Study

Development of fish communities in lakes after biomanipulation

  • Published source details Meijer M.-L., Lammens E.H.R.R., Raat A.J.P., Klein Breteler J.G.P. & Grimm M.P. (1995) Development of fish communities in lakes after biomanipulation. Aquatic Ecology, 29, 91-101.

Summary

Study 1

In order to restore lakes affected by eutrophication in the Netherlands, as a follow-up to reducing nutrient loading (primarily due to agricultural run-off), biomanipulation (i.e. fish stock reduction, and sometimes introduction of native piscivorous fish) has been undertaken. In three small shallow lakes (Noorddiep, Bleiswijkse Zoom and Zwemlust) nutrient reduction measures resulted in clear water and re-establishment of submerged macrophytes. However, fish communities developed differently. Here, development of fish communities at Bleiswijkse Zoom after initial restoration efforts, are presented.

Study site: Lake Bleiswijkse Zoom in Zuid Holland, western Netherlands, comprises three interconnected lakes (total length 2 km; area 14.4 ha; average depth 1.1 m). Subsequent to carp Cyprinus carpio stocking (1973-1974 and 1980-1982), during 1980-1987 the lake developed high nutrient concentrations and turbid water, and submerged macrophytes disappeared.

After initial restoration (nutrient reduction) in 1988/1989, water transparency greatly increased, algae were much reduced and macrophytes re-established (for further details see: www.www.conservationevidence.com/ViewEntry.asp?ID=1426).

Fish biomanipulation: The waterbody was divided into two parts by a dam (with a gauze covered opening allowing exchange of water, but not of fish). From one part fish were removed: about 80% of the fish stock removed in spring 1987, and pikeperch Stizostedion lucioperca fingerlings (with low subsequent survival) added in an attempt to regulate planktivorous fishes. Pike Esox lucius (from 1988 onwards) were added as the population was almost zero due to the previously turbid water conditions. The other part of the lake served as a control.

Fish monitoring: In both sections fish were monitored (up to 1992 presented here). The density of each species was estimated by mark-recapture, and density was converted to biomass. Small cyprinids could not be marked, thus their estimated biomass was based on the seine-net catches.

Before removal in 1987, the fish stock was about 760 kg/ha (>90% bream Abramis brama and carp). After reduction to c.100 kg/ha, bream and carp biomass increased to c. 250 kg/ha in 1991, despite further reductions in 1988 (90 kg/ha removed) and 1989 (100 kg/ha removed); roach Rutilus rutilus, rudd Scardinius erythrophthalmus and perch Perca fluviatilis also increased in density. Compared to the control, fish biomass was only a little lower, but in the treatment area there were more species. Bream and carp declined and were partly replaced by roach and perch.

The biomass of piscivorous fish did not change, but pike-perch was replaced by pike and perch. Pike increased (by growth, natural reproduction and stocking) from almost zero to 20 kg/ha and piscivorous perch from zero to 17 kg/ha. Despite this, pike and perch did not control young-of-the-year cyprinids, which reached a much higher biomass than in the control area; recruitment was similar or higher in the clear water areas with macrophytes than in the turbid water before restoration.

Study 2

In order to restore lakes affected by eutrophication in the Netherlands, as a follow-up to reducing nutrient loading (primarily due to agricultural run-off), major fish stock reduction and introduction of young pike Esox lucius (pike having declined or extirpated due to poor water conditions) has sometimes been undertaken. In three small shallow lakes (Noorddiep, Bleiswijkse Zoom and Zwemlust) nutrient reduction measures resulted in a clear water and re-establishment of submerged macrophytes. Here, development of fish communities at Noorddiep after initial restoration, are presented.

Study site: Noorddiep (average depth 1.5m), prior to nutrient loading reduction, had high nutrient concentrations; the Secchi disc transparency of the water was low (0.2-0.3 m) and algal biomass was high.

Fish stock manipulation: The lake was divided into two: from one part (surface area 4.5.ha) fish were removed, the other part served as a no fish stock reduction 'control' (11.1 ha;). Exchange of water (via a gauze-covered barrier) was possible between the sections, but not of fish. In March 1988, 545 kg/ha of fish were removed and a further 39 kg/ha in November (i.e. about 80% of the total fish stock); no pike were added as a reasonable population was present.

Monitoring: After reduction, biomass and fish composition were monitored during five years. The density of fish was estimated by mark-and-recapture, and density was converted to biomass. Young-of-the-year cyprinids could not be marked, thus their estimated biomass was based on seine-net catches.

Macrophytes: Macrophyte cover was determined by a survey in the summer.

In the first year after fish removal, the water became transparent to the lake bottom, macrophyte cover increased from 30% to 65% and the fish community became more diverse. Bream Abramis brama and carp Cyprinus carpio remained at a reduced stable level c. 100 kg/ha. Roach and perch increased from c. 50-75 kg/ha to 100-150 kg/ha in 1991-1992. Compared with the control section, total fish biomass decreased by about 66%. Pike-perch Stizostedion lucioperca was replaced by pike (biomass increasing from c. 15 to 30 kg/ha) and piscivorous perch (6 to 20 kg/ha).

Total biomass of planktivorous young of the year in both lake sections was similar, but composition changed: perch and roach increased from 10% (roach and perch equally present) in the control to 84% in the removal section (70% O+ perch, 14% O+ roach); total planktivorous fish stock was lower in the removal section.


Study 3

In order to restore lakes affected by eutrophication in the Netherlands, as a follow-up to reducing nutrient loading (primarily due to agricultural run-off), major fish stock reduction and introduction of young pike Esox lucius (pike having declined or extirpated due to poor water conditions) has sometimes been undertaken. In three small shallow lakes (Noorddiep, Bleiswijkse Zoom and Zwemlust) nutrient reduction measures resulted in a clear water and re-establishment of submerged macrophytes. Here, development of fish communities at Zwemlust after initial restoration, are presented.

Study site: Zwemlust (surface area 1.5 ha; average depth 2 m), prior to nutrient loading reduction, had high nutrient concentrations; Secchi disc transparency of the water was low (0.2-0.3 m) and algal biomass high.

Fish stock manipulation:In 1987, the total fish stock (1,000 kg/ha) was removed from the lake (mostly bream, >90%). In 1987, 140 adult rudd Scardinius erythrophtalmus and 1,600 O+ (yearling) pike were added. In 1988, a further 1,500 O+ pike were added, and in 1989, 169 adult roach Rutilius rutilus.

Monitoring: Fish biomass and fish composition were monitored to 1992. The density of fish was estimated by mark-and-recapture, and density was converted to biomass. Young-of-the-year cyprinids could not be marked, thus their estimated biomass was based on seine-net catches.

Macrophytes: Macrophyte cover was determined by a survey in the summer.

In the first year after fish removal the water became clear; macrophyte cover increased from 5% in 1987 to 80% thereafter (Nuttall's pondweed Elodea nutallii dominated initially, replaced by rigid hornwort Ceratophyllum demersum in later years).

The pike biomass increased to 16 kg/ha in the first year to approximately 30/kg ha thereafter i.e. approaching the 38 kg/ha prior to removal. Before manipulation, the pike population was dominated by older individuals; in the first two years after manipulation, the pike were of small size. Biomass of O+ pike decreased dramatically and the average length of the pike increased to 1992. The rudd population increased from 7 kg/ha in 1987 to 300-400 kg/ha in 1992.


Note: If using or referring to this published study, please read and quote the original paper, this can be viewed at:
http://www.springerlink.com/content/p2447257521443l1/fulltext.pdf

Output references
What Works 2021 cover

What Works in Conservation

What Works in Conservation provides expert assessments of the effectiveness of actions, based on summarised evidence, in synopses. Subjects covered so far include amphibians, birds, mammals, forests, peatland and control of freshwater invasive species. More are in progress.

More about What Works in Conservation

Download free PDF or purchase
The Conservation Evidence Journal

The Conservation Evidence Journal

An online, free to publish in, open-access journal publishing results from research and projects that test the effectiveness of conservation actions.

Read the latest volume: Volume 21

Go to the CE Journal

Discover more on our blog

Our blog contains the latest news and updates from the Conservation Evidence team, the Conservation Evidence Journal, and our global partners in evidence-based conservation.


Who uses Conservation Evidence?

Meet some of the evidence champions

Endangered Landscape ProgrammeRed List Champion - Arc Kent Wildlife Trust The Rufford Foundation Save the Frogs - Ghana Mauritian Wildlife Supporting Conservation Leaders
Sustainability Dashboard National Biodiversity Network Frog Life The international journey of Conservation - Oryx Cool Farm Alliance UNEP AWFA Bat Conservation InternationalPeople trust for endangered species Vincet Wildlife Trust