Newsletter June 2023

As we get closer to the goal of our operation, commercial glass eel farming, it also becomes increasingly clear what bumps we still have to overcome before we can start thinking about scaling up.
In the previous newsletter, we set ourselves quantitative targets for larval survival at the various stages. With that, we are aiming for a total production efficiency from fertilized egg to glass eel of at least 10%, a common efficiency for aquaculture of larval fish stages (which show much higher mortality in nature).
The maximum survival rate for survival from day 14 to 42 that still stood at 16% in 2022 has already risen (early 2023) to 24%, a new record. The target of 60% is approaching and seems achievable given the mortality trends. Indeed, survival on day 30 is still good (70%). After that, there is an accelerated decline, the cause of which is now being investigated.
But we also consider the duration of the production cycle. The length increase of our larvae is almost linear (does not flatten out), which is consistent with the growth curve of the Japanese eel. But growth is still too slow now. With the growth we achieved last year over a record life span of 93 days, it would (theoretically) take 346 days to reach a length at which the larva can become glass eel (see the figure).
A production cycle (egg to glass eel) of one year seems too long for commercial production. But in the first quarter of 2023, we have already achieved growth that was nearly 50% higher. That would mean a production cycle of 232 days. There is probably further optimization to be done here. We are working on incremental improvements in diet, feed dosage and tank conditions. With these, hopefully a growth rate of 0.2 mm per day can be achieved. That would bring the production cycle within 200 days.
Probably 3 more years of research will be needed after 2023 to get this done. Our long-term planning for 2024-2026 has been adjusted accordingly. At the general meeting of shareholders on June 19, confidence was expressed in the research strategy to be followed. A number of suggestions were also made for further refinement of the data analysis and experimental design. The great confidence was also expressed by the willingness of existing and new shareholders to invest again in Glasaal Volendam BV shares.