The Experts below are selected from a list of 327 Experts worldwide ranked by ideXlab platform
Tanasichuk - One of the best experts on this subject based on the ideXlab platform.
-
Interannual variation in the availability and utilization of euphausiids as prey for Pacific Hake (Merluccius productus) along the south‐west coast of Vancouver Island
Fisheries Oceanography, 1999Co-Authors: TanasichukAbstract:The species and size composition of euphausiids consumed by Pacific Hake (Merluccius productus) along the south-west coast of Vancouver Island were monitored during the 1989, 1990 and 1995–97 summer feeding seasons. Thysanoessa spinifera and Euphausia pacifica were the only euphausiid species eaten by Hake. Hake persisted in selecting krill longer than 17 mm and consistently preferred T. spinifera, even though there was a substantial reduction in euphausiid abundance, a change in species composition and a shift in the size distribution to smaller individuals after the 1992–93 warm water years. The biomass of euphausiids available to Hake after 1993 averaged 27% of that for 1991, the pre-ENSO year, and was 12% of the 1991 value in 1996. Hake predation was not responsible for the reduction in euphausiid abundance, as it was already low at euphausiid sizes smaller than those eaten by Hake.
Eva Garcia-vazquez - One of the best experts on this subject based on the ideXlab platform.
-
Seventeen years analysing mislabelling from DNA barcodes: Towards Hake sustainability
Food Control, 2020Co-Authors: Carmen Blanco-fernandez, Eva Garcia-vazquez, Gonzalo Machado-schiaffinoAbstract:Abstract Mislabelling is a common threat to fisheries sustainability. Over the last decades, molecular tools have been established as the main resource to detect mislabelling. This study focuses on these efforts in the genus Merluccius. A meta-analysis approach is taken in order to detect trends on mislabelling directions for the last 17 years. A total of 1291 DNA-identified Hake products from 45 different studies were compiled. An increase in number of publications using DNA forensics to detect mislabelling in Hake can be seen along the studied time period. However, representation of different Hake species varies, i.e. Pacific Hakes are underrepresented. Different risk of mislabelling has been identified depending on the regions: Highest risk of mislabelling was found in African Hake species (only 20.53% of African Hake were correctly labelled). Furthermore, a high amount of Hake products with incomplete labels (e.g. not reporting the species) were unevenly distributed. Directionality in mislabelling was detected for all cases between sympatric species. Differences in mislabelling rates were found for different regions (Africa, Europe, Pacific America and South America). While a decrease in mislabelling was reported between 2011 and 2014, this has not being sustained over time, as more recent data show an increase in mislabelling rates. Altogether, rigorous monitoring of product authenticity is called for, with special attention to the more vulnerable species.
-
Genetic markers reveal a gradient of hybridization between cape Hakes (Merluccius capensis and Merluccius paradoxus) in their sympatric geographic distribution
Journal of Sea Research, 2014Co-Authors: Laura Miralles, Gonzalo Machado-schiaffino, Eva Garcia-vazquezAbstract:Abstract The cape Hakes Merluccius capensis and Merluccius paradoxus are important fishing resources for African countries such as Namibia and South Africa. In this study we have genetically analyzed adult samples from the overlapping distribution of these species. Eight microsatellite loci, the nuclear 5S rDNA locus and the Cytochrome Oxidase subunit I (COI) gene were employed as molecular markers. A North–South gradient of interspecific hybridization was found, with discordant mitochondrial and nuclear genotypes at the northernmost edge of M. paradoxus distribution. These results suggest intense introgression in North Benguela off the Namibian coast. Independent Hake stock assessment is recommended in this region for sustainable management of this valuable resource.
-
Species misidentification in mixed Hake fisheries may lead to overexploitation and population bottlenecks
Fisheries Research, 2012Co-Authors: Eva Garcia-vazquez, Gonzalo Machado-schiaffino, Daniel Campo, Francis JuanesAbstract:Accurate species identification is required for stock assessment to monitor exploited species. Genetic tools are useful for species identification; employing SNP (single nucleotide polymorphisms) as markers, here we describe two cases of species misidentification which may lead to inaccurate estimates of stock size and adversely affect sustainable Hake fisheries management in the Atlantic Ocean. North American Hakes and African Hakes show evidence of erroneous labelling that may obscure exploitation estimates of the species caught together in mixed fisheries (Merluccius albidus and Merluccius bilinearis, and Merluccius capensis and Merluccius paradoxus in North America and Africa respectively). Use of genetic methodology for species identification is recommended for improving accuracy of stock estimates in these two pairs of Hakes.
-
Mislabeling of Two Commercial North American Hake Species Suggests Underreported Exploitation of Offshore Hake
Transactions of the American Fisheries Society, 2009Co-Authors: Eva Garcia-vazquez, Gonzalo Machado-schiaffino, Jose Luis Horreo, Daniel Campo, Iliana Bista, Alexandros Triantafyllidis, Francis JuanesAbstract:Abstract Mislabeling of North American merlucciid Hakes in stock surveys and commercial market samples was detected by employing nuclear 5S ribosomal DNA (rDNA) and mitochondrial cytochrome b variation as molecular markers. Results showed that offshore Hake Merluccius albidus is sold in European markets but is labeled as the morphologically similar silver Hake M. bilinearis, which is the target species of the fishery. This suggests that offshore Hake may be inadvertently included within silver Hake landings, as the two species overlap in the southern area of silver Hake distribution (approximately 41°-35°N latitude near North American coasts). An inexpensive and technically easy technique based on polymerase chain reaction (PCR) amplification of a fragment of 5S rDNA and visualization of PCR products in agarose gels is recommended for routine species assignation in landings for purposes of exploitation estimates and for authentication of commercial Hake species.
Gonzalo Machado-schiaffino - One of the best experts on this subject based on the ideXlab platform.
-
Seventeen years analysing mislabelling from DNA barcodes: Towards Hake sustainability
Food Control, 2020Co-Authors: Carmen Blanco-fernandez, Eva Garcia-vazquez, Gonzalo Machado-schiaffinoAbstract:Abstract Mislabelling is a common threat to fisheries sustainability. Over the last decades, molecular tools have been established as the main resource to detect mislabelling. This study focuses on these efforts in the genus Merluccius. A meta-analysis approach is taken in order to detect trends on mislabelling directions for the last 17 years. A total of 1291 DNA-identified Hake products from 45 different studies were compiled. An increase in number of publications using DNA forensics to detect mislabelling in Hake can be seen along the studied time period. However, representation of different Hake species varies, i.e. Pacific Hakes are underrepresented. Different risk of mislabelling has been identified depending on the regions: Highest risk of mislabelling was found in African Hake species (only 20.53% of African Hake were correctly labelled). Furthermore, a high amount of Hake products with incomplete labels (e.g. not reporting the species) were unevenly distributed. Directionality in mislabelling was detected for all cases between sympatric species. Differences in mislabelling rates were found for different regions (Africa, Europe, Pacific America and South America). While a decrease in mislabelling was reported between 2011 and 2014, this has not being sustained over time, as more recent data show an increase in mislabelling rates. Altogether, rigorous monitoring of product authenticity is called for, with special attention to the more vulnerable species.
-
Genetic markers reveal a gradient of hybridization between cape Hakes (Merluccius capensis and Merluccius paradoxus) in their sympatric geographic distribution
Journal of Sea Research, 2014Co-Authors: Laura Miralles, Gonzalo Machado-schiaffino, Eva Garcia-vazquezAbstract:Abstract The cape Hakes Merluccius capensis and Merluccius paradoxus are important fishing resources for African countries such as Namibia and South Africa. In this study we have genetically analyzed adult samples from the overlapping distribution of these species. Eight microsatellite loci, the nuclear 5S rDNA locus and the Cytochrome Oxidase subunit I (COI) gene were employed as molecular markers. A North–South gradient of interspecific hybridization was found, with discordant mitochondrial and nuclear genotypes at the northernmost edge of M. paradoxus distribution. These results suggest intense introgression in North Benguela off the Namibian coast. Independent Hake stock assessment is recommended in this region for sustainable management of this valuable resource.
-
Species misidentification in mixed Hake fisheries may lead to overexploitation and population bottlenecks
Fisheries Research, 2012Co-Authors: Eva Garcia-vazquez, Gonzalo Machado-schiaffino, Daniel Campo, Francis JuanesAbstract:Accurate species identification is required for stock assessment to monitor exploited species. Genetic tools are useful for species identification; employing SNP (single nucleotide polymorphisms) as markers, here we describe two cases of species misidentification which may lead to inaccurate estimates of stock size and adversely affect sustainable Hake fisheries management in the Atlantic Ocean. North American Hakes and African Hakes show evidence of erroneous labelling that may obscure exploitation estimates of the species caught together in mixed fisheries (Merluccius albidus and Merluccius bilinearis, and Merluccius capensis and Merluccius paradoxus in North America and Africa respectively). Use of genetic methodology for species identification is recommended for improving accuracy of stock estimates in these two pairs of Hakes.
-
Mislabeling of Two Commercial North American Hake Species Suggests Underreported Exploitation of Offshore Hake
Transactions of the American Fisheries Society, 2009Co-Authors: Eva Garcia-vazquez, Gonzalo Machado-schiaffino, Jose Luis Horreo, Daniel Campo, Iliana Bista, Alexandros Triantafyllidis, Francis JuanesAbstract:Abstract Mislabeling of North American merlucciid Hakes in stock surveys and commercial market samples was detected by employing nuclear 5S ribosomal DNA (rDNA) and mitochondrial cytochrome b variation as molecular markers. Results showed that offshore Hake Merluccius albidus is sold in European markets but is labeled as the morphologically similar silver Hake M. bilinearis, which is the target species of the fishery. This suggests that offshore Hake may be inadvertently included within silver Hake landings, as the two species overlap in the southern area of silver Hake distribution (approximately 41°-35°N latitude near North American coasts). An inexpensive and technically easy technique based on polymerase chain reaction (PCR) amplification of a fragment of 5S rDNA and visualization of PCR products in agarose gels is recommended for routine species assignation in landings for purposes of exploitation estimates and for authentication of commercial Hake species.
Mauricio F Landaeta - One of the best experts on this subject based on the ideXlab platform.
-
spawning of the southern Hake merluccius australis pisces merlucciidae in chilean fjords
Fisheries Research, 2007Co-Authors: Claudia A Bustos, Fernando Balbontin, Mauricio F LandaetaAbstract:The southern Hake Merluccius australis constitutes an important fishery in southern Chile, but its reproductive biology is scarcely known, and until now the Chilean fjords have not been considered as potential spawning zones. Oceanographic surveys carried out during austral spring and summer of 1995–2002 in the Chilean fjords (43 ◦ 30 � S–47 ◦ S), are used to describe for first time the spawning of M. australis in the inland sea of southern Chile. Large patches of eggs with undeveloped embryos ( 150 eggs per 10 m 2 ), eggs in late development and abundant southern Hake larvae (up to 385 larvae per 10 m 2 ) were observed inside Chilean fjords during austral spring season. Eggs and preflexion larvae (<9 mm) were scarcely detected in open ocean-influenced waters (<30 ind per 10 m 2 ). This pattern of horizontal distribution may be determined by spawning events of inland resident stocks and/or by inshore migration of adult Hakes during austral spring. The higher frequency of small larvae inside fjord waters, and the presence of postflexion larvae outside fjords are indicative that fjords are used also as nursery areas for early stages of southern Hake. Finally, inter-annual variability in egg size (i.e., diameter) was detected, despite the relatively constant seawater temperature (10–11 ◦ C). Further investigations are needed to determine the maintenance and the health of this spawning and early nursery area in a zone highly disturbed by salmon culture activity.
Vincent Balzano - One of the best experts on this subject based on the ideXlab platform.
-
Evaluating a large-mesh belly window to reduce bycatch in silver Hake (Merluccius bilinearis) trawls
Fisheries Research, 2016Co-Authors: Shannon M. Bayse, Chris Rillahan, Natalie F. Jones, Vincent BalzanoAbstract:Abstract Small-mesh trawls targeting silver Hake ( Merluccius bilinearis ) in Northeastern USA are managed as exemptions to the northeast multispecies management plan. These exemptions require that the catch of regulated groundfish species is less than 5% of the total catch weight for small-mesh gears targeting silver Hake. At present, only a raised footrope trawl (RFT) or drop-chain-only trawl (DOT) (in New England, it is specifically called “sweepless trawl”) in conjunction with a Nordmore-style grid can be used to land silver Hake with small mesh off the coast of Maine. The historical Maine silver Hake fishing grounds have a very rugged bathymetry that makes the use of these modified groundgears difficult, if not impossible. This study tested a trawl with and without a large-mesh belly window (LMBW) using a traditional rockhopper footrope for 58 tows and reduced the bycatch of red Hake ( Urophycis chuss ) and aggregated bycatch. There was no significant difference in the predicted mean catch of silver Hake between trawls (although the LMBW trawl had a 13.50% reduction). Additionally, there was no difference in catch for commercial-size silver Hake (>20 cm) between the two trawls. Both video and length analysis determined that small silver Hake were caught less frequently by the LMBW trawl. These results indicate that a small-mesh trawl employing a LMBW can effectively be used to commercially target silver Hake off Maine (USA), replace the requirement of a RFT or DOT, and maintain the less than 5% regulated groundfish requirement.
