Variable population responses by large decapod crustaceans to the establishment of a temperate marine no-take zone

Published source details Hoskin M.G., Coleman R.A., von C.E. & Davis C.M. (2011) Variable population responses by large decapod crustaceans to the establishment of a temperate marine no-take zone. Canadian Journal of Fisheries and Aquatic Sciences, 68, 185-200.
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This study is summarised as evidence for the following.

	Action	Category
	Designate a Marine Protected Area and prohibit all towed (mobile) fishing gear Action Link
	Designate a Marine Protected Area with a zonation system of activity restrictions Action Link
	Designate a Marine Protected Area and prohibit all types of fishing Action Link

Designate a Marine Protected Area and prohibit all towed (mobile) fishing gear

A replicated, site comparison study in summer 2004–2007 of eight sites in four areas of rocky and sandy seabed in the Bristol Channel and the Irish Sea, UK (Hoskin et al. 2011) found that a marine protected area closed to all towed gear for 33–36 years had mixed effects on the abundances and sizes of European lobster Homarus Gammarus, and three crab species. Abundances of large lobsters (≥90 mm) did not change over time in any areas, where they were similar (1–2 lobsters/line). Abundance of small lobsters (<90 mm) increased in the protected areas by 140% (due to spill-over effects from an adjacent no-take zone; from 2 to 4–7 lobsters/line), but not in the fished areas where abundance remained constant (2–4 lobsters/line). The size of large lobsters (≥90 mm) decreased similarly in all areas by 2–3% (from 98 to 95 mm). Abundance of velvet crabs Necora puber decreased inside the protected areas (from 5–6 to 1 crab/line) but increased in the fished areas (from 0–6 to 1–7 crabs/line). Abundance of brown crabs Cancer pagarus did not change over time in any areas but was on average higher in the protected areas (1–2 crabs/line) compared to the fished areas (0.3–2 crabs/line). The average size of brown crabs did not change over time in any areas, and was not different between protected (123–128 mm) and fished areas (116–130 mm). Abundance of spider crabs Maja squinado was similar in 2004 and 2007 for all areas but varied spatially. Lundy Island marine protected area was designated as a voluntary reserve in 1971 (statutory since 1986) and only allowed crab and lobster potting (all other fishing prohibited; apart from a small 4 km²no-take zone). In 2004–2007, lobsters and crabs were surveyed at two locations in the protected area (outside the no-take zone), and two unprotected fished locations (20–100 km away) (2 sites/location). Four lines of standard commercial baited shellfish pots were deployed (10 pots/line) at each site for 24 h. Upon retrieval, lobsters and crabs were counted and measured (carapace length). The pots were redeployed for five consecutive days each year.

(Summarised by: Anaëlle Lemasson & Laura Pettit)
Designate a Marine Protected Area with a zonation system of activity restrictions

A replicated, site comparison study in summer 2004–2007 of ten rocky and sandy sites, across two zones inside a marine protected area and two areas outside, in the Bristol Channel and the Irish Sea, UK (Hoskin et al. 2011) found that abundances and sizes of European lobster Homarus gammarus and three crab species varied with the levels of protection. Abundance of large lobsters (≥90 mm) increased by 127% inside the no-take zone between 2004 and 2007 (one to four years after designation of the no-take zone; from 3 to 7 lobsters/line) and was five times higher than in aa partly fished zone (potting only) inside the protected area and fully fished areas outside where abundance had not changed (1–2 lobsters/line). Abundance of small lobsters (<90 mm) increased by 97% in the no-take zone (from 3 to 7 lobsters/line) and by 140% in the potting-only zones (argued by the authors to be due to spill-over effects; from 2 to 4–7 lobsters/line), where they appeared greater than in the fully fished areas where abundance remained constant (2–4 lobsters/line). The size of large lobsters (≥90 mm) increased by 5% inside the no-take zone between 2004 (98 mm) and 2007 (103 mm) and became 9% larger than in the potting-only zone and fished areas where lobster size decreased by 2–3% (from 98 to 95 mm). The size of small lobsters did not change over time and was similar across all areas. Abundance of velvet crabs Necora puber decreased by 65% inside the no-take zone over time (from 2 to 1 crab/line; argued by the authors to be due to increased predation by lobsters) and decreased even more in the potting-only zones (from 5–6 to 1 crab/line), and appeared lower than in the fully fished areas where it increased (from 0–6 to 1–7 crabs/line). The average size of velvet crabs did not change over time and was similar across all areas. Abundance of brown crabs Cancer pagurus did not change over time inside the no-take zone (0.3 crab/line), nor in the potting-only zone and fished areas (from 0.3–2 crabs/line). The average size of brown crabs increased by 25% inside the no-take zone between 2004 (115 mm) and 2007 (144 mm) and became greater than in the potting-only zones (123–128 mm) but not in fully fished areas (116–130 mm). Abundance of spider crabs Maja squinado was similar in 2004 and 2007 for all areas but varied spatially (with the no-take zone having lower abundance). The average size of spider crabs did not change over time and was similar across all areas. Lundy Island marine protected area was designated as a voluntary reserve in 1971 (statutory since 1986). In 2003, it included a 4 km² no-take zone (no fishing or harvesting allowed), the rest being a refuge zone only allowing crab and lobster potting. In 2004–2007, lobsters and crabs were surveyed inside the no-take zone, at two locations in the refuge zone, and two distant fished locations (20–100 km away) (2 sites/location). Four lines of standard commercial baited shellfish pots were deployed (10 pots/line) at each site for 24 h. Upon retrieval, lobsters and crabs were counted and measured (carapace length). The pots were redeployed for five consecutive days each year.

(Summarised by: Anaëlle Lemasson & Laura Pettit)
Designate a Marine Protected Area and prohibit all types of fishing

A replicated, site comparison study in summer 2004–2007 of six sites in three rocky and sandy seabed areas in the Bristol Channel and the Irish Sea, UK (Hoskin et al. 2011) found that a marine protected area prohibiting all fishing (no-take) had mixed effects on the abundances and sizes of European lobster Homarus gammarus, velvet crab Necora puber, brown crab Cancer pagurus and spider crab Maja squinado. Abundance of large lobsters (≥90 mm) increased by 127% inside the no-take zone between 2004 and 2007 (from 3 to 7 lobsters/line) and was five times higher than in unprotected fished areas where abundance had not changed (1–2 lobsters/line). Abundance of small lobsters (<90 mm) increased by 97% (from 3 to 7 lobsters/line) in the no-take zone, but remained constant in the fished areas (2–4 lobsters/line). The size of large lobsters (≥90 mm) increased by 5% inside the no-take zone between 2004 (98 mm) and 2007 (103 mm) and became 9% larger than in the fished areas where lobster size decreased by 2% (from 98 to 95 mm). The size of small lobsters did not change over time and was similar across all areas. Abundance of velvet crabs decreased by 65% inside the no-take zone over time (from 2 to 1 crabs/line; likely due to increased predation by lobsters) but increased in the fished areas (from 0–6 to 1–7 crabs/line). The average size of velvet crabs did not change over time and was similar across all areas. Abundance of brown crabs did not change over time inside the no-take zone (0.3 crab/line), nor in the fished areas (from 0.3–2 crabs/line). The average size of brown crabs increased by 25% inside the no-take zone between 2004 (115 mm) and 2007 (144 mm) but was not greater than in fished areas (116–130 mm). Abundance of spider crabs was similar in 2004 and 2007 for all areas but varied spatially (with the no-take zone having a lower abundance). The average size of spider crabs did not change over time inside the no-take zone. Lundy Island Marine Protected Area was designated as a voluntary reserve in 1971 (statutory since 1986). In 2003, it included a 4 km² no-take zone (no fishing or harvesting allowed), the rest being a refuge zone only allowing crab and lobster potting. In 2004–2007, lobsters and crabs were surveyed inside the no-take zone and two unprotected fished locations (20–100 km away) (2 sites/location). Four lines of standard commercial baited shellfish pots were deployed (10 pots/line) at each site for 24 h. Upon retrieval, lobsters and crabs were counted and measured (carapace length). The pots were redeployed for five consecutive days each year.

(Summarised by: Anaëlle Lemasson & Laura Pettit)