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ISRA FACTSHEETS

EUROPEAN ATLANTIC

ISRA FACTSHEETS

EUROPEAN ATLANTIC

Sesimbra ISRA

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Sesimbra ISRA

Sesimbra

Summary

Sesimbra is located off the coast of southwest Portugal. It includes the eastern part of the Setúbal Peninsula. The area is heavily influenced by northerly winds which produce upwelling during the boreal spring and summer. The area overlaps with the West Iberia Canyons and Banks Ecologically or Biologically Significant Marine Areas. Within this area there are: reproductive areas (Blue Shark Prionace glauca).

Sesimbra

Sesimbra

DESCRIPTION OF HABITAT

Sesimbra is located off the coast of the Setúbal Peninsula in southwest Portugal. The area includes the eastern part of the Setúbal Canyon that extends from west to east. This area is heavily influenced by northerly winds which produce upwelling during the boreal spring and summer increasing productivity in the area. Upwelling conditions decrease during autumn and winter (Peliz et al. 2002).

The area overlaps with the West Iberia Canyons and Banks Ecologically or Biologically Significant Marine Areas (EBSA; CBD 2025).

This Important Shark and Ray Area is pelagic and is delineated from surface waters (0 m) to 1,000 m based on the bathymetry of the area.

CRITERION C

SUB-CRITERION C1 – REPRODUCTIVE AREAS

Sesimbra is an important reproductive area for one shark species.

The historical regular occurrence of neonate and young-of-the-year (YOY) Blue Sharks in the area has been reported since 2002 (Correia 2015; Ríos et al. 2025; J Correia unpubl. data 2025). Between 2002–2021, these life stages were regularly recorded during tag-and-release fishing tournaments in Sesimbra and additional tagging trips (Correia 2015; J Correia unpubl. data 2025). During tournaments, up to 130 YOY Blue Sharks were recorded in a single day in September 2009 inside the area (Correia 2015; J Correia unpubl. data 2025). Individuals measured <96 cm total length (TL) and were classified as neonate/YOY as their size is close to the reported size-at-birth (35–44 cm TL; Ebert et al. 2021) and YOY size reported for the species (<95 cm TL; Skomal & Natanson 2003). Tagging trips were conducted across the coast of Portugal, from Póvoa do Varzim in the north to Algarve in the south. From these trips and the tournaments, 420 Blue Sharks were recorded and sizes ranged between 30–250 cm TL (J Correia unpubl. data 2025). In Sesimbra, 202 individuals were recorded with a median size of 96 cm TL. In comparison, median size in Algarve was 125 cm TL confirming that neonate/YOY Blue Sharks concentrate in Sesimbra. Between 2019–2020, Baited Remote Underwater Video Station (BRUVS) surveys (n = 248) were conducted along the west coast of Portugal, around the Setúbal (inside the area) and Lisbon canyons (Ríos et al. 2025). Sizes of individuals were estimated from the videos and were classified in age classes according to growth curves for the species (Skomal & Natanson 2003). Blue Sharks between 50–96 cm TL were classified as YOY and between 97–125 cm TL as two years old (Rios et al. 2025). In these deployments, 79 Blue Sharks were recorded with the maximum number of individuals observed in a single frame (MaxN) being four. Of these individuals, 40 (50.6%) were classified as YOY and 21 (26.6%) as two-year old. These life stages were recorded mostly in spring and in locations with depths <1,000 m inside this area while adults were recorded mostly in autumn and in offshore locations outside this area.

Sesimbra

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