ANNEX 6
STOCKING PRACTICES IN EIFAC: AN INITIAL APPRAISAL

J. Banks
National Rivers Authority, Thames Region
Kings Meadow Road, Reading,
Berkshire RG1 8DQ, UK

Introduction:

One of the agreed tasks for the EIFAC Working Party on the effectiveness of stocking was to attempt to discover the extent and purpose of the type of stocking currently being undertaken. The Working Party circulated a questionnaire to national correspondents in 1992 which asked for information on species, life stage used and purpose for which stocking was undertaken. The proforma questionnaire was based on the stocking purposes as defined in EIFAC Technical Paper T42, Report of the Symposium on Stock Enhancement in the Management of Freshwater Fisheries (1982). These are defined in Appendix 1. Finally respondents were asked to give estimates of the numbers stocked in each life stage and an indication of whether stocking for each of the different purposes was carried out regularly, occasionally, never or no information. In presenting the data the last two categories have been combined.

Results and Discussion.

The list of countries responding is given in Table 1.

The returns recorded the stocking of 46 species and one hybrid. The most frequently occurring are list by species and country in Table 2, together with the years to which the data refer where these have been provided. The remainder of the species together with some additional points are listed as footnotes to the table. Whilst it is no surprise that the most obvious species of commercial importance, salmonids, coregonids and carp are widely stocked there is a great variety of other species deliberately stocked. The detailed analysis by species and stocking purpose is not complete but Tables 3, 4 and 5 present data for Salmo salar, Coregonus lavaretus and Salvelinus alpinus. Each life stage stocked is listed together with the estimates of numbers and frequency from the contributing countries regular stocking (a), occasionally, (b) never (c) or no information. For salmon stocking was reported by nine countries. Compensation, maintenance, enhancement, re-population and conservation are the principal stocking purposes. Ova are used much less than fry, parr and smolt. Norway is alone in reporting the stocking of large numbers of larvae.

The stocking of Coregonus lavaretus is reported by eight countries (nine when joint stocking of Lake Geneva between France and Switzerland are included). Compensation, maintenance, enhancement and conservation are once again important but instances of stocking for put-grow and-take, re-population, diversity and niche filling are all reported by more than one country. Fry are the most used stocking material. Finland is the most active country in stocking this species using mostly fry. Poland is also active but uses principally ova and hatchlings younger than fry.

Arctic char, (Salvelinus alpinus), have been reported by six countries; again there is also joint stocking between France and Switzerland in Lake Geneva. No details on the numbers or purposes for stocking this species are available for Germany or the United Kingdom. For Finland, Sweden, Norway and France there is a wide variety of life stages in use and purposes for stocking, although the importance of char as a sport fish is reflected in instances of stocking of larger fish including some of takeable size.

It is intended to extend this preliminary analysis to some other species and also to consider the return in terms of some of the major stocking purposes. some countries with significant stocking programmes have not yet responded and it is hoped that additional returns will make it possible to present a more comprehensive picture in the future. The data received so far demonstrate the widespread importance of stocking as a fishery activity in EIFAC countries.

TABLE 1 REPLIES TO QUESTIONNAIRE ON CURRENT STOCKING PRACTICES

* All data referred to the period before partition.

TABLE 2. STOCKING INDICATIONS BY SPECIES AND COUNTRY

1 Includes landlocked salmon and Baltic salmon.

2 Includes brown trout, sea trout, migratory trout and lake trout.

3 Includes C. oxyrhynchus (Denmark) and C. fera (France).

4 Includes Carassius var. auratus (Hungary).

5 Czechoslovakia additional species - Aristicthys nobilis, Scardinius erythrophthalmus, Vimba vimba.

6 Finland additional species - Leuciscus idus.

7 Germany additional species - Scardinius erythropthalmus, Leucaspius delineatus,Phoxinus phoxinus, Alburnus alburnus, Noemacheilus barbatulus, Cottus gobio, Gobio gobio, Rhodeus sericeus amarus, Pungitius pungitius, Gasterosteus aculeatus, Arichthys nobilis.

8 Hungary additional species - Acipenser ruthenus.

9 Poland additional species - Scardinius erythropthalmus, Leucisus idus.

10 Sweden additional species - Salvelinus namaycush × fontinalis, Gasterosteus aculeatus.

TABLE 3 OBJECTIVES FOR STOCKING ESTIMATES OF FREQUENCY & QUANTITIES STOCKED. MIGRATORY SALMON (S. SALAR) INCLUDING BALTIC SALMON

TABLE 4 OBJECTIVES FOR STOCKING, ESTIMATES OF FREQUENCY & QUANTITIES STOCKED. WHITEFISH (COREGONUS LAVARETUS)

TABLE 5 OBJECTIVES FOR STOCKING, ESTIMATES OF FREQUENCY & QUANTITIES STOCKED. ARCTIC CHAR (S. ALPINUS)

APPENDIX 1

The purposes for stocking

1. Compensation: To provide for a phase in the life cycle suppressed by human intervention (the stock would disappear without stocking)

2. Maintenance: To sustain stocks in face of environmental or fishing pressures which prevent their reaching natural carrying capacity.

3. Enhancement: To keep the production of stocks above the level that would be naturally sustained in the presence of heavy exploitation.

4. Put-and-take: To provide catchable-sized fish for rapid exploitation by anglers (minimal environmental input).

5. Put-grow-and-take: To provide fish that must grow to a catchable size before exploited by anglers (some environmental input).

6. Re-population: Establishment of a unit stock of community in waters from which it has previously been eliminated.

7. Increase diversity: To augment the range of species available to a fishery.

8. Niche filling: To provide stocks to utilize a trophic or spatial resource which is perceived as unexploited.

9. Forage: To provide a prey species to enhance the production of angling or commercially exploited species.

10. Pest control: To provide organisms to control flora or fauna perceived as unfavourable to man.

11. Environmental Improvement: To provide organisms expected to favourably modify the system.

12. Conservation: To maintain genetic diversity so as to conserve endangered species or stocks.