Evaluating the effects of protection on fish predators and sea urchins in shallow artificial rocky habitats: a case study in the northern Adriatic Sea

Published source details Guidetti P., Bussotti S. & Boero F. (2005) Evaluating the effects of protection on fish predators and sea urchins in shallow artificial rocky habitats: a case study in the northern Adriatic Sea. Marine Environmental Research, 59, 333-348.
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This study is summarised as evidence for the following.

	Action	Category
	Manage or restrict harvesting of species on subtidal artificial structures Action Link
	Cease or prohibit all types of fishing in a marine protected area Action Link

Manage or restrict harvesting of species on subtidal artificial structures

A site comparison study in 2002–2003 on three subtidal breakwaters on open coastline in the Adriatic Sea, Italy (Guidetti, Bussotti & Boero 2005; same experimental set-up as Guidetti et al. 2005) found higher abundances of white seabream Diplodus sargus, two-banded seabream Diplodus vulgaris and gilt-head seabream Sparus aurata, but similar abundance of sea urchins Paracentrotus lividus around a breakwater with restricted harvesting, compared with two unrestricted breakwaters. Sixteen years after harvesting restrictions were introduced, abundance was higher around the breakwater with restrictions than those without for white seabream in two of four surveys (restricted: 5–8 individuals/125m²; unrestricted: 0–2/125m²) and for two-banded seabream in three surveys (restricted: 2–46/125m²; unrestricted: 0–14/125m²). In the remaining surveys, abundances were similar around restricted (white: 3–10/125m²; two-banded: 4/125m²) and unrestricted breakwaters (white: 0–8/125m²; two-banded: 1–3/125m²). Gilt-head seabream were present only at the restricted breakwater in three of the surveys (1–2/125m²) and was more abundant in the fourth (restricted: 2/125m²; unrestricted: <1/125m²). Urchin abundance was similar around restricted and unrestricted breakwaters (both 2–11/20m²). Harvesting species on and around a boulder breakwater was restricted by creating a marine protected area in 1986, making fishing illegal with successful enforcement. Fishes and sea urchins were counted during four surveys at 4–7 m depth in 2002–2003 around the breakwater with restricted harvesting and around two nearby breakwaters with no restrictions.

(Summarised by: Ally Evans)
Cease or prohibit all types of fishing in a marine protected area

A site comparison study in 2002–2003 of three areas of artificial rock in the Adriatic Sea, Italy (Guidetta, Bussotti & Boero 2005, same experimental set-up as Guidetta et al. 2005) found higher abundances of white seabream Diplodus sargus, two-banded seabream Diplodus vulgaris and gilt-head seabream Sparus aurata at a breakwater in a marine protected area where all fishing had been prohibited for 16 years, and there were more medium and large individuals, compared to two nearby fished breakwaters. The density of white (unfished: 5.0–7.8, fished: 0.0–1.7 fish/125m²) and two-banded seabream (unfished: 11.6–45.7, fished: 1.0–14.3 fish/125 m²) was higher at the unfished breakwater than fished ones in two of the four sampling times, and all but small individuals were more abundant (white, small: 0.5 vs 0.0–0.5, medium: 3.7 vs 1.7–1.8, large: 1.8 vs 0.1–0.3; two-banded, small: 0.0 vs 0.0–1.0, medium: 11.1 vs 3.4–3.8, large: 2.2 vs 0.2–0.3 fish/125m²). Gilt-head seabream were present only at the unfished breakwater in three of four sampling times and were more abundant in the other (unfished: 1.3–2.2, fished: 0.5 fish/125m²). Fish were surveyed at one breakwater in the Miramare Marine Protected Area (121 ha, no fishing since 1986) and two fished breakwaters (adjacent and 3 km away) four times between spring 2002 to summer 2003. Four underwater visual transects (25 × 5 m) were done at each breakwater. The breakwaters were transplanted boulders 1–3 m wide running parallel to the coast, extending from the surface to depths of 5–8 m.

(Summarised by: Leo Clarke)