First confirmed complete incubation of a flapper skate (Dipturus intermedius) egg in captivity

An egg of the Critically Endangered flapper skate Dipturus intermedius was successfully incubated to hatching in captivity, in what is believed to be a first for the species. Water conditions (temperature, salinity, flow rate) were recorded, with mean water temperatures ranging from a monthly mean of 8.3±1.2 to 13.2±0.3oC and salinity from a monthly mean of 30.5±1.2 to 36.6±2.3 ppt. Hatching occurred after 534 days, suggesting that flapper skate eggs take approximately 5700 growing degree-days to incubate to hatching. The egg's prolonged embryonic development raises concerns about flapper skate eggs' vulnerability to anthropogenic disturbance.