Using bioacoustics and conventional netting methods to assess the initial effectiveness of a newly deployed artificial reef on fish assemblages in Xiangshan Bay near Ningbo, Zhejiang Province, China

Abstract

Summary Objectives of the study were ascertaining the temporal variation of fish density and biomass as well as the changes in fish species composition in a surveyed area before and after deployment of an artificial reef. The study was initiated within an area of 0.25 km2 in response to a strong demand for fisheries enhancement and resource conservation in Xiangshan Bay, Zhejiang Province, China. This survey data was collected through a SIMRAD EY60 system and bottom trinal nets pre‐ and post‐construction of the artificial reefs, May 2011 to September 2012 in Xiangshan Bay. The raw data were analyzed using fisheries acoustic Echoview (Myriax) software combined with bottom trinal net data. The results showed that estimated fish density, represented by a nautical area scattering coefficient (NASC) at the artificial reef increased by 14.04, 31.10, 17.35% in May, July and September 2012 after construction of the artificial reef, and that the fish biomass increased by 8.92, 29.06, and 18.09% in these three months of 2012 in contrast to 2011. The numbers of fish species varied from 7 to 9 in May, from 10 to 14 in July and from 9 to 12 in September of 2012. These temporal changes in the fishery status were considered as being mainly due to deployment of the artificial reefs in early April 2012.

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

“…In the past twenty years there has been an increasing use of the Multibeam Echosounder (MBES) for acoustic applications in fisheries research, with advancements in hardware technology, digital acquisition of acoustic backscatter in the water column and 3D visualization of acoustic data (Hafsteinsson and Misund, ; Gerlotto et al., , ; Misund and Coetzee, ; Gerlotto and Paramo, ; Soria et al., ; Paramo et al., ; Howell, ; Gurshin et al., ; Weber et al., ; Yuan et al., ). This technique has often been associated with other acoustic methodologies (Gerlotto et al., ; Misund and Coetzee, ; Brehmer et al., ; Gerlotto and Paramo, ; Gurshin et al., ) as well as with fishing surveys (Howell, ; Weber et al., ; Yuan et al., ), resulting in an extremely efficient tool to provide additional information on spatial distribution, school morphology and classification, migrations and abundance. More recently MBES has also been applied to detect fish at artificial reefs to evaluate the efficacy of artificial structures of different shape and size in aggregating benthic, nekto‐benthic and pelagic fish according to their own ecological needs (Yuan et al., ).…”

“…The present study was aimed to evaluate the suitability of MBES as an efficient tool capable of assessing consistence and spatial distribution of fish schools around gas extracting structures (one four-legged platform and one subsea well-site), thus providing additional information that, in association with data obtained through fishing surveys, would allow a better understanding of the effects induced by these structures on the fish communities inhabiting their surroundings. Table 6 Fishing survey: results of Analysis of Variance (ANOVA) carried out on factor 'Platform (C) vs P reference sites (F1 and F2)' (fixed factor), and 'Well-site (C) vs W reference sites (F1 and F2)' (fixed factor) comparing abundance of the main species categories caught during fishing surveys at the platform and at the well-site In the past twenty years there has been an increasing use of the Multibeam Echosounder (MBES) for acoustic applications in fisheries research, with advancements in hardware technology, digital acquisition of acoustic backscatter in the water column and 3D visualization of acoustic data (Hafsteinsson and Misund, 1995;Gerlotto et al, 1999Gerlotto et al, , 2000Misund and Coetzee, 2000;Gerlotto and Paramo, 2003;Soria et al, 2003;Paramo et al, 2007;Howell, 2008;Gurshin et al, 2009;Weber et al, 2009;Yuan et al, 2013). This technique has often been associated with other acoustic methodologies (Gerlotto et al, 2000;Misund and Coetzee, 2000;Brehmer et al, 2003;Gerlotto and Paramo, 2003;Gurshin et al, 2009) as well as with fishing surveys (Howell, 2008;Weber et al, 2009;Yuan et al, 2013), resulting in an extremely efficient tool to provide additional information on spatial distribution, school morphology and classification, migrations and abundance.…”

“…This technique has often been associated with other acoustic methodologies (Gerlotto et al, 2000;Misund and Coetzee, 2000;Brehmer et al, 2003;Gerlotto and Paramo, 2003;Gurshin et al, 2009) as well as with fishing surveys (Howell, 2008;Weber et al, 2009;Yuan et al, 2013), resulting in an extremely efficient tool to provide additional information on spatial distribution, school morphology and classification, migrations and abundance. More recently MBES has also been applied to detect fish at artificial reefs to evaluate the efficacy of artificial structures of different shape and size in aggregating benthic, nekto-benthic and pelagic fish according to their own ecological needs (Yuan et al, 2013).…”

“…Hence, the abundance of fish schools at that site was undoubtedly underestimated. As also highlighted by Yuan et al (2013), the noise could be minimized and increasing the TS threshold. However, in this case some fish traces would also be excluded (Watkins and Brierley, 1996;Romare, 2001), leading to an underestimation of the fish assemblages.…”

“…The use of acoustic techniques to map the spatial distribution of fish schools in relation to the presence of artificial structures has largely improved in the past few decades, (Stanley and Wilson, ; Fabi and Sala, ; Sala et al., ; Kang et al., ; Yuan et al., ). In this perspective, the Multibeam Echosounder (MBES), primarily developed for seafloor mapping, has successfully improved for digital acquisition in the water column and 3D visualization of acoustical data (Fernandes et al., ; Mayer et al., ; Howell, ).…”