chapter 3 - RiuNet

GENERAL INTRODUCTION
The other motion parameters that are automatically generated by the
tracker have not yet provided any additional useful information on sperm
quality in fish. Among them, the ratio of the net distance moved to the total
path distance (linearity, LIN) and the ratio of the net distance moved to the
smoothed path distance (straightness, STR) have been the most often used
parameter s for analyzing the curvature of the trajectory.
On the other hand, CASA systems are able to show a huge number of
spermatozoa per capture/frame, which means thousands of motion tracks
analyzed per sample (Figure 6). However, despite the advantage of working
with these extensive databases, sperm motility analyses often show the
mean parameter values, considering the whole sperm sample as
homogeneous. However, it has been pointed out that the sperm of some
species is not a homogeneous mixture, and different sperm subpopulations
coexist in the same sample. Although this topic has mostly been studied in
mammals (Quintero-Moreno et al., 2003; Dorado et al., 2011), there are
some reports in fish which have clearly shown the coexistence of distinct
motility-based sperm subpopulations within the same sample : Solea
senegalensis (Martinez-Pastor et al., 2008), Oncorhynchus mykiss (Kanuga
et al., 2012) or Anguilla anguilla (Gallego el al. , submitted b).
a
b
Figure 6. Images obtained by a CASA system. a) Full screen capture of sperm
sample; b) Detailed motion trajectory of one spermatozoon.
The CASA systems have been successfully applied in a wide range of
aquacultural matters (Table 3), but new fields could be improved by the
rapid assessment of sperm quality. In this respect, one of the possible
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