Fish detection around offshore artificial structures: preliminary results from hydroacoustics and fishing surveys

Abstract

The spatial distribution of fish assemblages was investigated through either hydro-acoustic surveys (using a Multibeam Echosounder) or fishing surveys (using trammel nets) carried out at increasing distance from two gas extraction structures in the Adriatic Sea and characterized by different building architecture: one, a four-leg platform; the other a subsea well-site. Both types of surveys were monthly and performed for 1 year starting after installation of the structures. Primary scope of the study was to evaluate whether the combination of the two methodologies could provide a more comprehensive insight into the fish communities associated with artificial structures. The findings showed that associating the Multibeam Echosounder survey with the fishing survey provided complementary information on the spatial distribution and abundance of fish in the water column surrounding the artificial structures. Both methodologies evidenced the presence of a greater abundance and biomass of fish close to the structures in respect to reference sites. In addition, fish abundance and biomass were generally greater in the surroundings of the four-leg platform than at the well-site, a possible consequence of the larger volume of the former.

Fish aggregations at oil and gas platform foundations in the North Sea

“…using gillnets (Løkkeborg et al, 2002), trawling (Fujii, 2015), remotely operated vehicles (Ajemian et al, 2015;Todd et al, 2018), tag and release (Wright et al, 2020), hydroacoustics (Gallaway et al, 2021;Punzo et al, 2015), and scientific angling (Karnauskas et al, 2017).…”

Acoustic mapping and classification of benthic habitat using unsupervised learning in artificial reef water

“…In addition, the different benthic organism populations observed in different types of ARs indicated that the shape and structure of ARs may have impacts for biological communities living on them and their productivity. This phenomenon was highlighted by Punzo et al (2015), who found that aggregation effect of ARs on fish assemblages is related to the bulk volume and building architecture of the structures. The ARs are effective in aggregating benthos and in holding them by Table 3 Particle size analysis of benthic samples taken from study area.…”

“…These information can assist the managers to make a reasonable evaluation on the effectiveness of ARs combined with biological data (e.g. abundance and biomass) and abiotic data such as temperature, pH, oxygen, and salinity (Punzo et al, 2015;Schygulla and Peine, 2013). In addition, this can provide reference for the future construction of ARs and help local managers to better monitor coastal waters.…”

A comparison of two remotely operated vehicle (ROV) survey methods used to estimate fish assemblages and densities around a California oil platform

“…The role that a platform's jacket plays as fish and invertebrate habitat can be part of that decision-making process [1], and the increasing number of platforms to be decommissioned increases the need for this information. Historically, these characterizations have come from targeted biological surveys (e.g., conducted by scuba divers, manned submersibles, remotely operated vehicles (ROVs), bioacoustics, and nets) of a limited number of offshore oil and gas structures [2][3][4][5][6][7]. However, there also exists oil and gas ROV engineering surveys of platforms and associated infrastructure (i.e., pipelines, subsea equipment and wellheads) conducted as part of routine physical integrity inspections.…”