seasonal conditions. In this case, differences in sea temperature act as a physiological
driver that modulates the estimated RNA/DNA ratios. A decoupling between larval
growth and biochemical indices can be observed consequent of a delayed response
of larval growth to sudden changes in environmental conditions (Ramírez et al.
2004).
The variability of seasonal growth patterns in small pelagic larvae, is modulated
by the temperature and feeding resources which may undergo abrupt changes.
Strong changes of trophic resources for larvae can originate from changes in the
phytoplankton composition as observed by Mercado et al. (2007), where a phytoplankton diatom-based community shifted towards a coccolithophorid type of community in 2001. Highest larval growth of anchovy and sardine cohorts corresponded
to this year-class (García 2006; García et al. 2003). Moreover, changes in phytoplankton community may have contributed to having higher carbohydrate content in
sardine larvae sampled in winter 2000 and 2001 (García et al. 2005; Cortés 2006;
García 2006; Mercado et al. 2007).
With respect to the Alboran Sea anchovy, its peak spawning occurs during
summer (July–August) (Rodríguez 1990). An unexpected high anchovy recruitment
occurred during 2001 (Abad and Giráldez 1990). Growth data on anchovy of the
2000 and 2001 year-class were compared which yielded a field-based study on the
influence of growth on annual recruitment (García et al. 2003). The 2001 anchovy
larval cohort showed a 20% increase in daily growth rates in comparison to the
previous year (García et al. 2003). The birth date distribution of both cohorts showed
that during 2001 these were born at an earlier period (late spring) which possibly
coupled with the spring bloom because zooplankton biomass was unexpectedly high
in 2001 in comparison to the previous year. Furthermore, Mercado et al. (2005,
2007) revealed important interannual changes in the predominance of the different
phytoplankton groups in the Alboran Sea) shifting from a diatom-based community
to a coccolithophorid- and dinoflagellate-based phytoplankton grouping.
Nevertheless, it is reasonable to think that a single event like the strong 2001
anchovy recruitment must have been triggered by changes or driving forces of
biological and hydro-physical nature that occurred in the Alboran Sea. Ruíz et al.
(2013) observed a relationship between the variability of the path and intensity of
Atlantic Jet with the anchovy recruitment. A high kinetic energy of the current favors
the production in northern Alboran, but negatively impacting anchovy recruitment,
possibly inducing a greater degree of larval advection and dispersion. The year 2001
constituted an outlier of the time series of data from 1988 to 2010. The climatic and
hydrographic forces of the Atlantic current are also responsible for maintaining the
temporal persistence of the anchovy and sardine nursery grounds (Macías et al. 2011).
13.6 New Approaches Towards ELHS Trophodynamics
The joint analysis of growth at ELHS together with other analytical tools has led
way to the development of new digital imaging tools for growth otolith microstructure analysis (Nava et al. 2018). This digital imaging tool is open to otolith experts
13 Evolving from Fry Fisheries to Early Life Research on Pelagic Fish Resources
511
driver that modulates the estimated RNA/DNA ratios. A decoupling between larval
growth and biochemical indices can be observed consequent of a delayed response
of larval growth to sudden changes in environmental conditions (Ramírez et al.
2004).
The variability of seasonal growth patterns in small pelagic larvae, is modulated
by the temperature and feeding resources which may undergo abrupt changes.
Strong changes of trophic resources for larvae can originate from changes in the
phytoplankton composition as observed by Mercado et al. (2007), where a phytoplankton diatom-based community shifted towards a coccolithophorid type of community in 2001. Highest larval growth of anchovy and sardine cohorts corresponded
to this year-class (García 2006; García et al. 2003). Moreover, changes in phytoplankton community may have contributed to having higher carbohydrate content in
sardine larvae sampled in winter 2000 and 2001 (García et al. 2005; Cortés 2006;
García 2006; Mercado et al. 2007).
With respect to the Alboran Sea anchovy, its peak spawning occurs during
summer (July–August) (Rodríguez 1990). An unexpected high anchovy recruitment
occurred during 2001 (Abad and Giráldez 1990). Growth data on anchovy of the
2000 and 2001 year-class were compared which yielded a field-based study on the
influence of growth on annual recruitment (García et al. 2003). The 2001 anchovy
larval cohort showed a 20% increase in daily growth rates in comparison to the
previous year (García et al. 2003). The birth date distribution of both cohorts showed
that during 2001 these were born at an earlier period (late spring) which possibly
coupled with the spring bloom because zooplankton biomass was unexpectedly high
in 2001 in comparison to the previous year. Furthermore, Mercado et al. (2005,
2007) revealed important interannual changes in the predominance of the different
phytoplankton groups in the Alboran Sea) shifting from a diatom-based community
to a coccolithophorid- and dinoflagellate-based phytoplankton grouping.
Nevertheless, it is reasonable to think that a single event like the strong 2001
anchovy recruitment must have been triggered by changes or driving forces of
biological and hydro-physical nature that occurred in the Alboran Sea. Ruíz et al.
(2013) observed a relationship between the variability of the path and intensity of
Atlantic Jet with the anchovy recruitment. A high kinetic energy of the current favors
the production in northern Alboran, but negatively impacting anchovy recruitment,
possibly inducing a greater degree of larval advection and dispersion. The year 2001
constituted an outlier of the time series of data from 1988 to 2010. The climatic and
hydrographic forces of the Atlantic current are also responsible for maintaining the
temporal persistence of the anchovy and sardine nursery grounds (Macías et al. 2011).
13.6 New Approaches Towards ELHS Trophodynamics
The joint analysis of growth at ELHS together with other analytical tools has led
way to the development of new digital imaging tools for growth otolith microstructure analysis (Nava et al. 2018). This digital imaging tool is open to otolith experts
13 Evolving from Fry Fisheries to Early Life Research on Pelagic Fish Resources
511