Trachurus Research Articles

Numerical Study on Evaluation of Environmental DNA Approach for Estimating Fish Abundance and Distribution in Semi-Enclosed Bay

Despite efforts to use environmental DNA (eDNA), accurately quantifying fish populations remains a challenge. A recent eDNA approach provided reliable estimates of coastal fish population abundance, but it was not as effective for assessing spatial distribution due to a lack of eDNA samples relative to the study area. Therefore, we conducted a numerical case study to evaluate the ability of the eDNA approach to estimate fish (Jack mackerel) abundance and distribution based on the number of eDNA samples in a semi-enclosed bay (Jinhae Bay). Our study revealed that the eDNA approach can provide reliable estimates of fish abundance, even with knowledge of the eDNA concentration in just 1% of the study area. However, for estimating spatial distribution and fish school, significant estimates were obtained only when the eDNA concentration was identified in more than 70% of the study area. Our results confirm that the eDNA approach can reflect fish abundance but has limitations in estimating fish distribution.

The complete mitochondrial genome of Chilean Jack Mackerel, Trachurus murphyi Nichols, 1920 (Teleostei, Carangidae)

The Chilean jack mackerel (Trachurus murphyi, Nichols, 1920) is a pelagic fish of high fishery interest, with a global capture of 828,358 mt in 2021. We report the complete mitochondrial genome of T. murphyi (Teleostei, Carangidae), collected in Bahia de Zapallar, Chile (32°33’02.59’’ S, 71°27’55.38’’ W). The size of the mitogenome is 16,561 bp (H-strand composition: 25.9% A, 16.7% C, 29.8% G, and 27.5% T). The mitogenome has the classic vertebrate gene content of 13 protein-coding, two rRNA, and 22 tRNA genes, as found in Carangidae and other Teleostei families. Phylogenetic analysis using mitochondrial genomes of 22 related species revealed that T. murphyi formed a well-supported monophyletic group with the other Trachurus species, being T. simmetricus its closest relative. Sequencing the mitochondrial genome from T. murphyi is the first step in developing traceability tools based on DNA analysis to enforce fishing quotas and trace the processed food and foodstuff containing Chilean jack mackerel following the objective of the South Pacific Regional Fisheries Management Organization (SPRFMO).

Otolith elemental composition indicates differences in the habitat use for larvae and early juveniles of Japanese jack mackerel (Trachurus japonicus) in the waters around Japan

AbstractTrace element analysis of otoliths from core to edge was used to reveal differences in habitats of larvae and early juveniles of Japanese jack mackerel (Trachurus japonicus) caught in the East China Sea (ECS), Pacific Ocean, and Sea of Japan. Multi‐element signatures (Sr:Ca, Mg:Ca, Na:Ca, K:Ca, and Ba:Ca) were analyzed with multivariate statistics to determine whether these element signatures provide insight into regional population structure. The median values of elements: Ca ratios in otolith core region differed significantly among areas, with most elements between the ECS and the Pacific Ocean or Sea of Japan showing significant differences. The Sr:Ca ratios exhibited a V‐shaped trend from the otolith core to the edge, which was likely related to the vertical habitat layer shift of larvae and early juveniles of T. japonicus. Canonical analysis of principal coordinates using the element: Ca ratios and the hatching day were re‐classified according to the sampling area with higher accuracy in the ECS (88–95%) and the Sea of Japan (76–83%) compared to the Pacific Ocean (69–72%). These results indicate that the proportion of eggs, larvae, and early juveniles transported by the Kuroshio Current from the southern ECS—the main spawning ground—to the Pacific Ocean or the Sea of Japan is low and that juveniles distributed in the coastal waters off southwestern Japan may have originated from local spawners. These results suggest that determining the elemental composition of larvae and juveniles of T. japonicus is effective in determining the habitat differences of this species in the three regions. These findings will help to understand population structure and recruitment process of this species around Japan.

Manipulation impacts of jack mackerel meal in low fish meal diets on growth, feed availability, and biochemical composition of olive flounder (Paralichthys olivaceus) and economic analysis

AbstractManipulation effects of jack mackerel meal (JMM) in the low fish meal (FM) diets substituting 50% FM with meat meal (MM) on growth performance of olive flounder and economic analysis were determined. Seven experimental diets were created. The control (Con) diet contained 60% FM. In the other diets, 50% of the FM level used for the Con diet was substituted with MM, and then graded levels (0, 10, 20, 30, 40, and 50%) of JMM were included at the expense of FM, named the MJ0, MJ10, MJ20, MJ30, MJ40, and MJ50 diets, respectively. The experimental diets were distributed to triplicate groups of fish. A total of 525 fish was divided into 21 flow‐through tanks. Fish were hand‐fed to apparent satiation for 8 weeks. Weight gain, specific growth rate (SGR), and feed consumption of fish fed the Con diet were comparable with fish fed the MJ20, MJ30, MJ40, and MJ50 diets. Weight gain, SGR, and feed consumption of fish linearly improved with JMM inclusion levels in the low FM diets replacing 50% FM with MM. The strong correlation between isoleucine and lysine content among essential amino acids in the experimental diets versus weight gain, SGR, and feed consumption of olive flounder were observed. Dietary treatments did not influence feed utilization, chemical composition, and amino acid profiles of fish. Incorporated 20%–50% JMM as an effective feed attractant and enhancer in the low FM diets replacing 50% FM with MM achieved comparable weight gain, SGR, and feed consumption to fish fed a 60% FM‐based diet. Finally, the MJ50 diet led to the highest economic profit index (EPI) for farmers.

Genome-wide SNP analysis coupled with geographic and reproductive-phenological information reveals panmixia in a classical marine species, the Japanese jack mackerel (Trachurus japonicus)

Identification of genetic population structures in classical marine species—species with large population sizes, wide range distributions, and high dispersal potential—can be a challenging task because of expectedly weak genetic signals of population structure. The Japanese jack mackerel, Trachurus japonicus, is a classical marine species and one of the most important fishery resources in the East Asian seas. In this study, we tested the hypothesis of genetic panmixia in the Japanese jack mackerel using genome-wide SNP analyses coupled with geographic and reproductive phenology information. We generated a highly contiguous genome assembly and performed Genotyping by Random Amplicon Sequencing-Direct (GRAS-Di) to produce at least 19,904 SNPs that were genotyped in 614 samples from seas around the Japanese archipelago. Genetic population structure analyses did not reveal any evidence of genetic differentiation. Neither geographical barriers in the Japanese archipelago nor phenological differences in reproductive timing affected the genetic population structure. Overall, these findings were consistent with the interpretation of genetic panmixia, providing evidence for high genetic connectivity across the population’s distribution. Considering the current knowledge about the distribution and life history of T. japonicus, we suggest that the panmictic status may reflect a metapopulation structure with source-sink dynamics and/or extensive gene flow across the distribution range.

Inclusion Effect of Various Levels of Jack Mackerel Meal in Olive Flounder (Paralichthys olivaceus) Diets Substituting 50% Fish Meal with Duck By-Product Meal on Growth and Feed Utilization.

This experiment was performed to evaluate the inclusion impact of various levels of jack mackerel meal (JMM) in olive flounder (P. olivaceus) feeds substituting 50% FM by duck by-product meal (DBM) on growth, feed availability, and economic efficiency. Seven experimental diets were prepared. The control (Con) diet contained 60% FM. Fifty percent FM in the Con diet was substituted with DBM, and then the graded levels (0%, 10%, 20%, 30%, 40%, and 50%) of JMM were added instead of FM, named the DJ0, DJ10, DJ20, DJ30, DJ40, and DJ50 diets, respectively. All feeds were assigned to triplicate fish groups. At the end of 56 days' feeding, fish fed the DJ40 and DJ50 diets exhibited comparable weight gain and specific growth rate to fish fed the Con diet. Higher feed consumption was observed in fish fed the Con, DJ40, and DJ50 diets compared to fish fed the DJ0 and DJ10 diets. Lower feed conversion ratio was observed in fish fed the Con diet compared to fish fed the DJ0, DJ10, DJ20, and DJ30 diets. Furthermore, the DJ50 diet led to the highest economic profit index (EPI). In conclusion, inclusion of 50% JMM in the olive flounder diet replacing 50% FM with DBM seems to be the most recommendable dietary treatment based on growth and feed consumption of olive flounder and EPI.

Inclusion effect of jack mackerel meal in diets substituting fish meal with corn gluten meal on growth and feed utilization of olive flounder (Paralichthys olivaceus)

Inclusion effect of jack mackerel meal in diets substituting fish meal with corn gluten meal on growth and feed utilization of olive flounder (Paralichthys olivaceus)

Inclusion effect of jack mackerel meal in olive flounder (Paralichthys olivaceus) diet substituting blended fish meal with tuna by-product meal on growth, feed availability, and economic efficiency

The low fish meal (FM) diet commonly causes deteriorated palatability, and eventually leads to lowered feed consumption and growth performance of fish. This study was, therefore, designed to determine inclusion impact of the graded levels of jack mackerel meal (JMM) in olive flounder (P. olivaceus) diets replacing 50% FM with tuna by-product meal (TBM) on growth, feed availability, biochemical composition, blood chemistry, and economic efficiency. Six isonitrogenous (55.5%) and isolipidic (10.0%) diets were formulated. Sixty percent FM was incorporated in the control (Con) diet. In the Con diet, fifty percent of FM was replaced by TBM, and then 10, 20, 30, 40, and 50% JMM were included at the cost of FM, referred as the TJ10, TJ20, TJ30, TJ40, and TJ50 diets, respectively. Three hundred and sixty juvenile fish (18.0 ± 0.01g; mean ± SD) were delivered into 18, 50-L flow-through tanks. All diets were randomly assigned to triplicate groups of fish. Fish were hand-fed to apparent satiation twice daily for 56 days. Weight gain, specific growth rate, and feed consumption of fish fed the TJ30, TJ40, and TJ50 diets were significantly (P < 0.001, P < 0.001, and P < 0.002, respectively) greater than those of fish fed the Con and TJ10 diets, but not significantly (P > 0.05) different from those of fish fed the TJ20 diet. Feed utilization, proximate composition, amino acid profiles, and blood chemistry of fish were not significantly (P > 0.05) altered by dietary treatments. However, the TJ30 diet was the most recommendable to farmers in terms of economic profit index (EPI). Conclusively, 30% inclusion of JMM is the most recommendable in the olive flounder diet substituting 50% FM with TBM based on growth performance, feed availability, and EPI.

Impact on Growth and Feed Availability from Including Jack Mackerel (Trachurus japonicas) Meal in Rockfish (Sebastes schlegeli) Feeds Which Otherwise Replace Fish Meal with Chicken By-Product Meal.

This study was conducted to elucidate the impact on the growth and feed availability of rockfish (Sebastes schlegeli) from including jack mackerel meal (JMM) in feeds which otherwise substitute 20% fish meal (FM) with chicken by-product meal (CBM). Six formulated feeds were designed to be isonitrogenous and isolipidic. Specifically, 55% FM was included in the control (Con) diet. In the Con diet, 20% FM was substituted by CBM, and then the graded levels (0, 20, 40, 60, and 80%) of JMM were included instead of FM, named as the C20J0, C20J20, C20J40, C20J60, and C20J80 diets, respectively. Five hundred and forty juvenile rockfish (initial weight of 11.2 g) were assigned to 18 tanks. All experimental feeds were fed to triplicate groups of rockfish twice daily for 8 weeks. Superior weight gain, specific growth rate (SGR), and feed intake of rockfish fed the C20J60 and C20J80 diets compared to rockfish fed the Con and C20J0 diets were observed. However, the feed utilization, biological indices, proximate composition, amino acid profiles, and blood chemistry of the rockfish were not affected by the dietary treatments. The slightly but not significantly higher economic profit index and growth performance were obtained in the C20J60 diet compared to the C20J80 diet. In conclusion, the C20J60 diet was the most recommendable treatment based on the improvement in growth performance (weight gain and SGR) and feed intake of rockfish, and the highest economic return to farmers.

Innovation in the quest for compatibility: Interplay of jurisdiction and allocation in the South Pacific Regional Fisheries Management Organisation

This paper explores how the legal obligation that management measures for straddling stocks in the high seas and for areas under national jurisdiction must be ‘compatible’ is interpreted within the forum of Regional Fisheries Management Organisations, by considering the example of the ongoing conflict over allocation of jack mackerel (Trachurus murphyi) managed by the South Pacific Regional Fisheries Management Organisation (SPRFMO). To do so, the paper presents the innovative framework through which to realise compatibility set forth by the treaty instituting SPRFMO, the Convention on the Conservation and Management of High Seas Fishery Resources in the South Pacific Ocean, together with the practice implementing these provisions as seen in the annual SPRFMO jack mackerel management measure. This measure has evolved as coastal States Chile and Ecuador have consented over time to apply the measure in the areas under their national jurisdiction, and as it has been used to urge coastal State Peru to ensure measures under its area of jurisdiction are compatible with those in the SPRFMO measure. Methodologically, the paper draws from a mix of doctrinal analysis of international treaties alongside document analysis of SPRFMO Commission meeting reports, management measures, and reports of the SPRFMO Review Panel, enriched through interviews with persons with experience of the workings of SPRFMO. Ultimately, the paper grapples with the challenges in interpreting and applying the legal obligation of compatibility within the political context of allocation decisions by a Regional Fisheries Management Organisation such as SPRFMO.

The impact of ocean warming on selected commercial fisheries in New Zealand

AbstractWarming oceans affect the growth, reproduction and location of fish species. Using a bioeconomic framework, we estimate the relationship between sea surface temperature (SST) and the catch of de facto open‐access commercial fisheries of flatfish, trevally and jack mackerel in New Zealand. Assuming either a logarithmic or quadratic relationship between the SST and the carrying capacity of the fish stock, we consider three fishing methods (bottom trawl, set net and midwater trawl) and two measures of effort (count and duration). We show that ocean warming results in an increase in catch for all species if we assume a logarithmic relationship, with the highest marginal product of SST () for jack mackerel caught using midwater trawl. The highest marginal revenue product (computed by the MPSST, current price and fished area) is found for flatfish caught by set net. However, when assuming a quadratic relationship, there is a threshold above which catch starts to decrease, with the maximum catch of species ranging between 10 and 12.2°C. These results also vary spatially, with higher values of MPSST observed in areas closer to the South Pole. Our findings are relevant for any review of fisheries management systems in response to ocean warming.

Combined stomach contents and stable isotope analysis reveal feeding habits of Japanese jack mackerel (Trachurus japonicus) in the East China Sea

Japanese jack mackerel (Trachurus japonicus) is an economically important pelagic fish in the East China Sea. Knowledge is still limited regarding the feeding habits of this species in this area. Based on bottom trawl surveys conducted in the southern coastal area of Zhejiang during August in 2019 and 2020, we analyzed the feeding ecology of T. japonicus using stomach contents analysis and the stable isotope approach. The results indicated that the δ13C value for T. japonicus ranged from − 17.72 % to ;−14.30 %, and the δ15N value ranged from 10.89 % to 13.03 %. Two-way analysis of variance indicated significant annual and ontogenetic variations in the δ13C value, thereby suggesting changes in the final nutrient sources for T. japonicus in different growth stages and years. The trophic level of T. japonicus was estimated as from 3.35 to 4.46. In general, the trophic level of T. japonicus increased with growth, although the ontogenetic variation was not significant. The main food groups identified for T. japonicus based on stomach contents analysis were fish, shrimp, crabs, cephalopods, and small crustaceans. The results obtained by stable isotope analysis showed that the nutrient contribution rate of small crustaceans to the diet of T. japonicus was highest in both years, followed by shrimp. The feeding habits of T. japonicus had obvious ontogenetic variations, and the average contribution of fish species increased as the size of the predator increased. The results obtained in this study provide detailed feeding information about T. japonicus in the East China Sea.

Patterns of variability of species composition of catches from the russian fishing vessels in the south-eastern Pacific ocean for 2015–2022

The work provides information on the patterns of species composition of catches from the Russian fishing vessels conducted fishing of jack mackerel (Trachurus murphyi Nichols 1920), chub mackerel (Scomber japonicus Houttuyn 1782) and redbait (Emmelichthys spp.) in the South-Eastern Pacific Ocean outside the economic zones of the coastal States. According to scientific observations, an analysis of the composition of species caught by the Russian fishing vessels is given. When fishing in the pelagic zone over ocean depths, jack mackerel was the main target species, chub mackerel formed the bycatch. At the same time, the proportion of chub mackerel in catches in the northern parts was higher than in the southern ones. When fishing on seamounts of the Nazca Ridge, catches were dominated by redbait with jack mackerel and alfonsino (Beryx splendens Lowe, 1834) as bycatch. According to the similarity of the species composition of catches, three areas – 1) all the Southern and Central subareas and part of the Northern subarea; 2) seamounts of Nazca ridge; 3) part of the Northern subarea near the border of the EEZ of Peru between 17–20°S, were singled out using the cluster analysis method.

Effects of Dietary Inclusion of a Crude Protein Source Exhibiting the Strongest Attractiveness to Red Sea Bream (Pagrus major) on Growth, Feed Availability, and Economic Efficiency.

Dietary incorporation of an attractive feed protein source is a practical method of enhancing feed intake and consequently improving the growth of fish. The attractiveness of 18 crude protein sources to juvenile red sea bream (Pagrus major) and the effects of the dietary inclusion of the crude protein source that exhibited the strongest attractiveness on growth, feed availability, and economic efficiency were determined. Jack mackerel meal (JMM) showed the strongest attractiveness to red sea bream among 18 crude protein ingredients. In an 8-week feeding trial, 810 juveniles were randomly distributed into 27 tanks (30 fish/tank). Nine experimental diets were prepared. The control (Con) diet included 60% fish meal (FM). Various levels (1, 3, 5, 10, 20, 40, 60, and 100%) of JMM were included at the expense of FM in the Con diet, and the resulting diets were named the JMM1, JMM3, JMM5, JMM10, JMM20, JMM40, JMM60, and JMM100 diets, respectively. Fish were hand-fed to apparent satiation twice daily for 8 weeks. The weight gain, specific growth rate, and feed consumption of red sea bream that were fed the JMM40, JMM60, and JMM100 diets were significantly (p < 0.0001 for all) higher than those of the fish fed all other diets. However, dietary JMM inclusion had no remarkable impacts on the feed utilization, biological indices, and chemical composition of the whole body of red sea bream. In terms of the economic view of the study, the economic profit index of red sea bream fed the JMM40, JMM60, and JMM100 diets was significantly (p < 0.0001) greater than that of the fish fed all other diets. In conclusion, the strongest attractiveness to red sea bream among 18 crude protein sources was observed in JMM. The inclusion of more than 40% JMM at the expense of FM in the diet of red sea bream is highly recommended for practical feed formulations to induce remarkable improvement in the growth performance of fish and the economic returns for farmers.

Substitution effect of fish meal with various plant protein sources on growth performance and feed utilization in rockfish (Sebastes schlegeli) diets including jack mackerel meal used as feed stimulants

Incorporating feed stimulants and attractants in low fish meal (FM) diets is a very effective way to improve palatability and increase feed intake and fish growth. This research aims to elucidate the substitution impact of different levels of FM with various plant proteins in diets with jack mackerel meal (JMM) inclusion as feed stimulants on the growth and feed utilization of rockfish (Sebastes schlegeli). A two-way (2 substitution levels [25% and 50%] × 3 substitution sources [corn gluten meal (CGM), soybean protein concentrate (SPC), and corn protein concentrate (CPC)]) ANOVA experimental design was adopted. In total, 525 fish averaging 8.3 g were assigned to 21 tanks (25 juvenile/tank). Seven isoprotetic and isolipidic feeds were formulated. The control (Con) diet contained 55% FM. CGM, SPC, and CPC were replaced for 25% and 50% FM in the Con diet, and then 22% JMM as feed stimulants was included at the cost of FM, named as the CGM25, CGM50, SPC25, SPC50, CPC25, and CPC50 diets, respectively. All diets were assigned to triplicate groups of rockfish. Rockfish were hand-fed to apparent satiation twice a day for 8 weeks. Rockfish fed the 25% FM substitution diets achieved superior (p &amp;lt; 0.0001 for both) weight gain and specific growth rate (SGR) compared to rockfish fed the 50% FM substitution diets, while rockfish fed the CGM-replaced diets achieved superior (p &amp;lt; 0.0001 for both) weight gain and SGR compared to rockfish fed the SPC- and CPC-replaced diets. The weight gain and SGR of rockfish fed the Con and CGM25 diets were superior to rockfish fed all other diets. Rockfish fed the 25% FM substitution diets achieved superior (p &amp;lt; 0.0001 for both) feed efficiency (FE) and protein efficiency ratio (PER) compared to rockfish fed the 50% FM substitution diets, while rockfish fed the CGM-replaced diets achieved superior FE and PER compared to rockfish fed the CPC-replaced diets. Rockfish fed the 25% FM substitution diets led to superior (p &amp;lt; 0.0001) protein retention (PR) compared to rockfish fed the 50% FM substitution diets. The biological indices, proximate composition, and amino acid profiles of the whole body, as well as the plasma and serum parameters of rockfish, were not changed by either substitution level or substitution source. In conclusion, the replacement of CGM for 25% FM in the rockfish diet with JMM inclusion can be made without deteriorating growth performance, feed consumption and utilization, biochemical composition, and plasma and serum parameters.

Feeding Habits of Jack Mackerel, Trachurus japonicus, in the Coastal Waters of South Sea, Korea

Feeding Habits of Jack Mackerel, Trachurus japonicus, in the Coastal Waters of South Sea, Korea

Extraction of neutral lipids and phospholipids from marine biomasses using subcritical and supercritical fluids

Supercritical carbon dioxide (scCO2) and subcritical dimethylether (DME) were used to extract lipids from partially to fully dry marine biomass - whole jack mackerel (WJM), Hoki frames and heads (HFH), and Greenshell mussel meat (GSM). scCO2 gave a lower extraction yield of total lipids from GSM (42%) compared to WFH and HFH (86 - 88% yield) due to the higher concentration of phospholipids present in GSM. DME gave a higher extraction yield of total lipids and phospholipids than scCO2 for all marine biomass types. Phospholipid yield from GSM using DME was dependent on moisture content of the feed marine biomass and decreased with decreasing moisture content. Our results suggested that phospholipid extraction yield can be optimised by partly drying biomass to 30 - 50% moisture prior to extraction. DME extracts contained good levels of omega-3 fatty acids with minimal hydrolytic phospholipid degradation, thus providing a potential processing technology option to recover them from marine biomass.

Panorama actual de la pesca ribereña en la desembocadura del río Actopan, Chachalacas, Veracruz (periodo 2014-2023)

Currently, human activities such as tourism, human settlements, agricultural and industrial activities have generated an alteration of the biological communities associated with the coastal zone, particularly fish communities. The coastal zones of the State of Veracruz in the Gulf of Mexico are characterized by their high biodiversity and include a great variety of fishery resources, occupying fourth place in national fish production. However, there are no recent records on the ichthyofauna of the area of Chachalacas, Veracruz. In the present study, 12 samplings were carried out from February 2014 to March 2023 at the mouth of the Actopan River in both the marine and brackish water zones. Twenty species were recorded, highlighting the white jack mackerel (Carax latus), snook (Centropomus undecimalis), ocellated croaker (Sciaenops ocellatus) and mullet (Mugil liza), as frequent species, in all sampling periods, being the latter. The mullet is the only species that has remained relatively constant in terms of the abundance of organisms caught, in contrast to the white jack mackerel, which has reduced its abundance in the area. In addition, in relation to the cpue, there is a constant decrease over the years. The results of this study will help lay the groundwork for designing management plans for fishery resources in the area of Chachalacas, Veracruz. Key words: Ichthyofauna, Biodiversity, Fishing, Veracruz, CPUE

Hydrophobic natural deep eutectic solvents for marine lipid extraction

Abstract‘Type V' natural deep eutectic solvents (TV NADES) are a novel class of solvent media with many potential ‘green chemistry’ applications. Here, we assess the potential of two TV NADES: menthol:carvacrol (M:C) and menthol:thymol (M:T), and a single terpenoid extraction media carvacrol (C), as media from total lipid extraction of three compositionally diverse, freeze‐dried marine tissues: hoki (Macruronus novaezelandaiae), jack mackerel (Trachurus declivis) and green‐lipped mussel (kuku, Perna canaliculus). Room temperature extraction yields into these media were benchmarked relative to lipid yields from chloroform‐methanol‐water extractions. Relative extraction yields using the M:C and M:T media were (both) 87% for jack mackerel, 85%–87% for hoki, and 43%–47% for green‐lipped mussels. Comprehensive chemical analyses of TV NADES lipid extracts suggested that neutral lipids were extracted in greater yield than phospholipids, and that phosphatidylinositol, lysophospholipids and (in the case of mussels) ceramideaminoethylphosphonates were particularly resistant to extraction into C, M:C and M:T. C—a thymol isomer that, unlike menthol and thymol is a liquid at room temperature—appeared to perform (marginally) better than M:C and M:T systems, implying there may be no advantage to using the TV NADES over a single terpenoid with similar chemistry for total lipid extraction.

Marine megafauna interactions with the Peruvian artisanal purse-seine fleet

Bycatch is a global problem for marine megafauna. Peru is a major fishing nation known in particular for its industrial purse-seine fishery for the Peruvian anchovy (Engraulis ringens). However, Peru also has an artisanal purse-seine fishery for this same resource and other species such as Pacific bonito (Sarda chiliensis), Pacific chub mackerel (Scomber japonicus) and Chilean jack mackerel (Trachurus murphyi) used for human consumption. While there is limited documentation of bycatch of megafauna by the industrial purse-seine fishery, there is no similar information for the artisanal purse-seine fishery. Therefore, this study aimed to assess the marine megafauna (small-cetaceans, seabirds, sea turtles, and elasmobranchs) bycatch interactions of the Peruvian artisanal purse-seine fishery for consumption for the year 2019 (before the COVID-19 pandemic) through interviews with artisanal fishers in 5 landing ports (San Jose, Santa Rosa, Callao, Pucusana, and San Andres). We found that these fisheries had bycatch with all taxa groups, with dusky dolphins (Lagenorhynchus obscurus), guanay cormorants (Leucocarbo bougainvilliorum) and eagle rays (Myliobatis spp.) having the highest quantity and most frequently reported bycatch. Multiple correspondence analysis (MCA) indicated an association between the bycatch of 1–3 common dolphins (Delphinus spp.) per set from the northern ports (San Jose and Santa Rosa) and vessels of 20–36 MT. Likewise, a relationship was found between smooth hammerhead sharks (Sphyrna zygaena) and vessel storage capacity, with a similar result reported for the bycatch of humpback smoothhounds (Mustelus whitneyi). In addition, a relationship of eagle ray (Myliobatis spp.) bycatch with a landing port was identified, and several respondents mentioned catching more than 1 MT per set. Fifty-three percent of fishers considered bycatch to be a problem, mainly because it wastes their time during fishing operations. This preliminary study is the first research that demonstrates bycatch in artisanal purse-seine in Peru and can serve as a baseline for future research. We also highlight the need to quantify bycatch rates of marine megafauna using additional methodologies, such as monitoring with onboard observers.