Estimating total abundance of a large temperate-reef fish using visual strip-transects

McCormick, Mark I.; Choat, J. Howard

doi:10.1007/bf00397964

Cited by 123 publications

(80 citation statements)

References 28 publications

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“…Population sizes of adult C. vagabundus were estimated at the six sites where adults were sampled, using visual transects and a stratified random sampling design 49 . A total of ~3,700 visual transects were undertaken across the six locations before the adult sampling, with transects distributed among all habitat types.…”

Section: Nature Ecology and Evolutionmentioning

confidence: 99%

“…Snorkellers surveyed each habitat type using a towed GPS unit that recorded the length of each transect and the positions at which individual C. vagabundus were observed. Densities within each strata were calculated, and a total population estimate was derived from an estimate of the area of each strata calculated using ArcGIS (Supplementary Table 5), with greater sampling effort placed in larger and more variable habitats 22,49 . Given a known number of adult fish that were finclipped, we were able to calculate the overall percentage of the population that was sampled for genetic analysis.…”

Section: Nature Ecology and Evolutionmentioning

confidence: 99%

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Larval fish dispersal in a coral-reef seascape

et al. 2017

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Larval dispersal is a critical yet enigmatic process in the persistence and productivity of marine metapopulations. Empirical data on larval dispersal remain scarce, hindering the use of spatial management tools in efforts to sustain ocean biodiversity and fisheries. Here we document dispersal among subpopulations of clownfish (Amphiprion percula) and butterflyfish (Chaetodon vagabundus) from eight sites across a large seascape (10,000 km 2 ) in Papua New Guinea across 2 years. Dispersal of clownfish was consistent between years, with mean observed dispersal distances of 15 km and 10 km in 2009 and 2011, respectively. A Laplacian statistical distribution (the dispersal kernel) predicted a mean dispersal distance of 13-19 km, with 90% of settlement occurring within 31-43 km. Mean dispersal distances were considerably greater (43-64 km) for butterflyfish, with kernels declining only gradually from spawning locations. We demonstrate that dispersal can be measured on spatial scales sufficient to inform the design of and test the performance of marine reserve networks. R obust descriptions of larval dispersal are fundamental to studies of fish population dynamics 1,2 , fisheries management 3,4 and the design of reserve networks tasked with conserving ocean biodiversity 5,6 . Yet descriptions of larval dispersal patterns in ocean environments remain scarce. The combination of a pelagic larval phase that may last several days to many months and an ocean environment characterized by energetic diffusive and advective flows may allow passive larvae to disperse hundreds to thousands of kilometres from natal locations 7,8 . It has proved difficult, however, to verify directly how far fish larvae travel, because it is almost impossible to follow them as they disperse rapidly from spawning sites and are subject to high rates of natural mortality throughout the larval phase 9 . Our inability to describe the spatial extent of larval dispersal is problematic because our understanding of metapopulation dynamics relies on largely untested models that quantify where larvae arriving at a subpopulation originate from and where larvae spawned at each subpopulation eventually settle [10][11][12] . Moreover, to be of practical use, these data must be assembled on large enough scales for evaluating and optimizing spatial management strategies for fisheries or conservation 1,13 .Patches of reef habitat are frequently isolated from each other by deeper water that forms a barrier to adult movement, and so larval dispersal is likely to be a critical process in the persistence of many reef fish populations over demographic and evolutionary timescales 10,14 . Effective management of coral-reef seascapes is therefore particularly reliant on spatial tools to achieve conservation objectives. Although reef fish larvae clearly have the potential for long-distance movements 14 , there is increasing evidence that dispersal may be more limited than previously assumed 15,16 . The most compelling evidence of larvae returning to natal or nearby reefs has...

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Section: Nature Ecology and Evolutionmentioning

confidence: 99%

Section: Nature Ecology and Evolutionmentioning

confidence: 99%

Larval fish dispersal in a coral-reef seascape

et al. 2017

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“…Surveys were conducted 1-2 hr prior to sunset at three sites subject to removals: Bus Stop (one removal), Mixing Bowl (three removals), and Blacktip Boulevard (seven removals), as well as at Rock Bottom (a control site not subject to lionfish removal). Such surveys should yield reliable estimates of relative densities, because lionfish are easy to identify, active during the hours just before dusk, and not prone to being attracted to or repelled by divers (Brock, 1954;Sale and Douglas, 1981;McCormick and Choat, 1987;Green et al, 2011). During surveys, one diver deployed a 50-m line, and two other divers made a single pass to count lionfish in 2-m wide transects on either side of this line.…”

Section: Methodsmentioning

confidence: 99%

Coping with the Lionfish Invasion: Can Targeted Removals Yield Beneficial Effects?

Frazer

Jacoby

Edwards

et al. 2012

Reviews in Fisheries Science

130

119

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“…In reef fisheries, the use of visual census techniques to survey relative (GBRMPA 1979, Munro 1983, Bell et al 1985 and more recently absolute (McCormick & Choat 1987) population density and biomass has been recognised. Visual censuses have been used to determine the size structure of populations of coral reef fishes and make estimates of their biomass and standing stocks (e.g.…”

Section: Introductionmentioning

confidence: 99%

Accuracy and bias of visual estimates of numbers, size structure and biomass of a coral reef fish

StJohn¹,

Russ²,

Gladstone³

1990

Mar. Ecol. Prog. Ser.

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Accuracy and bias of visual estimates of the number, size structure and biomass of juveniles of a small coral reef fish, Salarias fasciatus, were examined on 10 artificial patch reefs at One Tree Reef, Great Barrier Reef. Visual estimates of the number and length of flsh were made by 3 observers for 3 different durat~ons (5, 10 and 15 min) at each reef. These estimates were compared to measurements obtained from subsequent destructive sampling of reefs (98.5 % of flsh collected from all reefs). An increase in census penod does not continue to improve the accuracy of the estimates of numbers of fish The accuracy of the 10 min census did not differ significantly from the 15 min census, although it was signif~cantly higher than the 5 min census. Also, observers had unique biases for specific size-classes when estimating the size structure of the population. Biomass was estimated from the visual censuses of one observer, using a length-weight relationship, and compared to a known bion~ass from subsequent destructive collections. The mean accuracy of the biomass estimate derived from visual estimates of lengths was 72.3 %. This level of accuracy was obtained when the length-weight relationship was good (r2 = 0.97) and the estimates of lengths of each size-class (mean accuracy = 86 %, pooled for observer, times and sites) and the estimate of numbers (mean accuracy = 91.690 for the 10 min census) both had high levels of accuracy. But such high accuracies may not b e expected for censuses of larger mobile species. The use of visual censuses to estimate the biomass of such fish populations are likely to b e subject to greater inaccuracy. Most of the error in the visual estimates of biornass was explained by the inaccuracies of estimating the length of fish visually. Categorising fish into 5 mm sizeclasses or using a length-weight relationship to convert length to biomass did not significantly affect the accuracy of the estimates.

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Estimating total abundance of a large temperate-reef fish using visual strip-transects

Cited by 123 publications

References 28 publications

Larval fish dispersal in a coral-reef seascape

Larval fish dispersal in a coral-reef seascape

Coping with the Lionfish Invasion: Can Targeted Removals Yield Beneficial Effects?

Accuracy and bias of visual estimates of numbers, size structure and biomass of a coral reef fish

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