301
9 Studying and Monitoring Aggregating Species
simple documentation of behaviour (detailed in Colin et al. 2003 ) . Video recording
is also invaluable for conveying to others the large numbers of fi sh and dynamic
nature of aggregations that cannot be obtained from any other medium. Aspects of
video recording are discussed subsequently.
Fig. 9.5 A single transect up to several hundred meters in length is commonly used to quantify
numbers of fi sh in spawning aggregations, generally through counting fi sh numbers in a swath
width either side of the transect. Such surveys provide only a single measure of fi sh density and
numbers. Single transect surveys can be easily improved by dividing the transect into a series of
segments, in this case by distance, and counting fi sh in each segment separately, but multiple such
transects are likely needed to cover an entire aggregation site (see Sect. 9.6.5 )
9 Studying and Monitoring Aggregating Species
simple documentation of behaviour (detailed in Colin et al. 2003 ) . Video recording
is also invaluable for conveying to others the large numbers of fi sh and dynamic
nature of aggregations that cannot be obtained from any other medium. Aspects of
video recording are discussed subsequently.
Fig. 9.5 A single transect up to several hundred meters in length is commonly used to quantify
numbers of fi sh in spawning aggregations, generally through counting fi sh numbers in a swath
width either side of the transect. Such surveys provide only a single measure of fi sh density and
numbers. Single transect surveys can be easily improved by dividing the transect into a series of
segments, in this case by distance, and counting fi sh in each segment separately, but multiple such
transects are likely needed to cover an entire aggregation site (see Sect. 9.6.5 )