ecological effects of marine protected areas empafish project ...

EMPAFISH Booklet no. 1 Ecological effects of Atlanto-Mediterranean MPAs in the EU
samples were collected during summer and autumn in 1995 and 1996 at the
16 FADs using a surrounding net. Visual observations of fishes associated with
the FADs were also conducted to obtain qualitative information about the
spatial distribution of species.
A total of 1632 specimens weighing 144 kg and belonging to 8 species were
caught during the survey. Seriola dumerili, Caranx crysos, C. rhonchus and
Coryphaena hippurus were the most frequent and abundant species
accounting for 96% of the total catch. Average fish abundance and weight,
characterised by high variance, were significantly higher at the sites with
experimental FADs than at the sites with traditional FADs. S. dumerili was the
only species with higher catches around the experimental FADs. Some spatial
and temporal variations in fish abundance and size were also detected.
Younger individuals of S. dumerili were observed to show high affinity for the
experimental FAD tufts. This studies highlights the role and the efficiency of
bottom and floating FAD not only in attracting fish, but also in hosting and
supporting a characteristic fish assemblage.
The role of floating FADs in the distribution and shoreward migrations of
juvenile of the greater amberjack Seriola dumerili has also been studied in the
Gulf of Castellammare (Sinopoli et al. 2006). In this study, we hypothesised
that FADs located along a distance gradient from the shore might lead the
greater amberjack inshore. In such case, mean abundance of S. dumerili
should decrease over time in offshore FADs and increase in inshore FADs. To
test the hypothesis three FAD systems were positioned in the Gulf of
Castellammare (Sicily, Italy), between July and September 2001, at
increasing distances from the coast. During the study period, five visual
censuses were carried out within FADs fields. During the first sampling
period, no significant difference in abundance and size of juvenile S.
dumerili were found between the three FAD systems. All the other
sampling periods reported higher abundances and sizes in the offshore FADs
than in the two inshore FADs. The findings suggest that FAD systems might
be exerting two different effects on YOY S. dumerili distribution: (a) offshore
FADs tend to retain associated fish for longer periods of time, (b)
coastal FADs favour the transition of YOY S. dumerili from the pelagic to the
benthic domain.
A preliminary Cellular Automata model was also developed to visualise and
predict the behaviour of juveniles of the greater amberjack Seriola dumerili
during the first year of life in the presence of fish aggregating devices (FADs)
(Piscitelli et al., 2000, 2001). The model was utilised for simulations,
concerning the area of the Castellammare Gulf, NW Sicily. First simulations
have given encouraging results; they account for the main characteristics of
the phenomenon and agree with the observations. The results show that the
model could be applied for the optimization of FADs distribution and the
evaluation of their environmental impact.
� Marine ranching
A pilot experiment of marine ranching using hatchery-reared juveniles of
white seabream, Diplodus sargus, was made in the Gulf of Castellammare
78