Cormorant Management

The large increase in cormorant populations across Europe over the past 30 to 40 years has resulted in widespread conflicts with different fishery interests since the sites where cormorants choose to feed are often those most valued by recreational anglers, commercial fishermen or fish farmers. Where such conflicts occur, there may be a requirement for management action to alleviate the damage that the birds are doing, or might do, to the fish stocks at particular sites.

Management measures

There are numerous management measures that can be used to limit the interaction between cormorants and fish. They fall into four broad categories:

Techniques that scare cormorants away from a fishery, such as various audible and visual deterrents.
Measures that help to directly protect the fish by preventing cormorants from reaching them (e.g. using nets and overhead wires).
Measures that alter the availability of fish to cormorants by making a fishery less attractive as a foraging site (e.g. removing roosts or introducing artificial refuges for fish).
Shooting locally a small number of cormorants out of a flock to reinforce scaring at specific sites and to divert them to other feeeding sites.
Measures to reduce overall cormorant numbers in a wider region, by either preventing the establishment of new roosts or colonies, or more intensive shooting of birds or reducing their reproductive efficiency by various means (egg oiling etc.)

Legislation allows for exceptions

Although stakeholders are often free to apply non-lethal measures to protect fisheries or reduce cormorant impact, it should be remembered that cormorants are protected under the European Wild Birds Directive 79/409EEC, and additional cormorant protection legislation applies in most countries. This legislation allows exceptions to be made (technically, these are called derogations) to authorise the use of specific non-lethal or lethal measures where the birds are causing “serious damage” to a site, or there is a reasonable expectation that this will happen, or for the protection of flora and fauna, and where there are no other satisfactory solutions. The European Commission is developing guidance on Article 9 of the Birds Directive which relates to the use of derogations and interpretation of “serious damage”, and a link to the guidance document will be inserted on this platform after being finalized.

Complex conflicts

Cormorant-fishery conflicts are usually complex – they are seen in different ways by different stakeholders, and they affect a range of fishery sectors across a variety of aquatic habitats. Moreover, conflicts are also subject to change over time, partly because of the population dynamics of birds and fish, seasonal variations in other factors, particularly weather conditions, and the large-scale movements of the birds. Managing such conflicts is also complex and influenced by wide-ranging factors, making it impossible to provide specific recommendations for different fishery sectors or aquatic habitats, or to recommend a list of actions that could instantly ‘solve’ any particular ‘problem’.

Control measures

The efficacy of control measures – that is their capacity to produce an effect – will therefore depend on many factors, including a) whether birds are sedentary (remaining or living in one area) or migrating, b) the proximity of alternative foraging sites, c) the numbers of birds and food resources in the area, d) the features of specific sites, particularly the size or area of water, e) variations in cormorant numbers in particular areas, f) the type of fishery involved and its characteristics, and g) the size and nature of the fish populations at risk.

Cormorant Management Toolbox

Information on the large number of techniques that can be used to manage cormorant/fishery conflicts has recently been compiled as part of the INTERCAFE COST entitled “Conserving biodiversity: interdisciplinary initiative to reduce pan-European cormorant-fishery conflicts”. This information will be published as the “INTERCAFE Cormorant Management Toolbox – methods for reducing cormorant problems at European fisheries”. It is anticipated that the Toolbox will be become available on this platform.

The Toolbox aims to provide as comprehensive a list as possible of management options that might be applicable at different sites and, as well as detailed descriptions of the various techniques, including photographs and case studies. It describes and discusses both lethal and non-lethal techniques ranging from site-specific bird and fishery management tools to the issue of co-ordinated culling of cormorants for population control. Importantly, the Toolbox, recognises that management measures may need to be applied over very different temporal and spatial scales, and discusses the main advantages and constraints surrounding their use. For each main technique, or group of similar ones, the descriptive text is followed by a general evaluation in terms of a tool’s: efficacy, practicability, cost and acceptability. Thus, the Toolbox seeks to provide as objective an overview as possible of the effectiveness of specific cormorant management techniques.

However, the Toolbox also stresses that the most appropriate deterrents or mitigation techniques at any site will require careful consideration by individual stakeholders, and that this may include decisions on whether or not efforts need to be co-ordinated over a wider area. Further, the Toolbox recommends that those faced with addressing conflicts should experiment with different techniques and be creative in devising mitigation programmes to best suit their individual needs.