Spurdog (Squalus acanthias) is a widely distributed shark with a long history of exploitation. This study characterises its spatial ecology in the heavily fished Adriatic Sea using fishery-dependent data and a combination of models and mapping methodologies. The subsequent comparison with a part of the considerably more researched Northeast (NE) Atlantic population, inhabiting the coastal waters and fjords of southern Norway, allowed for the exploration of similarities and differences in this species' use of space. In the Adriatic Sea, this shark prefers northern regions, where the waters are shallower and more productive. Similar preferences for more productive locations were seen in the NE Atlantic population, which was more numerous at lower latitudes. Seasonality in one sex was then confirmed for both areas, although a different pattern was noted. While adult and pregnant females were only found in the northern Adriatic during the spring and summer months, when warmer waters and greater oxygen levels may have driven their migration to reproduce and give birth, adult females were mostly found in southern Norway throughout the winter. Males, on the other hand, appeared to remain stationary on a more local scale and were seen throughout the year in both study regions. Finally, modelling analysis revealed a decreasing trend in the Adriatic spurdog population, not detected in the NE Atlantic counterpart that instead appeared to have maintained its abundance during the investigated period. Findings of the spurdog spatial distributions, seasonality and temporal changes are expected to inform the sustainable management of this species and to develop future projects targeting the conservation of the ecosystems it inhabits (e.g., design of acoustic arrays, implementation of MPAs, etc.).
Lo spinarolo (Squalus acanthias) è uno squalo ampiamente distribuito con una lunga storia di sfruttamento. Questo studio caratterizza la sua ecologia spaziale nel Mare Adriatico, utilizzando dati dipendenti dalla pesca e una diversa combinazione di modelli e metodologie di mappatura. Il successivo confronto con una parte della ben più studiata popolazione dell'Atlantico nord-orientale (NE), che abita le acque costiere e i fiordi della Norvegia meridionale, ha permesso di esplorare le somiglianze e le differenze nell'uso dello spazio da parte di questa specie. Nel Mare Adriatico, questo squalo preferisce le regioni settentrionali, dove le acque sono meno profonde e più produttive. Preferenze simili per luoghi più produttivi sono state riscontrate nella popolazione del NE Atlantico, più numerosa alle latitudini più basse. La stagionalità nelle femmine adulte è stata poi confermata per entrambe le aree studiate, anche se è stato notato un pattern diverso. Mentre le femmine adulte e gravide sono state trovate nell'Adriatico settentrionale solo durante i mesi primaverili ed estivi, quando le acque più calde e i maggiori livelli di ossigeno possono aver favorito la loro migrazione per riprodursi e partorire, nella Norvegia meridionale le femmine adulte sono state al contrario trovate soprattutto durante l'inverno. I maschi, invece, sembravano rimanere stazionari su scala più locale e sono stati osservati durante tutto l'anno in entrambe le regioni di studio. Infine, l'analisi modellistica ha rivelato una tendenza alla diminuzione della popolazione di spinarolo dell'Adriatico, non rilevata nella controparte Norvegese, che invece sembra aver mantenuto la sua abbondanza. I risultati relativi alle distribuzioni spaziali, alla stagionalità e ai cambiamenti temporali dello spinarolo dovrebbero informare la gestione sostenibile di questa specie e lo sviluppo di progetti futuri mirati alla conservazione degli ecosistemi in cui vive (ad esempio, la progettazione di array acustici, l'attuazione di MPA e così via).
Investigation on the spiny dogfish (Squalus acanthias) spatial distribution and life history traits: a comparison between the Adriatic and the Northeast Atlantic populations
BEGGIATO, ANTONIO
2021/2022
Abstract
Spurdog (Squalus acanthias) is a widely distributed shark with a long history of exploitation. This study characterises its spatial ecology in the heavily fished Adriatic Sea using fishery-dependent data and a combination of models and mapping methodologies. The subsequent comparison with a part of the considerably more researched Northeast (NE) Atlantic population, inhabiting the coastal waters and fjords of southern Norway, allowed for the exploration of similarities and differences in this species' use of space. In the Adriatic Sea, this shark prefers northern regions, where the waters are shallower and more productive. Similar preferences for more productive locations were seen in the NE Atlantic population, which was more numerous at lower latitudes. Seasonality in one sex was then confirmed for both areas, although a different pattern was noted. While adult and pregnant females were only found in the northern Adriatic during the spring and summer months, when warmer waters and greater oxygen levels may have driven their migration to reproduce and give birth, adult females were mostly found in southern Norway throughout the winter. Males, on the other hand, appeared to remain stationary on a more local scale and were seen throughout the year in both study regions. Finally, modelling analysis revealed a decreasing trend in the Adriatic spurdog population, not detected in the NE Atlantic counterpart that instead appeared to have maintained its abundance during the investigated period. Findings of the spurdog spatial distributions, seasonality and temporal changes are expected to inform the sustainable management of this species and to develop future projects targeting the conservation of the ecosystems it inhabits (e.g., design of acoustic arrays, implementation of MPAs, etc.).File | Dimensione | Formato | |
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https://hdl.handle.net/20.500.12608/35105