713 research outputs found
Results from Bottom Trawl Survey on Flemish Cap of June-July 2010
A stratified random bottom trawl survey on Flemish Cap was carried out from June 21st to July 22nd 2010. The area surveyed was extended up to depths of 800 fathoms (1400 meters) following the same procedures as in previous years and decreasing the number of hauls planned (158). The survey was carried out by the R/V Vizconde de Eza with the usual survey gear (Lofoten). A total of 153 valid hauls were made by the vessel R/V Vizconde de Eza, 97 up to 730 meters depth and 56 up to 1400 meters. Survey results including abundance indices of the main commercial species and age distributions for cod, redfish, American plaice, Greenland halibut and Shrimp are presented. The general indexes for this year are estimated taken into account the traditional swept area (strata 1-19, up to depths of 730 m.) and the total area surveyed (strata 1-34, up to depths of 1400 m.)
Results from Bottom Trawl Survey on Flemish Cap of July 2004
A stratified random bottom trawl survey on Flemish Cap was carried out from June 25th to August 2nd 2004. This year, the area surveyed was extended up to depths of 800 fathoms (1400 meters) following the same procedures as in previous years and increasing the number of hauls planned (195). The survey was carried out by the R/V Vizconde de Eza and the last eleven days of the surveys were used to make 61 paired hauls with the R/V Cornide de Saavedra and to conclude the comparative fishing trial for calibration initiated in 2003 between the former vessel and the new one. A total of 124 valid hauls were made by the vessel R/V Vizconde de Eza with the usual survey gear (Lofoten) up to 730 meters depth. Survey results including abundance indices of the main commercial species and age distributions for cod, redfish, American plaice and Greenland halibut are presented. The general indexes for this year are estimated taken into account the traditional swept area (strata 1-19, up to depths of 730m) and the total area surveyed (strata 1-34, up to depths of 1400m). From the comparative fishing trial carried out during 2003 and 2004, the correction factors for the main species were estimatad and the indexes from 1988 to 2002 were corrected to the scale of the new vessel. In the same way the corrected abundance at age indices was presented for cod, American plaice, redfish and Greenland halibut
Results from Bottom Trawl Survey on Flemish Cap of June-July 2014
A stratified random bottom trawl survey on Flemish Cap was carried out from June 25th to July 23th 2014. The area surveyed was extended up to depths of 800 fathoms (1460 meters) following the same procedures as in previous years and 181 fishing stations planned. The survey was carried out by the R/V Vizconde de Eza with the usual survey gear (Lofoten). A total of 181 valid hauls were made by the vessel R/V Vizconde de Eza, 118 up to 730 meters depth and 56 up to 1460 meters. Survey results including abundance indices of the main commercial species and age distributions for cod, redfish, American plaice, Greenland halibut, roughhead grenadier and shrimp are presented. The general indexes for this year are estimated taken into account the traditional swept area (strata 1-19, up to depths of 730 m.) and the total area surveyed (strata 1-34, up to depths of 1460 m.)
Results from Bottom Trawl Survey on Flemish Cap of June-July 2012
A stratified random bottom trawl survey on Flemish Cap was carried out from June 26th to July 24th 2012. The area
surveyed was extended up to depths of 800 fathoms (1460 meters) following the same procedures as in previous
years and 181 fishing stations planned. The survey was carried out by the R/V Vizconde de Eza with the usual
survey gear (Lofoten). A total of 174 valid hauls were made by the vessel R/V Vizconde de Eza,118 up to 730 meters
depth and 56 up to 1460 meters. Survey results including abundance indices of the main commercial species and age
distributions for cod, redfish, American plaice, Greenland halibut, roughhead grenadier and shrimp are presented.
The general indexes for this year are estimated taken into account the traditional swept area (strata 1-19, up to
depths of 730 m.) and the total area surveyed (strata 1-34, up to depths of 1460 m.)
Calculation of the Calibration Factors from the Comparative Experience between the R/V Cornide de Saavedra and the R/V Vizconde de Eza in Flemish Cap in 2003 and 2004
EU carries out a stratified random summer bottom trawl survey in Flemish Cap, Division 3M of the NAFO Regulatory Area, since 1988. Since 1991, the survey was made with the R/V Cornide de Saavedra. In 2003, this vessel was replaced for the R/V Vizconde de Eza, so, in order to maintain the series obtained from the old vessel, a two year comparative fishing trial betweel the two vessels was made in the years 2003 and 2004. This work presents the methods used for the transformation of the series and their results for biomass and length distribution for the principal species in the area: Atlantic cod, American plaice, Redfish (Sebastes fasciatus, Sebastes marinus, Sebastes mentella and Sebastes juveniles), Greenland halibut, Roughhead grenadier and Northern shrimp. For all the species except for Roughhead grenadier the R/V Vizconde de Eza is more efficient that the R/V Cornide de Saavedra for the biomass, with values of FPC varying between 1.0159 (Greenland halibut) and 1.4455 (Juvenile redfish). In lengths, in all species except for Roughhead grenadier too, the new vessel is more efficient catching the smallest individuals and less or equal efficient for the biggest lengths
Results from Bottom Trawl Survey on Flemish Cap of June-July 2008
A stratified random bottom trawl survey on Flemish Cap was carried out from June 18th to July 22th 2008. The area surveyed was extended up to depths of 800 fathoms (1400 meters) following the same procedures as in previous years and decreasing the number of hauls planned (175). The survey was carried out by the R/V Vizconde de Eza with the usual survey gear (Lofoten). A total of 167 valid hauls were made by the vessel R/V Vizconde de Eza, 111 up to 730 meters depth and 56 up to 1400 meters. Survey results including abundance indices of hte main commercial species and age distributions for cod, redfish, American plaice, Greenland halibut and shrimp are presented. The general indexes for this year are estimated taken into account the traditional swept area (strata 1-19, up to depths of 730 m)
Northern Shrimp (Pandalus borealis) on Flemish Cap in June 2003
Since 1988, a stratified random summer bottom trawl survey in Flemish Cap (NAFO Regulatory Area of Div.
3M) was conducted by UE. In June 2003, the survey was carried out by the new research vessel R/V Vizconde de
Eza. For this reason during the first ten days of the survey a comparative Fishing Trial (calibration) was conducted
between the old research vessel R/V Cornide de Saavedra and the new research vessel R/V Vizconde de Eza in order
to calibrate the new ship. The corresponding Factor Power Correction (FPC) was calculated by generalized linear
regression model by haul, and a length conversion method. The transformed entire series of abundance, biomass,
mean catch per tow and length distribution for northern shrimp (Pandalus borealis) are presented for the period
1988-2002, and the no-transformed data for the year 2003. Also the standard error was shown for mean catch per
tow. This year a decreasing in shrimp biomass was observed. It was mainly due to declining of female biomass.
Also the youngest model group (age 1) appeared well represented, predicting a good recruitment in next years.
However, all these results must be taken carefully because the scarce number of hauls carried out during the
calibration
Revision of the Northern Shrimp (Pandalus borealis) on Flemish Cap in June 2003
Since 1988, a stratified random summer bottom trawl survey in Flemish Cap (NAFO Regulatory Area of
Division 3M) was conducted by UE. In June 2003, the survey was carried out by the new research vessel R/V
Vizconde de Eza, which will continue for this survey in the future. In order to calibrate the new ship, the
comparative fishing trial (calibration) initiated in 2003 between the old research vessel R/V Cornide de Saavedra
and the new R/V Vizconde de Eza, will continue during the survey in 2004. Because of this, the indexes in the series
from 1988 to 2002 were not changed to the new scale by now. Still, the 2003 current indices from R/V Vizconde de
Eza were transformed to the R/V Cornide de Saavedra scale, to make them comparable to the results obtained in
previous years. The 2003 indexes were transformed by a length conversion method. The entire series of abundance,
biomass, mean catch per tow and length distribution for northern shrimp (Pandalus borealis) are presented for the
period 1988-2002, and the transformed data for the year 2003. In this year, a decreasing of shrimp biomass was
observed. It was mainly due to declining of 3 and 5 age-classes. Also the youngest model groups (age 1 and 2)
appeared well represented, predicting a good recruitment in next years.
However, all these results must be taken carefully because the scarce number of hauls carried out during the
calibration in 2003
Northern Shrimp (Pandalus borealis) on Flemish Cap Surveys 2003 and 2004
Since 1988, a stratified random summer bottom trawl survey in Flemish Cap (NAFO Regulatory Area of Div. 3M) was conducted by UE. Since 2003 the trawl vessel was replaced, the new vessel was calibrated and the indexes transformed. The lack of time has no permitted to transform the biomass and abundance shrimp indexes of the whole time series. So, the indexes in the series from 1988 to 2002 have not been changed by now and only the 2003 and 2004 indexes from the R/V Vizconde de Eza have been transformed to the R/V Cornide de Saavedra scale, to make them comparable to the results obtained in previous years. The shrimp catches taken with the same gear type Lofoten by both vessels from comparative fishing trials were very different, not only in weight but also in number. These results were interpreted on main differences between both vessels: trawl winch with an automatic control of the warp tension, higher vertical opening in the net and trawl warp length longer in the new vessel. Also, in the catches of the new vessel the presence of young shrimps was higher than in the old one. Because of this, abundance and biomass indexes from 2003 and 2004 were transformed using two methods based in conversion of CPUE and length frequencies and comparing the resulting estimates between them. Although there was not severe differences between these two methods, the marked differences in the length distribution of the catches makes the catch rate strongly dependent of the fish length (Warren, 1997), and thus we think the length conversion method reflects better the differences between the vessels. About the situation of the stock, a significan decreasing shrimp abundance and biomass is observed in the last two years (2003-2004), probably due to declining of 3 and 5 age-classes. Also, the strong presence of the youngest model groups (age 1 and 2) in the catches predicts good recruitment in next years
Spiny Dogfish (Squalus acanthias) and Black Dogfish (Centroscyllium fabricii) Spanish Data (Surveys and Fishery) in NAFO Divisions 3LMNO.
The analysis of Spanish survey and fishery dat a from Divisions 3LMNO show that Spiny dogfish (Squalus
acanthias) is not abundant and that this species appears in these Divisions sporadically and in depths of l ess than
500 meters.
Black dogfish (Centroscyllium fabricii) data show that this speci es is present in all Divisions, but is more abundant
in Div. 3NO and in depths of more than 900 m. Biomass estimated from the 3NO survey displays an increasing
trend over the last three years. Commercial catches of this species are mainly a by-cat ch of the Greenland halibut
fishery in Div. 3LMNO. Size compositions are mainly in between 50 and 70 cm of length, both for commercial and
survey catches
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