Observational methods used in marine spatial monitoring of fishes and associated habitats: a review

Abstract

Management areas are used in marine spatial planning to conserve biodiversity of marine ecosystems and to protect fish from fishing pressure. To evaluate the effectiveness of these protected areas, observational techniques are used to determine densities, sizes, biomass, habitat types and distribution of fish species in and around management areas. Two types of observational techniques are used in spatial monitoring: (1) fishery-independent techniques, which include underwater visual census (UVC), underwater video, remote sensing, acoustics, and experimental catch and effort data; and (2) fishery-dependent techniques, which include catch, effort and catch per unit effort data from commercial and recreational fisheries. This review summarises the applications, advantages, disadvantages and biases of each of these observational categories and highlights emerging technologies. The main finding from this review was that a combination of observational techniques, rather than a single method, was the most effective approach to marine spatial monitoring. For example, a combination of hydroacoustics for habitat mapping and UVC or video for fish surveys was one of the most cost-effective and efficient means of obtaining fish-habitat linkages and fish assemblage data. There are also emerging technologies that could increase the precision and efficiency of monitoring surveys. There is a need for continued development of non-intrusive technology for marine monitoring studies.

Marinas as habitats for nearshore fish assemblages: comparative analysis of underwater visual census, baited cameras and fish traps

“…In the case of the marina located in southern Portugal, however, the efficiency of UVCs and BCs was lower, resulting in a lower number and relative abundance of species recorded, which were comparable to those recorded by FTs. This might be attributed to increased turbidity in this region, which greatly reduce the efficiency of visual techniques (Murphy and Jenkins 2010). Greater efficiencies of UVCs and BCs are not surprising, especially in sampling complex habitat types such as artificial structures.…”

“…Several methods exist for monitoring fishes at shallow depths (Murphy and Jenkins 2010), including nonextractive methods, such as underwater visual census techniques (hereinafter UVCs) and baited cameras (hereinafter BCs), and extractive fishing techniques, such as fish traps (hereinafter FTs). UVCs are the most commonly used procedure, as they allow a rapid, cheap and replicable acquisition of several quantitative variables simultaneously (e.g.…”

Advanced Spatial Modeling to Inform Management of Data-Poor Juvenile and Adult Female Rays

“…We know these species are mobile enough within the Irish Sea to mix into and out of refugia rather than being extirpated in fine spatial scales [3,5,8,38]. Before implementing spatial management based on this method, one should ground-truth such areas with directed sampling trips [39,40], incorporate additional datasets where possible (e.g., from the catch and discard observer program), or use manual testing/training splits to test predictive power. When implementing management for data-poor fisheries, such approaches to dedicated data collection will help to maximize the information returned from deployment of scarce monitoring resources.…”

Variation in the Effective Range of a Stereo‐Video Lander in Relation to Near‐Seafloor Water Clarity, Ambient Light and Fish Length

“…The moral rights of the named author(s) have been asserted data from baited RUVs (BRUVS) or other sampling techniques to obtain a more comprehensive view of fish diversity and abundance (Bernard and Gotz 2012;. One difficulty in combining data from various visual survey tools is that the area surveyed with single-camera RUVs is frequently unknown (Murphy and Jenkins 2010). However, the development of stereo-video systems for RUVs creates the potential to quantify the area viewed, at least approximately, and produce fish density estimates (Harvey et al 2004;Hannah and Blume 2014).…”

“…Baited or unbaited remote underwater video stations (RUVs) are increasingly being used to sample reef fish populations (Murphy and Jenkins 2010;Campbell et al 2015). Typically, RUVs are point-sampling systems that are deployed to the seafloor to record for a set period of time and then retrieved.…”