Furthermore, ontogenic changes are the result of the allocation of energy toward the
formation of vital organs and, in consequence, influence growth variability (Garcia
et al. 2006; Garcia et al. 2003; Quintanilla 2016). In post-flexion stages, the
development of fin rays provides swimming capabilities at small vertical and
horizontal scales, which in turn determine survival probabilities by optimizing
feeding potential.
The spawning phenology of benthopelagic species in the Alboran Sea is far less
known than of epipelagic species. Nonetheless, species living in deeper layers close
to the seabed where temperature is rather stable have the potentiality of year-round
spawning. The NW Atlantic hake is known to spawn throughout the year with
seasonal peaks in spring and autumn/winter (Recansens et al. 2008), which contrasts
with the pattern observed in the Alboran Sea that is expected to occur in late
winter—early spring since recruits are mainly observed in autumn (Rey and Gil de
Sola 2004). The longer exposure of ~40 days PLD of this species in the Mediterranean (Hidalgo et al. 2009, 2019) implies greater risks for predation, which effect is
likely buffered by their deeper depth distribution where less predation may occur.
12.6 Implications on the Populations and Ecosystems
of the Alboran Sea
The transitional nature of the Alboran Sea and Gulf of Cadiz systems between
Europe and Africa implies changes in ocean and ecosystem governance but also a
strong commitment toward integrative co-management of the ecosystems and
marine resources inhabiting these regions. Given the short distances in the Alboran
Sea, populations and ecosystems might be intuitively connected due to energetic
hydrodynamics in the region. However, connectivity pathways are not straight
forward, as discussed in this chapter, and the likelihood of successful connectivity
and its implications depend on several elements: PLD, larval behavior, timing and
location of the spawning, and the capacity of each species to cross and overcome
strong hydrodynamic barriers (e.g., topography and the AJ). From a perspective of
the fisheries resources, there is a general acceptance of a mismatch between biological and management structures currently used in fisheries assessment (Kerr et al.
2016): spatial and demographic structures of marine populations are more complex
than currently accounted for. This has, however, two complementary components: a
historic question on fish stocks delineation (inter-stock) but also a more recent
recognition of sub-structuring within stocks areas as a set of subunits displaying
different ecological or demographic functions (intra-stock). Thus, there is a need to
take into account the spatial heterogeneity of fish populations within management
units beyond simple stock delineation (Berger et al. 2017). It requires the incorporation of those ecological processes that are spatially structured or, alternatively, the
consideration of different population sub-units that have different demographic
properties or ecological functions (metapopulations, Hidalgo et al. 2017). This is
12 Biophysical Processes Determining the Connectivity of the Alboran Sea Fish. . .
479
formation of vital organs and, in consequence, influence growth variability (Garcia
et al. 2006; Garcia et al. 2003; Quintanilla 2016). In post-flexion stages, the
development of fin rays provides swimming capabilities at small vertical and
horizontal scales, which in turn determine survival probabilities by optimizing
feeding potential.
The spawning phenology of benthopelagic species in the Alboran Sea is far less
known than of epipelagic species. Nonetheless, species living in deeper layers close
to the seabed where temperature is rather stable have the potentiality of year-round
spawning. The NW Atlantic hake is known to spawn throughout the year with
seasonal peaks in spring and autumn/winter (Recansens et al. 2008), which contrasts
with the pattern observed in the Alboran Sea that is expected to occur in late
winter—early spring since recruits are mainly observed in autumn (Rey and Gil de
Sola 2004). The longer exposure of ~40 days PLD of this species in the Mediterranean (Hidalgo et al. 2009, 2019) implies greater risks for predation, which effect is
likely buffered by their deeper depth distribution where less predation may occur.
12.6 Implications on the Populations and Ecosystems
of the Alboran Sea
The transitional nature of the Alboran Sea and Gulf of Cadiz systems between
Europe and Africa implies changes in ocean and ecosystem governance but also a
strong commitment toward integrative co-management of the ecosystems and
marine resources inhabiting these regions. Given the short distances in the Alboran
Sea, populations and ecosystems might be intuitively connected due to energetic
hydrodynamics in the region. However, connectivity pathways are not straight
forward, as discussed in this chapter, and the likelihood of successful connectivity
and its implications depend on several elements: PLD, larval behavior, timing and
location of the spawning, and the capacity of each species to cross and overcome
strong hydrodynamic barriers (e.g., topography and the AJ). From a perspective of
the fisheries resources, there is a general acceptance of a mismatch between biological and management structures currently used in fisheries assessment (Kerr et al.
2016): spatial and demographic structures of marine populations are more complex
than currently accounted for. This has, however, two complementary components: a
historic question on fish stocks delineation (inter-stock) but also a more recent
recognition of sub-structuring within stocks areas as a set of subunits displaying
different ecological or demographic functions (intra-stock). Thus, there is a need to
take into account the spatial heterogeneity of fish populations within management
units beyond simple stock delineation (Berger et al. 2017). It requires the incorporation of those ecological processes that are spatially structured or, alternatively, the
consideration of different population sub-units that have different demographic
properties or ecological functions (metapopulations, Hidalgo et al. 2017). This is
12 Biophysical Processes Determining the Connectivity of the Alboran Sea Fish. . .
479