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Photo: courtesy Revista Puerto
Illex Squid: X-ray of abundance
ARGENTINA
Wednesday, January 27, 2021, 07:00 (GMT + 9)
The INIDEP presented the report of the campaign carried out last month. Estimates of biomass and number of recruits from the summer spawning stock were 130 thousand tons and 699 million individuals. It is estimated that at the beginning of the harvest, 60 percent of the specimens had passed the reproductive process.
The Technical Report contains the results of the research campaign carried out by INIDEP scientists research vessel 'Víctor Angelescu' at the end of last year to estimate the abundance of the summer spawning stock (SDV) of the Argentine squid.
The study, prepared by Marcela Ivanovic, Beatriz Elena, Martha Mc Innes, Nicolas Prandoni and Gabriel Rossi, determines the population structure, biomass and number of squid recruits from the summer spawning stock.
The campaign was carried out between December 4 and 23 in an area between 44 ° and 46 ° 30 'South, a total area of 21 million square nautical miles in which five strata were delimited and 50 sets of bottom trawling of 15 minutes each and a limit of 5 sets per stratum was adopted. Due to adverse weather conditions, two sets were suspended, so there were finally 48.
With the early opening of the squid season, defined by the CFP for more than three years, it was sought to take better advantage of the abundance of the summer spawning stock, which by the beginning of the year is in the final stage of its cycle vital.
Image: courtesy C.A.P.A.
With this early start, the composition of the catches and the contributions that each stock had in the fleet's unloadings were modified. Traditionally, with the beginning of the fishing season on February 1, the catches were mainly composed of the sudpatagponico stock (SSP).
But from this change and early start, it is now the SDV that contributes between 80% and 90% of the catches in the last two years of the management unit south of 44 ° South. As a result of this situation, it became essential to study and analyze this stock, which was possible thanks to the contribution of the shipowners who financed the campaign due to INIDEP's budget deficiency.
Image: courtesy C.A.P.A.
“The estimates of biomass and number of recruits from SDV were 130 thousand tons; 699 million individuals ”, reported INIDEP researchers. "The two strata located between 44º and 45º South contributed around 80% of the abundance both in weight and in number of individuals," he specifies.
"There is nothing to compare the figures with because it is the first time that this stock has been studied," explained Marcela Ivanovic yesterday in consultation with this medium.
For the sampling of individuals, samples of up to 150 individuals were taken per set, which produced a total of 4,688 individuals sampled. In total, 4,216 kilos of Argentine squid were caught in the 48 sets carried out. "75% of the total catch was obtained north of 45 ° South", details the report to which REVISTA PUERTO had access.
Photo: courtesy Revista Puerto
The average density for the entire investigated area was 6.22 tons per square nautical mile. The highest concentrations were located north of 45 ° South where the mean varied between 21 and 35 tons per square nautical mile. Between 45 ° and 46 ° South, the highest yields were observed in stations more than 100 meters deep.
T e size of the squid varied between 170 and 298 millimeters and 30% of the individuals of both sexes were in reproduction and post-production, which indicates that the reproductive process had already begun for that portion of the stock, the researchers detailed.
“Between 26 and 28% of the specimens were in a state of advanced maturity, close to beginning the reproductive process. Of the rest of the specimens sampled, 39% of the males and 13% of the females had an incipient maturation process and the remaining 30% of the females were immature or in maturation, typical of the delay of the maturation process in the females with respect to the characteristic males of the species ”, considered the scientists in the Report.
During the campaign, two stocks could be identified in the catches. In addition to SDV, the South Patagonian Stock. For the identification of the two squid stocks, the analysis criteria of the size structure and the degree of maturity were applied. Thus, immature or incipiently mature males with a mantle length of less than 20 centimeters, and immature or maturing females with a BL of less than 22 centimeters, were identified as corresponding to SSP, the rest were identified as SDV.
The results of the campaign allowed determining that 30% of the BDS had started their reproductive process while 28% were in advanced maturity, close to starting it.
Author: Roberto Garrone / Revista Puerto
editorial@seafood.media
www.seafood.media
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