389 research outputs found
Acoustic assessment and distribution of the main pelagic fish species in ICES Subdivision 9a South during the ECOCADIZ 2019-07 Spanish survey (July–August 2019).
Acoustic assessment and distribution of the main pelagic fish species in ICES Subdivision 9a South during the ECOCADIZ-RECLUTAS 2019-10 Spanish survey (October 2019)
Acoustic assessment and distribution of the main pelagic fish species in ICES Subdivision 9a South during the ECOCADIZ-RECLUTAS 2018-10 Spanish survey (October 2017).
The present working document summarises the main results obtained during the ECOCADIZ-RECLUTAS 2018-10
Spanish (pelagic ecosystem-) acoustic survey. The survey was conducted by IEO between 10th and 29th October 2018 in
the Portuguese and Spanish shelf waters (20-200 m isobaths) off the Gulf of Cadiz onboard the R/V Ramón Margalef.
The survey’s main objective is the acoustic assessment of anchovy and sardine juveniles (age 0 fish) in the recruitment
areas of the Gulf of Cadiz. The 21 foreseen acoustic transects were sampled. A total of 25 valid fishing hauls were
carried out for echo-trace ground-truthing purposes. Chub mackerel was the most frequent species in those hauls,
followed by sardine, anchovy, horse mackerel, mackerel, bogue and Mediterranean horse mackerel. Acoustic sampling
was carried out with the recently installed Simrad™ EK80 echo-sounder working in multi-frequency and in CW mode.
A misconfiguration of the range of the acoustic active layer entailed to slow down the ping rate (1.5-2.0 seconds) in
relation to the standard values (at about 0.3 seconds), resulting an acoustic sampling rate much lower than it should
be. Therefore, the results from this acoustic sampling and the resulting estimates from this survey should be
considered with caution. Anchovy abundance and biomass were of 953 million fish and 10 493 t. The abundance and
biomass of age-0 anchovies were estimated at 543 million fish and 3 834 t, 57% and 36% of the total population
abundance and biomass, respectively. Despite the methodological problems, these estimates seem to suggest a
recent decrease in relation to previous years. The estimates for Gulf of Cadiz sardine in the surveyed area were of 1
134 million fish and 20 679 t. Estimates of age-0 sardine were of 1 036 million fish and 15 224 t, 91% and 74% of the
total estimated abundance and biomass, respectively. Even taking into account a possible underestimation for the
abovementioned methodological problems, the values reached in 2018 were above the historical mean for the total
population and recruits abundance and for the recruit biomass, and they might suggest a relatively stable situation
since the maxima registered in 2016
Acoustic assessment and distribution of anchovy, sardine and chub mackerel in ICES Subdivision 9a South during the ECOCADIZ-RECLUTAS 2021-10 Spanish survey (October 2020) with notes on the distribution of other pelagic species. Preliminary information.
The present working document summarises a part of the main results obtained during the ECOCADIZ-RECLUTAS 2021-10 Spanish (pelagic ecosystem-) acoustic survey. The survey was conducted by IEO between 21st October and 07th November 2021 in the Portuguese and Spanish shelf waters (20-200 m isobaths) off the Gulf of Cadiz (GoC) onboard the R/V Ramón Margalef. The survey suffered a ten-day delay in relation to the usual starting dates, resulting in ending dates very close to the starting ones of the WGACEGG meeting. Therefore, no acoustic estimates were available at the time of WG meeting. The survey’s main objective is the acoustic assessment of anchovy and sardine juveniles (age 0 fish) in the recruitment areas of the GoC. The 21 foreseen acoustic transects were sampled. A total of 18 valid fishing hauls were carried out for echo-trace ground-truthing purposes. This working document only provides information on the results of these hauls in terms of species-specific occurrences, yields in numbers and weight, size ranges, mean size and mean weight in catches
Acoustic assessment and distribution of anchovy and sardine in ICES Subdivision 9a South during the ECOCADIZ 2017-07 Spanish survey (July-August 2017) with notes on the distribution of other pelagic species.
Acoustic assessment and distribution of anchovy, sardine and chub mackerel in ICES Subdivision 9a South during the ECOCADIZ 2019-07 Spanish survey (July-August 2019) with notes on the distribution of other pelagic species.
Acoustic assessment and distribution of the main pelagic fish species in ICES Subdivision 9a South during the ECOCADIZ-RECLUTAS 2017-10 Spanish survey (October 2017).
The present working document summarises the main results obtained during the ECOCADIZ‐RECLUTAS
2017‐10 Spanish (pelagic ecosystem‐) acoustic survey. The survey’s main objective is the acoustic
assessment of anchovy and sardine juveniles (age 0 fish) in the recruitment areas of the Gulf of Cadiz. The
survey was planned to be conducted by IEO between 12nd and 31st October 2017 in the Portuguese and
Spanish shelf waters (20‐200 m isobaths) off the Gulf of Cadiz onboard the R/V Ramón Margalef. However,
a serious breakdown of the vessel’s propulsion system detected in the afternoon of the 22th October led to
the early termination of the survey in that day. Only the seven (7) easternmost acoustic transects were
sampled, which were accompanied by the conduction of eight (8) fishing hauls. The resulting estimates are
therefore referred to this surveyed area, which corresponded to the eastern sector of the Spanish shelf
waters, comprising the shelf between Doñana and Cape Trafalgar, and they are not comparable to the
previous available estimates.
Anchovy abundance and biomass in that surveyed area were 1 492 million fish and 7 641 t. The
abundance and biomass of age 0 anchovies in the surveyed area were estimated at 1 433 million fish and 7
290 t. This juvenile fraction accounted for 96% and 95% of the total estimated population abundance and
biomass, respectively. The estimates for Gulf of Cadiz sardine in the surveyed area were of 591 million fish
and 12 103 t. Estimates of age‐0 sardine were of 483 million fish and 8 778 t, 82% and 72% of the total
population, respectively. These estimates cannot be compared with the remaining data points in the series
because the abovementioned problems with acoustic sampling coverage
Acoustic assessment and distribution of the main pelagic fish species in ICES Subdivision 9a South during the ECOCADIZ 2017-07 Spanish survey (July-August 2017).
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