Dissertation - HQ

46 Behaviour in models
1.10 Conclusions
Information is
often lacking
All seven behaviours considered here — vertical and horizontal swimming,
orientation, foraging, predators avoidance, schooling, selectivity in
settlement — have the potential to influence the outcome of the pelagic
larval phase, through modifications of dispersal trajectories, survival
probability, and growth. For most behaviours, information is still cruelly
lacking, hampering precise estimation of their impact and making their
introduction in models particularly sensible. In addition, the importance
of any particular behaviour depends on the species/location of interest
and on the question the model is designed to address. We tried to
provide enough information in each section to help the reader to choose
which to include. Given current knowledge and assuming a general
interest in predicting where and how many larvae settle, we propose
a hierachisation of their impact in Figure 1.2. Once again this should
really be considered as a general rule, and adapted to each modelling
scenario.
Figure 1.2 Tentative hierarchy of larval behaviours, ordered by decreasing
importance. When two behaviours are placed on the same level, the one on the
left should be preferred for slow swimming, temperate larvae, for which growth
is critical, while the one of the right should be preferred for faster swimming
larvae, usually tropical ones.
Swimming
should be tackled
Many models now consider the importance of vertical position; and
those which do not should be regarded with caution. In cases where
settlement opportunity is very localised, settlement locations are also
represented 45 . The dynamics of larval growth has been well studied
in temperate environments and several modelling frameworks exist.
Therefore, the next step in many cases is to incorporate swimming by
fish larvae, whether it occurs on large spatial scales (oriented swimming)
or finer ones (schooling).