Abundance ratios in/out of species for MPAs in Croatia.

In general, commercial target species are more abundant in MPAs, significantly, so this is the first demonstration of significantly positive effect of Croatian MPAs on target commercial fish species.  For example, Sparus aurata and Dentex dentex are 5.5 times more abundant inside MPAs than outside (see Table below). Six taxa were found only inside MPAs (Brijuni, Kornati, Lastovo, Mljet), and 21 taxa were found only outside MPAs. This difference however is probably an artifact of the much larger sample size of census transect outside MPAs (about fivefold difference), which results in rare species more likely to be seen outside the MPA than inside simply due to sampling error.

Species more abundant inside of MPAs tend to be those more likely associated with rock habitat and a mixture of rock and vegetation (seagrass and macroalgae).  Species more abundant outside of MPAs tend to be more likely associated with unconsolidated or unvegetated habitat.  These habitat correlates may in part explain the differences inside/outside, since outside and unprotected areas are more likely to be developed and degraded.

These results are based on over 10.000 lure assisted visual transects at 146 sampling sites.