Effect of closed areas on distribution of fish and epibenthos

Published source details Hoffmann E. & Dolmer P. (2000) Effect of closed areas on distribution of fish and epibenthos. ICES Journal of Marine Science, 57, 1310-1314.
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This study is summarised as evidence for the following.

	Action	Category
	Cease or prohibit all towed (mobile) fishing gear Action Link
	Cease or prohibit shellfish dredging Action Link
	Cease or prohibit mobile fishing gears that catch bottom (demersal) species and are dragged across the seafloor Action Link

Cease or prohibit all towed (mobile) fishing gear

A replicated, site comparison study in 1997 of 17 sites in the Limfjord, northern Denmark (Hoffmann & Dolmer 2000) found that ceasing towed gear fishing in an area for nine years had mixed effects on invertebrate community composition. Sites in the northern part of the area closed to towed gear had different invertebrate composition to adjacent northern fished sites, but sites in the southern part of the closed area had similar assemblages to adjacent southern fished sites (community data were presented as graphical analyses and statistical model results). Within the closed area, northern sites also had different composition to southern sites. Authors suggest towed gears might not have been the cause of the observed changes in invertebrate and fish compositions prior to the closure. A 40 km² area was closed to towed gears (static gears allowed) in 1988 following changes in invertebrate and fish assemblages. In September 1997, divers identified and counted sessile invertebrates at 17 sites (ten 0.24 m² quadrats/site) across four areas: northern fished area (four sites), northern closed area (five sites), southern closed area (four sites), and southern fished area (four sites).

(Summarised by: Anaëlle Lemasson)
Cease or prohibit shellfish dredging

A before-and-after, site comparison study in 1981–1998 of a fjord in the North Sea, Denmark (Hoffmann & Dolmer 2000) reported that prohibiting all towed fishing gears (mainly mussel dredges) in an area had no effect on the abundance and species richness of bottom-dwelling fish in the following 10 years, and compared to open areas. Data were not statistically tested. In trawl surveys, fish abundance (closed: 0–13 kg/30 min, open: 0–31 kg/30 min) and number of species (closed: 4–11, open: 1–9) varied between years but no effect of the closure was detected in either area. In set net and trap samples, catch rates were higher in the fished area (closed: 37–486 g/fishing unit, fished: 132–915 g/fishing unit) but there was no difference in the number of species (closed: 3–8, fished: 4–8). In 1988, a 40 km² mussel Mytilus edulis fishing ground in the Limfjord was closed to all towed fishing gears (to prohibit mussel dredging as the only towed gears in use) and only static fishing gears allowed. Fish data was collected by two methods: annual trawl surveys from 1981–1998 in August/September at two stations inside and two just outside the closed area; and in 1995, 1996 and 1997, experimental fishing with fixed set nets (48 deployments) and eel traps (38 deployments) at three locations inside and three outside the closed area. Catch rates and number of species were recorded. No fish species groups (other than demersal) or individual species were specified.

(Summarised by: Natasha Taylor)
Cease or prohibit mobile fishing gears that catch bottom (demersal) species and are dragged across the seafloor

A before-and-after, site comparison study in 1981–1998 of a fjord in the North Sea, Denmark (Hoffmann & Dolmer 2000) reported that prohibiting all towed bottom fishing gears in an area had no effect on the abundance and species richness of bottom-dwelling fish in the following 10 years, and compared to open areas. Data were not statistically tested. In trawl surveys, fish abundance (closed: 0–13 kg/30 min, open: 0–31 kg/30 min) and number of species (closed: 4–11, open: 1–9) varied between years but no effect of the closure was detected in either area. In set net and trap samples, catch rates were higher in the fished area (closed: 37–486 g/fishing unit, fished: 132–915 g/fishing unit) but there was no difference in the number of species (closed: 3–8, fished: 4–8). In 1988, a 40 km² fishing area in the Limfjord (previously fished commercially using poundnets, trawls – types unspecified – but most recently and extensively by mussel dredges) was closed to all towed fishing gears (in practice however the ban was focussed on stopping mussel dredging as little or no other towed gears were being used, static gears allowed). Fish data was collected by two methods: annual trawl surveys from 1981–1998 in August/September at two stations inside and two just outside the closed area; and in 1995, 1996 and 1997, experimental fishing with fixed set nets (48 deployments) and eel traps (38 deployments) at three locations inside and three outside the closed area. Catch rates and number of species were recorded. No fish species groups (other than demersal) or individual species were specified.

(Summarised by: Natasha Taylor)