Hostname: page-component-78c5997874-fbnjt Total loading time: 0 Render date: 2024-11-10T07:37:33.114Z Has data issue: false hasContentIssue false
  • English
  • Français

Abundance, seasonality and size of Atlantic salmon smolts entrained on power station intake screens in the Severn Estuary

Published online by Cambridge University Press:  11 May 2009

P.N. Claridge  and
I.C. Potter
Get access Rights & Permissions [Opens in a new window]

Abstract

Atlantic salmon smolts were sampled from the intake screens of the Oldbury power station in the inner Severn Estuary at weekly intervals between July 1972 and June 1977. These catches, and those taken over nearly three years from the nearby Berkeley power station, demonstrated that the abundance of smolts in the estuary peaked in autumn (October) and, to a far greater extent, in spring (April and May). However, small numbers of smolts were occasionally found in all other months of the year except July. Standard length-frequency distributions of smolts remained unimodal throughout the year. Lengths ranged from 76 to 187 mm, mean 130·2 ±1·87 mm (95% CL), and wet weights ranged from 5·4 to 68·0 g, mean 26·9 ±1·17 g. The mean monthly standard length of smolts increased slightly between the autumn of one year and the spring/early summer of the next year, suggesting that, on average, the former were six months younger than the latter. The condition factor was significantly greater in autumn (1·40) than in spring (1·23). It is estimated that the total number of salmon smolts entrained annually on the screens at Oldbury during the five years ranged from 92 to 791, with a mean of 405. Total estimated numbers at Berkeley ranged from 196 to 788 per annum. The numbers at Oldbury are lower than those estimated for the downstream migrants of the Twaite shad, another anadromous species, and far lower than those of the most abundant of the marine fish species that use the Severn Estuary as a nursery area.

Type
Research Article
Information
Journal of the Marine Biological Association of the United Kingdom , Volume 74 , Issue 3 , August 1994 , pp. 527 - 534
Copyright
Copyright © Marine Biological Association of the United Kingdom 1994

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Bird, D.J., Potter, I.C., Hardisty, M.W. & Baker, B.I., 1994. Morphology, body size and behaviour of recently-metamorphosed sea lampreys, Petromyzon marinus, from the lower River Severn, and their relevance to the onset of parasitic feeding. Journal of Fish Biology, 44, 67–74.Google Scholar
Claridge, P.N. & Gardner, D.C., 1978. Growth and movements of the twaite shad, Alosa fallax (Lacépède), in the Severn Estuary. Journal of Fish Biology, 12, 203–211.CrossRefGoogle Scholar
Claridge, P.N., Potter, I.C. & Hardisty, M.W., 1986. Seasonal changes in movements, abundance, size composition and diversity of the fish fauna of the Severn Estuary. Journal of the Marine Biological Association of the United Kingdom, 66, 229–258.Google Scholar
Cunjak, R.A., Chadwick, E.M.P. & Shears, M., 1989. Downstream movements and estuarine residence by Atlantic salmon parr (Salmo salar). Canadian Journal of Fisheries and Aquatic Sciences, 46, 1466–1471.CrossRefGoogle Scholar
Elson, P.F., 1957. The importance of size in the change from parr to smolt in Atlantic salmon. Canadian Fish Culturist, 21, 1–6.Google Scholar
Fried, S.M., McCleave, J.D. & Labar, G.W., 1978. Seaward migration of hatchery-reared Atlantic salmon, Salmo salar, smolts in the Penobscot River Estuary, Maine: riverine movements. Journal of the Fisheries Research Board of Canada, 35, 76–87.CrossRefGoogle Scholar
Huntingford, F.A., Thorpe, J.E., Garcia, De Leaniz C. & Hay, D.W., 1992. Patterns of growth and smolting in autumn migrants from a Scottish population of Atlantic salmon, Salmo salar L. Journal of Fish Biology, 41, supplement B, 43–51.CrossRefGoogle Scholar
Jessop, B.M., 1975. Investigation of the salmon (Salmo salar) smolt migration of the Big Salmon River, New Brunswick. Canadian Fisheries and Marine Service, Ottawa, Technical Report Series, Mar/T-75–1,57 pp.Google Scholar
Jonsson, B. & Ruud-Hansen, J., 1985. Water temperature as the primary influence on timing of seaward migration of Atlantic salmon (Salmo salar) smolts. Canadian Journal of Fisheries and Aquatic Sciences, 42, 593–595.CrossRefGoogle Scholar
Labar, G.W., McCleave, J.D. & Fried, S.M., 1979. Seaward migration of hatchery-reared Atlantic salmon (Salmo salar) smolts in the Penobscot River Estuary, Maine: open water movements. Journal du Conseil International Exploration du Mer, 38, 257–269.CrossRefGoogle Scholar
McCleave, J.D., 1978. Rhythmic aspects of estuarine migration of hatchery-reared Atlantic salmon (Salmo salar) smolts. Journal of Fish Biology, 12, 559–570.CrossRefGoogle Scholar
Meister, A.L., 1962. Atlantic salmon production in Cove Brook, Maine. Transactions of the American Fisheries Society, 91, 208–212.CrossRefGoogle Scholar
Mills, D.H., 1964. The ecology of the young stages of the Atlantic salmon in the River Bran, Ross-shire. Freshwater and Salmon Fisheries Research. Edinburgh, 32, 1–58.Google Scholar
Mills, D.H., 1989. Ecology and management of Atlantic salmon. New York: Chapman and Hall.Google Scholar
Österdahl, L., 1969. The smolt run of a small Swedish River. In Salmon and trout in streams (ed. T.G., Northcote), pp. 205–215. Vancouver: University of British Columbia. [H.R. MacMillan Lectures in Fisheries.]Google Scholar
Ricker, W.E., 1975. Computation and interpretation of biological statistics of fish populations. Bulletin. Fisheries Research Board of Canada, no. 191, 382 pp.Google Scholar
Riddell, B.E. & Leggett, W.C., 1981. Evidence of an adaptive basis for geographic variation in body morphology and time of downstream migration of juvenile Atlantic salmon (Salmo salar). Canadian Journal of Aquatic and Fisheries Sciences, 38, 308–320.CrossRefGoogle Scholar
Ruggles, C.P., 1980. A review of the downstream migration of Atlantic salmon. Canadian Technical Report of Fisheries and Aquatic Sciences, no. 952, 37 pp.Google Scholar
Solomon, D.J., 1978. Some observations on salmon smolt migration in a chalkstream. Journal of Fish Biology, 12, 571–574.CrossRefGoogle Scholar
Thorpe, J.E. & Morgan, R.I.G., 1978. Periodicity in Atlantic salmon Salmo salar L. smolt migration. Journal of Fish Biology, 12, 541–548.Google Scholar
Thorpe, J.E., Morgan, R.I.G., Pretswell, D. & Higgins, P.J., 1988. Movement rhythms in juvenile Atlantic salmon, Salmo salar L. Journal of Fish Biology, 33, 931–940.CrossRefGoogle Scholar
Tytler, P., Thorpe, J.E. & Shearer, W.M., 1978. Ultrasonic tracking of the movements of Atlantic salmon smolts (Salmo salar L.) in the estuaries of two Scottish rivers. Journal of Fish Biology, 12, 575–586.CrossRefGoogle Scholar
Youngson, A.F., Buck, R.J.G., Simpson, T.H. & Hay, D.W., 1983. The autumn and spring emigrations of juvenile Atlantic salmon, Salmo salar L., from the Girnock Burn, Aberdeenshire, Scotland: environmental release of migration. Journal of Fish Biology, 23, 625–639.CrossRefGoogle Scholar