Chamelea gallina reproductive biology and Minimum Conservation Reference Size: implications for fishery management in the Adriatic Sea

Giada Bargione; Fortunata Donato; Giulio Barone; Massimo Virgili; Pierluigi Penna; Alessandro Lucchetti

doi:10.1186/s40850-021-00096-4

Chamelea gallina reproductive biology and Minimum Conservation Reference Size: implications for fishery management in the Adriatic Sea

BMC Zool. 2021 Nov 25;6(1):32. doi: 10.1186/s40850-021-00096-4.

Authors

Giada Bargione^{1

2}, Fortunata Donato³, Giulio Barone³, Massimo Virgili³, Pierluigi Penna³, Alessandro Lucchetti³

Affiliations

¹ National Research Council (CNR), Institute for Biological Resources and Marine Biotechnologies (IRBIM), Largo Fiera della Pesca, 1, 60125, Ancona, Italy. giada.bargione@irbim.cnr.it.
² Department of Biological, Geological and Environmental Sciences, University of Bologna, Piazza di Porta San Donato 1, 40126, Bologna, Italy. giada.bargione@irbim.cnr.it.
³ National Research Council (CNR), Institute for Biological Resources and Marine Biotechnologies (IRBIM), Largo Fiera della Pesca, 1, 60125, Ancona, Italy.

Abstract

Background: The striped venus clam Chamelea gallina is an economically important species in Adriatic Sea fisheries. The use of hydraulic dredging for its catch has a long history in Italy and its management faced several stages of development in the last 40 years. A great effort has been made in the past two decades to move from poorly or weakly managed fisheries to a well-structured co-management system to improve the sustainability of this fishery. However, a prerequisite for appropriate resource management is a sound knowledge of the biology and reproductive strategy of the species.

Results: We investigated three major biological features- the gametogenic cycle, size at sexual maturity and partial fecundity - by microscopic, histological and video analysis techniques. We demonstrated that its breeding season is driven by rises in seawater temperature and chlorophyll-a concentration and that its spawning period lasted from March to September. Size at sexual maturity was reached very early in the life cycle. As regards partial fecundity - the number of mature oocytes potentially released by females with ripe gonads in a single release event - varied in relation to size. Nevertheless, the reduction on the Minimum Conservation Reference Size (MCRS) from 25 to 22 mm (Delegated Regulation (EU) 2020/2237) lead to a 40% reduction in the number of emitted eggs.

Conclusions: We suggest that the ability of Adriatic clam stocks to withstand the strong fishing pressure of the past 40 years and the present one is due to their high reproductive potential and multiple spawning events combined with the effect of management measures (closed areas/seasons, quota, MCRS) and technical constraints on the gear and the sieve on board. Moreover, since the reduced MCRS for Venus shells is still larger than the size at maturity, it will probably not be detrimental to the reproductive capacity of the stock.

Keywords: Chamelea gallina; Fishery management; Minimum Conservation Reference Size (MCRS); Partial fecundity; Reproductive cycle; Sexual maturity.