Using tagging experiments to evaluate the potential of closed areas in protecting migratory Atlantic cod (Gadus morhua)

Published source details Schopka S.A., Solmundsson J., Ragnarsson S.A. & Thorsteinsson V. (2010) Using tagging experiments to evaluate the potential of closed areas in protecting migratory Atlantic cod (Gadus morhua). ICES Journal of Marine Science, 67, 1024-1035.
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This study is summarised as evidence for the following.

	Action	Category
	Cease or prohibit all commercial fishing Action Link

Cease or prohibit all commercial fishing

A replicated, controlled study in 1994–1995 of five areas of seabed in the Greenland Sea, off northwest Iceland (Schopka et al. 2010) reported that prohibiting all or some commercial fishing in marine protected areas and other areas closed to trawling, provided more protection from fishing for immature cod Gadus morhua, whose movement patterns indicate they are relatively stationary, but not for the migratory adults. The spatial distribution of recaptured cod over time was similar for all sites and tagging years, and there were no differences between cod tagged inside protected areas compared to outside (data reported graphically). However, there were clear seasonal and size-based differences over time, and the proportion of small cod recaptured at sizes <55 cm was lower for the area with the highest level of protection from fishing (4–9%) than most of the fished areas (7%, 21% and 25%), and the other marine protected area (15%). In addition, for small cod but not large cod, distance from areas of higher fishing intensity may also have influenced recapture patterns. Tagging surveys took place within five areas in July 1994 and June 1995 using two types of conventional tags. A total of 5,173 small cod (40–54 cm) were tagged in five areas: a marine protected area closed permanently to commercial fishing since 1993 (1,687 cod); a protected area closed to otter trawling and longlining since 1993, but open to a seasonal fishery (Oct-Mar) since 1997 (572 cod); two nearby inshore areas closed to trawling (1,916 cod); and one nearby area with no fishing restrictions (998 cod). Data on cod recaptures were analysed from a subset (224, anchor tags only) of the 719 (14%) tag returns made by fishers to the Marine Research Institute from 1994–2000. Most recaptured fish (78–94%, depending on tagging area) were caught in the first 3 years after tagging.

(Summarised by: Natasha Taylor)