136 research outputs found
Hake Food Consumption In The South Bay Of Biscay Estimated From A Gastric Evacuation Model
No full textNo abstracts are to be cited without prior reference to the author. Hake, Merluccius merluccius (L. 1758) food consumption per quarter and age class is estimated using the results of the analysis of 11504 hake stomach contents. Samples were collected and analysed on board in two quarterly samplings carried out in the Cantabrian Sea and off the Galician north coast during 1994 and 1997. Food consumption is estimated through a general gastric evacuation model for gadoids including as variables: water temperature, predator size, stomach content weight and prey energy density. According to our results, hake quarterly food consumption varies from 29 g for an age 0 class hake to 1513 g for an age 6+ class hake. Compared with the other quarters, consumption in quarter 2 is lower for hake of age classes 1 and 2, and generally higher for older hake. Quarterly rations are allocated into the main commercial species and other prey groups using hake diet composition in volume by age class and quarter. Results show that blue whiting is the most important prey for hake and makes up more than half of the consumption from age class 2-3 upwards. In its lifetime from age class 0 to age class 5 one hake consumes 11.6 kg, and almost 8 kg of them are of blue whiting. Crustaceans are only important for younger hake but are almost negligible from age class 2 upwards. The importance of the rest of the fish species varies among ages and quarters. Using blue whiting, horse mackerel and hake length distributions in stomachs, the number of blue whiting, horse mackerel and hake of each length range consumed per quarter by one hake of each age class and quarter is estimated
Silver hake tracks changes in Northwest Atlantic circulation
No full textAuthor Posting. © The Author(s), 2011. This is the author's version of the work. It is posted here by permission of Nature Publishing Group for personal use, not for redistribution. The definitive version was published in Nature Communications 2 (2011): 412, doi:10.1038/ncomms1420.Recent studies documenting shifts in spatial distribution of many organisms in response
to a warming climate highlight the need to understand the mechanisms underlying species
distribution at large spatial scales. Here we present one noteworthy example of remote
oceanographic processes governing the spatial distribution of adult silver hake, Merluccius
bilinearis, a commercially important fish in the Northeast US shelf region. Changes in spatial
distribution of silver hake over the last 40 years are highly correlated with the position of the
Gulf Stream (GS). These changes in distribution are in direct response to local changes in
bottom temperature on the continental shelf that are responding to the same large scale
circulation change affecting the GS path, namely changes in the Atlantic Meridional Overturning
Circulation (AMOC). If AMOC weakens as is suggested by global climate models, silver hake
distribution will remain in a poleward position, the extent to which could be forecast at both
decadal and multidecadal scales.J.A.N. was supported by the NOAA
Fisheries and the Environment program (FATE). T.M.J. and Y.O.K. were supported by the
WHOI Ocean Climate Change Institute and Ocean Life Institute
Silver hake tracks changes in Northwest Atlantic circulation
No full textNo abstracts are to be cited without prior reference to the author. Recent studies documenting shifts in spatial distribution of many organisms in response to a warming climate highlight the need to understand the mechanisms underlying species distribution at large spatial scales. Previous work documented the remote oceanographic processes governing the spatial distribution of adult silver hake, Merluccius bilinearis, a commercially important fish in the Northeast US shelf region. Changes in spatial distribution of silver hake over the last 40 years are highly correlated with the position of the Gulf Stream (GS). Silver hake shifted their spatial distribution in direct response to local changes in bottom temperature on the continental shelf that are responding to the same large scale circulation change affecting the GS path, namely changes in the Atlantic Meridional Overturning Circulation (AMOC). Further analysis illustrates that other species also respond to this remote forcing, suggesting that the GS position is the best leading indicator of thermal conditions resulting in ecosystem change on the shelf. If AMOC weakens as is suggested by global climate models, silver hake and other species will remain in a poleward position, the extent to which could be forecast at both decadal and multidecadal scales
Spatially-varying effects of the California Undercurrent on Pacific hake distribution
No full textIn the California Current Ecosystem, the California Undercurrent (CU) is the predominate subsurface current that transports nutrient rich water from southern California poleward. In this study, we used a large data set of spatially explicit in situ observations of Pacific hake and the CU (36.5–48.3°N) to estimate relationships between northward undercurrent velocity and hake distribution and determine if these relationships vary across space or life-history stage. We found that both hake occurrence and density had strong spatially complex relationships with the CU. In areas north of 44°N (central Oregon), the CU effect was spatially consistent and opposite for occurrence (negative) and density (positive), indicating that hake may aggregate in areas of high northward velocity in this region. In areas south of 44°N, the CU effect showed a cross-shelf gradient for both occurrence and density, indicating a more nearshore hake distribution when northward velocity is higher in this region. Together, our results suggest that future changes in the CU due to climate change are likely to impact hake differently in northern and southern areas.The presentation of the authors' names and (or) special characters in the title of the pdf file of the accepted manuscript may differ slightly from what is displayed on the item page. The information in the pdf file of the accepted manuscript reflects the original submission by the author
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The fishery for Argentine hake (Merluccius hubbsi) and oceanic processes in the southwestern Atlantic Ocean
No full textThe fishery for Argentine hake (Merluccius hubbsi) was examined using data from the Argentine offshore fishing fleet and research cruises for 1978-1979. The composition of the Argentine fleet required the standardization of fishing effort, via the determination of relative fishing power (RFP). The RFP of a fishing vessel was found to increase almost linearly for engine powers between 300 and 1000 HP, remaining fairly constant at greater engine powers.The second part of the study provides a statistical description of the commercial fishery data, concentrating on CPUE and its validity as an index of relative abundance. The monthly frequency distributions of hake CPUE were examined to select adequate statistical estimators and to gain insight into the dynamics of fish concentrations and fishermen. Four characteristic shapes of CPUE frequency distribution were identified corresponding to intra-annual changes in the spatial aggregation of fish due to environmental and behavioural factors and corresponding changes in deployment of fishing effort.A third part of the dissertation examines the annual migratory pattern of hake. Hake show an annual north-south, offshore-inshore migration between feeding and spawning grounds. The oceanic processes that shape the migratory pattern were discussed as they affect the availability of forage and the survival of hake larvae. An apparent difference in the northern extension of the migration was found between years: in 1979 hake were found approximately three degrees latitude further south along the shelf break than in 1978. The difference was linked to apparent changes in the location of the convergence of the Brazil and Malvinas currents.The final part of the dissertation examines the effect of sea surface and bottom temperature on the distribution of hake. Discriminant analysis separated fishing stations with high and low abundance of hake. Bottom temperature contributed more than SST to the separation in autumn-winter, but both variables were equally relevant during spring-summer. Large numbers of hake were found at bottom temperatures between 6-8\sp\circC year-round, whereas the sea surface temperatures associated with dense hake concentrations fluctuated seasonally. Geographically, the stations with high abundance of hake were always located on the middle and outer shelf, bound by shallow coastal waters and the shelf break. (Abstract shortened with permission of author.)</p
A Graphical Approximation Of Hake Growth In The North-Eastern Atlantic During 1987-2000
No full textNo abstracts are to be cited without prior reference to the author.1) 25 896 Hake (Merluccius merluccius L 1758) otoliths (sagittae) were collected on a quarterly basis from Basque landings in the period 1987-2000.Fish were caught in ICES Divisions VIIIa,b,d (21 162), VIIIc (3 859) and VIIh,j (875).Otoliths preparation and the criteria used for ring interpretation were those agreed in the two International Workshops on hake otolith age readings held in 1997 and 1999.2) Fish aged [0-9+] years old were observed. Synthetic Age-Length Keys (ALKs) were built and plotted for the whole period, to check for eventual differences between mean lengths by quarters
A bayesian model for European hake with priors based on life history invariants
No full textNo abstracts are to be cited without prior reference to the author. European hake is a main target fish for the fleet operating in Atlantic waters, although there are many biological unknowns that compromise the quality of the current assessment and scientific advice. Growth, natural mortality and reproduction are main biological processes required to develop population dynamic models for assessment purposes. Currently, the parameters defining these processes such Von Bertalanffy asymptotic length, M, L 50% of maturity or Beverton-Holt steepness are estimated outside the model and set as constants. Population dynamic bayesian models provide a suitable platform to develop solutions to this kind of problems since Bayesian models allow using additional knowledge from similar species in the form of the priors. Informative priors for biological key parameters have been developed based on available data for Northern hake combined with information from other hake species all over the world. This information is analyzed on the light of ecological theory for life history invariants (LHI) to produce the required priors. LHI figures are relatively constant among similar species. Information from other hakes may help to fill the gap in assessment and management of European hake. The pros and cons of using these informative priors to improve hake assessment are finally discussed
Hake is author of stagecraft book \u27Here\u27s How,\u27 The College Eye, July 31, 1942
No full textHerbert V. Hake attended graduate school at the University of Iowa, where he earned his master\u27s degree in scenic design in 1933. In the summer of 1936, he began his career at the Iowa State Teachers College (ISTC) with the Theater Department. From 1938 to 1942 he served as technical director, scenic designer, and instructor of speech courses. He was a pioneer in radio and television.https://scholarworks.uni.edu/uninoteworthy_documents/1145/thumbnail.jp
Integrating microsatellite DNA markers and otolith geochemistry to assess population structure of European hake (merluccius merluccius)
No full textAuthor Posting. © The Author(s), 2014. This is the author's version of the work. It is posted here by permission of Elsevier for personal use, not for redistribution. The definitive version was published in Estuarine, Coastal and Shelf Science 142 (2014): 68-75, doi:10.1016/j.ecss.2014.03.010.Population structure and natal origins of European hake were investigated using
microsatellite DNA markers and otolith geochemistry data. Five microsatellites were
sequenced and otolith core geochemical composition was determined from age-1 hake
collected in the northeast Atlantic Ocean and the Mediterranean Sea. Microsatellites
provided evidence of a major genetic split in the vicinity of the Strait of Gibraltar,
separating the Atlantic and the Mediterranean populations, with the exception of the Gulf
of Cádiz. Based on classification models using otolith core geochemical values
individuals’ natal origins were identified, although with an increased error rate. Coupling
genotype and otolith data increased classification accuracy of individuals to their potential
natal origins while providing evidence of movement between the northern and southern
stock units in the Atlantic Ocean. Information obtained by the two natural markers on
population structure of European hake was complementary as the two markers act at
different spatio-temporal scales. Otolith geochemistry provides information over an
ecological time frame and on a fine spatial scale, while microsatellite DNA markers report
on gene flow over evolutionary time scales and therefore act on a broader spatio-temporal
resolution. Thus, this study confirmed the usefulness of otolith geochemistry to
complement the assessment of early life stage dispersal in populations with high gene flow
and low genetic divergence.This study was funded by ‘Fundação para a
Ciência e a Tecnologia’ (FCT), Pest-OE/MAR/UI0199/2011 and
PTDC/MAR/117084/2010. S.E. Tanner was funded with a grant by FCT
(SFRH/BPD/84278/2012)
Comparison of results for the South African Hake 2017 Reference Case Assessment before and after the correction of some minor coding errors
No full textWe thank OLRAC for checking the code for the hake assessment provided by the first author. This exercise identified some small errors and/or inconsistencies with the specifications document (DEM/11).The 2017 Reference Case (Rademeyer and Butterworth, 2017) has been rerun with those errors/inconsistencies corrected, and the results are compared with those circulated earlier in the Table and Figures below.</div
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