Photo: Courtesy Revista Puerto
Knowledge about kingclip is expanding
Friday, June 11, 2021, 08:00 (GMT + 9)
By comparing the data obtained in the March 2021 survey with that of May 2020, the INIDEP researchers were able to develop hypotheses about the migration of the resource after spawning and its size distribution in an area of interest above the 200-mile limit.
In March, a kingclip survey was carried out on a corridor located on the edge of the 200-meter isobath, between the parallels of 40 and 43 degrees. The comparison with the survey carried out in the same place in May 2020 allowed the INIDEP researchers to establish a hypothesis regarding the migration of kingclip after spawning. In March a majority of adult and sexually active specimens were observed, while in May a majority of juveniles in a resting state had been detected. Directed campaigns and surveys are adding knowledge about the resource, which for science is in a state of overexploitation, while the business sector insists that there is an underestimation of abundance.
During the survey carried out averaging the month of March, the estimated total catch of kingclip was 588.6 tons, a volume close to the quota of 600 tons assigned for the survey; and a discard of less than 1.1% was verified.
Photo: Revista Puerto
Six vessels were involved in the experience, 270 fishing sets were made and in 89 samples were collected inside and outside the survey area. In seven of the 12 trips, kingclip catches exceeded 50 tonnes and the species accounted for between 36 and 67% of the total catch. Within the prospecting area, 215 fishing sets were made, 76 samples were collected and 12,470 individuals were analyzed.
Some vessels made fishing sets outside the areas defined for the survey. A total of 55 sets were observed distributed in six statistical rectangles, where a total catch of approximately 320 tons was recorded, with a low presence of kingclip, only 1.5%.
The area with the highest catch was 3, located between the parallels of 41º and 42º South, from where 61% of the total pollack (360 tons) was extracted, a fact related to the largest number of sets, discards and average yield estimated at rate of 2.6 tons per hour. It was followed in order of importance by zone 1, at the height of the parallel of 40º South, with 168 tons (28% of the total), associated with the second place in number of sets and discards. The estimated average yield for this area was 1.85 tons. The remaining areas had total catches below 32 tons and average yields below 1.53 tons per hour.
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Comparison of returns
"Given that the areas visited during the May 2020 and March 2021 surveys were the same, some relevant differences with respect to hourly yields can be noted," the document states.
Zone 3, during March of this year, registered the highest average yield, reaching 2.64 tons, while in May of the previous year it was the lowest: 0.1 tons per hour. In zone 2, on the other hand, the situation was the opposite; that is, lower average yields were obtained in 2021. Zones 1 and 4 showed similar average yields, while in zone 5, located south of the parallel of 43º, low yields were recorded in the two surveys, with values below 0 , 5 tons.
The researchers emphasize that this year some high sets were registered, with up to 30 tons per hour, particularly in zones 1 and 3, which were not observed during 2020 and which show the presence of a high concentration of the resource.
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There were high proportions of adults in most of the surveyed areas, except in 5 where juvenile individuals predominated. In zones 1 and 2, adults exceeded 75%, while in zones 3 and 4 they were close to 65%. From north to south, a decrease was observed not only in the proportion of adult individuals but also in the maximum length, which was 140 centimeters in total length in zone 1 to 107 in zone 5.
Photo: Revista Puerto
In all areas, greater representation of adults and larger sizes was observed compared to the survey carried out in May 2020, with the exception of area 5. This area was characterized mainly by the presence of juvenile specimens in both years.
The sex ratio was in favor of females, except in zone 3, contrary to what was observed in 2020 when the sex ratio was in favor of males for all zones.
Maturity and reproduction
Regarding the reproductive condition of kingclip, the researchers analyzed the maturation stage of 7,142 individuals, finding a high proportion of adult individuals, mostly reproductively active, unlike what was observed in the May 2020 survey.
The analyzed population was characterized mainly by individuals mature that, together, constituted approximately 68% of the specimens analyzed. The sexually active fraction was the most represented and reached approximately 60% of the analyzed specimens. Individuals in laying were the least frequent, 1.74%, contrary to what was observed in the May 2020 survey, when more than 50% of the population corresponded to juvenile individuals. The sexually active fraction barely exceeded 10% and most of the adult individuals presented in the resting stage.
“This difference could be related to the summer reproductive concentration that occurs in areas adjacent to the surveyed area in the summer months. The species congregates in the area 43º - 48º South from December to March to carry out reproduction ”, it is indicated in the report.
Photo: Revista Puerto
“This evidence would allow us to suppose that the adults observed in the present work could be migrant individuals that leave the reproduction zone, since the time in which this work was carried out coincides with the end of the reproductive season. In turn, this hypothesis could also explain, at least in part, the differences observed with respect to the survey carried out in May 2020, where most of the catch was made up of juveniles, and the adults were mostly sexually inactive (state of rest) ”.
These data are incorporated into the historical series that is counted on kingclip, built from the data collection in the hubbsi hake and illex squid campaigns over decades, with the unfortunate gaps that the lack of campaigns of these species It has generated. Expanding knowledge about the resource will allow better management, which may ultimately result in the maintenance of restrictive measures for its preservation or an expansion of the catch based on a proven improvement in the indicators.
Kingclip is one of the species that inhabit not only the Argentine Sea, but it is also found outside our Exclusive Economic Zone, where foreign fleets catch it uncontrollably. Strengthening the data is not only important for the national fleet that intends to exploit it but also as a discussion tool about what happens at Mile 201.
Source: Revista Puerto