Elasmobranch bycatch in the Italian Adriatic pelagic trawl fishery

Abstract

Elasmobranchs are among the most threatened long-lived marine species worldwide, and incidental capture is a major source of mortality. The northern central Adriatic Sea, though one of the most overfished basins of the Mediterranean Sea, supports a very valuable marine biodiversity, including elasmobranchs. This study assesses the impact of the northern central Adriatic pelagic trawl fishery on common smooth-hound (Mustelus mustelus), spiny dogfish (Squalus acanthias), common eagle ray (Myliobatis aquila), and pelagic stingray (Pteroplatytrygon violacea) by examining incidental catches recorded between 2006 and 2015. The distribution of bycatch events was evaluated using geo-referenced data. Generalized Linear Models were computed to standardize the catch of the four species and to predict the relative abundance of bycatch events. Data analysis shows that most bycatch events involving all four species occurred in the northern Adriatic Sea. The models predicted significant, distinct temporal patterns of standardized catches in line with previous investigations. Water depth, season, and fishing region were the best predictors to explain bycatch events. The present data suggest that the northern Adriatic may be an important nursery area for several elasmobranchs. They also highlight the urgent need for a better understanding of the interactions between elasmobranchs and fisheries to develop and apply suitable, ad hoc management measures.

Peer Review #3 of "Pots vs trammel nets: a catch comparison study in a Mediterranean small-scale fishery (v0.2)"

“…easy to control by inspection authorities). With reference to bycatch of sensitive and protected species, during our study the trammel nets caught five specimens of the pelagic stingrays (Pteroplatytrigon violacea), a frequent event in several Adriatic fisheries (Bonanomi et al, 2018). This Elasmobranch species, usually discarded due to its scarce commercial value, is considered as a 'Least Concern' species in the IUCN red list (Baum et al, 2016).…”

Sistema Integrado De Manejo De Fauna

“…On the other hand, accompanying fauna (bycatch) comprises several organisms captured incidentally when capturing higher commercial value fishing resources (BONANOMI et al, 2017). However, as they are the object of lesser interest, sharks and rays are often discarded, either dead or with little chance of survival, usually without any control concerning their diversity and quantitative records (BONANOMI et al, 2018).…”

Opportunities from citizen science for shark conservation, with a focus on the Mediterranean Sea

“…At the moment, there are no management measures in place for sharks in the region and some options (e.g. fishing closure in critical habitats of the northern Adriatic Sea) are urgently required to restore depleted populations (Bonanomi et al 2018). Several other shark species, however, are part of fisheries' bycatch (Cavanagh & Gibson 2007).…”