COMMISSION OF THE EUROPEAN COMMUNITIES 
Brussels, 05.05.1995 
COM(95) 40 final 
COMMUNICATION FROM THE COMMISSION TO THE COUNCIL 
EVALUATION OF THE BIOLOGICAL IMPACT OF FISHERIES 
1. Background 
The following declaration was made at the meeting of the Council of Fisheries Ministers of 
the European Union of December 1993: 
"The Commission and the Council confirm the need to secure rational 
and responsible exploitation of marine living resources on a sustainable 
basis taking into account implications on the marine ecosystem of 
fishing in general and industrial fishing in particular and the need to 
develop objectives and priorities for future work within the Common 
Fisheries Policy. 
In this context, the Commission will establish a working group of 
marine ecologists and fishery biologists to define ways and means to 
improve the quality and the range of data used as a basis for fisheries 
management, incuding by-catch and discard data, and descriptions of 
the effects of various fishing gears on juvenile fish, non-commercial fish 
species, sea-bed biota, seabirds and small cetaceans and to make a list 
of priority subjects" 
Following this declaration, the Commission established a Working Group which met 
at the Danish Institute for Fisheries and Marine Research, Charlottenlund, Denmark 
in the period 6-10 May 1994. 
The Working Group was given the following terms of reference : 
1. Define the data base(s) required to quantitatively estimate the impact of 
fisheries on all relevant biota and to estimate the effect of all relevant 
biota on fisheries. 
2. Indicate the current status of the required data base(s) and, in particular, 
indicate areas in which data are not available or where augmentation of 
existing data is required. 
3. Define priority areas for study 
4. Report the proceedings of the meeting to the Commission. 
The proceedings of the Working Group have been circulated as a Commission Staff 
Working Paper entitled 
"Report on the Meeting on the Data Base for Evaluation of Biological Impact of 
Fisheries - Charlottenlund, Denmark, 6-10 May, 1994" SEC(94)1453, Brussels 
07.09.94 
The present document summarises the contents of the scientific report and indicates 
possible future developments. 
2. Summary of the Scientific Report 
2.1. Scope of the discussions 
The group recognised that the greatest ecological impact of fisheries on the marine 
ecosystem is upon the target species for these fisheries. However, the means by which 
these effects may be quantified is already well understood and methods for doing so 
are currently implemented by a number of international organisations (e.g.ICES) in 
their routine assessments of the state of exploitation of fish stocks. Therefore, the 
efforts of the group were focussed on the effects of fisheries on non-target biota and 
the effects of non-target biota on fisheries. 
Discussion was confined to groups of biota which have been directly identified in 
public debate i.e. fish, birds, mammals and benthos (organisms which live on or 
under the sea-bed). 
No consideration was given to possible impacts of mariculture or stock enhancement 
programmes. 
2.2. Ecosystem effects of fisheries 
The Working Group considered the interactions between fisheries and four groups of 
organisms : 
- Fish 
- Birds 
- Mammals 
- Benthos 
The Group indicated cases of direct removals of organisms by fisheries, the effects 
of fisheries on food availability and habitat modifications brought about by fisheries. 
The Group also mentioned a number of other interrelationships between fisheries and 
various biota. 
2.2.1. Direct Removal of Organisms bv Fisheries 
The role of fisheries is to directly remove fish, shellfish etc. of various species from 
their respective populations. At present, for many species, removal rates are excessive 
leading to yields less than those otherwise obtainable or even to depletion of stocks 
to levels at which self-replenishment by reproduction is endangered. In addition, 
removal over a period of years of fish within a specific size range may affect the 
genetic make-up of fish stocks. 
Birds, mammals and benthic organisms are also removed from their respective 
populations as a result of fishing activity. Birds, mammals and benthic organisms are 
caught and killed, usually accidentally, in fishing gears and benthic organisms may 
be crushed by the passage of fishing gears over the seabed. Birds and mammals are. 
known to become entangled in discarded fishing gear. 
2.2.2. Effects on food availability 
Removals of fish from one stock can be expected to have complex consequences for 
its predators, competitors and prey. Many of the latter are other fish species which 
are themselves exploited by fisheries. In addition, in certain instances, non-fish 
species may also be affected. The nature and magnitude of the consequences will 
depend upon the respective positions of the respective interacting elements in the food 
web and upon the "rules" which determine the nature of the interactions both among 
themselves and with fisheries. 
The consequences of these multispecies interactions manifest themselves in a variety 
of ways. Breeding colonies of birds and mammals may be affected by fisheries 
competing for the species on which they depend. Depletion in food availablity may 
result in reduction, in breeding success of birds and mammals. Changes in the 
availability of a particular prey species may cause predatory fish species to redirect 
their prédation to other species and thereby increase the mortality rate of the latter. 
Fisheries may also provide extra food for certain organisms. Discards and offal 
produced during commercial fishing operations provide for scavenging birds a food 
supply which would not otherwise be available. Various species of fish may also feed 
upon discards and offal. Inter-tidal harvesting of shellfish may expose otherwise 
unavailable food for birds. Some benthic animals such as starfish and hermit crabs 
are relatively immune to damage from trawls etc and exploit other organisms which 
have been exposed or damaged or killed by the passage of fishing gear. 
2.2.3. Habitat modifications 
Some types of benthic organisms, both flora and fauna, provide sites for development 
of eggs larvae and juveniles of organisms of various types and damage to benthos of 
this type may have disadvantageous ecological effects. Some benthic organisms form 
comunities which stabilise the sediments on which they grow and damage of these 
communities may lead to erosion of the underlying sediments. 
Marine mammals may receive fatal or debilitating injuries from boat traffic. In the 
case of seals, the bond between mother and young may be disrupted by disturbance 
caused by fishing and other marine activities. Marine mammals may also be affected 
by various sources of noise including the use of echo sounders. 
2.2.4. Other interrelationships 
Some types of animals can be perceived as having adverse effects on fisheries. Seals 
eat, wholly or partially, fish which have been caught in static fishing gears. Large 
populations of piscivorous marine mammals and birds can be perceived as major 
competitors of fisheries. Seals act as hosts to the reproductive life-stage of at least 
two parasites capable of infecting humans. The pre-reproductive phases of the 
parasites are found in various species of fish. Increased levels of mammal populations 
will result in increased infection of fish with consequent increased probability of 
infection of humans. 
2.2.5. Recommendations of the Working Group 
The Group made 23 recommendations which are recorded in the Annex to this report. 
2.3. Problems 
2.3.1. Existence of appropriate data 
Data allowing the estimation of the removal rates of fish species by fisheries are, in 
many instances, routinely collected by fisheries scientists and form the input for 
annual assessments of the state of fish stocks. However, it has always been the case 
that only the most commercially important species/stocks have been investigated and 
little or no information is available for many stocks of fish. In addition, in recent 
years, reduction in funds to support the data collection for routine fish stock 
assessment has led to considerable deterioration in the state of knowledge. 
Data allowing estimation of removal rates of other biota are generally lacking or 
incomplete or have been collected only with reference to specific scientific projects. 
2.3.2. Scale and compatabilitv of data 
The data currently available are often voluminous and are well suited to their original 
purpose. However, these data are difficult to synthesise in a common data base and 
hence are inappropriate for developing a more comprehensive understanding of the 
ecological effects of fisheries. 
The main problem in this respect is that data collected for investigation of a given 
problem are of a temporal and geographical scale which renders them inappropriate 
for investigation of other problems. For example, data for the assessment of the state 
of fish stocks are usually collected by quarter or by year for large geographical areas 
such as the North Sea. Such data are of little use in analysing the effects of possible 
depletion of food supplies in the immediate vicinity of a breeding colony of birds, 
established each year for only a few weeks or months. 
2.3.3. Choice of species or groups of species for investigation 
It seems unlikely that sufficient resources will ever be available to study everything 
of relevance. A choice of the area of study is therefore required. 
From a purely scientific viewpoint it might be desirable to study those species 
suspected of playing a dominant role within marine communities. On the other hand, 
managers may prefer a more problem-oriented approach in which study is directed 
towards species or communities which are particularly vulnerable or are of particular 
public interest. In either event, it is probable that the species studied will change as 
a result of increase in knowledge or change in public perception. 
2.3.4. Experimental approaches 
Whenever possible, and to separate natural and anthropogenic effects (including those 
of fisheries) on the ecosystem, direct experimentation is desirable. Experimentation 
of the effects of fisheries on benthos has already been undertaken. Similar 
experimentation on the effects of fisheries on other types of organisms may be more 
difficult to accomplish. 
2.3.5. Mathematical analyses 
Basically, two types of mathematical approach might be considered. The holistic 
approach attempts to quantify properties at ecosystem/community level and may be 
developed to indicate the way in which various indices of population complexity and 
interactions might change following imposition of fisheries management measures. 
The reductionist approach attempts to describe components of the system and their 
interrelationships and is appropriate for modelling specific interactions of various 
groups of species such as the effects of areal closures in the vicinity of bird colonies. 
Both approaches need to be further developed. 
2.3.6. Defining the concept of risk 
The formal scientific definition of risk incorporates concepts such as "loss of utility" 
and therefore is not readily comprehensible to laymen. In general, risk is often taken 
to mean the probability that "something bad will happen". However, this concept is 
open to very wide interpretation - it might mean the extinction of a species or the 
reduction of a population to below some minimum level. An agreed definition of risk 
is clearly required since it is against this that the appropriateness of possible 
management measures will be judged. 
3. Comments of the Commission 
From the report of the Working Group, two major points are evident : 
(i) Although it has a clear idea of the scope of work required in the future, the 
scientific community is not, at present and in general, able to supply responses 
to many of the questions which might be addressed to it. 
(ii) For the scientific community to be provided with the means by which it can 
respond to all probable questions will require a considerable effort in 
coordination and a very large budget (as yet unspecified) to establish and 
maintain mis capability. 
These statements should not be taken to mean that the scientists can do nothing at 
present. In a number of specific instances it appears that preliminary work has already 
taken place or that a sufficiently comprehensive réponse to particular problems might 
be provided. 
At present, however, there is considerable public concern on a number of possible 
problems. The Commission feels that top priority should be given to responding to 
these concerns. On this basis, and with a view to developing appropriate methods to 
control and monitor the biological impact of fisheries, work should in the immediate 
future be directed towards quantitative investigation of the following topics : 
(1) The effects of fishing on cetaceans, seals, reptiles and birds. 
(2) The direct and indirect effects of industrial fishing on birds and top-level predator 
fish species. 
(3) The direct and indirect effects of fishing on benthic communities. 
In the light of the recommendations of the Working Group, the work undertaken in 
these fields will focus on the acquisition and standardisation of data on the fate of the 
different species, on their abundance and mortality rates, on testing methods and 
assessment tools and on incorporation of such elements into existing or new models. 
Such work programmes should be internationaly coordinated and appropriately 
funded. The Commission believes that the International Commission for the 
Exploration of the Sea (ICES) is the most appropriate scientific organisation to play 
the central role in the coordination of such work in the north-east Atlantic and the 
Baltic and that the General Fisheries Council for the Mediterranean (GFCM) could 
perform a similar role for its appropriate area. The Commission will approach these 
organisations to seek their assistance. 
As the work develops, the Commission intends to make appropriate proposals to 
include the developed operational objectives and measures in Community fisheries 
legislation. 
An adequate budget will be required to support the research. The Commission 
envisages that Member States will be required to contribute to the budget as will third 
countries to the extent that the latter are involved in the research programmes. The 
Commission will investigate possibilities for obtaining support from the European 
Union. 
ANNEX : Recommendations of the Working Group 
The Working Group made 23 recommendations which are repeated below. 
Immediate problems 
1. Studies should be undertaken (a) to examine the utility of existing data sets for 
answering questions about the wider effects of fisheries and (b) to determine the 
extent to which existing data acquisition procedures might reasonably be modified 
to improve their usefulness. 
2. Initiatives to develop robust strategic modelling tools, to provide management 
advice on issues of concern should be encouraged. 
Ecosystem and community descriptors (emergent properties) 
3. The usefulness of these summary parameters should be explored by making 
comparative studies of size structure, biodiversity, trophic structure, 
stability/resilience and changes in energy flux on historic time series and between 
areas. 
4. To assist with placing these results in the context of fisheries effects, the fishing 
mortality by size components of the ecosystem should be evaluated. 
5. Empirical tests of the response of communities to changes in fishing pressure 
should be undertaken. 
6. The utility of the system descriptors should be explored by modelling the 
anticipated direction and magnitude of change under hypothetical fishing regimes. 
Data compatabilitv 
7. The development of databases at international level which allow access to data 
in disaggregated format as well as aggregation of data to common areas should 
be supported. Appropriate units for disaggregation would be ICES rectangle and 
month. 
Effects of fisheries on components of the ecosystem and interactions between 
components 
Fishing mortality and risk; the effect of direct removals 
8. Appropriate methods and data for estimating mortalities due to landings, discard 
and non-catch deaths should be developed for all taxa. 
9. All landed species should be recorded in EU logbooks. 
10. Estimates of the catchability (the proportion of the population caught by a unit of 
fishing effort) of standard survey gears should be developed for fish species of 
concern in order to estimate population abundance. 
11. Continue monitoring and improve the assessment of abundance, distribution and 
population structure of marine mammals and birds. 
12. Studies of trawl path mortalities and life history parameters should be acquired 
for benthic species. 
13. Where possible, time series or past data for all biota should be compiled. The 
priority for this would be on species perceived to be at risk from fishing and on 
populations of concern. 
14. The risk of fishing should be estimated for species of concern. This would 
require the estimation of the appropriate life history parameters and alternative 
sources of mortality. 
15. Population genetic studies should be conducted on species subject to intense size 
selection. 
16. New fisheries (e.g. for deep-water species) often have consequences for relatively 
unchanged ecosystems. Interactions between these fisheries and the system should 
be studied at an early stage of exploitation. 
Effects arising through food chain interactions 
17. Study the population structure, mobility and life history of small fish. Identify 
and quantify sources of energy required by these fish and the rates of their 
removal by predators as well as by fisheries. Data must be collected at local and 
region-wide scales. Develop models for predicting the impact of fisheries on the 
ecological role of these fish. 
18. Discards should be quantified in a standard fashion by species, size and temporal 
distribution and mode of production. 
19. Studies on the fate of discards and offal, particularly below the water surface, 
should be carried out. 
20. Develop existing multispecies models (such as MSVPÂ - Multispecies Virtual 
Population Analysis) to incorporate spatial considerations ang higher predators. 
Review available estimates of the diet of seabirds and marinemammals. Obtain 
estimates of removals by higher predators on a scale appropriate for multispecies 
models. 
21. Develop generalised modelling tools for assessing local scale interactions between 
biota and fisheries. Apply these to selected local problems. 
Effects on habitats 
22. Selected benthic communities (flora and fauna) should be monitored to assess the 
effects of fishing activity on resident communities and the recruitment of other 
biota. 
23. Characteristics of critical habitats for marine mammals and the behaviour of 
mammals under disturbed and undisturbed conditions should be determined. 
10 
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COM(95) 40 final 
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