A comparison of methods for estimating fish assemblages associated with estuarine artificial reefs

Abstract

A B S T R A C TMonitoring strategies which adequately represent the entire community associated with artificial structures will enable more informed decisions regarding the broader effects of artificial structures and their role in the management of fisheries resources. Despite the widespread application of a range of in situ visual monitoring methodologies used in the assessment of artificial structures, the relative biases associated with each method have not been critically examined and remain poorly understood. Estimates of fish abundance on six estuarine artificial reefs carried out by divers using underwater visual census techniques (UVC) were compared with estimates of relative abundance determined by baited remote underwater video (BRUV). It was found that when combined, both methods provided a more comprehensive description of the species associated with estuarine artificial reefs. However, the difference in the number of species detected and the frequency of detection varied between methods. Results indicated that the differences in rates of detection between UVC and BRUV methodologies were primarily related to the ecological niche and behaviour of the species in question. UVC provided better estimates of the rare or cryptic reef associated species. BRUV sampled a smaller proportion of species overall but did identify key recreational species such as Acanthopagrus australis, Pagrus auratus and Rhabdosargus sarba with increased frequency. Correlation of abundance indices for species classified as "permanent" identified interspecific interactions that may act as a source of bias associated with BRUV observations. R E S U M OO monitoramento biológico da comunidade associada a substratos artificiais permite a tomada de decisões corretas em relação ao uso e o papel dos novos habitats no manejo de recursos pesqueiros. Apesar da enorme aplicação das técnicas de censo visual no estudo da ictiofauna em recifes artificiais, os erros relativos de cada metodologia ainda não foram analisados. Estimativas de abundância de peixes obtidas através de censos visuais subaquáticos (CVS) em seis recifes artificias assentados em ambientes estuarinos, foram comparadas com a abundância relativa estimada através de técnicas de monitoramento remoto com vídeo subaquático (MRVS) e isca para atração dos animais. Os resultados combinados de ambas as técnicas descreveram melhor as espécies associadas aos recifes artificiais de regiões estuarinas. Entretanto, a diferença no número de espécies identificadas e a freqüência de detecção entre ambas as técnicas foram devidas principalmente aos nichos ocupados e ao comportamento específico de cada espécie. A técnica de CVS estimou melhores as espécies raras e crípticas associadas aos recifes. A técnica de MRVS estimou uma proporção menor de espécies, mas foi capaz de identificar mais frequentemente e com mais precisão as espécies recreacionais tais como Acanthopagrus australis, Pagrus auratus e Rhabdosargus sarba. Índices de correlação de abundância de espécies "permanentes" revelaram inte...

Ecosystem attributes of trophic models before and after construction of artificial oyster reefs using Ecopath

“…The CI of S B was higher than that of S AR+Re , showing that ARs can shorten and modify the food web and increase net production. Claudet & Pelletier (2004) and Lowry et al (2011) reported higher biomasses in reef areas than in areas without reefs, with reef areas supporting large numbers of fish. Pitcher et al (2002) utilized Ecopath to simulate the marine ecosystem of Hong Kong and investigate the relationship between reef fish biomass and the relative size of ARs inside marine protected areas (AR/MPA).…”

“…They can influence nutrient cycling and transport (Falcão et al 2007, Vicente et al 2008 and sediment biogeochemistry (Alongi et al 2008), with subsequent changes in community structure and richness of associated organisms (Langlois et al 2006). Lowry et al (2011) reported higher fish biomasses in reef areas compared to areas without reefs, with reef areas supporting larger numbers of fish. Although quantitative assessments of artificial ecosystems including ARs have been performed in Li Island, Rongcheng City, China (Wu et al 2016) and Zhangzi Island, Dalian City, China (Z. , few studies have compared ecosystem status before and after AR deployment.…”

Point‐Combination Transect (PCT): Incorporation of small underwater cameras to study fish communities

“…Although bias by observer presence is reduced or entirely eliminated, the moving object of the STAVIRO apparatus might still alter fish behaviour (Mallet, Wantiez, Lemouellic, Vigliola, & Pelletier, 2014). The often-used Baited-Remote Underwater Video (BRUV) technique involves video surveillance of bait, which is placed in a particular habitat (Lowry, Folpp, Gregson, & Mckenzie, 2011;Unsworth, Peters, McCloskey, & Hinder, 2014). The resulting footage is then used to estimate fish abundance.…”

ROV-based Underwater Vision System for Intelligent Fish Ethology Research

“…Fish ethology, a discipline concerned with exploring the movement, behaviours and activities of either wild or cultivated fish under natural conditions, has shown great prospects in aquaculture, fisheries, and other marine related surveys and applications [3][4][5][6][7][8].…”

“…Traditional studies mainly focus on in situ observations periodically conducted by marine biologists, which are time consuming and dependent on strict knowledge and the ability to observe, count and describe [3][4][5][6][7][8]. Underwater vision systems, either tethered to a vessel or a shore-based facility, or operated by remotely operated vehicles (ROV) and autonomous underwater vehicles (AUV), have increased rapidly over the last decade [9][10][11][12][13][14][15][16].…”