true

ISRA FACTSHEETS

SOUTH AMERICAN ATLANTIC REGION

ISRA FACTSHEETS

SOUTH AMERICAN ATLANTIC REGION

Mar del Plata-Mar Chiquita ISRA

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Mar del Plata-Mar Chiquita ISRA

Mar del Plata-Mar Chiquita

Summary

Mar del Plata-Mar Chiquita is located in Argentina. It is situated in the Buenos Aires Province and encompasses waters from the coast in front of Mar del Plata city to Mar Chiquita to the north. The area is characterised by low visibility waters, rocky substrates, and soft corals. It is influenced by the convergence of the Subtropical Brazil-Malvinas Confluence and the freshwater discharge from the Río de la Plata. Within the area there are: threatened species (e.g., Copper Shark Carcharhinus brachyurus); reproductive areas (Copper Shark); and undefined aggregations (Sandtiger Shark Carcharias taurus).

Mar del Plata-Mar Chiquita

Mar del Plata-Mar Chiquita

DESCRIPTION OF HABITAT

Mar del Plata-Mar Chiquita is located in Buenos Aires Province in Argentina. The area encompasses waters from the coast in front of Mar del Plata city to Mar Chiquita to the north. It is characterised by low visibility waters, rocky substrates, and soft corals (WCS Argentina 2025). The area is influenced by the Subtropical Brazil-Malvinas Confluence (Rodrigues et al. 2023). Additionally, it is influenced by freshwater discharge from the Río de la Plata and the interaction of these currents with the upper slope’s topography inducing upwelling and fronts (Rodrigues et al. 2023).

This Important Shark and Ray Area is benthic and pelagic and is delineated from inshore and surface waters (0 m) to 25 m based on the bathymetry of the area.

CRITERION A

VULNERABILITY

Two Qualifying Species considered threatened with extinction according to the IUCN Red List of Threatened Species regularly occur in the area. These are the Critically Endangered Sandtiger Shark (Rigby et al. 2021) and the Vulnerable Copper Shark (Huveneers et al. 2020).

CRITERION C

SUB-CRITERION C1 – REPRODUCTIVE AREAS

Mar del Plata-Mar Chiquita is an important reproductive area for one shark species.

Between 2010–2025, a citizen science program involving recreational fishers monitored and tagged captured sharks before release along the coast of Argentina. Fishers used rod and reel (with one hook per line) while fishing from kayaks, the shore, or small boats (J Cuevas unpubl. data 2025). Collected information included: species, sex, total length (TL), coordinates, tag number assigned to the animal, and photos or videos (J Cuevas unpubl. data 2025).

Between 2013–2016, 22 neonate and young-of-the-year (YOY) Copper Sharks were captured and measured by recreational fishers in the area (individuals ranged between 63–105 cm TL; mean 87.2 cm TL) and 14 additional individuals were captured and visually estimated to be <100 cm TL (J Cuevas unpubl. data 2025). Size-at-birth for this species is 59–70 cm TL (Ebert et al. 2021). Neonates and YOY were captured in 2013 (n = 4 individuals), 2014 (n = 2), 2015 (n = 2), and 2016 (n = 28). Captures occurred between December–March, with most recorded in December (n = 7) and January (n = 27) (J Cuevas unpubl. data 2025). Additionally, in January 2016, 81 individuals weighing between 6–35 kg, ranging from neonates to juveniles, were captured in the area (J Cuevas unpubl. data 2025). Further several YOY were captured and released by recreational fishers in the area in November 2015 (n = 1 YOY) and January 2025 (n = 2 YOY and one juvenile) (EF Cañueto pers. obs. 2025). Pregnant females (inferred from distended abdomens) (n = 4) ranging in size between 265–286 cm TL were captured in the area from the beach and tagged, during the months of December (n = 3) and March (n = 1) in 2021 (n = 2), 2023 (n = 1), and 2024 (n = 1) (J Cuevas unpubl. data 2025). Although neonates and YOY were captured along the coast of Buenos Aires Province, this area includes the locations with the highest number of records in Argentina and Uruguay (De Wysiecki 2024; De Wysiecki et al. 2025; J Cuevas unpubl. data 2025).

Furthermore, a compilation of data for Copper Sharks (n = 407 occurrences) derived from published and unpublished research literature, social media, biodiversity repositories, commercial fishing, and research campaigns was carried out between 2010–2021 along the coast of Argentina (De Wysiecki 2024). Only records with date, TL, and coordinates were used to determine the distribution of neonates (n = 17) ranging in size from 60–83.5 cm TL (De Wysiecki 2024; De Wysiecki et al. 2025). Mar del Plata-Mar Chiquita had at least seven neonate records from December–March and this area was the only area where neonates were consistently found across the years in the Southwestern Atlantic (De Wysiecki 2024; De Wysiecki et al. 2025).

CRITERION C

SUB-CRITERION C5 – UNDEFINED AGGREGATIONS

Mar del Plata-Mar Chiquita is an important area for undefined aggregations of one shark species.

Between 1991–2025, aggregations of Sandtiger Shark were regularly observed every year during the months of December–March, when water temperatures in the area are warmer (EF Cañueto pers. obs. 2025). Observations from a recreational fisher collaborating on the tagging program, previously mentioned, with more than 35 years of experience fishing in the area (conducting an average of 20 fishing trips per month) have reported aggregations of up to 20 Sandtiger Sharks observed from the surface in the area (EF Cañueto pers. obs. 2025). During these aggregations, up to 10 Sandtiger Sharks have been captured and released during a five-hour session fishing in the same location, with a significantly higher number of bites or strikes (as fishing is done using circle hooks, and it is more difficult for sharks to get hooked). In this area, during December–March, Sandtiger Sharks captures often begin within 10 minutes of arriving at the site, indicating a high density of individuals aggregated in the area (EF Cañueto pers. obs. 2025). Aggregations were only captured in this area along the Buenos Aires Province (J Cuevas unpubl. data 2025). Additionally, in January 2018, an aggregation of >10 adults were filmed while diving in the area (with at least three sharks in the same frame, even though visibility was low) (EF Cañueto pers. obs. 2025). This species is known to exhibit complex social behaviours and forms large aggregations (20–80 sharks) around rocky formations in the wild (Ebert et al. 2021).

Although several neonates were recorded in the area during a compilation of data spanning from 2010–2021 derived from research literature, social media, biodiversity repositories, commercial fishing, and research campaigns (De Wysiecki 2024; De Wysiecki et al. 2025); and pregnant females, inferred from distended abdomens, and a mating event was witnessed form the surface (EF Cañueto pers. obs. 2025), further information is required to understand the nature and function of these aggregations.

Mar del Plata-Mar Chiquita

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