spectra being partially driven by the proliferation of fish in smaller size classes:
for the North Sea (Daanet al., 2005), Fijian reefs (Dulvyet al., 2004) and the Celtic
Sea (Blanchardet al., 2005) (Fig.14.3). The model of Popeet al.(2006) suggests that
the relationship between the strength of compensation in the spawner–recruit
relationship and body size play an important role in controlling the extent of
prey release.
The Popeet al.(2006 ) size-based model is an important development because
they have captured the dynamics of individual species within the size spectrum,Relative change in biomass2 4 8 10 12
Body mass class (log 2 )0–0.6–1.00.40.2–0.4–0.2–0.86(a)
Relative change in biomass0–0.6–1.0
20 40 50 60
Body mass class (cm)0.40.2–0.4–0.2–0.830(b)
Figure 14.3Relative
changes in biomass
as a function of body
size across (a) a
temporal gradient
in multispecies
fishing mortality in
the Celtic Sea and
(b) a spatial gradient
in fishing effort on
Fijian reefs. Both
examples show
evidence for prey
release following
predator depletion.
Data from
Blanchardet al.
(2005 ) and Dulvy
et al.(2004 ).BODY SIZE AND EXPLOITATION 279