The River Endrick - then and now, monitoring by photography

A major survey of the River Endrick was carried out in 1959-60. This survey was repeated three decades later in 1989-90 and comparisons were made of the fauna at the two times of sampling. During both surveys, photographs were taken of all the sampling sites and the objective of the present paper is to compare some of these photographs and discuss the value of photography in studies of river ecology. The sites used for photographic comparison were not chosen originally for that purpose but as appropriate places on the river from source to mouth to study its ecology. The pairs of photos now available have proved of interest and value and some lessons have been learned in relation to the selection of sites for any future photographic studies. Ideally photos should be taken in more than one season of the year as much of the river can be obscured by riparian trees and shrubs during the vegetative season. The exact position from which each photograph is taken is also a major factor to be considered.

Offshore Migratory Corridors and Aerial Photogrammetric Body Length Comparisons of Southbound Gray Whales, Eschrichtius robustus, in the Southern California Bight, 1988–1990

Through most of their annual migration, gray whales, Eschrichtius robustus, remain within 10 km of shore, but in the Southern California Bight many individuals migrate much farther from shore. This paper summarizes aerial survey and photogrammetric efforts to determine body lengths and temporal and spatial distributions of migratory gray whales in the southern portion of the Southern California Bight. Aerial surveys were flown along 13 east–west transects between lat. 32°35′N and 33°30′N during the southbound gray whale migratory seasons of 1988–90 in the Southern California Bight. Photogrammetry was used to obtain body length estimates of animals during some of the surveys. A total of 1,878 whales in 675 groups were sighted along 25,440 km of transect distance flown and 217 body lengths were measured. Using position and heading data, three major migratory pathways or corridors in the southern portion of the bight are defined. Those migrating offshore were split almost evenly between two corridors along the west sides of Santa Catalina and San Clemente Islands. These corridors converge on the mainland coast between San Diego and the United States–Mexico border. No whales larger than 11.5 m were photographed within 30 km of the mainland coast, suggesting that smaller, and presumably younger, whales use the coastal migratory corridor through the California Bight.

Beluga, Delphinapterus leucas, Group Sizes in Cook Inlet, Alaska, Based on Observer Counts and Aerial Video

Belugas, Delphinapterus leucas, groups were videotaped concurrent to observer counts during annual NMFS aerial surveys of Cook Inlet, Alaska, from 1994 to 2000. The videotapes provided permanent records of whale groups that could be examined and compared to group size estimates ade by aerial observers.Examination of the video recordings resulted in 275 counts of 79 whale groups. The McLaren formula was used to account for whales missed while they were underwater (average correction factor 2.03; SD=0.64). A correction for whales missed due to video resolution was developed by using a second, paired video camera that magnified images relative to the standard video. This analysis showed that some whales were missed either because their image size fell below the resolution of hte standard video recording or because two whales surfaced so close to each other that their images appeared to be one large whale. The correction method that resulted depended on knowing the average whale image size in the videotapes. Image sizes were measured for 2,775 whales from 275 different passes over whale groups. Corrected group sizes were calcualted as the product of the original count from video, the correction factor for whales missed underwater, and the correction factor for whales missed due to video resolution (averaged 1.17; SD=0.06). A regression formula was developed to estimate group sizes from aerial observer counts; independent variables were the aerial counts and an interaction term relative to encounter rate (whales per second during the counting of a group), which were regressed against the respective group sizes as calculated from the videotapes. Significant effects of encounter rate, either positive or negative, were found for several observers. This formula was used to estimate group size when video was not available. The estimated group sizes were used in the annual abundance estimates.

Monitoring of streambank stability and streamside vegetation in a livestock exclosure on the Warm Springs River, Oregon : comparison of ground-based surveys with aerial photographic analysis

The objective of this monitoring project was to determine the baseline condition for a 960-m long stream reach and its associated streamside zone, which terminates at the confluence with the Deschutes River. This stream reach had been damaged heavily in the February 1996 flood and had also received many years of overuse by livestock grazing. The monitoring project was conducted in July 1997 just after installation of riparian exclosure fencing. Future resurvey of the study area will allow determination of progress made in ecological recovery.

An aerial survey for surface tuna resources in the seas around Ceylon

An aerial survey of the off shore range around Ceylon, for a quick evaluation of the potential surface tuna resources, for commercial exploitation, was organised by Mr. Manuel R. Cintas of Ocean Blazer Inc. (Commercial tuna), San Diego, California and his associate Mr. R. Perera. The organisers offered, through the Hon'ble Minister of Fisheries, to take an officer of the Fisheries Research Station, Ceylon, as an observer and the author participated in that capacity. Dr. V. Arkely served as the photographer. The survey period was within the South-West monsoon season and extremely bad weather with high speed winds were experienced particularly off the North-West and South coasts. Except during these two trips, an average altitude of 1,000 ft. and a flying speed of 110-115 m.p.h. were maintained. The program was to cover the off shore range between 15 miles and 50 miles, from shore. The total number of hours of flying was eighteen. Details of the flight plan are shown in figure 1.