The number of eggs in each dish was firstly calculated by using Albrecht’s approach [30]. The size of ten eggs was measured with a Vernier caliper which was close to 0.1 mm. Then the total volume of each spawn was measured with Vernier caliper as well. The number of eggs in the spawn was calculated by using spawn volume dividing the average volume of eggs. Secondly, another estimation method was adopted which weighted a single egg by using electronic analytical balance (ACCULAB ALC-210.4, Sartorius AG Germany) and weighted the total mass of all eggs. The ratio of total mass and single mass was considered as egg quantity. Finally, the averages of these two measurements were taken as the number of eggs