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Best Practice Guidelines for Surveys and Monitoring of Great Ape Populations Occasional Paper of the IUCN Species Survival Commission No. 36
"... Founded in 1948, IUCN brings together States, government agencies and a diverse range of nongovernmental organizations in a unique world partnership: over 1,000 members in all, spread across some 140 countries. As a Union, IUCN seeks to influence, encourage and assist societies throughout the world ..."
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Founded in 1948, IUCN brings together States, government agencies and a diverse range of nongovernmental organizations in a unique world partnership: over 1,000 members in all, spread across some 140 countries. As a Union, IUCN seeks to influence, encourage and assist societies throughout the world to conserve the integrity and diversity of nature and to ensure that any use of natural resources is equitable and ecologically sustainable. IUCN builds on the strengths of its members, networks and partners to enhance their capacity and to support global alliances to safeguard natural resources at local, regional and global levels. IUCN Species Survival Commission The Species Survival Commission (SSC) is the largest of IUCN’s six volunteer commissions with a global membership of 8,000 experts. SSC advises IUCN and its members on the wide range of technical and scientific aspects of species conservation and is dedicated to securing a future for biodiversity. SSC has significant input into the international agreements dealing with biodiversity conservation. Web: www.iucn.org/themes/ssc
J. CETACEAN RES. MANAGE. 9(1):1–13, 2007 1 Designing line transect surveys for complex survey regions
"... Line transect surveys are widely used to estimate the density and/or size of cetacean populations. Good survey design is essential for obtaining reliable results using standard (designbased) analysis methods. Even for more complex (modelbased) analysis methods, a good survey design is valuable. A ..."
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Line transect surveys are widely used to estimate the density and/or size of cetacean populations. Good survey design is essential for obtaining reliable results using standard (designbased) analysis methods. Even for more complex (modelbased) analysis methods, a good survey design is valuable. A ‘good ’ design is one (a) that employs randomisation in laying out transects; (b) that is stratified if density is known to vary on a large scale; (c) where each location within a stratum has an equal probability of being surveyed (uniform coverage probability); (d) that produces an even distribution of transects throughout each stratum (e.g. systematic random designs); (e) that produces at least 1020 transects per stratum; (f) that, given the previous points, gives maximum efficiency per unit effort – for example by minimising time spent travelling between survey lines (offeffort time). We discuss strategies for creating good designs given the constraints inherent in many shipboard surveys of cetaceans: severely limited ship time and complex topography. We advocate the use of computer software, such as the program Distance, to create designs and compare their properties using simulation. We provide a link between the concepts and their implementation through a concrete example of survey design: a multispecies survey of cetaceans in coastal British Columbia. The design uses an equally spaced zigzag configuration of transects in more open strata combined with substratification to minimise offeffort time. In the highly convex inshore stratum we develop a systematic cluster sampling algorithm, and within the selected clusters use a systematic parallel line layout to ensure equal coverage probability in the long, narrow fjords. To aid those wishing to learn automated design methods, we provide Distance project files online.
REVIEW Distance software: design and analysis of distance sampling surveys for estimating population size
"... 1. Distance sampling is a widely used technique for estimating the size or density of biological populations.Many distance sampling designs andmost analyses use the softwareDistance. 2. We briefly review distance sampling and its assumptions, outline the history, structure and capabilities of Distan ..."
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1. Distance sampling is a widely used technique for estimating the size or density of biological populations.Many distance sampling designs andmost analyses use the softwareDistance. 2. We briefly review distance sampling and its assumptions, outline the history, structure and capabilities of Distance, and provide hints on its use. 3. Good survey design is a crucial prerequisite for obtaining reliable results. Distance has a survey design engine, with a builtin geographic information system, that allows properties of different proposed designs to be examined via simulation, and survey plans to be generated. 4. A first step in analysis of distance sampling data is modelling the probability of detection. Distance contains three increasingly sophisticated analysis engines for this: conventional distance sampling, which models detection probability as a function of distance from the transect and assumes all objects at zero distance are detected; multiplecovariate distance sampling, which allows covariates in addition to distance; and mark–recapture distance sampling, which relaxes the assumption of certain detection at zero distance. 5. All three engines allow estimation of density or abundance, stratified if required, with associated measures of precision calculated either analytically or via the bootstrap.
8. Financial Account of the Activity
"... Little is known about nearshore Irrawaddy dolphins (Orcaella brevirostris) in the Gulf of Thailand. The Irrawaddy dolphin is generally found in shallow estuaries and coastal waters throughout Southeast Asia (Reeves et al. 2008). For example, in the Philippines, most sightings were made within 6 mete ..."
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Little is known about nearshore Irrawaddy dolphins (Orcaella brevirostris) in the Gulf of Thailand. The Irrawaddy dolphin is generally found in shallow estuaries and coastal waters throughout Southeast Asia (Reeves et al. 2008). For example, in the Philippines, most sightings were made within 6 meters of depth (Dolar et al. 2002). Like the dugong, Irrawaddy dolphins are vulnerable to incidental fisheries catch and proximity to coastal development (Dolar et al. 2002, Reeves et al. 2003). All three of the species we have sighted (Orcaella brevirostris, Sousa chinensis, and Neophocaena phocaenoides) had not been studied in this area previous to our project’s commencement in 2008. We found a relatively large population of Orcaella, and have had repeated sightings of the other 2 species. Chantrapornsyl et al. (1996), Stacey and Leatherwood (1997), Stacey and Arnold
Distance sampling
"... Distance sampling is a widely used group of closely related methods for estimating the density and/or abundance of biological populations. The main methods are linetransect sampling and pointtransect sampling (also called variable circular plot sampling). These have been used successfully in a ve ..."
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Distance sampling is a widely used group of closely related methods for estimating the density and/or abundance of biological populations. The main methods are linetransect sampling and pointtransect sampling (also called variable circular plot sampling). These have been used successfully in a very diverse array of taxa, including trees, shrubs and herbs, insects, amphibians, reptiles, birds, fish, and marine and land mammals. In both cases, the basic idea is the same. One or more observers perform a standardized survey along a randomly located set of lines or points, searching for objects of interest (usually animals or clusters of animals). For each object detected, they record the distance from the line or point to the object. Not all the objects will be detected, but a fundamental assumption of the basic methods is that all objects that are actually on the line or point are detected. Intuitively, one would expect that objects become harder to detect with increasing distance from the line or point, resulting in fewer detections with increasing distance. The key to distance sampling analyses is to fit a detection function to the observed distances, and use this fitted function to estimate the proportion of objects missed during the survey. From here, we can readily obtain point and interval estimates for the density and abundance of objects in the survey area. The basic methods (sometimes called standard or conventional distance sampling) are described in detail in Ref. 1, which is an updated version of Ref. 2. Various extensions and more advanced methods are considered in Ref. 3. Free software, Distance [4], provides for the design and analysis of distance sampling surveys, implementing the methods described in Ref. 1 and many of those in Ref. 3. Distance sampling is an extension of quadratbased sampling methods. Two forms of quadrat sampling are strip transects, in which one or more observers move along a line, counting all objects within a predetermined distance of the line, and point
Journal of Applied Ecology doi: 10.1111/j.13652664.2009.01737.x REVIEW Distance software: design and analysis of distance sampling surveys for estimating population size
"... 1. Distance sampling is a widely used technique for estimating the size or density of biological populations. Many distance sampling designs and most analyses use the software Distance. 2. We briefly review distance sampling and its assumptions, outline the history, structure and capabilities of Dis ..."
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1. Distance sampling is a widely used technique for estimating the size or density of biological populations. Many distance sampling designs and most analyses use the software Distance. 2. We briefly review distance sampling and its assumptions, outline the history, structure and capabilities of Distance, and provide hints on its use. 3. Good survey design is a crucial prerequisite for obtaining reliable results. Distance has a survey design engine, with a builtin geographic information system, that allows properties of different proposed designs to be examined via simulation, and survey plans to be generated. 4. A first step in analysis of distance sampling data is modelling the probability of detection. Distance contains three increasingly sophisticated analysis engines for this: conventional distance sampling, which models detection probability as a function of distance from the transect and assumes all objects at zero distance are detected; multiplecovariate distance sampling, which allows covariates in addition to distance; and mark–recapture distance sampling, which relaxes the assumption of certain detection at zero distance. 5. All three engines allow estimation of density or abundance, stratified if required, with associated measures of precision calculated either analytically or via the bootstrap.
J. CETACEAN RES. MANAGE. Designing line transect surveys for complex survey regions 1 2 3 4 5
"... Line transect surveys are widely used to estimate the density and/or size of cetacean populations. Good survey design is essential for obtaining reliable results using standard (design based) analysis methods. Even for more complex (model based) analysis methods, a good survey design is very helpful ..."
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Line transect surveys are widely used to estimate the density and/or size of cetacean populations. Good survey design is essential for obtaining reliable results using standard (design based) analysis methods. Even for more complex (model based) analysis methods, a good survey design is very helpful. By ‘good ’ we mean a design (a) that employs randomization in laying out transects; (b) that is stratified if density is known to vary on a large scale; (c) where each location within a stratum has an equal probability of being surveyed (equal coverage probability); (d) that produces at least 1020 transects per stratum; (e) that, given the previous points, gives maximum efficiency per unit effort – for example by minimizing time spent travelling between survey lines (offeffort time). We discuss strategies for creating good designs given the constraints inherent in many shipboard surveys of cetaceans: severely limited ship time and complex topography. We advocate the use of computer software, such as the program Distance, to create designs and compare their properties using simulation. We provide a link between the concepts and their implementation through a concrete example of survey design: a multispecies survey of cetaceans in coastal British Columbia. The design uses an equally spaced zigzag configuration of transects in more open strata combined with substratification to minimize offeffort time. In the highly convex inshore stratum we develop a systematic cluster sampling algorithm, and within the selected clusters use a systematic parallel line layout to ensure equal coverage probability in the long,
Designing line transect surveys for complex survey regions
"... Line transect surveys are widely used to estimate the density and/or size of cetacean populations. Good survey design is essential for obtaining reliable results using standard (designbased) analysis methods. Even for more complex (modelbased) analysis methods, a good survey design is valuable. A ‘ ..."
Abstract
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Line transect surveys are widely used to estimate the density and/or size of cetacean populations. Good survey design is essential for obtaining reliable results using standard (designbased) analysis methods. Even for more complex (modelbased) analysis methods, a good survey design is valuable. A ‘good ’ design is one (a) that employs randomisation in laying out transects; (b) that is stratified if density is known to vary on a large scale; (c) where each location within a stratum has an equal probability of being surveyed (uniform coverage probability); (d) that produces an even distribution of transects throughout each stratum (e.g. systematic random designs); (e) that produces at least 1020 transects per stratum; (f) that, given the previous points, gives maximum efficiency per unit effort – for example by minimising time spent travelling between survey lines (off effort time). We discuss strategies for creating good designs given the constraints inherent in many shipboard surveys of cetaceans: severely limited ship time and complex topography. We advocate the use of computer software, such as the program Distance, to create designs and compare their properties using simulation. We provide a link between the concepts and their implementation through a concrete example of survey design: a multispecies survey of cetaceans in coastal British Columbia. The design uses an equally spaced zigzag configuration of transects in more open strata combined with substratification to minimise offeffort time. In the highly convex inshore stratum we develop a systematic cluster sampling algorithm, and within the selected clusters use a systematic parallel line layout to ensure equal coverage probability in the long, narrow fjords. To aid those wishing to learn automated design methods,
sampling surveys for estimating population size
"... Distance software: design and analysis of distance ..."
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