Absolute abundance estimates from shallow water baited underwater camera surveys; a stochastic modelling approach tested against field data

Dunlop, Katherine M.; Ruxton, Graeme D.; Scott, E. Marian; Bailey, David M.

doi:10.1016/j.jembe.2015.07.010

Cited by 7 publications

(2 citation statements)

References 53 publications

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“…Nevertheless, several problems precludes any reliable estimation of absolute density using baited cameras (Whitmarsh et al 2017). Namely, the unknown dynamics of the bait odour plume, how such dynamics is affecting attractiveness (Dunlop et al 2015), how the fish already attracted by the bait are themselves a visual cue for other fish, and the plausible existence of species-specific responses and internal state dependence of the individual. Instead, several relative abundance metrics have been proposed.…”

Section: Introductionmentioning

confidence: 99%

Estimating the density of resident coastal fish using underwater cameras: accounting for individual detectability

Follana-Berná¹,

Palmer²,

Campos-Candela³

et al. 2019

Mar. Ecol. Prog. Ser.

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2Technological advances in underwater video recording are opening novel opportunities for monitoring wild fish. However, extracting data from videos is often challenging. Nevertheless, it has been recently demonstrated that accurate and precise estimates of density for animals (whose normal activities are restricted to a bounded area or home range) can be obtained from counts averaged across a relatively low number of video frames. The method, however, requires that individual detectability (P ID , the probability of detecting a given animal provided that it is actually within the area surveyed by a camera) has to be known. Here we propose a Bayesian implementation for estimating P ID after combining counts from cameras with counts from any reference method. The proposed framework was demonstrated using Serranus scriba as a case-study, a widely distributed and resident coastal fish. Density and P ID were calculated after combining fish counts from unbaited remote underwater video (RUV) and underwater visual censuses (UVC) as reference method. The relevance of the proposed framework is that after estimating P ID , fish density can be estimated accurately and precisely at the UVC scale (or at the scale of the preferred reference method) using RUV only. This key statement has been extensively demonstrated using computer simulations yielded by real empirical data. Finally, we provide a simulation tool-kit for comparing the expected precision attainable for different sampling effort and for species with different levels of P ID .Overall, the proposed method may contribute to substantially enlarge the spatio-temporal scope of density monitoring programs for many resident fish.

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Section: Introductionmentioning

confidence: 99%

Estimating the density of resident coastal fish using underwater cameras: accounting for individual detectability

Follana-Berná¹,

Palmer²,

Campos-Candela³

et al. 2019

Mar. Ecol. Prog. Ser.

View full text Add to dashboard Cite

show abstract

“…The model developed by Priede et al () is parameterized to t arrival data from abyssal scavengers that are generally slower and more sparsely distributed than bathyal scavenger species. When abyssal models are applied to non‐abyssal scavengers, such as M. glutinosa and N. norvegicus that have relatively shorter arrival rates than their abyssal counterparts, model abundance estimates can be overestimated owing to the inverse square law of the model (Stobart et al ; Dunlop et al ). This may therefore be one of the main reasons for the higher abundances we estimated in this study.…”

Section: Discussionmentioning

confidence: 99%

Scavenging processes on jellyfish carcasses across a fjord depth gradient

Dunlop

Jones

Sweetman

2017

Limnology & Oceanography

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Gelatinous zooplankton populations have increased in some regions, specifically Norwegian fjords, which has likely increased the occurrence of dead jellyfish aggregations on the seafloor (jelly‐falls). The importance of scavengers in the redistribution of organic material from jelly‐falls and their biogeochemical influence on the benthic environment has been demonstrated. However, scavenger responses to jelly‐falls across environmental gradients have not been studied, but would significantly advance our understanding of the impact of jelly‐falls on benthic ecosystems in different regions. This study examined scavenging ecology on jelly‐falls across an upper‐bathyal depth gradient in a boreal oxygenated fjord using baited time‐lapse camera lander deployments. The mean maximum abundance of scavengers increased with depth (eight individuals at 250 m, 10 at 600 m, and 18 at 1250 m) and at shallower depths more scavenger species fed on the bait (six species at 250 m, five at 600 m, and four at 1250 m). Mean scavenging rates (841.5 g d−1 at 250 m; 667.7 g at 600 m; and 883.7 g at 1250 m), however, did not vary significantly with depth. The lack of detection of a significant depth effect in this study may result from steep fjord topography enhancing food supply to deep waters reducing food limitation at the seafloor. Significant temporal changes in scavenging dynamics were primarily caused by changes in the dynamics of lyssianassoid amphipods. This study demonstrates that scavengers can rapidly remove jellyfish carcasses at the seafloor across a range of upper bathyal depths, potentially reducing the effects of jellyfish decomposition in fjord benthic environments.

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Estimating Pelagic Fish Biomass in a Tropical Seascape Using Echosounding and Baited Stereo-Videography

et al. 2021

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The pelagic ecosystem is the ocean's largest by volume and of major importance for food provision and carbon cycling. The high fish species diversity common in the tropics presents a major challenge for biomass estimation using fisheries acoustics, the traditional approach for evaluating mid-water biomass. Converting echo intensities to biomass density requires information on species identity and size, which are typically obtained by lethal means, and thus unsuitable in the portion of the ocean that is 'no take'. To improve conservation and ecosystembased management, we present a procedure for determining fish biomass density, using data on species identity, relative abundance, and lengths obtained from stereo baited remote underwater video systems (stereo-BRUVS) to inform the scaling of echosounder survey data (at 38 kHz). We apply the procedure in the British Indian Ocean Territory marine protected area, using acoustic data from 3,025 km of survey transects and 546 BRUVS deployments recording relative abundance and size of 12,335 individual fish. Using a Generalised Additive Model of biomass density (GAM, adjR 2 = 0.61) we predict, on the basis of oceanographic conditions and bathymetry, that the top 200 m pelagic ecosystem in the Chagos Archipelago, some 118,324 km 2 ,

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Absolute abundance estimates from shallow water baited underwater camera surveys; a stochastic modelling approach tested against field data

Cited by 7 publications

References 53 publications

Estimating the density of resident coastal fish using underwater cameras: accounting for individual detectability

Estimating the density of resident coastal fish using underwater cameras: accounting for individual detectability

Scavenging processes on jellyfish carcasses across a fjord depth gradient

Estimating Pelagic Fish Biomass in a Tropical Seascape Using Echosounding and Baited Stereo-Videography

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