The National Institute for Fisheries Research and Development (INIDEP) has launched a new scientific campaign focused on large pelagic fish in the amberjack shoal , an area that in recent years has become a benchmark for the study of these resources. This initiative continues a line of research that has already spanned several editions and aims to strengthen the existing knowledge base on key species for the marine ecosystem of the southwestern Atlantic.
The expedition is taking place aboard the Argentine Sea Oceanographic Fisheries Research Vessel (BIP) , a platform specifically designed for this type of work in the open sea. From there, the team of specialists from the Pelagic Fish Fisheries Research Program is deploying a range of sampling and biological analysis techniques to better understand the status of populations such as the Argentine anchovy, the amberjack, and various tuna species.
A new stage in the study of large pelagic fish
The project currently underway is part of a series of consecutive scientific campaigns in the amberjack shoaldesigned to track the evolution of populations de peces large pelagic species over time. This continuity allows for comparison of results between years and the detection of changes in the presence, distribution, and structure of these species in the area.
This year, the campaign focuses once again on three groups of great fishing and ecological interest: anchovies, amberjack, and tuna . All of them primarily inhabit open waters, far from the coast, and play a vital role in the marine food chain, both as smaller predators and prey for larger species.
The research area is located in the so-called amberjack shoal , a zone that has gained prominence due to its biological richness and growing scientific and fishing interest. There, researchers take advantage of local oceanographic characteristics to study how these schools of amberjack concentrate and distribute themselves based on factors such as water temperature, food availability, and ocean currents.
Because the region is exposed to changing weather conditions, the vessel adjusts its position based on wind and wave reports . At times, the ship has been forced to move to shallower areas, such as Samborombón Bay, to take shelter from strong southwest winds that could exceed 30 knots in the main area of ​​operations.
Capture and sampling methods in the amberjack shoal
To gather reliable information on these populations, the scientific team uses a combination of fishing and sampling techniques that allow them to obtain representative data on the different species present. The central strategy involves adapting each method to the behavior and habitat of the large pelagic fish.
Among the tools used, jigging and trolling techniques stand out . Jigging involves using lures that move vertically in the water column, mimicking the behavior of prey and facilitating the capture of species that feed at different depths. Trolling, on the other hand, consists of dragging lures or fishing lines behind the moving vessel, allowing for the coverage of wide areas and the location of schools of fish moving on the surface or in midwater.
In addition to these selective techniques, the campaign incorporates midwater seine fishing . This type of gear is deployed in the area of ​​the water column where pelagic fish congregate, without reaching the bottom, thus reducing the impact on other benthic organisms. Thanks to this combination, researchers can access specimens of different sizes as well as species that move at different depths.
The objective is not so much the capture itself as the obtaining of carefully recorded biological samples . Each cast, whether with adapted sport fishing gear or scientific nets, is accompanied by the collection of data on the location, time, environmental conditions, and composition of the catch, which later allows the presence of the fish to be related to the physical and biological environment.
Biological analysis: feeding, reproduction and growth
Once the catches arrive on board, another crucial phase of the work begins: the processing and analysis of the samples . At this stage, researchers focus on a range of organs and tissues that provide key information about the biology of the species being studied.
To do this, stomachs, gonads, and muscle samples are extracted from the selected specimens. The stomach contents allow researchers to determine what types of prey they consume most frequently, how their diet varies according to the size of the fish or the time of year, and their exact place within the ecosystem's food web.
The gonads (reproductive organs) provide data on sexual maturity, spawning seasons, and the reproductive strategy of each species. Analyzing these aspects helps identify the seasons when fish reproduce most intensely, crucial information for defining management measures that prevent overexploitation during critical periods of their life cycle.
Muscle samples, meanwhile, are used in various types of analysis, from growth studies through internal structures to more advanced work that may include biochemical or genetic markers. All of this is integrated into a combined approach to population dynamics analysis , which is not limited to counting individuals, but seeks to understand how these populations change and organize themselves over time.
Importance of these campaigns for fisheries management
Beyond the strictly scientific aspect, the purpose of these campaigns is to build a solid information base for the sustainable management of fisheries resources . Understanding relative abundance, age structure, feeding patterns, and breeding seasons allows for more accurate assessments of population status.
The amberjack shoal is currently considered a natural laboratory for understanding the behavior of large pelagic fish in the southwestern Atlantic. The results obtained in this area can serve as a reference for other areas with similar characteristics, both regionally and in other parts of the ocean.
The information generated by INIDEP and its Pelagic Fish Fisheries Research Program is subsequently incorporated into stock assessment models and management recommendations , which support the authorities responsible for defining conservation and responsible exploitation policies. In this way, scientific activity aboard vessels in the Argentine Sea translates, over time, into concrete tools for decision-making.
In a context where environmental variations and fishing pressure can rapidly alter the balance of marine ecosystems, having up-to-date data and extensive time series becomes essential. This series of surveys in the amberjack shoal contributes precisely to this continuous monitoring, which is crucial for anticipating changes and adapting management strategies when necessary.
In general, these initiatives promoted by INIDEP demonstrate the central role of oceanographic and fisheries research in understanding marine resources in the southwestern Atlantic. Through repeated campaigns, using established methodologies and detailed analyses of the biology of species such as amberjack, anchovy, and tuna, an increasingly comprehensive map is being developed of how these populations function and what factors influence their evolution—a key element for ensuring their responsible use and long-term conservation.