Assessment of Argos Location Accuracy From Satellite Tags Deployed on Captive Gray Seals

Abstract

The Argos satellite system is commonly used to track and relay behavioral data from marine mammals, but their underwater habit results in a high proportion of locations of non‐guaranteed accuracy (location classes (LC) O, A, and B). The accuracy of these locations is poorly documented in marine mammals. We assessed the accuracy of all LCs on four juvenile gray seals fitted with Argos satellite relay data loggers and held in captivity in an outdoor tank for a total of 61 seal‐days. Four hundred and twenty‐six locations were obtained from seals in captivity, and their latitude and longitude error was assessed before and after filtering, following MConnell et al. (1992). There was significantly more error in longitude than latitude in all LCs except I. C A. The ratio of the standard deviations of longitude : latitude ranged from 1.77 (LC 3) to 2.58 (LC 1). Filtering had very little effect on errors in LCs 3‐1, but in the remaining LCs filtering resulted in error reductions ranging from 8% to 63%. In LCs O, A, and B, error reduction was greater in the 95th percentile errors, especially in longitude. The averages of the latitude and longitude 68th percentile errors and those predicted by Argos (in brackets) were 226 (150), 372 (350), and 757 (1000) m for LCs 3, 2, and 1 respectively. Both latitude and longitude errors of LCs > O were normally distributed. Both filtered and unfiltered LC A locations were of a similar accuracy to LC 1 locations, and considerably better than LC O locations.

Satellite Tracker Deployments On Adult, Male Australian Fur Seals (Arctophalus Pusillus Doriferus): Methods And Preliminary Results

“…Errors in location predictions in our study were greater than those predicted by Argos and greater than those recorded in other studies of marine pinnipeds (e.g., Boyd et al 1998;Bonadonna et al 2000;Vincent et al 2002). Variations in location errors could relate to the quality of transmitters, the behaviour of the seals (such as some seals lying on their sides more frequently than others), or external factors (such as atmospheric conditions at different latitudes, or geological features).…”

Link between vertical and horizontal movement patterns of cod in the North Sea

“…So a second approach is to attach tags to animals that are kept in enclosures to ensure they are essentially in a fixed position (e.g. Vincent et al 2002, Schaefer & Fuller 2006. In the present study we made use of occasions when there was both (1) very little vertical movement by fish which implies that the fish were stationary and (2) geolocation estimates that showed no EDM.…”

The Spring Migration of Adult North American Ospreys

“…All the Doppler-based satellite telemetry units (ARGOS PTTs) were programmed to transmit data for an 8-or 10-hr period followed by a 20-72-hr off period. Accuracy of ARGOS provided location estimate depends on a variety of factors which have been commented on by other researchers (see Keating et al 1991, Britten et al 1999, Vincent et al 2002, Soutullo et al 2007). …”