clearly demonstrated the joint use of otolith microstructure and biochemical analysis
as new tools for assessing the effect of the processes affecting larval survival and
better understand the underlying causes of interannual fluctuations in the recruitment
success of small pelagic species (Buckley 1984; Campana and Neilson 1985;
Moksness and Wespestad 1989; Clemmessen 1994). Some of these studies and
others demonstrated that enhanced growth at early life stages shows significant
relationships with larval survival rates for many fish species around the world
(Hovenkamp 1992; Takasuka et al. 2003; García et al. 2003; Meekan et al. 2006).
The implementation of these research tools was applied in the field, beginning
with the NW Mediterranean anchovy which represents the greatest resource of this
species in the Spanish Mediterranean (García et al. 1998). The experience gathered
in these ELHS research proved in later years that the early life stages of sardines and
anchovies confirm the growth-mortality hypothesis (Anderson 1988) by which
growth is intricately related to larval mortality (Houde 1987, 2008).
In small pelagic larvae, enhanced growth is attained with higher RNA/DNA
influenced by the amount of trophic resources between regions in western Mediterranean coasts (García et al. 1998, 2003; Quintanilla et al. 2015).
Thus, differences in somatic growth, otolith growth, and larval nutritional condition of anchovy larvae, from different spawning areas of the NW Mediterranean,
suggested important effect of seawater temperature on larval condition as estimated
from RNA/DNA. Those effects were confirmed by Ramírez et al. (2004) who
studied the effect of temperature and microzooplankton biomass on biochemical
nutrition indices of anchovy larvae in the NW Mediterranean Sea where temperature
and microzooplankton accounted for >70% of the variability in RNA, DNA, and
protein. However, the ratios of RNA/DNA and protein/DNA were only related to
temperature. On average, both ratios in anchovy larvae decreased with temperature,
probably reflecting the effect of temperature on larval metabolism, supporting the
findings of previous studies conducted with other species (e.g., Goolish et al. 1984;
Ferguson and Danzmann 1990).
Accurate estimates of growth rates and nutritional condition of larvae were
needed to understand and predict fluctuations in recruitment. The ECOMALAGA
quarterly sampling program supported the small pelagic larval sampling which is a
methodological framework in establishing precision and accuracy under an
EU-funded project (PARS, FAIR961371) grouping teams from different EU
countries.
The research conducted involved different interlaboratory test studies, including
samples of Alboran Sea sardine larvae, to analyze the precision and accuracy of
otolith readings and the use of the RNA/DNA as tools for determining larval growth
and nutritional condition. Among the main outcomes of the project was the publication of a practical manual of the tools used for recruitment studies of small pelagic
fish species (Belchier et al. 2004) where different protocols regarding otolith microstructure analysis and nutritional condition were tested through intercalibration procedures and applied accordingly.
García et al. (2006a, b) observed differentiated larval growth patterns between the
sardine stocks of the NW Mediterranean and the northern Alboran Sea. Larval daily
13 Evolving from Fry Fisheries to Early Life Research on Pelagic Fish Resources
505
as new tools for assessing the effect of the processes affecting larval survival and
better understand the underlying causes of interannual fluctuations in the recruitment
success of small pelagic species (Buckley 1984; Campana and Neilson 1985;
Moksness and Wespestad 1989; Clemmessen 1994). Some of these studies and
others demonstrated that enhanced growth at early life stages shows significant
relationships with larval survival rates for many fish species around the world
(Hovenkamp 1992; Takasuka et al. 2003; García et al. 2003; Meekan et al. 2006).
The implementation of these research tools was applied in the field, beginning
with the NW Mediterranean anchovy which represents the greatest resource of this
species in the Spanish Mediterranean (García et al. 1998). The experience gathered
in these ELHS research proved in later years that the early life stages of sardines and
anchovies confirm the growth-mortality hypothesis (Anderson 1988) by which
growth is intricately related to larval mortality (Houde 1987, 2008).
In small pelagic larvae, enhanced growth is attained with higher RNA/DNA
influenced by the amount of trophic resources between regions in western Mediterranean coasts (García et al. 1998, 2003; Quintanilla et al. 2015).
Thus, differences in somatic growth, otolith growth, and larval nutritional condition of anchovy larvae, from different spawning areas of the NW Mediterranean,
suggested important effect of seawater temperature on larval condition as estimated
from RNA/DNA. Those effects were confirmed by Ramírez et al. (2004) who
studied the effect of temperature and microzooplankton biomass on biochemical
nutrition indices of anchovy larvae in the NW Mediterranean Sea where temperature
and microzooplankton accounted for >70% of the variability in RNA, DNA, and
protein. However, the ratios of RNA/DNA and protein/DNA were only related to
temperature. On average, both ratios in anchovy larvae decreased with temperature,
probably reflecting the effect of temperature on larval metabolism, supporting the
findings of previous studies conducted with other species (e.g., Goolish et al. 1984;
Ferguson and Danzmann 1990).
Accurate estimates of growth rates and nutritional condition of larvae were
needed to understand and predict fluctuations in recruitment. The ECOMALAGA
quarterly sampling program supported the small pelagic larval sampling which is a
methodological framework in establishing precision and accuracy under an
EU-funded project (PARS, FAIR961371) grouping teams from different EU
countries.
The research conducted involved different interlaboratory test studies, including
samples of Alboran Sea sardine larvae, to analyze the precision and accuracy of
otolith readings and the use of the RNA/DNA as tools for determining larval growth
and nutritional condition. Among the main outcomes of the project was the publication of a practical manual of the tools used for recruitment studies of small pelagic
fish species (Belchier et al. 2004) where different protocols regarding otolith microstructure analysis and nutritional condition were tested through intercalibration procedures and applied accordingly.
García et al. (2006a, b) observed differentiated larval growth patterns between the
sardine stocks of the NW Mediterranean and the northern Alboran Sea. Larval daily
13 Evolving from Fry Fisheries to Early Life Research on Pelagic Fish Resources
505