Trachurus Murphyi Research Articles

Isolation and Polyphasic Investigation of the Carotenoids-Producing Marine Bacterium from <i>Trachurus murphyi</i> Chile Fishery

The pelagic fishery locates the wide international public sea regions and contains huge resource and technical benefits. The increasingly greater potential for exploitation of new marine microbes resource in these special sea areas has become conspicuous. Carotenoids are one of the most widely distributed and structurally diverse classes of natural pigments in plants, microorganisms and animals, performing important biological functions. The marine contains abundant biological resources and has great potential to be explored for the carotenoid resource. In this paper we reported the isolation and polyphasic investigation of the new carotenoids-producing marine bacteria from Trachurus murphyi Chile Fishery. The result has showed that marine bacterial isolated from Trachurus murphyi Chile fishery demonstrated good potential for the further exploration for bioactive carotenoids.

Isolation and Bioactivity Screening of Marine Environmental Bacteria from Trachurus Murphyi Chile Fishery

Marine bacteria have been proven to be a profound resource on the development of natural product chemistry and upon the medical sciences. The pelagic fishery locates the wide international public sea regions and contains huge resource and technical benefits. The increasingly greater potential for exploitation of new marine microbes resource in these special sea areas has become conspicuous. In this paper, the marine environmental bacterial strains were isolated from water sampled from the Trachurus murphyi Chile fishery in southeast Pacific Ocean, and the anti-bacterial bioactivity screening for the crude extract from the strain fermentation, and taxonomic identification of the screened bioactive strains were then performed. The obtained result in this study has showed that marine environmental bacterial isolated from Trachurus murphyi Chile fishery demonstrated good potential for the further exploration for marine bioactive natural products.

Effect of slaughter methods on the quality of Chilean jack mackerel (Trachurus murphyi) during refrigerated storage.

The main objective of this study was to assess the influence of slaughter methods on the quality of Chilean jack mackerel (Trachurus murphyi) during refrigerated storage on board. Fishes were slaughtered by asphyxia in air (AA), asphyxia in ice water (AI) or stunning fish heads (SH), and the rigor mortis, pH, total volatile basic nitrogen (TVB-N), trimethylamine (TMA), 2-thiobarbituric acid reactive substances (TBARS) and sensory properties for the fishes were analyzed. On day 0, Chilean jack mackerel samples of AI group displayed higher pH values than those of AA and SH groups. TVB-N, TMA and TBARS values of all samples increased with the storage time, and these values of AI had a lower increase than AA and SH. Moreover, samples of AI had a better sensory score than AA and SH during storage. It can be concluded that slaughter method of asphyxia in ice water for Chilean jack mackerel exhibit the better efficiency on maintaining the fish quality during refrigerated storage on board.

Standardization of CPUE for Chilean jack mackerel (Trachurus murphyi) from Chinese trawl fleets in the high seas of the Southeast Pacific Ocean

The generalized linear model (GLM) and generalized additive model (GAM) were applied to the standardization of catch per unit effort (CPUE) for Chilean jack mackerel from Chinese factory trawl fishing fleets in the Southeast Pacific Ocean from 2001 to 2010 by removing the operational, environmental, spatial and temporal impacts. A total of 9 factors were selected to build the GLM and GAM, i.e., Year, Month, Vessel, La Nina and El Nino events (ELE), Latitude, Longitude, Sea surface temperature (SST), SST anomaly (SSTA), Nino3.4 index and an interaction term between Longitude and Latitude. The first 5 factors were significant components in the GLM, which in combination explained 27.34% of the total variance in nominal CPUE. In the stepwise GAM, all factors explained 30.78% of the total variance, with Month, Year and Vessel as the main factors influencing CPUE. The higher CPUE occurred during the period April to July at a SST range of 12–15°C and a SSTA range of 0.2–1.0°C. The CPUE was significantly higher in normal years compared with that in La Nina and El Nino years. The abundance of Chilean jack mackerel declined during 2001 and 2010, with an increase in 2007. This work provided the relative abundance index of Chilean jack mackerel for stock assessment by standardizing catch and effort data of Chinese trawl fisheries and examined the influence of temporal, spatial, environmental and fisheries operational factors on Chilean jack mackerel CPUE.

The influence of oceanographic processes on jack mackerel (Trachurus murphyi) larval distribution and population structure in the southeastern Pacific Ocean

Abstract Vásquez, S., Correa-Ramírez, M., Parada, C., and Sepúlveda, A. 2013. The influence of oceanographic processes on jack mackerel (Trachurus murphyi) larval distribution and population structure in the southeastern Pacific Ocean. – ICES Journal of Marine Science, 70: 1097–1107. The distribution of jack mackerel larvae in the main oceanic spawning area of the southeastern Pacific Ocean was investigated through three consecutive spring bio-oceanographic surveys (2003–2005). In this study, otolith microstructure analysis revealed a spatial age gradient with the smallest/youngest larvae specimens found primarily in the offshore area and the largest/oldest found in the coastal area, implying offshore-inshore larval drift. This suggests a connection between the oceanic spawning area and the historical coastal nursery ground (north of 30°S). In order to understand the oceanographic processes that drive this larval transport, we inferred circulation patterns from two data sources: mesoscale eddy trajectories identified by applying the Okubo-Weiss parameter to satellite geostrophic currents, and 20 years of satellite tracking data of drifters. Our results showed that eddy trajectories lead to net northwestward offshore transport (the opposite direction of larval connectivity). In addition, mean circulation associated with the subtropical anticyclonic gyre and recurrent energetic meandering structures seem to be the major mechanisms driving the spatial dynamics of the early jack mackerel life history, determining a net transport to nursery grounds. These mechanisms could play a key role in recruitment, which supports the continuity of the jack mackerel population.

Accuracy of the Kirchhoff-Approximation and Kirchhoff-Ray-Mode Fish Swimbladder Acoustic Scattering Models

The acoustic backscatter from pressure release prolate spheroids and a three-dimensional representation of a fish swimbladder (Chilean jack mackerel, Trachurus symmetricus murphyi) was calculated using four target strength models (Kirchhoff-approximation, Kirchhoff-ray-mode, finite element solution of the Helmholtz equation, and prolate-spheroid-modal-series). Smoothly varying errors were found in the Kirchhoff-approximation and Kirchhoff-ray-mode model results when compared to the other models, and provide objective criteria for constraining the use of the KA and KRM models. A generic correction technique is also proposed for the prolate spheroid estimates and tentatively tested on a jack mackerel swimbladder, resulting in improvements to the target strength estimates from the Kirchhoff-approximation and Kirchhoff-ray-mode models.

Food web and fish stock changes in central Chile: comparing the roles of jumbo squid (Dosidicus gigas) predation, the environment, and fisheries

We analyzed recent food web and fish stock changes in the central Chile marine ecosystem, comparing the roles of jumbo squid (Dosidicus gigas) as predator, the environment, and fishing. To accomplish this we used food web modeling and the Ecopath with Ecosim software (EwE). The principal fish stocks have experienced wide decadal fluctuations in the past 30 years, including stock collapses of horse mackerel (Trachurus murphyi) and hake (Merluccius gayi), and there was a large influx of jumbo squid during the mid-2000s. We used two EwE models representing the food web off central Chile to test the hypothesis that predation by jumbo squid has been significant in explaining the dynamics of the main fishing resources and other species in the study area. Results indicate that predation by jumbo squid on fish stocks is lower than that of other predators (e.g. hake) and the fishery. Long-term fluctuations (1978–2004) in the biomass of the main fish stocks (as well as other components of the food web) seem to be related to fishing and to variation in primary production, rather than to predation by jumbo squid alone. Jumbo squid seems to play a role as predator rather than prey in the system, but its impacts are low when compared with the impacts of other predators and fishing. Therefore, we conclude that jumbo squid predation on its prey was not the primary force behind the collapse of important fish stocks off central Chile. Future efforts should be directed to better understanding factors that trigger sudden increases in jumbo squid abundance off central Chile, as well as modeling its trophic impacts.

Insight on population structure of the Chilean jack mackerel (Trachurus murphyi)

The Chilean Jack Mackerel (Trachurus murphyi, Nichols), is one of the most important fish exploited population in the world. Its area of distribution covers the sub-tropical waters of the South Pacific Ocean, from South America up to New Zealand and even Australia. It is subject to strong variation in its biomass, with world catches varying from less than 0.5 to almost 5 millions of tonnes. Its management requires a correct understanding of the population structure. Although s everal hypotheses have been submitted, suggesting up to 4 independent populations, the genetic analysis depicted a single population in the South Pacific Ocean. Here, we consider the two most probable structures for this population: a “patchy population” where all the fish belong to a single population that expands and contracts depending on the biomass; and a metapopulation, where a source population creates several subpopulations that can remain independent during prolonged periods, depending on the environmental conditions. The conditions for these hypotheses to represent the real case are studied, and especially the demographic structure and the exist ence of different spawning areas. Using the knowle dge obtained from fisheries and acoustic surveys we show that if we apply strictly their definitions, none of the two hypotheses can be fully rejected. Nevertheless some particular spatial characteristics observed recently between the Peruvian and centre-south Chilean parts of the distribution induce us to conclude that the metapopulation is likely to better describe the stock. The consequences of each population structure for fisheries management are list ed. They allow considering that the metapopulation hypothesis represents a safer definition as far as stock assessment is concerned. The paper concludes that T. murphyi can be described as a metapopulation, but also that the definitions proposed in the literature for metapopulation are not fully adapted to fish pelagic populations presenting a basin-scale range of distribution, and suggests specific research that could be done in this field.

Trends in spatio temporal distribution of Peruvian anchovy and other small pelagic fish biomass from 1966 2009

Changes in abundance and distribution of anchovy and other species of pelagic fish of the Northern Humboldt Current System (NHCS) are driven by environmental forcing variations in different time and spatial scales between the coastal 'cold' ecosystem and the 'warm' oceanic one. Data to study these fluctuations have come mostly from the fishery to show how anchovy (Engraulis ringens) increases when sardine (Sardinops sagax) declines and vice versa. However, using acoustic data on latitudinal biomass we show that other species as mackerel (Scomber japonicus) and jack mackerel (Trachurus murphyi) also follow the same opposed trend, then the fishery data hides the true dimension of the balance of abundance among species. Based on Hovmoller diagrams we scrutinized the changes in interannual latitudinal acoustic biomass, landings and influence of El Nino events from 1966 to 2009 in order to describe: 1) how the anchovy decadal distribution pattern moved from south to north since the 1960's; 2) how there have been produced concomitant changes in the latitudinal abundance and distribution of other species such as sardine, jack mackerel and mackerel before, during and after El Nino events; and 3) what was the overall effect of the succession of El Nino events on all these pelagic species. We concluded that: a) every El Nino event has had an effect on the expansion or contraction of pelagic species distribution and abundance, with different latitudinal effects; and b) the El Nino 1997-98 did not trigger but accelerated a decline phase on the abundance of sardine, jack mackerel and mackerel by a reduction of their ideal habitat due to an expansion of the coastal ecosystem caused by a shallower location of the upper limit of the Oxygen Minimum Zone (OMZ) These findings observed using past data might be taken into consideration for fishery management purposes when considering future scenarios.

Species composition and distributional pattern of ichthyoplankton of the Southern Pacific Ocean

Distributional pattern and qualitative composition of ichthyoplankton in waters of the Southern Pacific in September 2002–January 2003 and in August–November 2009 are analyzed. We noted approximately 70 species of fish pelagic eggs and larvae of fishes belonging to 34 families in this region. Change in distribution of the basic object of commercial fishery of this region, i.e., Peruvian-Chilean jack mackerel Trachurus murphyi, in early ontogenesis are considered in detail. The obtained data on the species composition, distribution, and abundance of ichthyoplankton in this region are compared with the results of investigations in the past years. The spawning biomass of jack mackerel is also estimated in the work by the amount of the eggs spawned by females in the places of their greatest concentrations.

A comparison of multi-class support vector machine and classification tree methods for hydroacoustic classification of fish-schools in Chile

The purpose of this study was to compare the results of the multi-class support vector machines (SVM) classification method to those of the classification tree (CART) method for automatic classification of fish schools. The discrimination study was done using descriptors of morphology, bathymetry, energy, and space positions for schools of three species; anchovy ( Engraulis ringens), common sardine ( Strangomera bentincki), and jack mackerel ( Trachurus murphyi) from acoustic data in southern-central Chile. The classification rate averages were 86.8% with classification trees and 89.5% with SVM. The levels of importance of the descriptors presented by the two methods are not fully concordant (Kendall's rank coefficient of concordance is 0.77). However, the two methods agree on the groups of descriptors considered as effective for classification. The bottom depth descriptor was the most important for classification trees, while the school-altitude index was the most important for SVM. This highlights the importance of the bathymetric and positional descriptors in the classification of species compared to energetic and morphometric descriptors. Advantages and disadvantage of the methods are presented. Classification trees have the advantages over SVM of being easier to implement and interpret, but have a lesser performance. One major problem with trees is their high degree of variance. Because each classification method has its own performance, limitations and advantages, a good practice is to use two or more classifiers.

남동태평양의 전갱이트롤어업 현황

To investigate the catches of jack mackerel fishery, a series of fishing experiments was conducted in the high seas of the southeastern Pacific Ocean (<TEX>$30^{\circ}S-38^{\circ}S,\;82^{\circ}W-95^{\circ}W$</TEX>) during the period of 9 August to 18 December, 2003 by commercial fishing vessel and research vessel. The number of 205 tows fishing was carried out in the southeastern Pacific Ocean. The total catch was 1,988 ton and CPUE was 2.4 ton/hour. CPUE showed high values in the frontal zone during the survey. Main target species caught from the experimental fishing were the jack mackerel, Trachurus murphyi (98.1%) and chub mackerel, Scomber japonicus (1.9%) as bycatch. Body length of the jack mackerel was different between female and male. The high mean catch per unit effort of jack mackerel was showed when the fishing ground of jack mackerel fishery was over the <TEX>$110^{\circ}W$</TEX> in the southeastern Pacific Ocean. But the fluctuation of the catch per unit effort in the western part of fishing ground was not matched with those year. Reliable physical and oceanographical information will be useful for the efficiency of fishing activity. According to the result of monthly movement of center of fishing ground, the fishing activity of jack mackerel fishery was performed northward in the southeastern Pacific Ocean as time passes.

Otolith chemistry indicates large-scale connectivity in Chilean jack mackerel ( Trachurus murphyi), a highly mobile species in the Southern Pacific Ocean

Chemistry in material laid down prior to capture along the edges of otoliths of Chilean jack mackerel ( Trachurus murphyi) showed strong spatial heterogeneity corresponding to hydrographic structure across putative population boundaries between (i) the western and eastern South Pacific Ocean, and (ii) Chile and Peru. Yet the chemistry of the otolith nucleus, in material laid down during early life, showed no evidence supporting the existence of these boundaries. Instead, jack mackerel from New Zealand had similar nucleus chemistry to most sampling areas off South America; and those off southern Peru showed similar nucleus chemistry to most sampling areas off Chile. Strong differences were found between southern and northern Peru, and cluster analysis indicated this was caused by a group of fish off northern Peru with chemistry found nowhere else. Most other fish grouped in two clusters, which showed properties suggesting correspondence with a major spawning zone in oceanic water off central Chile, and a smaller area in coastal water off northern Chile, characterized by similar sea surface temperature, lack of westward transport, and low kinetic energy. Rather than discrete populations separated by boundaries, these results suggest complex spatial structure defined by environmentally mediated survival and connectivity: fish caught off New Zealand may be of South American origin; the spawning zone off central Chile may supply fisheries around the South Pacific; and spawning off northern Chile may be an important source of fish caught locally and in Peru. However, northern Peru does not supply areas further south.

Euphausia mucronata: A keystone herbivore and prey of the Humboldt Current System

Abstract Euphausiids are important components of many ecosystems, especially in productive regions of temperate and high latitudes. The present paper makes the case that E. mucronata plays a keystone role in the food web of the Humboldt Current System (HCS) based on a synthesis of new and published data supporting its potential role as a primary grazer, as well as a principal prey for upper trophic level fish. E. mucronata is an endemic species, concentrated in the coastal upwelling belt of the HCS, with morpho-physiological adaptations to vertically migrate into the Oxygen Minimum Zone (OMZ). Within the 100-km coastal belt of the HCS it accounts for ca. 50% of the meso zooplankton wet weight in winter. In the mixed layer, it is a herbivore with high night ingestion rates (612.2 ng Chl eq ind−1 h−1 or 1013.9 μg C ind−1 d−1, in winter), and accounted for a 19.3% impact on primary production in winter, at an intermediate population abundance (3.8 ind m−3). At higher abundances (50 ind m−3) equivalent to swarms, impact on primary production could reach 254%. Additionally E. mucronata is a common prey of numerous upper trophic level predators. The diet of jack mackerel (Trachurus murphyi) off central Chile (34-39°S) indicates a striking dependence on E. mucronata prey (average of 75% of stomach content in weight). The fishing season off central Chile extended from austral fall (March–April) and continued at least until the end of austral winter (September). The average daily ration of jack mackerel was 17.4 g, which is equivalent to 2.3% of fish body weight per day. The total E. mucronata consumed in 1991 by the landed population of fish (3.7 million tons yr−1) amounted to 23.2 million tons yr−1. The total estimated population of jack mackerel that year (17.6 million tons) would have consumed ca. 110.2 million tons of E. mucronata. Based on stomach contents, consumption of E. mucronata by other nektonic predators off Chile and off Peru is also outstanding. Four different food web scenarios are offered for the northern and southern sectors of the HCS, according to regime shifts of small pelagics such as anchovy and jack mackerel, under the assumption that E. mucronata is a keystone link.

Genetic population structure in the Chilean jack mackerel, Trachurus murphyi (Nichols) across the South-eastern Pacific Ocean

The Chilean jack mackerel Trachurus murphyi, is a pelagic fish from the Carangidae family that is distributed in the South Pacific Ocean. Because this species constitutes an important economic resource across the South Pacific and plays an important ecological role in this ecosystem there is a growing interest in determining its population structure. In this study, we used molecular markers (mitochondrial DNA sequences and microsatellites) from Chilean jack mackerel samples to investigate its genetic population structure across the South Pacific Ocean. The mitochondrial DNA did not detect a genetic structure in T. murphyi populations in the Pacific Ocean, but revealed very low haplotype diversity and a short genealogy history compared to other small-pelagic species. The same general pattern of a lack of genetic structure was found with microsatellite loci; however, a large genetic diversity was revealed with microsatellite markers. The present results did not support the existence of different stock units for T. murphyi across the South Pacific Ocean but a more holistic approach will be necessary to determine an adequate management strategy for this fishery.

Distribution and foraging behaviour of the Peruvian Booby (Sula variegata) off northern Chile

The Peruvian Booby (Sula variegata) is one of the most numerous guano bird species in the Humboldt Current. We used a combination of data logger deployment, at-sea observations and colony-based work to investigate the foraging and diving behaviour, as well as the at-sea distribution and food choice of Peruvian Boobies breeding at Isla Pajaros, northern central Chile. Birds foraged in the vicinity of Isla Pajaros. They performed short foraging trips, varying between a few minutes and several hours. Average foraging range was 17.1 ± 3.5 km and diving took place between 2 and 10 km off the coast. Birds dived to depth of up to 10 m with an average depth of 4.3 ± 1.5 m. By at-sea observations as well as by data logger deployment, we identified important foraging areas close to the coast, especially around protruding points. The birds’ diet was highly variable between years, with Inka scad (Trachurus murphyi) and anchovy (Engraulis ringens) being the overall dominant prey species. Despite limited sample sizes, this paper presents first results about the foraging behaviour of Peruvian Boobies at the largest breeding colony in northern Chile. This information is essential for a better understanding of the effects of environmental changes as well as for the implementation of conservation measures.

Isolation and characterization of microsatellite loci for the jack mackerel (Trachurus murphyi Nichols, 1920)

Eight microsatellite loci were developed for the jack mackerel (Trachurus murphyi), a fish of significant commercial importance in the Southeast Pacific. Genetic variation at these loci was examined in 15 samples from the locality of Talcahuano (Chile). All eight were highly polymorphic, with a number of alleles per locus ranging from 4 to 22 and an observed heterozygosity from 0.429 to 1. These markers will be useful to address issues of population genetics, ecology, conservation and fisheries management related to that species.

Chemical changes during the chilled storage of Chilean jack mackerel (Trachurus murphyi): Effect of a plant-extract icing system

Chilean jack mackerel (Trachurus murphyi) is an underutilised medium-fat fish species, captured in large volumes but commercialised in the fish meal and surimi industries. This study provides a first approach including a novel technology for the commercialisation of this fish species as a chilled product for human consumption. Ice prepared from aqueous extracts of oregano (Origanum vulgare) and rosemary (Rosmarinus officinalis) leaves was applied as chilling system and compared to traditional ice. Chemical changes related to quality criteria were analysed throughout a 23-day chilling period. A marked antioxidant effect (p < 0.05) could be detected with fish kept under both plant-extract icing systems, according to peroxide and thiobarbituric acid reactive substance formation; meanwhile, the employment of such icing systems led to lower (p < 0.05) scores for pH value and total volatile amine formation. Additionally, the plant extract presence in the chilling medium provided a lower (p < 0.05) lipid hydrolysis (free fatty acid formation) development. According to the preservative effect observed for both plant extract systems, further research is envisaged concerning their optimal employment, this including the qualitative and quantitative analysis of active molecules present in the extracts.

Modelling the target strength of Trachurus symmetricus murphyi based on high-resolution swimbladder morphometry using an MRI scanner

Abstract Peña, H., and Foote, K. G. 2008. Modelling the target strength of Trachurus symmetricus murphyi based on high-resolution swimbladder morphometry using an MRI scanner. – ICES Journal of Marine Science, 65: 1751–1761. The acoustic target strength (TS) of Chilean jack mackerel (Trachurus symmetricus murphyi) was computed from three-dimensional reconstructions of the swimbladder form. The primary morphometric data were derived from high-resolution images made with a clinical whole-body 3-tesla magnetic resonance imaging (MRI) scanner. The fish were obtained from a commercial purse-seiner operating off Chile during 2003. Transverse MRI sequences of 18 fish were performed with a volumetric pixel 0.5 × 0.5 mm in cross section and 0.7 mm in the axial direction. From each transverse section, the swimbladder contour was traced manually using a digital pen tablet and smoothed using an automatic interpolation routine. The digital contours were used to build a triangular mesh spanning the swimbladder surface. The high-resolution swimbladder models revealed details such as undulations in the dorsal surface of the swimbladder caused by the backbone, and holes where the haemal spines penetrate the posterior end of the swimbladder. The Kirchhoff approximation was used to compute TS as a function of fish orientation at 38 kHz. The mean dorsal-aspect TS was computed for several orientation patterns and regressed on the logarithm of total fish length to derive operationally simple formulae.

Biases in determining the diet of jumbo squid Dosidicus gigas (D’ Orbigny 1835) (Cephalopoda: Ommastrephidae) off southern-central Chile (34°S–40°S)

The diet of jumbo squid (Dosidicus gigas) off southern-central Chile is described to examine potential biases in the determination of their main prey. Specimens were collected from catches using different fishing gear (jigging, trawl and purse-seine), from July 2003 to January 2004, and from December 2005 to October 2006. The stomach contents were analyzed in terms of frequency of occurrence, number, and weight of prey items and the diet composition was analyzed using Detrended Correspondence Analysis. In the industrial purse-seine fleet for jack mackerel (Trachurus murphyi), the dominant prey of D. gigas was T. murphyi. In the industrial mid-trawl fishery for Patagonian grenadier (Macruronus magellanicus), the dominant species in the diet of D. gigas was M. magellanicus. Similarly, Chilean hake (Merluccius gayi) was the main prey in the diet of D. gigas obtained in the industrial trawl fishery for Chilean hake; and, in both artisanal fisheries (purse-seine for small pelagics and jigging), small pelagic fish and D. gigas were the main prey in the stomach contents of D. gigas. Cannibalism in D. gigas varied between different fleets and probably is related to stress behavior during fishing. The Detrended Correspondence Analysis ordination showed that the main prey in the diet of D. gigas is associated with the target species of the respective fishery. Consequently, biases are associated with fishing gear, leading to an overestimate in the occurrence of the target species in the diet. We recommend analyzing samples from jigging taken at the same time and place where the trawl and purse-seine fleets are operating to avoid this problem, and the application of new tools like stable isotope, heavy metal, and fatty acid signature analyses.