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Preliminary assessment of sheltered sandy beaches as fish nursery grounds along the eastern coast of the Adriatic Sea

The availability of nurseries and settler supply patterns along the eastern coast of the middle Adriatic was analysed during 2018 by locating and quantifying nursery microhabitats and estimating the settlement pattern. In total, 23 locations (3 replicas) of the 925 km- long shore were monitored. Among them, 3 locations characterized by exposure, slope, sediment and type (cove Prapratna, Stari Trogir and Petrčane) were sheltered, having medium slope, while they slightly differ in sediment type. Prapratna cove is sandy, Stari Trogir is sandy with sea grass and Petrčane is pebble sandy with sea grass. In total 43 juvenile fish species were recorded on that 3 locations and Stari Trogir location has highest number of recorded species (31), following with Petrčane (23) and Prapratna (11). In total, highest number of individuals was recorded on Stari Trogir (654), following with Prapratna cove (373) and Petrčane (346). The most common species in this habitats were Pagellus acarne (21, 12%) and Mullus barbatus (20, 98%). However, in Prapratna cove Bothus podas and Lithognatus mormyrus contributed in sample with 49, 04% and 32, 83% respectively. Stari Trogir location seems to be important area for young Mullus barbatus (28, 13%), Bothus podas (24, 69%), Oedalechilus labeo (10, 17%) and Arnoglossus laterna (7, 27%). Nursery area Petrčane were dominated by Pomatoschistus marmoratus, Atherina boyeri and Symphodus cinereus which contributed with 51, 62%, 16, 83% and 8, 64% respectively. Juveniles of Pagrus pagrus and Bothus podas were found just on these 3 locations of total 23 indicating that these grounds can be essential nursery grounds for these two species. Thus, these shallow, soft, coastal habitats sheltered within coves, covered partially with seagrass meadows, are vulnerable to human-induced habitat modifications and thus have to be carefully monitored. Defining specific nursery grounds related to different habitat characteristics (bottom types, vegetation, slope) for certain economically important or exploited fish species and highlighting and resolving the important gaps in biological knowledge for selected species, would provide new data for management and conservation guidance. However, the density of juveniles in coastal habitats and estuaries alone does not provide full information on enhanced juvenile growth or recruitment. As defined by Beck et al. (2001), in order to adequately assess if these identified important sites for juveniles are in fact nursery areas, it is necessary to determine their effective contribution to coastal adult stocks which is a next step of investigation on project NurseFish.

fisheries, fish ecology, Adriatic sea, nursery grounds, juvenile fish

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