On Monday 4 May 2020, with the first loosening of the work restrictions imposed by the COVID-19 pandemic, the Hellenic Centre for Marine Research (HCMR) started the experiments in Work Package 4 of the project Newtechaqua, with the objective of closing the reproductive cycle of new/emerging species. The experiments involve the assessment of the effects of salinity manipulations on reproductive maturation, spawning success and egg/sperm quality in meagre (Argyrosomus regius). The success of this trial will enable the production of “organic” larvae -without hormonal therapies of the broodstock– for further development of meagre aquaculture. The work is the responsibility of the Work Package 4 leader Dr. Constantinos C Mylonas.
Individualized couples of meagre (n=8) have been placed in 5-m3 spawning tanks (in duplicates), and were exposed to full salinity with a GnRHa treatment for spawning (positive control), while the other six tanks were exposed to full or reduced salinity (20 or 10 ppt) without a GnRHa treatment. Gonadal biopsies, histological evaluation and sperm quality evaluation using Computer Assisted Sperm Analysis (CASA) were conducted at the start of the experiment, and blood was collected to estimate the plasma sex steroid hormone levels (HCMR, Greece) and gonadotropins (RARA Avis, Spain), in order to correlate them with reproductive stage. Evaluation of spawning quality (fecundity, fertilization success and larval survival) has begun and will be carried out for the following 4 weeks. At the end of the experiment, fish will be sampled again as above.
More information about the species of this experiment can be found here.