1 to 1.28 mg kg−1 in fried fish and from 0.84 mg kg−1 to 0.87 mg kg−1 in boiled fish. No statistically significant differences were determined for selenium levels in raw and cooked samples and in different marine species. Estimated selenium intake agrees well with recommendations and is far below the Upper Tolerable Nutrient Level. This is the first study concerning the evaluation of the effects of cooking methods on selenium contents of marine species consumed in Portugal.

The complete mitochondrial genome sequence of the cutlassfish Trichiurus japonicus (Perciformes: Trichiuridae): Genome characterization and phylogenetic considerations

Mitochondrial genome sequence and structure analysis has become a powerful tool for studying molecular evolution and phylogenetic relationships. To understand the systematic status of Trichiurus japonicus in suborder Scombroidei, we determined the complete mitochondrial genome (mitogenome) sequence using the long-polymerase chain reaction (long-PCR) and shotgun sequencing method. The entire mitogenome is 16,796 bp in length and has three unusual features, including (1) the absence of tRNA Pro gene, (2) the possibly nonfunctional light-strand replication origin (O L) showing a shorter loop in secondary structure and no conserved motif (5'-GCCGG-3'), (3) two sets of the tandem repeats at the 5' and 3' ends of the control region. The three features seem common for Trichiurus mitogenomes, as we have confirmed them in other three T. japonicus individuals and in T. nanhaiensis. Phylogenetic analysis does not support the monophyly of Trichiuridae, which is against the morphological result. T. japonicus is most closely related to those species of family Scombridae; they in turn have a sister relationship with Perciformes members including suborders Acanthuroidei, Caproidei, Notothenioidei, Zoarcoidei, Trachinoidei, and some species of Labroidei, based on the current dataset of complete mitogenome. T. japonicus together with T. brevis, T. lepturus and Aphanopus carbo form a clade distinct from Lepidopus caudatus in terms of the complete Cyt b sequences. T. japonicus mitogenome, as the first discovered complete mitogenome of Trichiuridae, should provide important information on both genomics and phylogenetics of Trichiuridae.

An evaluation of resource partitioning between two billfish, Tetrapturus belone and Xiphias gladius, in the central Mediterranean Sea

The present study attempts to give information on the resource partitioning between the Mediterranean spearfish (Tetrapturus belone) and the swordfish (Xiphias gladius). The contents of 53 T. belone and 95 X. gladius non-empty stomachs were analysed from specimens caught in the central Mediterranean Sea (Strait of Messina), from 2004 to 2006, by the harpoon fishery. Daily catches (expressed as number of fish) showed the contemporary occurrence of both species in the studied area then allowing direct comparison of diets. Epipelagic fish were the dominant prey (%IRI = 99.1) of T. belone. Eight families were identified among them, with the dominance of Belonidae and Clupeidae, which represented 40.9% and 36.8%, respectively, of the total preyed items in terms of %IRI and were mostly composed of Sardinella aurita and Belone belone.Xiphias gladius preyed mainly on teleosts and cephalopods, which represented 59% and 39.1%, respectively, of the total preyed items in terms of %IRI. Eleven teleost and five cephalopod families were recognized among them with the dominance of Trichiuridae (IRI% = 30.5) and Ommastrephidae (IRI% = 27.6). The first was represented only by Lepidopus caudatus (IRI% = 30.5), while the latter by the squid Todarodes sagittatus (IRI% = 21.1) and Illex coindettii (IRI% = 6.5). Results of a multivariate statistical analysis demonstrated that the dietary compositions differed significantly between swordfish and spearfish. Diet overlap analysed with the Schoener and Horn indices showed low values (0.23 and 0.21 for the two indices) underlining a food partitioning that prevents competitive exclusion. Our results highlight a feeding strategy that is more related to the habitat of the species than to the food availability. In fact, migration patterns of the two predators are quite different. Swordfish show vertical migrations from 0 to 800 m while spearfish are characterized by limited migrations, ranging between 0 and 200 m depths. The observation of specific prey items in the stomach content of both billfish confirmed the bathymetric range of their migrations.

DNA barcoding of shared fish species from the North Atlantic and Australasia: minimal divergence for most taxa, but Zeus faber and Lepidopus caudatus each probably constitute two species

Fifteen fish species, totalling 149 specimens, were cytochrome c oxidase I sequenced— barcoded—from Northern (Atlantic and Mediterranean) and Southern (Australasian) Hemisphere waters. Thirteen species showed no significant evidence of spatial genetic differentiation for this gene, although small sample sizes reduced statistical power. For marine fish, barcodes collected in one part of a species range are likely to be useful as identifiers in all other parts of its range. Two spe- cies did show striking north-south differentiation, with FST values of 0.84 and 0.96 (both p << 0.001). One of these, the silver scabbardfish Lepidopus caudatus, showed 2.75% genetic distance between northern and southern clades. The other, John dory Zeus faber, showed 7.44% differentiation between northern and southern clades. All specimens of these 2 species fell correctly into the north- ern or southern clade. We suggest that both taxa conceal a currently unrecognised, cryptic species, and recommend further taxonomic and genetic investigation.

Visual observations of fish from seamounts of the Southern Azores region (the Atlantic Ocean)

Results of observations from the underwater inhabited device “Sever-2” of the behavior and distribution of fish on seamounts of the Azores region up to a depth of 1200 m are provided. In the natural habitat, 52 species of fish of 46 genera belonging to 36 families were recorded. In the ichthyofauna of the studied region, bottom (37.0%) and near-bottom (29.2%) species dominate; the proportion of off-bottom and off-bottom-pelagic species is 18.0 and 12.4%, respectively, and pelagic species account for only 3.4%. Pelagic species Scomber japonicus and Trachurus picturatus; off-bottom-pelagic Beryx splendens, Lepidopus caudatus, and Aphanopus carbo; and near-bottom species Zenopsis conchifer, Macrorhamphosus scolapax, Antigonia capros, Capros aper, Anthias anthias, and Callanthias ruber dominate by numbers and the amount of biomass.

Mercury in fish: Concentration vs . fish size and estimates of mercury intake

Total mercury concentrations were determined in different fish size classes of commercial importance such as, conger eel (Conger conger), starry ray (Raja asterias), forkbeard (Phycis blennoides), frostfish (Lepidopus caudatus), striped mullet (Mullus barbatus), red gurnard (Aspitrigla cuculus) and yellow gurnard (Trigla lucerna) in order to evaluate variations in consumer exposure to mercury as a function of fish consumption of a spectrum of different sizes. The highest mean levels of total mercury were detected in conger eel (0.80 µg g−1) and starry ray (0.75 µg g−1). Forkbeard (0.67 µg g−1), frostfish (0.59 µg g−1) and striped mullet (0.55 µg g−1) showed slightly lower levels, while red gurnard (0.33 µg g−1) and yellow gurnard (0.22 µg g−1) exhibited the lowest concentrations. The results of linear regression analysis showed a significant relationship between mercury concentrations and fish size for all species. Consequently, dietary consumption of larger size specimens leads to an increase in the exposure level for consumers. Understanding by consumers of all factors leading to an increase of exposure to mercury is the first step to enable them to make decisions about eating fish.

Intra- and inter-specific variability in total and methylmercury bioaccumulation by eight marine fish species from the Azores

We relate fish biological and ecological characteristics to total and organic mercury concentrations to determine whether accumulation is influenced by trophic level, Hg concentration in the diet, and vertical distribution. Levels of total mercury and methylmercury were determined in the muscle tissue of eight species of fish: Pagellus acarne, Trachurus picturatus, Phycis phycis, P. blennoides, Polyprion americanus, Conger conger, Lepidopus caudatus and Mora moro, caught in the Azores. All such fishes are commercially valuable and were selected to include species from a wide range of vertical distributions from epipelagic (<200 m) to mesopelagic (>300 m) environments. Methylmercury was the major form accumulated in all species, comprising an average of 88.1% of total mercury. Concentrations of mercury (total and methylmercury) increased with age, length and weight. Based on data from other studies, mercury concentrations in fish diet were estimated. Mercury levels in food ranged from 0.08 to 0.32 ppm, dry weight. Hg concentrations in the food and in muscle tissue from different species were positively correlated. Total Hg levels in the muscles were approximately nine times those estimated in food. Total mercury concentrations in muscle were positively correlated with both trophic level and median depth. Such enhanced mercury bioaccumulation in relation to depth appears to be determined primarily by concentrations in food and ultimately by water chemistry, which controls mercury speciation and uptake at the base of the food chain.

Discarding practices in a Mediterranean small‐scale fishing fleet (Patraikos Gulf, Greece)

Abstract Discarding practices from 110 fishing operations in a Mediterranean small‐scale fishing fleet (Patraikos Gulf, western Greece) from August 2004 to July 2005 were analysed. On average, 1 kg of fish was discarded per fishing operation (10% of the catch). The reasons for discarding were: low commercial value (78% of discards), damage at sea before retrieval of the gear (5%), and bad handling on‐board (17%). More than half of discards belonged to Spicara flexuosa (L.), Lepidopus caudatus (Euphrasen), Sardinella aurita Valenciennes and Merluccius merluccius (L.). The bulk of discards of each species were associated with a single fishing method (metier). A Generalized Linear Model (Delta‐X – error‐model) indicated that, when discards were present, significant differences existed in the discard ratio among different métier groups (groups comprising métiers with similar characteristics). Longlines and trammel nets with small mesh‐sizes had the highest discard ratios. Discarding practices for the species Diplodus annularis (L.), S. aurita, Squilla mantis (L.), S. flexuosa and Scorpaena scrofa (L.) did not follow a consistent pattern (these species were either fully discarded or fully retained during a fishing operation). The decision seemed to be dependent on market demands rather than fish size. Significant correlation was found between discarded and catch weight, but the presence of many outliers indicated deviance from a case where discards are high when there is an abundant catch. The findings of the study imply that monitoring and management should be carried out preferably on the métier level. Discards could be reduced by technical measures, controlling effort regulations and by improving working conditions on‐board fishing vessels.