In June 2019, the Ministry of Environmental Protection and Energy granted a permit for the collection of healthy individuals (33) from the Pula coastal area and their subsequent maintenance under controlled conditions. Over the subsequent two-year period, all individuals succumbed to the effects of the bacterium Mycobacterium sherrisii.

In 2020, a further 300 individuals were introduced, which were subsequently identified as infected with H. pinnae and subsequently died over the following two years. In June 2022, the last surviving adult individual, which had survived for 28 months in ex situ conditions, died. Analyses conducted on this individual showed that it was no longer infected with H. pinnae but was found to be infected with Mycobacterium sherrisii.

At the end of 2020, as part of the national project "Conservation of the Noble Pen Shell (Pinna nobilis) in the Adriatic Sea," the first collectors for the reception of young pen shells were installed at 15 locations across the Adriatic. A total of 41 juvenile specimens were collected from three locations—Omiš, Rovinj, and Brijuni National Park—and subsequently transferred to the quarantine section of Aquarium Pula. Subsequently, juvenile specimens have been collected annually from the collectors and transported to Aquarium Pula. The individuals are placed in reception tanks containing specially prepared seawater, which has been purified and continuously treated with ozone and UV light. The tanks are also filtered to 1 micron in order to prevent unwanted microorganisms. Upon arrival, the individuals are maintained at a temperature of up to 13.5 degrees Celsius for approximately thirty days, as the parasite H. pinnae is only active at higher temperatures. The juvenile individuals are fed several times a day with various species of single-celled algae, or phytoplankton, the most significant of which are Isochrysis galbana, Tetraselmis suecica, Phaeodactylum tricornutum, and Nannochloropsis sp.