Pots vs trammel nets: a catch comparison study in a Mediterranean small-scale fishery

Andrea Petetta; Claudio Vasapollo; Massimo Virgili; Giada Bargione; Alessandro Lucchetti

doi:10.7717/peerj.9287

Pots vs trammel nets: a catch comparison study in a Mediterranean small-scale fishery

PeerJ. 2020 Jul 17:8:e9287. doi: 10.7717/peerj.9287. eCollection 2020.

Authors

Andrea Petetta^#^{1

2}, Claudio Vasapollo^#², Massimo Virgili², Giada Bargione^{1

2}, Alessandro Lucchetti²

Affiliations

¹ Department of Biological, Geological and Environmental Sciences, University of Bologna, Bologna, Italy.
² Institute for Biological Resources and Marine Biotechnologies (IRBIM), Italian National Research Council (CNR), Ancona, Italy.

^# Contributed equally.

Abstract

Passive bottom-set nets are the most widely used fishing gears in Mediterranean small-scale fisheries (SSFs). Trammel nets, in particular, have key advantages such as their ease of use and handling and high capture efficiency for numerous commercial species. However, they entail high discard rates (5-44% of the total catch) connected to high mortality, thus exerting an adverse impact on benthic communities, besides catching individuals of commercial species under the minimum conservation reference size (MCRS) and specimens of protected species. Fish pots are seen as alternative and a more sustainable gear type that allow reducing discards in SSFs. In this study, a collapsible pot was tested at three coastal sites in the north-western Adriatic Sea (GFCM GSA 17) to compare its catch efficiency with that of the local traditional trammel nets. Data analysis demonstrated a similar catch efficiency for the commercial species, both among sites and as a whole. Moreover, the trammel net caught a larger amount of discards, both in terms of species number and of CPUE_W. The catch comparison study involved the two most abundant landed species, common cuttlefish Sepia officinalis and annular sea bream Diplodus annularis. The pots were more effective for S. officinalis, whereas the trammel net was more effective for the shorter length classes for D. annularis, which were mostly under the MCRS (12 cm). The innovative pots could provide a valuable alternative to the trammel nets traditionally used in the Adriatic Sea, at least in certain areas and periods. Their main advantages include that they do not require a different rigging and they can be used without bait, while their foldable design allows large numbers to be easily loaded on board SSF vessels. The results of this pilot study indicate that pots can achieve the objectives of reducing discards and bycatch in SSFs without penalizing the catch of commercial species.

Keywords: Alternative fishing gears; Catch comparison; Discard reduction; Experimental pot; Fish pots; Mediterranean sea; Passive gears; Set nets; Small-scale fisheries; Sustainable fishery.

Grants and funding

This study was conducted with the contribution of the LIFE Financial Instrument of the European Community, Tartalife Project - Reduction of sea turtle mortality in professional fishing (LIFE12NAT/IT/000937). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.