Individual study: Review of fish control methods for the great crested newt species action plan. Countryside Council for Wales Contract Science Report No 476
Watson W.R.C. (2002) Review of fish control methods for the great crested newt species action plan. Countryside Council for Wales Contract Science Report No 476. Countryside Council for Wales report.
This study is summarised as evidence for the intervention(s) shown on the right. The icon shows which synopsis it is relevant to.
Remove or control fish by catching
A before-and-after study in 1992–2000 at two sites in England, UK (Watson 2002) found that fish control by catching and treatment with rotenone had no significant effect on great crested newt Triturus cristatus populations. At one site, there was no significant increase in great crested newt numbers in the three years following fish removal, which the authors considered to have been only partially effective. At the second site, although great crested newt adults and eggs were recorded following fish control, no larvae were seen. Over 2,000 sticklebacks were removed from the pond, but they were observed again a few years after treatment. Electro-fishing and treatment with rotenone were undertaken at a forest pond in 1996. At the other site, a pond (600 m2) was netted twice to remove trout in autumn 1997. Great crested newts were surveyed at that site in 1992–2000.
Remove or control fish by drying out ponds
A review of fish control programmes from 1992 to 2001 at a pond in England, Australia and Alabama, USA (Watson 2002) found that breeding success increased for two frog species following pond draining. At the Australian site, green and golden bell frogs Litoria aurea bred successfully the year after a reduction of non-native plague minnows Gambusia holbrooki. In Alabama, breeding success of dusky gopher frogs Rana capito sevosa increased following draining and rotenone treatment (egg masses: 10 to 150). In England, one great crested newt Triturus cristatus colonized a pond in the first year following elimination of sticklebacks (Gasterosteidae). A pond (690 m2) in England was drained down to 20 cm and bottom sediments agitated to release gases in 2001. A pond on Kooragang Island, Australia was drained in 1997. A pond in Alabama was drained, fish removed and then rotenone added in 1992.
Remove or control fish using rotenone
A review of fish control programmes from 1992 to 1998 of two ponds in England, UK and one in Australia and Alabama, USA (Watson 2002) found that breeding success increased for dusky gopher frogs Rana sevosa, green and golden bell frogs Litoria aurea, great crested newts Triturus cristatus and smooth newts Lissotriton vulgaris. Egg masses of the gopher frogs increased from 10 to 150. At one site in England both newt species re-colonized and reproduced in a treated pond in the first year following stickleback (Gasterosteidae) elimination (2,000–3,000 fish). At the second site in England, although great crested newt adults and eggs were recorded following stickleback removal, no larvae were seen. Fish were recorded at two of the sites within a few years of treatment. At the first English site, rotenone (5%) was applied, dredge netting undertaken and aquatic plants introduced to an isolated concrete pond (104 m2) in May 1992. At the other site, rotenone and electrofishing were undertaken in 1996. In Alabama a pond was drained, fish removed and rotenone added in 1992. On Kooragang Island, Australia, rotenone was added to a pond to remove non-native plague minnows Gambusia holbrooki in 1998.