Trachurus Murphyi Research Articles

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).

Molecular identification and prevalence of plerocercoid larvae (Cestoda: Diphyllobothriidae) in some commercial fish species from Peru.

Diphyllobothriosis, a fish-borne zoonosis in South America, is mainly caused by the Pacific broad tapeworm Adenocephalus pacificus Nybelin, 1931, a parasite of considerable concern in fishery resources due to its impact on public health. A new diphyllobothrid, Diphyllobothrium sprakeri Hernández-Orts et al. Parasites Vectors 14:219, 2021, was recently described from sea lions from the Pacific Coast, but marine fish acting as intermediate hosts are unknown. The objective of this study was to confirm the presence of plerocercoid larvae of Diphyllobothriidae Lühe, 1910 (Cestoda: Diphyllobothriidea) in nine fish species of commercial importance in Peru. Of a total of 6999 fish (5861 Engraulis ringens, 853 Sciaena deliciosa, 6 Sciaena callaensis, 171 Scomber japonicus, 40 Trachurus murphyi, 40 Ariopsis seemanni, 18 Merluccius peruanus, 5 Sarda chiliensis, and 5 Coryphaena hippurus), 183 were infected with plerocercoid larvae, representing a total prevalence of 2.61% and a mean intensity of 3.2. Based on mtDNA cox1 sequences of 43 plerocercoids, a phylogenetic analysis revealed that 41 belong to A. pacificus and two to D. sprakeri. These findings are first molecular data for D. sprakeri larvae, and the infections of E. ringens and T. murphyi by plerocercoid larvae represent the first records of intermediate/paratenic hosts for this species. Hence, the findings of the current study enhance our understanding of the presence of diphyllobothriid species in commercial fish from the Southeastern Pacific Ocean and their potential impact on seafood safety for local human populations.

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.

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.

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.

Population Genetics of Chilean Jack Mackerel, Trachurus murphyi Nichols, 1920, (Pisces, Carangidae), in Waters of the South Pacific Ocean

Estimating genetic diversity and population structure with polymorphic markers might provide information for the better management of fish that have economic importance. We used the Chilean jack mackerel, Trachurus murphyi, a pelagic species distributed in the south Pacific Ocean, to test the population genetic structure across its distribution. A total of 522 samples were collected from 11 locations in 2008, to be analyzed using six loci microsatellites. We conducted traditional genetic analyses to describe the genetic diversity of T. murphyi and whether it shows spatial genetic structure. The results showed a high genetic diversity across locations (Ho = 0.551 to 0.980; He = 0.676 to 0.959). Estimates for the population structure showed a low and non-significant pairwise FST in all comparisons. We supported the non-genetic differentiation previously reported with the used microsatellite panel. Further comparative temporal studies should be conducted to identify the stability of this pattern. Overall, this study reinforces the hypothesis that, in the Pacific Ocean, Chilean jack mackerel correspond to a large single population.

Remote Sensing of the Subtropical Front in the Southeast Pacific and the Ecology of Chilean Jack Mackerel Trachurus murphyi

The Subtropical Front (STF) plays a key role in the ecology of Chilean jack mackerel Trachurus murphyi. Nonetheless, there are few remote sensing studies of the STF in the open Southeast Pacific, and almost all of them have been conducted by satellite oceanographers in Russia and Ukraine to support respective large-scale fisheries of jack mackerel in this region. We reviewed these studies that documented long-term seasonal and interannual variability of the STF from sea surface temperature (SST) and sea surface height (SSH) data. We also mapped the STF from satellite sea surface salinity (SSS) data of the SMOS mission (2012–2019). The Subtropical Front consists of two fronts–North and South STF about 500 km apart–that border the Subtropical Frontal Zone (STFZ) in-between. The STF is density-compensated, with spatially divergent manifestations in temperature and salinity. In the temperature field, the STF extends in the WNW to ESE direction in the Southeast Pacific. In the salinity field, the STFZ appears as a broad frontal zone, extending zonally across the entire South Pacific. Three major types of satellite data-SST, SSH, and SSS-can be used to locate the STF. The SSH data is most advantageous with regard to the jack mackerel fisheries, owing to the all-weather capability of satellite altimetry and the radical improvement of the spatial resolution of SSH data in the near future. Despite the dearth of dedicated in situ studies of the South Pacific STFZ, there is a broad consensus regarding the STFZ being the principal spawning and nursing ground of T. murphyi and a migration corridor between Chile and New Zealand. Major data/knowledge gaps are identified, and key next steps are proposed to mitigate the data/knowledge gaps and inform fisheries management.

Synchronous spatio-temporal changes in potential habitats of Trachurus murphyi and Dosidicus gigas off Chile in relation to regime shift of Pacific decadal oscillation

Understanding concurrent responses of habitat pattern of pelagic fish species to climate variability is favorable for sustainable exploitation and fisheries management. In this study, the key environmental factors affecting Dosidicus gigas (sea surface salinity (SSS), sea surface height anomaly (SSHA) and water temperature at 400 m (Temp_400m), and Trachurus murphyi (sea surface temperature (SST), mixed layer depth (MLD) and Temp_400m), were used in combination with the Pacific Decadal Oscillation (PDO) index to examine synchronous habitat variations off Chile based on habitat suitability index model (HSI). All environmental factors were significantly related to the PDO. A significantly negative relationship was found between the HSI of D.gigas and the PDO index, while a significantly positive correlation was observed in the HSI of T.murphyi. In the warm PDO regime, MLD was shallower, SST increased, and SSHA decreased from the northeast to the southwest off Chile. SSS and Temp_400m in northern waters off Chile were higher than those in southern waters. The suitable habitats of D.gigas contracted and shifted southwestward. While the area and distribution of T.murphyi changed little, but its habitat quality enhanced. In the cold PDO regime, SST and SSHA decreased, and MLD deepened. Variations in SSS and Temp_400m were consistent with those in the warm PDO regime. The suitable habitats of D.gigas enlarged and moved northeastward. Whereas the suitable habitats of T.murphyi slightly reduced with small change occurred with its spatial location. Our findings suggested that the PDO played important roles in the long-term concurrent habitat variations of Chilean T.murphyi and D.gigas.

Tandem mass tag-based proteomics analysis of protein changes in the freezing and thawing cycles of Trachurus murphyi.

We investigated the proteome variations in Trachurus murphyi with different cycles of freezing and thawing (FT) under frozen storage. A total of 2,482 proteins were assessed quantitatively, of which 269 proteins were recognized as differential abundance proteins during the second FT cycle until the eighth FT cycle. Bioinformatics analysis on gene ontology (GO) functional annotation and Kyoto Encyclopedia of Genes and Genomes pathway analyses of Differential Analysis of Proteins (DAPs) indicated multiple DAPs engaged with the protein structure, metabolic enzymes, and protein turnover. In addition, some of the observed proteins were probably the underlying markers of protein oxidation (PO). The analysis of PO sites revealed the sites of PO, such as amino adipic semialdehydes, γ-glutamic semialdehydes, and Schiff bases. Bioinformatics analyses demonstrated the involvement of differentially expressed proteins in the Hippo signaling pathway (Ko04390), indicating strong protein degradation with greater numbers of FT cycles under frozen storage. It provides an insight into quality stability from a proteomics quality perspective at the molecular level. The results obtained have deepened our current understandings of the mechanisms that reveal variations in proteomes and quality, as well as help promote quality control of T. murphyi across the cold transportation chain. PRACTICAL APPLICATION: Temperature fluctuation is one of the core issues during frozen food storage and distribution faced by the frozen food industry. Fluctuation may result in microstructural changes, ice recrystallization, and protein change in frozen food products. Tandem mass tag-based methods were adopted to study proteome variations in Trachurus murphyi muscles under different cycles of freezing and thawing under frozen storage conditions in this paper. The results obtained have deepened our current understandings of the mechanisms that reveal variations in proteomes and quality, as well as help promote quality control of T. murphyi across the cold transportation chain.

Bomb Radiocarbon, Otolith Daily Increments and Length Modes Validate Age Interpretations of Chilean Jack Mackerel (Trachurus murphyi)

Ages of Chilean jack mackerel (Trachurus murphyi) in the southern Pacific Ocean were validated using three methods: 1) daily microincrement readings in sagittal otoliths of young-of-the year (YOY) fish to validate the first annulus; 2) modal progression of strong year-classes (PSYC) to validate the first, second and third annuli, and 3) bomb radiocarbon analysis of otolith cores to validate the absolute age in older fish >38 cm fork length (FL). A Laird-Gompertz (LG) model was fitted to fork length (cm) at age (days) relationship in fish ranging from 3.4 to 25.0 cm FL and from 56 to 550 days in age. The LG model estimated a mean FL of 22 cm at the end of the first year of life, which was large compared with the mean FL estimated through conventional ageing in whole otoliths. The comparison between daily age with annual growth bands from whole otoliths, showed a false increment formed at 185 ± 34 days and a second translucent increment formed at 352 ± 79 days, corresponding to the first annulus for fish with the mean FL of 21.4 ± 1.8 cm. The PSYC coinciding with the recruits of 2008 (age 0), was tracked through three subsequent years with high accuracy, attaining 23, 27 and 30 cm FL in 2009, 2010 and 2011, respectively. These modes identified as age 1, age 2 and age 3 in the PSYC, matched to the mean length of fish with 2, 4 and 5 translucent increments in sagittal otoliths. Results from bomb radiocarbon analysis confirmed that most of the ages were correct, because the Δ14C content of adult otolith core matched the reference chronology. The absolute mean ages for the assayed otoliths, based on the comparison with the reference chronology, ranged from 7 to 13 years for sizes between 39 and 60 cm FL. The age validation for T. murphy as addressed in the current study provided crucial information for enhancing stock assessment output of this important transboundary commercial species.

Habitat Variations of Two Commercially Valuable Species Along the Chilean Waters Under Different-Intensity El Niño Events

The synchronous response of the spatial distribution pattern of Dosidicus gigas and Trachurus murphyi habitat along the Chilean waters to different-intensity El Niño events was examined based on the habitat suitability index (HSI) models inclusive with the key environmental factors of sea surface height anomaly (SSHA), sea surface salinity (SSS), water temperature at 400-m depth (Temp_400 m) for D. gigas, sea surface temperature (SST), mixed layer depth (MLD), Temp_400 m for T. murphyi, and Niño 1 + 2 index. Results showed that all the environmental factors except MLD were significantly correlated with the Niño 1 + 2 index. Compared with weak (WE) and moderate (ME) El Niño events, the suitable range of SSHA and SSS for D. gigas decreased, resulting in a decreased suitable habitat area and increased poor habitat area during the strong (SE) El Niño years. In space, the suitable habitat of D. gigas was mainly distributed in north-central Chile with an east–west strip pattern; it decreased significantly in the northwestern waters off Chile and moved southwestward under SE El Niño events. For T. murphyi, the ME El Niño events yielded a contracted suitable range of water temperature and MLD decreased, consequently leading to a decreased suitable habitat area and increased poor habitat area of T. murphyi compared to WE and SE El Niño events. The suitable habitat of T. murphyi was mainly distributed in the 42°–47°S area and varied non-significantly during the WE and SE El Niño events; however, it clearly decreased in the southwest area of Chile and shifted northeastward under ME El Niño events. Our results indicated that El Niño events with different intensities strongly affected the habitat pattern of D. gigas and T. murphyi off Chile by changing the regional marine environment.

Safeguarding Seafood Security, Marine Biodiversity and Threatened Species: Can We Have Our Fish and Eat It too?

The ocean contains an abundance of biodiversity that is vital to global food security. However, marine biodiversity is declining. Marine protected areas and marine reserves have been used to protect biodiversity, conserve threatened species and rebuild exploited species, but are perceived as restrictive to fishing, which has slowed progress towards ocean protection targets. Here, we perform a spatial prioritisation of the ocean to protect biodiversity, threatened species and food security. Food security was quantified using catch in tonnes per km2, per 0.5-degree cell of the ocean, using data from the Sea Around Us, a global database of industrial, artisanal, subsistence, and recreational fishing catches. Using Representative Biodiversity Areas [RBAs (the top 30% of the ocean based on holistic measures of biodiversity)], maps of 974 threatened species, and catch data for 2,170 exploited species, we find that these multiple, competing objectives are achievable with minimal compromise. Protecting 30% of the ocean using a multi-objective solution could protect 89% of RBAs, 89% of threatened species and maintain access to fishing grounds that provide 89% of global catch. Even when prioritising food security above conservation objectives we find significant protection for biodiversity and threatened species (85% RBAs, 73% threatened species). We highlight four exploited species for improved management, as they are consistently caught in areas of high conservation importance (skipjack tuna,Katsuwonus pelamis; yellowfin tuna,Thunnus albacares; Atlantic cod,Gadus morhua; Chilean jack mackerel,Trachurus murphyi). We show that a globally coordinated approach to marine conservation and food security is necessary, as regional scale strategies are shown to be less efficient and may result in conflict between food security and conservation objectives. Our results add support for calls to protect 30% of the ocean by 2030, and show where protection would best protect food security and conserve biodiversity and threatened species.

Spatial and Temporal Variability of Parasite Communities: Implications for Fish Stock Identification

The spatial and temporal variability of parasite communities have received little attention when used as biological tags for identifying fish stocks. This study evaluated the potential spatial and temporal variability of the parasite communities affecting three marine fish species collected between 1993 and 2017. To avoid the potential effect of host age in parasite communities, individuals of similar ages were selected: 1123 Engraulis ringens (12–24 months old), 1904 Trachurus murphyi (24–36 months old), and 630 Merluccius gayi (36–48 months old). Most taxa show differences in the prevalence at the spatial and temporal scales, but the prevalence of some larval endoparasites remains constant at the temporal scale. At the spatial scale, an analysis of similarity (ANOSIM) showed differences in the parasite communities of three species; a canonical analysis of principal coordinates (CAP) showed low values of correct allocations (CA; ≈50%) and values of allocation due to chance (AdC) were lower than the CA. At the temporal scale, an ANOSIM showed differences between the three species. A CAP showed low values of CA (≈50–60%) and the AdC was always lower than CA. Samples at the spatial scale were well allocated to their localities or nearby localities, suggesting a spatial stability. Samples from different years were not well discriminated, suggesting temporal variability. Therefore, in studies regarding parasites as a tool for stock identification, temporal variability must be taken into account.

Concurrent habitat fluctuations of two economically important marine species in the Southeast Pacific Ocean off Chile in relation to ENSO perturbations

AbstractENSO‐driven concurrent habitat fluctuations of two economically important marine species jumbo squid Dosidicus gigas and jack mackerel Trachurus murphyi in the Southeast Pacific Ocean off Chile during 1950–2017 were examined using a habitat suitability index (HSI) modeling approach. The optimal HSI models sourced from 10 weighing‐based scenarios were developed, selected and validated using the crucial factors water temperature at 400 m depth (Temp_400m), sea surface height anomaly (SSHA) and sea surface salinity (SSS) for D. gigas and sea surface temperature (SST), Temp_400m, and mixed layer depth (MLD) for T. murphyi. Results suggested that the optimal HSI model could accurately predict the habitat hotspots for D. gigas and T. murphyi. The ENSO event (indicated by Niño 3.4 index, NI) was significantly related to environmental conditions off Chile. Cross‐correlation revealed positive relationships between NI and SST, SSHA, SSS, and Temp_400m and negative correlation between NI and MLD. Synchronous opposite habitat fluctuations were shown between D. gigas and T. murphyi under different ENSO events. The NI was significantly negatively related to the HSI of D. gigas and positively correlated with the HSI of T. murphyi. Comparing with the El Niño years, suitable habitats of D. gigas and T. murphyi dramatically enlarged and contracted, respectively, during the La Niña years. Both suitable habitats moved southwestward under this climate conditions. Our finding suggested that ENSO‐driven environmental changes played important roles in the concurrent habitat fluctuations of D. gigas and T. murphyi. Such studies are conducive to the effective utilization and management of multiple related species.

The effect of multiple freeze–thaw cycles on protein oxidation and quality of Trachurus murphyi

In this study, we investigated the changes in protein oxidation and quality of Trachurus murphyi due to repeated freezing and thawing (F-T) during refrigerated storage using physicochemical and texture profile analysis. The results showed that protein oxidation occurred through the formation of carbonyl groups and reduction in sulfhydryl content and Ca2+-ATPase activity. The oxidative modifications in myofibrillar protein gels were evaluated using SDS-polyacrylamide gel electrophoresis that observed along with a decrease in the intensity of the 75, 48, and 35 kDa bands. Color, water migration, and texture profile were used to evaluate the quality of T. murphyi. As shown by the Atomic force microscopy analysis (AFM) results, the length of myofibrils in the sample increased with freeze–thawing from 1.08 µm at the second cycle of the freezing and thawing (F-T 2) to 1.54 µm at the eighth cycle of the freezing and thawing (F-T 8), whereas the height of myofibrils decreased from 111.8 to 74.87 nm. Raman spectroscopy further revealed that the α-helix content was reduced, along with the contents of β-turns, β-sheets, and random coils of myofibrillar protein with increasing freeze–thaw cycles. These results indicated that multiple freezing–thawing decreased T. murphyi quality during refrigerated storage. Practical applications The study was performed to investigate the effect of freeze–thaw cycles on the protein oxidation and quality of T. murphyi. We provided the method of the evaluation for the oxidation and the quality of freeze and thaw fish, and a theoretical basis for freezing and thawing fish products.

The Effect of Multiple Freeze-Thaw Cycles on the Microstructure and Quality of Trachurus murphyi.

Temperature fluctuation in frozen food storage and distribution is the perpetual and core issue faced by the frozen food industry. Ice recrystallisation induced by temperature fluctuations under cold storage causes microstructural changes in fish products and irreversible damages to cells and tissues, which lower the frozen fish quality in the food chain. This study is intended to explore how repeated freezing–thawing affected the microstructure and quality of Trachurus murphyi during its frozen storage. The results showed the consistency between the increase in ice crystal diameter, volume, and porosity in frozen fish and the increase in centrifugal loss (from 22.4% to 25.69%), cooking loss (from 22.32% to 25.19%), conductivity (from 15.28 Ms/cm to 15.70 Ms/cm), TVB-N (from 16.32 mg N/100 g to 19.94 mg N/100 g), K-value (from 3.73% to 7.07%), and amino acid composition. The muscle structure change observed by Fourier-Transform Infrared spectroscopy (FT-IR) showed that the content of α-helix reduced from 59.05% to 51.83%, while the β-sheet fraction grew from 15.44% to 17.11%, β-turns increased from 5.45% to 7.58%, and random coil from 20.06% to 23.49%. Moreover, muscular structure exhibited varying degrees of deterioration with increasing cycles of freezing and thawing as shown by scanning electron microscopy (SEM). We studied the muscular morphology, which included the measurement of porosities (%) of pore that increased (from 1.4% to 4.3%) and pore distribution, by X-ray computed tomography (uCT). The cycles of the freeze–thaw resulted in structural changes, which seemed to be closely associated with ultimate quality of frozen fish products.

Individual growth in Jack mackerel (Trachurus murphyi) of the Southeastern Pacific Ocean using sagitta otolith weight, daily rings, and annual rings

We estimated the growth of Jack mackerel (Trachurus murphyi) using increments of daily growth, otolith weight and annual ring reading in sagittal otoliths. The daily micro-increments were used to fit ring density to the otolith radius (n = 4481) and then to estimate the age of the individual in days. The parameters of the von Bertalannfy growth equation were: maximum theoretical fork length, FL∞ = 75 cm; individual growth coefficient, K = 0.16 year-1; theoretical age at which fish length is zero, t0= –0.19 years. The growth parameters of T. murphyi estimated using annual rings reading were: K = 0.10 year-1, FL∞ = 74.7 cm, t0 = –0.50 years. The growth parameters estimated using otolith weight were: K = 0.15 year-1, FL∞ = 75.0 cm, t0 = –0.48 years. The parameter K estimated with the daily micro-increments was similar to the K estimated using sagittal otolith weights. We constructed a size-age key for T. murphyi using otolith weight, OW (milligrams) as a variable was: OW= 0.0323*t-15.197 (r2= 0.68). We recommend using otolith weight to estimate age in T. murphyi due to this technique is statistically reliable, but also cheap and fast.

Fishing specialization and the inland trade of the Chilean jack mackerel or jurel, Trachurus murphyi, in far southern Peru

Beginning by at least the Andean Middle Horizon (AD 600–1000), sites located more than 60 km inland from the Pacific coast in far southern Peru contain the remains of jack mackerel (Trachurus murphyi). The coastal region near the modern Peruvian city of Ilo was the habitat where people procured fish and transported them to sites in the Moquegua Valley. Abundant neurocranial fragments indicate that coastal occupants shipped whole fish, not processed body portions, to inland destinations. I previously interpreted the remains of jack mackerel as imported fishes indicating high status deposits, particularly at imperial administrative outposts associated with the Wari Empire. The recent identification of jack mackerel at highly provisional, agricultural sites inhabited by non-elite residents suggests that these fishes were everyday, rather than elite, fare. The analysis indicates that the pre-Hispanic inhabitants discontinued trade in marine fishes after the collapse of the politically integrated empires in the region, but people reestablished fish trade in subsequent time periods. I examine the probable capture methods and possible culinary reasons as to why the Chilean jack mackerel is common at some inland sites in far southern Peru.

The growth and age structure of Chilean jack mackerel (Trachurus murphyi) following its influx to New Zealand waters

The Chilean jack mackerel (Trachurus murphyi) is a predominantly Southeast Pacific Ocean species. It is relatively difficult to determine its age, and multiple studies of its growth off South America have produced markedly different sets of von Bertalanffy parameters. T. murphyi was first identified from New Zealand waters in the mid-1980s and has comprised part of the commercial landings of Trachurus species (along with Trachurus declivis and Trachurus novaezelandiae) since then. Results from 13 years of age determination of New Zealand samples using sectioned otoliths indicate that a partially validated age determination method has been developed, with a precision level (average percentage error) of 4.6%. The best available von Bertalanffy growth parameters for the New Zealand population (sexes combined) are as follows: L∞ , 51.9 cm fork length; K, 0.223 per year; t0 , -0.5 year. Analyses by sex showed that males have a significantly larger L∞ than females. Estimated annual catch-at-length and catch-at-age distributions from the fishery are presented for 2007-2019. There have been at least two episodes of immigration of T. murphyi from international waters, but little evidence of spawning success to maintain the New Zealand population.

A first assessment of atresia in the Chilean jack mackerel <i>Trachurus murphyi</i> (Teleostei, Carangidae) from the South-eastern Pacific Ocean

The Chilean jack mackerel Trachurus murphyi support an important fishery in the South-eastern Pacific Ocean and has declined considerably over time. T. murphyi have asynchronous ovarian development with an oceanic spawning (September to January). Despite the economic importance of this resource critical issue such as characteristics and dynamics of atresia, which affect the reproductive output, are unknown. Females of T. murphyi caught in different spawning seasons were analysed to describe patterns of prevalence and intensity of atresia. General linear models (GLM) were performed by using prevalence and intensity atresia as response variables and gonadosomatic index, condition factor, sea surface temperature, postovulatory follicles and month/year as explanatory variables. The batch fecundity and relative fecundity were compared between females showing atresia, postovulatory follicles and non-atretic females. The stages of atresia identified were alpha, beta and gamma. The GLM showed that variations in the prevalence and intensity of atresia were explained for all variables, except condition factor for prevalence, and gonadosomatic index for intensity of atresia. According to our results, the dynamic of alpha and beta atresia could be considered a potential proxy for any disruption of spawning season. The batch fecundity and relative fecundity were lowest compared with other Trachurus spp. This is the first assessment comparing fecundity between atretic and not atretic females for this species.