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Common, rare or extirpated? Shifting baselines for common angelshark, Squatina squatina (Elasmobranchii: Squatinidae), in the Northern Adriatic Sea (Mediterranean Sea)
Fortibuoni, T.; Borme, D.; Franceschini, G.; Giovanardi, O.; Raicevich, S. (2016). Common, rare or extirpated? Shifting baselines for common angelshark, Squatina squatina (Elasmobranchii: Squatinidae), in the Northern Adriatic Sea (Mediterranean Sea). Hydrobiologia 772(1): 247-259. http://dx.doi.org/10.1007/s10750-016-2671-4
In: Hydrobiologia. Springer: The Hague. ISSN 0018-8158; e-ISSN 1573-5117
Peer reviewed article  

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    Vlaams Instituut voor de Zee: Non-open access 295579 [ request ]

Keywords
    Endangered species
    Squatina squatina (Linnaeus, 1758) [WoRMS]
    Marine/Coastal
Author keywords
    Naturalists’ accounts; Landings; Scientific survey; histological ecology; Fishers’ ecological knowledge

Authors  Top | Datasets 
  • Fortibuoni, T.
  • Borme, D.
  • Franceschini, G.
  • Giovanardi, O.
  • Raicevich, S.

Abstract
    Historical baselines are needed to reconstruct long-term changes in marine animal populations and enhance our ability to articulate management recommendations. We reconstructed common angelshark (Squatina squatina) abundance in the Northern Adriatic Sea over the last two centuries by integrating different sources of formal and informal information. The wide amount of information collected helped assessing if the species is actually extirpated from the area, as stated in previous studies. According to naturalists’ accounts and historical documents, in the nineteenth and early twenty-first centuries the species was so abundant to sustain targeted fisheries, and large quantities of S. squatina were sold in the main fish markets. In the 1960s, the species collapsed and got economically extinct. Even if it was never caught in the area through scientific surveys during the period 1948–2014, from fishermen interviews emerged that the species is not extirpated. However, only 50% of interviewees caught S. squatina at least once and they were significantly older than the fishermen that never caught it (shifting baseline syndrome). Moreover, the size of the fish caught significantly decreased through time, indicating the depletion of larger individuals. Our integrated approach can be applied to any poorly assessed species so that appropriate international conservation measures can be prioritized.

Datasets (4)
  • Early naturalists’ accounts (1818-1936) on the Adriatic Sea (Mediterranean Sea) fish fauna
  • Trawl-survey data from the “expedition Hvar” in the Adriatic Sea (Mediterranean) collected in 1948-1949
  • Trawl-survey data from the Pipeta programme in the Northern Adriatic Sea (Mediterranean) collected in 1988 and 1991
  • Trawl-survey data in the Adriatic Sea (Mediterranean) collected in 1972, 1975 and 1981

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