The chief objectives of this four-year project were:
(i) To examine the thermal metabolic performance of selected freshwater fish species that provide sustainable fisheries of economic importance, and to develop growth models, based on water temperature, food consumption and fish size, that can predict changes in growth as a result of environmental change. The target species were brown trout, including sea-trout (Salmo trutta L.), Atlantic salmon (Salmo salar L.), Arctic charr (Salvelinus alpinus (L.)) and perch (Perca fluviatilis L.).
(ii) To study intraspecific variation in thermal performance along latitudinal and climatic clines, to evaluate possible responses to persistent temperature changes among economically important species, and determine geographical variation in several metabolic traits that may influence fish production.
In conclusion, experiments on a total of 37 populations of four species, and field studies on 63 populations of two salmonid species, provided no clear-cut evidence for either of the two hypotheses on thermal adaptation. Hence, one important question remained to be answered: why did none of the four target species show evidence for thermal adaptation? It was concluded that: (i) trade-offs may exist between growth and phylogeny, limiting the possibility for thermal adaptation; (ii) there may be no, or very little, genetic variability for the traits in question because selection favours phenotypic plasticity rather than local adaptation. Finally, it is also evident from the present experiments that several populations should be explored before strong inference is made about thermal adaptations. As this project has progressed, adaptive patterns have emerged, and disappeared again, as new populations were included in the experiments. Several combinations of populations from cold and warm localities may give a pattern consistent with the counter gradient variation hypothesis. Other combinations may oppose the hypotheses. There is an obvious need for further evaluation of the existing evidence for counter gradient variation, and particularly for re-analyses of the smaller data-bases in these earlier studies compared with the exceptionally large data-base attained within the present project.
The unifying theme of a common modelling framework was a particular strength of this project. Models from a single model family were fitted to data for the four target species across different geographic locations. As the models shared a common set of parameters with biological meaning, valid comparisons were made possible between different species, and between the same species in different locations. Thus, clear conclusions have been made with regard to thermal performance and adaptation of the four target species. The models have also provided a base line against which field results could be judged. Indeed, the basic growth models derived from laboratory data have been extended to fit extensive field data from a wide geographical area by adding extra variables, such as latitude and average temperature for a particular river. Model development is essentially an iterative process, and future improvement and refinement will enhance predictive power, and increase the benefit of the modelling approach.
The results of this project have been, and will be, published in international journals subject to peer review. They will also be communicated at scientific meetings and at meetings at which representatives of the fishing industry are present. These results will therefore be regarded as in the public domain and, once published, will be readily available to the general public.
The following publications have been produced as part of this project (arranged in order of years and then alphabetically within years):
1. Elliott, J.M. Hurley, M.A. & Allonby, J.D. (1996) A functional model for maximum growth of immature stone-loach, Barbatula barbatula, from three populations in northwest England. Freshwater Biology 36, 547-554.
2. Ojanguren, A. F., Reyes-Gavilan F. G. & Brana, F. (1996) Effects of egg size on offspring development and fitness in brown trout, Salmo trutta L. Aquaculture 147, 9-20.
3. Elliott, J.M. & Hurley, M.A. (1997) A functional model for maximum growth of Atlantic salmon parr, Salmo salar, from two populations in northwest England. Functional Ecology 11, 592-603.
4. Nicieza, A. G. & Metcalfe, N. B. (1997) Effects of light level and growth history on attack distances of visually foraging juvenile salmon in experimental tanks. Journal of Fish Biology 51, 643-649.
5. Nicieza, A. G. & Metcalfe, N. B. (1997) Growth compensation in juvenile Atlantic salmon: responses to depressed temperature and food availability. Ecology 78, 2385-2400.
6. Reyes-Gavilan F. G., Ojanguren, A. F. & Brana, F. (1997) The ontogenic development of body segments and sexual dimorphism in brown trout (Salmo trutta L.). Canadian Journal of Zoology 75, 651-655.
7. Elliott, J.M. & Hurley, M.A. (1998) a new functional model for estimating the maximum amount of invertebrate food consumed per day by brown trout, Salmo trutta. Freshwater Biology 39, 339-349.
8. Elliott, J.M. & Hurley, M.A. (1998) An individual-based model for predicting the emergence period of sea trout fry in a Lake District stream. Journal of Fish Biology 53, 414-433.
9. Elliott, J.M. & Hurley, M.A. (1998) Predicting fluctuations in the size of newly-emerged sea-trout fry in a Lake District stream. Journal of Fish Biology 53, 1120-1133.
10. Larsson, S. & Berglund, I. (1998) Growth and food consumption of 0+ Arctic charr fed pelleted or natural food at six different temperatures. Journal of Fish Biology 52, 230-242.
11. Mooij, W.M. & van Nes, E.H. (1998) Statistical analysis of the somatic growth rate of 0+ fish in relation to temperature under natural conditions. Canadian Journal of Fisheries and Aquatic Sciences 55, 451-458.
12. Reiriz, L., Nicieza, A.G. & Brana, F. (1998) Prey selection by experienced and naive juvenile Atlantic salmon. Journal of Fish Biology 53, 100-114.
13. Elliott, J.M. & Hurley, M.A. (1999) A new energetics model for brown trout, Salmo trutta. Freshwater Biology 42, 235-246.
14. Forseth, T., N?sje, T.F. Jonsson, B. & Harsaker, K. (1999) Juvenile migration of brown trout: a consequence of energetic state. Journal of Animal Ecology 68, 783-793.
15. Jensen, A.J. & Johnsen, B.O. (1999) The functional relationship between peak spring floods and survival and growth of juvenile Atlantic salmon (Salmo salar) and brown trout (Salmo trutta). Functional Ecology 13, 778-785.
16. Mooij, W.M. Van Rooij, J.M. & Wijnhoven, S. (1999) Analysis and comparison of fish growth from small samples of length at age data: detection of sexual dimorphism in Eurasian perch as an example. Transactions of the American Fisheries Society 128, 483-490.
17. Ojanguren, A.F. & Brana, F. (1999) Discrimination against water containing unrelated conspecifics, and a marginal effect of relatedness on spacing behaviour and growth in juvenile brown trout (Salmo trutta L.). Ethology 105, 937-948.
18. Ojanguren, A.F. Reyes-Gavilan, F.G. & Rodriguez Munoz, R. (1999) Effects of temperature on growth and efficiency of yolk utilisation in eggs and pre-feeding larval stages of Atlantic salmon. Aquaculture International 7, 81-87.
19. Thyrel, M., Berglund, I., Larsson, S. & Naslund, I. (1999) Upper thermal limits for feeding and growth of 0+ Arctic charr. Journal of Fish Biology 55, 199-210.
20. Elliott, J.M. & Hurley, M.A. (2000) Daily energy intake and growth of piscivorous trout, Salmo trutta. Freshwater Biology 44, 237-245.
21. Elliott, J.M. & Hurley, M.A. (2000) Optimum energy intake and gross efficiency of energy conversion for brown trout, Salmo trutta, feeding on invertebrates or fish. Freshwater Biology 44, 605-615.
22. Elliott, J.M. Hurley, M.A. & Maberly, S.C. (2000) The emergence period of sea trout fry in a Lake District stream correlates with the North Atlantic Oscillation. Journal of Fish Biology 56, 208-210.
23. Jensen, A.J. (2000). Atlantic salmon (Salmo salar) in the regulated River Alta: effects of altered water temperature on parr growth. Regulated Rivers (In press).
Unpublished Dissemination Activities
(in alphabetical order)
Berglund, I. (1997) New findings on growth in Arctic charr. IV Svenska Fiskbiologiska Symposiet. 16-19 November 1997, Umea, Sweden.
Berglund, I. & Larsson, S. (1998) Effects of temperature on voluntary food intake in Arctic charr. The Feeding Behaviour of Fish in Culture. Second workshop of the COST 827 action on: Voluntary Food Intake in Fish. Umea, Sweden. 20-22 August 1998.
Van Dijk, M. (1998) De aerobe capaciteit als functievan temperatuur voor baars (Perca fluviatilis) van een aantal verschillende populaties. Nevendoelstelling: (Relatie tussen kieuwfrequentie en zuurstofverbruik). (Final degree thesis).
Elliott, J.M. (1996) The scientific basis of stocking in salmonid rivers and streams. Lecture to representatives of Angling Clubs and National Rivers Authority. 2 March 1996, Newton Rigg, Cumbria, UK.
Elliott, J.M. (1997) Stock-recruitment relationships and the role of density-dependent and density-independent factors in the population dynamics of salmonids. Key-note address to a workshop on brown trout ecology: habitat requirements, life history and population regulation, Lund, Sweden.
Elliott, J.M. (1998) The importance of long-term research, illustrated by two case-studies. Invited lecture to the Department of Ecology, University of Lund, Sweden.
Forseth, T. (1998) Energy-budgeting and life history studies of fish - using cesium as a tracer. Invited speaker: McGill University, Montreal, Canada, February 1998; University of Trondheim, Norway, March 1998.
Hurley, M.A. (1997) Modelling egg development and emergence of sea-trout fry. Lecture to staff and students of Glasgow Caledonian and Strathclyde Universities, 30 Sept. 1997.
Hurley, M.A. (1998) Predicting the emergence time of sea-trout fry. Paper presented at the 1998 bi-annual conference of the Royal Statistical Society in Glasgow, UK.
Jensen, A.J. (1996) Temperature dependent growth of Atlantic salmon and brown trout parr. Fiskessymposiet 1996 (Fish Symposium 1996). 15-16 February 1996, Trondheim, Norway.
Jensen, A.J. (1997) Atlantic salmon (Salmo salar) in the regulated River Alta: Effects of altered water temperature on parr growth. Seventh International Symposium on Regulated Streams. 25-29 August 1997, Chattanooga, Tennessee, USA.
Jonnson, B. (1999) Temperature adaptation in salmonids in relation to climatic change. Conference on biodiversity, Norwegian Research council, Vettre, Norway, 20-21 October 1999.
Larsson, S. (1997) Effecter av Temperatur och diet pa tillvaxt och fodokonsumtion hos roding (Salvelinus alpinus). Master of Science thesis, Swedish University of Agricultural Sciences.
Larsson, S. (1999) Counter gradient variation in growth of Arctic charr? Fifth Meeting of Ph D students in Evolutionary Biology. Umea, Sweden.
Larsson, S., Thyrel, M. & Berglund, I. (1998) Upper thermal limits of feeding and growth of 0+ Arctic charr, Salvelinus alpinus L. The Feeding Behaviour of Fish in Culture. Second workshop of the COST 827 action on: Voluntary Food Intake in Fish. Umea, Sweden. 20-22 August 1998.
Ojanguren, A.F. & Brana, F. (1999) Influence of size and morphology on swimming performance in juvenile brown trout (Salmo trutta L.). Poster presented at Environment, development and growth of fishes. Annual International Symposium of the Fisheries Society of the British Isles. 5-8 July 1999, University of St. Andrews, Scotland.
Rodriguez Munoz, R., Nicieza, A.G. & Brana, F. (1999) Effects of incubation temperature on survival, timing and growth during the embryonic development of sea lamprey. Poster presented at Environment, development and growth of fishes. Annual International Symposium of the Fisheries Society of the British Isles. 5-8 July 1999, University of St. Andrews, Scotland.
van Rooij, J.M. & Mooij, W.M. (1997) Oxygen as a (neglected) factor limiting the production of perch (Percids). Percid Workshop of the meeting on 'Island Aquaculture and Tropical Aquaculture'. 3-9 May 1997, Les Trois Ilets, Martinique, French West Indies.
Thyrel, M. (1998) Upper thermal limits for feeding and growth of Arctic charr Salvelinus alpinus L. Master of Science thesis, Swedish University of Agricultural Sciences.
Wijnhoven, S. (1997) Growth of perch (Perca fluviatilis) in the field and during a laboratory experiment. Report of a 6-months master's project in part fulfilment of a Master's Degree in biology at the University of Nijmegen.
All these objectives were fulfilled. Apart from brown trout, there was a paucity of detailed studies on the thermal performance of the target species before the present project commenced. One major advance of this project compared with previous work has been the development of truly generic models for growth, food consumption and energetics. These are its major products.
The project has provided a wealth of information on the geographical variation in the thermal performance of the four target species, with information from northern Norway and Sweden, through Britain and the Netherlands, to northern Spain. The overall conclusion is that there is no conclusive evidence for geographical variation in growth performance. Although it is possible that results from an even wider geographical range could reveal a thermal performance pattern as yet unknown, the probability of this is low, considering the large number of populations from a wide geographical area in the present study.
The overall role of thermal adaptation was examined in relation to the large amount of data that have been produced in the project. Two contrasting hypotheses for thermal adaptation were examined through analyses of field data and data from controlled experiments in the laboratory: (i) adaptation to local optima; (ii) the counter gradient variation hypothesis. The latter hypothesis is that populations in apparently hostile environments (low temperature, short growth season, strong competition) perform better at all temperatures than co specifics from benign environments. The results provided little, if any, support for either of these two hypotheses.
In addition to experimental data, analyses were performed on field data for growth of brown trout from 42 populations located between 44 and 70 on, and for growth of Atlantic salmon from 21 populations located between 57 and 70 on. The growth model developed in the project explained 80.6 % of the variance in annual growth rates of the trout. Therefore, most of the observed variance in growth rate was phenotypically induced and a product of local conditions. A similar model, developed for Atlantic salmon, explained 64.7% of the variance in annual growth rate.
Funding SchemeCSC - Cost-sharing contracts
4401 NT Yerseke
901 83 Umea