Conditioning of the Mediterranean Scallop Pecten Jacobaeus (Linneaus, 1758) in Recirculation Systems with Different Types of Feed

Mariculture bivalve production is limited to a small number of species, so there is a need for the introduction of new species. The Mediterranean scallop Pecten jacobaeus (Linnaeus, 1758) seems like a potential bivalve mariculture candidate, but there is a lack of spat from nature for farming purposes. Two experiments on conditioning of P. jacobaeus broodstock in recirculation systems were conducted, the first one in April 2023 and the second one in March 2024. Condition indices were calculated: condition (CI), muscle (MI), gonadosomatic (GSI) and gonad index (GI) in both experiments. For the second experiment, a histology examination of the gonads was also conducted. In the first experiment broodstock fed with live algae Isochrysis galbana for 21 days, showed a rise in GSI and GI values, with constant CI and a slight decline of MI. In the second experiment, broodstock was fed for 25 days with two different types of feed: Group 1 with live algae I. galbana, while Group 2 concentrated frozen algae mix of 3% of the dry body mass per day. Better results were achieved with the live feed, evidenced by higher CI and MI results in Group 1. The GSI and GI results, along with gonad histological examination, indicate that gonads developed with both types of feed, but the process appeared to be accelerated with live feed. We conclude that gonad development in Group 1 was at the expense of ingested food, while in Group 2, at the expense of storage of nutrient reserves from muscle and other tissues.