Dr. Urzua-Osorio, Angel

Pleuroncodes monodon from the Chilean coast has seasonal reproduction. During the seasonal period, females and their eggs are exposed to seasonal variation in environmental conditions. In P. monodon populations inhabiting the Southern Pacific coast near Concepción, Chile, we quantified late summer (February–March 2014) and late winter (August–September 2014) seasonal variations in female reproductive parameters (carapace length, fecundity, reproductive output (RO), ash weight, organic content) as well as eggs parameters (length, volume, dry weight, organic content). There was conspicuous seasonal variation in the main reproductive parameters of this species. During the summer, the number of eggs and organic content of females were higher than winter, whereas RO was slightly higher in winter than in summer. Significant variation in the size and biomass of the eggs was also found between seasons. For example, eggs laid in summer were smaller, had a lower measured dry mass, and had a lower organic content than eggs laid in winter. Seasonal variations in the fecundity and size of the eggs have implications for fishery models, which can be used to estimate the relative contribution of different cohorts to recruitment and stability of adult benthic populations.

Pleuroncodes monodon is an important fishery resource and key species from the Southeastern Pacific. During its prolonged reproductive period (from February to December), ovigerous females are exposed to seasonal variation in environmental factors (e.g. temperature and food availability), with higher levels of these environmental parameters during summer and lower in winter, and must adjust their biochemistry to ensure their own survival and that of their embryos. The aim of this study was to analyse seasonal changes in the biochemical composition of ovigerous females and their eggs. The data show that the content of lipids, proteins and organic matter in the hepatopancreases of females was significantly higher in winter than in summer. Similarly, the lipid content of the eggs was significantly higher in winter than in summer, yet the protein content of the eggs had the opposite pattern with greater values found in summer. Consistent with the ‘reproductive energetic model’, the initial and final energy produced by the hepatopancreas showed significant seasonal variations, whereas female investment in egg production (in absolute values) did not show significant seasonal differences. The seasonal differences observed in the biochemistry, organic matter and energy content of the female hepatopancreases may be related to the storage of energy for growth and reproduction. Furthermore, the seasonal variation in the content of lipids, proteins and energy in eggs is likely related to embryogenesis and larval hatching in function with environmental conditions. Seasonal variation in the biochemical composition of P. monodon has direct effects on the marine food web and also upon fisheries.

Environmental variables are key drivers of reproductive traits in marine organisms, which can have significant economic consequences in commercial species. Pleuroncodes monodon is an important resource of the industrial fisheries’ fleet of the Humboldt Current System. This species is subject to seasonal variations in pivotal variables such as temperature and food availability, as well as, climatic events. We herein analyse the variations in reproductive parameters and in the eggs’ biochemical profiles in relation to environmental conditions. Differences in all studied parameters were found between 2014 and 2015. In 2015, fecundity (measured as total number of eggs) and protein content were higher than 2014, but lipid content showed the opposite pattern. Seasonal and interannual variations were also observed in the energy content per egg; whilst the brood energy content did not show seasonal or interannual variation. This information is of utmost importance for integrative management of this commercial good as the data measures dynamic variations in the species populations. Currently, this squat lobster is overexploit and so far, no seasonal nor interannual variations have been considered in its management plan. The present study provides evidences that the female lobsters need different management strategies to maintain sustainable fisheries of Concepcion, Chile.