The case for no-take zones

This article was first published in Fishing News, 12 March 1999

by Simon Jennings of the Cefas Lowestoft Laboratory

The plaice box was set up in 1989 to protect juvenile plaice by restricting beam trawling in 38,000 sq km of the North Sea. An ICES study shows that the box reduces mortality of younger fish.

No-take zones have been proposed as an alternative management tool in several European fisheries.The 1997 Intermediate Ministerial Meeting on the Integration of Fisheries and Environmental Issues in Bergen highlighted cases where protected areas should be considered as a management option, and various fishing and conservation interests have argued the case for no-take zones.

But what is the scientific evidence for the potential benefits, and otherwise, of management systems based on no-take zones? Can they be expected to improve the yields of target species, simplify management and ensure sustainability? Are they a real alternative to a system based on TACs and quotas? With growing interest in the use of no-take zones, practical experience and scientific studies are starting to provide a good indication of what can be achieved.

Many small no-take zones have been set-up around the world. They range in size from a fraction of a square km to hundreds of square km, but are usually far smaller than the no-take zones of thousands of km squared and more that have been proposed for European waters by the Marine Conservation Society and other groups.

The impetus for the establishment of no-take zones has come from countries such as Australia, New Zealand and Seychelles where they have been in use since the 1970s, and are a key part of Government strategies for conservation, marine environmental management and promoting ecotourism.

No-take zones have many conservation benefits, such as protecting species that have been overfished and protecting vulnerable habitats such as corals. They may also benefit fisheries through the ‘spillover’ of fish, eggs and larvae to fished areas and hence provide some insurance against fishery collapse. Such benefits do not apply to all fish all of the time. Whether they are realised depends on the biology of the stock and its movement in and out of the reserve at different times in its life cycle. It also depends on the response of fishermen.

No-take zones in European waters
For no-take zones to work as a fishery management tool they have to reduce overall fishing mortality. Several fisheries boxes are already in use in Europe, such as the Norway pout, mackerel and plaice boxes or boxes that protect spawning herring. Since fishing is not totally prohibited, these boxes are not true no-take zones and should correctly be called ‘protected areas’ since they may be closed only seasonally, protect only some fish stocks and restrict only certain types of vessels or gears. However, they do allow us to look at the probable effects of no-take zones as a management tool.

The various boxes where fishing restrictions exist in EU waters

Protection of juvenile fish
The plaice box was set-up in 1989. It protects an area where juvenile plaice tend to gather by restricting beam trawling in 38,000 sq km of the North Sea. The biology of North Sea plaice is better known than that of most stocks and the International Council for the Exploration of the Seas (ICES) has studied the effects of the plaice box in detail.

Its study shows that the box provides fishery benefits by reducing mortality of younger fish and hence boosting recruitment to the adult stock. Young plaice do not migrate as widely as the adults and tend to stay within the box where they are protected from fishing. Adult plaice, on the other hand, move more widely and are accessible to fishermen.

Closure of the whole box to all vessels on a year round basis would provide even greater fisheries benefits than the present more limited closure because many young plaice currently die when discarded from vessels such as shrimpers that are allowed to enter the box. In June, this year, ICES will re-evaluate the utility of the plaice box.

Table 1. Effect of the plaice box

Predicted effects of different management options on the spawning stock biomass and landings of North Sea plaice. Values given as percentage change relative to the quarters 2 and 3 closure that was in place during 1994 (source: ICES)

Closure of spawning grounds
It is often said that closure of spawning grounds will benefit fisheries. While this is the case for stocks such as herring it is not always true. The Trevose Head area in the eastern Celtic Sea is an important spawning ground for sole, plaice, bass and other species.

At the suggestion of the National Federation of Fishermen’s Organisations a careful study of the possible benefits of fishing restrictions has been done by Cefas staff. This concluded that there would be no fisheries benefits. At first sight this may seem surprising. The reason is that the quota that was once taken on the spawning grounds would simply be caught elsewhere.

When will closed areas help?
In countries where true no-take zones are already popular, their success as a fisheries management tool depends on two factors: first, the life history of the stock; and second, the extent to which fishing is controlled outside the no-take zone. The key point is that closing a large area to fishing will sometimes be of value, but because of varying circumstances it will not provide benefits to all stocks all of the time.

Looking again to the North Sea, where a protected area for plaice has already been shown to be a useful management tool, the same closure would probably have no impact on the cod fishery. Indeed, ICES has already simulated the effects of closing each of four areas that approximate to 25% of the North Sea on the cod fishery.

In this case, closure of any one of these areas would provide no detectable fishery benefit. This is because the cod is such a mobile wide-ranging fish and would move in and out of any closed area; and because fishing effort in the closed area would be diverted elsewhere so that cod mortality would be just as high.

Given that no-take zones can be a very useful fisheries management tool, but do not work for all species, all of the time, where does this leave us? The value of no-take zones as a management tool really has to be considered on a case by case basis and will depend both on how the fish behave and on the fishermen’s response.

To be effective a no-take zone must reduce fishing mortality. No single design of no-take zone will work for all stocks all of the time. And although they may help conservation, no-take zones will not help to allocate catches between fleets and so they are not an alternative to quotas. The benefits which no-take zones may provide for fisheries really need to be compared with the benefits offered by other management options.

Protecting the marine environment
Moving on from fisheries management and the revision of the CFP then, there is little doubt that no-take zones will have other potentially important roles in marine environmental management. They are, for example, one of the most effective ways of protecting vulnerable habitats, such as marl beds, from the effects of fishing disturbance.

No-take zones could also be used to protect species of conservation concern, such as the common skate, from fishing. In this case the success or failure of the no-take zone would depend on the biology of the species to be conserved and whether or not the no-take zone could reduce the rate they were killed by fishing.