Stephen Gregory

Stephengregory3Fisheries Scientist


Twitter: @stephendgregory

  • PhD in Ecology and Statistics (2007-10) Detection of demographic Allee effects; Dr F. Courchamp; Université Paris-Sud XI, France
  • MSc by Research (2005-06) Interspecific overlap in resource and space use of the endemic Santiago Rice rat and the invasive Black rat on Santiago, Galapagos; Prof. D.W. Macdonald; University of Oxford, UK
  • Marine Biology (1997) Scripps Institute, University of California, San Diego, US
  • BSc Zoology (1996-99) University of Wales, Swansea, UK
  • BSc dissertation (1999) The feeding behaviour of the lesser horseshoe bat, Rhinolophus hipposideros, University of Wales, Swansea, UK

Short biography

I am a conservation biologist and I use population modelling to better understand and propose management actions for a variety of animal populations, from native Galapagos rodents to Malaysian orangutans. I am currently researching the effects of environmental drivers on salmonid vital rates and consequences for their population dynamics.

Past projects

  • MorFish: monitoring for migratory fish. Europe INTERREG 4a Channel; 2012-2015



  • Olivia Simmons (2018-current) Atlantic salmon smolt survival at sea. PhD at Bournemouth University with Rob Britton and Pippa Gillingham. Website:
  • Alexander Harris (2018) Environmental factors and individual characteristics affect the speed of Atlantic salmon and brown trout seaward migration. MSc at Imperial College London with Guy Woodward. Result: 1st
  • Tea Bašić (2017) Roles of discharge and temperature in recruitment of a cold‐water fish, the European grayling Thymallus thymallus, near its southern range limit. Postdoc at Bournemouth Univiersity with Rob Britton. Website:
  • Elinor Parry (2015) The effect of climate-driven low flow on Atlantic salmon (Salmo salar) redd distribution in a UK chalkstream. MSc at Cardiff University with Siân Griffiths. Result: Distinction
  • Jacopo Cerri (2014) Factors influencing the overwinter survival of age 0 parr to age 1 Atlantic salmon smolts. Erasmus MSc student. Website:
  • Felicity Lowther (2014) A study of the effect of environmental factors on the size distribution of migrating Atlantic salmon smolts (Salmo salar) in the River Frome, Dorset. BSc at Southampton University with Paul Carling. Result: 1st

External links and affiliations

Scientific publications

Recent Peer-reviewed Articles

Marsh, J. E., Lauridsen, R. B., Gregory, S. D., Kratina, P., Scott, L. J., Cooling, D., Jones, J. I. (in revision). High summer macrophyte cover increases abundance, growth and feeding of juvenile Atlantic salmon. Ecological Applications.

Marsh, J. E., Lauridsen, R. B., Riley, W. D., [8 authors], Gregory, S. D. (in revision). Warm winters and cool springs negatively influence recruitment of Atlantic salmon (Salmo salar L.) in southern England. Journal of Fish Biology.

Simmons, O. M., Gregory, S. D., Gillingham, P. K., Riley, W. D., Scott, L. J. & Britton, J. R. (in revision). Biological and environmental influences on the migration phenology of Atlantic salmon Salmo salar smolts in a chalk stream in southern England. Freshwater Biology.

Marsh, J. E., Cove, R. J., Britton, J. R., Wellard, R. G., House, A. & Gregory, S. D. (in revision) Medium-term environmental changes impact age-specific survival in a salmonid population near its southern range limit. Freshwater Biology.

Tréhin, C., Rivot, E., Lamireau, L., Meslier, L., Besnard, A.-L., Gregory, S. D. & Nevoux, M. (online early) Growth during the first summer at sea modulates sex-specific maturation schedule in Atlantic salmon. Canadian Journal of Fisheries and Aquatic Sciences. DOI 10.1139/cjfas-2020-0236

Gregory, S. D., Bewes, V., Davey, A. J. H., Roberts, D., Gough, P. & Davidson, I. C. (2020) Environmental drivers modify density-dependent salmonid recruitment: insights into the 2016 recruitment crash in Wales. Freshwater Biology, 65:2135-2153. DOI 10.1111/fwb.13609

Gillson, J. P., Maxwell, D. L., Gregory, S. D., et al. (2020) Can aspects of the discharge regime associated with juvenile Atlantic salmon (Salmo salar L.) and trout (S. trutta L.) densities be identified using historical monitoring data from five UK rivers? Fisheries Management and Ecology, 27:567-579. DOI 10.1111/fme.12456

Simmons, O. M., Britton, J. R., Gillingham, P. K. & Gregory, S. D. (2020). Influence of environmental and biological factors on the over-winter growth rate of Atlantic salmon Salmo salar parr in a UK chalk stream. Ecology of Freshwater Fish, 29:665-678. DOI 10.1111/eff.12542

Marsh, J. E., Lauridsen, R. L., Gregory, S. D., Beaumont, W. R. C., Scott, L. J., Kratina, P. & Jones, J. I. (2020). Above parr: lowland river habitat characteristics associated with higher juvenile Atlantic salmon (Salmo salar) and brown trout (S. trutta) densities. Ecology of Freshwater Fish, 29:542-556. DOI 10.1111/eff.12529

Gregory, S. D., Ibbotson, A. T., Riley, W. D., Nevoux, M., et al. (2019) Atlantic salmon return rate increases with smolt length. ICES Journal of Marine Science, 76:1702-1712. DOI 10.1093/icesjms/fsz066.

Riley, W. D., Ibbotson, A. T., Gregory, S. D., Russell, I. C., et al. (2018) Under what circumstances does the capture and tagging of wild Atlantic salmon Salmo salar smolts affect probability of return as adults? Journal of Fish Biology, 93:477-489. DOI 10.1111/jfb.13655.

Bašić, T., Britton, J. R., Cove, R. J., Ibbotson, A. T. & Gregory, S. D. (2018) Roles of discharge and temperature in recruitment of a cold-water fish, the European grayling Thymallus thymallus, near its southern range limit. Ecology of Freshwater Fish, 27:940-951. DOI 10.1111/eff.12405.

Gregory, S. D., Armstrong, J. D. & Britton, J. R. (2018) Is bigger really better? Towards improved models for testing how Atlantic salmon Salmo salar smolt size impacts marine survival. Journal of Fish Biology, 92: 579-592. DOI 10.1111/jfb.13550.

Angulo, E., Luque, G., Gregory, S. D., Wenzel, J. W., et al. (2018) Allee effects in social species. Journal of Animal Ecology, 87:47-58. DOI 10.1111/1365-2656.12759

Parry, E. S. , Gregory, S. D., Lauridsen, R. B., & S. W. Griffiths (2018) The effects of flow on Atlantic salmon (Salmo salar) redd distribution in a UK chalk stream between 1980 and 2015. Ecology of Freshwater Fish, 27:128-137. DOI 10.1111/eff.12330

Gregory, S. D., Nevoux, M., Riley, W. D., Beaumont, W. R. C., et al. (2017) Patterns on a parr: drivers of long-term salmon parr length in UK and French rivers depends on geographical scale. Freshwater Biology, 62:1117-1129. DOI 10.1111/fwb.12929

Harris, D. B., Gregory, S. D., Brook, B. W., Ritchie, E. G., et al. (2014) The influence of non-climate predictors at local and landscape resolutions depends on the autecology of the species. Austral Ecology, 39:710-721. DOI 10.1111/aec.12134

Gregory, S. D., Ancrenaz, M., Brook, B. W., Goossens, B., et al. (2014) Forecasts of habitat suitability improve habitat corridor efficacy in rapidly changing environments. Diversity & Distributions, 20:1044–1057. DOI 10.1111/ddi.12208 [cover image]

Harris, J. B. C., Dwi Putra, D., Gregory, S. D., Brook, B. W., et al. (2014) Rapid deforestation threatens mid-elevational endemic birds but climate change is most important at higher elevations. Diversity & Distributions, 20:773-785. DOI 10.1111/ddi.12180

Bradshaw, C. J. A., [8 authors], Gregory, S. D., [20 authors] (2013) Brave new green world - the costs and benefits of a carbon economy for the conservation of Australian biodiversity. Biological Conservation, 161:71-90. DOI 10.1016/j.biocon.2013.02.012

Haby, N. A., Prowse, T. A. A., Gregory, S. D., Watts, M. J., et al. (2013) Scale dependency of metapopulation models used to predict climate change impacts on small mammals. Ecography, 36:832-841. DOI 10.1111/j.1600-0587.2012.07749.x

Gregory, S. D., B. W. Brook, B. Goossens, Ancrenaz, M., et al. (2012) Long-term field data and climate-habitat models show that orangutan persistence depends on effective forest management and greenhouse gas mitigation. PLoS ONE, 7:e43846. DOI 10.1371/journal.pone.0043846

Harris, D. B., Gregory, S.D., Bull, L. & F. Courchamp (2011) Island prioritisation for alien rodent eradications with an emphasis on reinvasion risk. Biological Invasions 14:1251-1263. DOI 10.1007/s10530-011-0153-1

Gregory, S. D. & G. Jones (2011) Bats and Allee effects: When social behaviours go batty. Biologist, 57:198-203.

Gregory, S. D. & F. Courchamp (2010) Safety in numbers: extinction arising from predator-driven Allee effects. Journal of Animal Ecology 79:511-514. DOI 10.1111/j.1365-2656.2010.01676.x

Gregory, S. D., Bradshaw, C. J. A., Brook, B. W. & F. Courchamp (2010) Limited evidence for the demographic Allee effect from numerous species across taxa. Ecology 91:2151-2161. DOI 10.1890/09-1128

Gascoigne, J., Berec, L., Gregory, S. D., & F. Courchamp (2009) Dangerously few liaisons: a review of mate-finding Allee effects. Population Ecology 51:355-372. DOI 10.1007/s10144-009-0146-4

Gregory, S. D. & D. W. Macdonald (2009) Prickly coexistence or blunt competition?  Opuntia refugia in an invaded rodent community. Oecologia 159:225-236. DOI 10.1007/s00442-008-1196-6

Harris, D. B., Gregory, S. D. & D. W. Macdonald (2006) Space invaders?  A search for patterns underlying the coexistence of alien black rats and Galápagos rice rats. Oecologia 149:276-288. DOI 10.1007/s00442-006-0447-7

Conference papers

Gregory, S. D. (2018) Could bigger be better? Longer Atlantic salmon smolts seem more likely to return as adults. In: Proceedings of the 33 International Workshop on Statistical Modelling. Volume 1: 112-117. University of Bristol, Bristol.

Books and book chapters

Harris, D. B., Gregory, S. D. & D. W. Macdonald (2018) Endemic rats in Galapagos. In Atlas of the species of Galapagos, Charles Darwin Foundation and World Wildlife Fund.

Lauridsen, R. B., Moore, A., Gregory, S. D., Beaumont, W. R. C., et al. (2017) Migration behaviour and loss rate of trout smolts in the transitional zone between freshwater and saltwater. In Proceedings of the Second International Sea Trout Symposium, October 2015, Dundalk, Ireland.

Bertelsmeier, C., Bonnaud, E., Gregory, S.D. & F. Courchamp (2012) Applied Ecology. In Encyclopedia of Theoretical Ecology (Alan Hastings and Louis Gross, eds.), University of California Press, California

Technical reports and handouts

Chaput, G. (ed), Bardarson, H., Gillson, J.P., Gregory, S.D., Head, E., Jacobsen, J.A., Licandro, P., Santos, A.R., Utne, K.R., Ó Maoiléidigh, N. (2020) NASCO Workshop for North Atlantic Salmon At-Sea Mortality (WKSalmon, outputs from 2019 meeting). ICES Scientific Reports, 2: 69. DOI 10.17895/

Robertson, M. (ed), [14 authors], Gregory, S. D., [18 authors] (2020) Working Group on North Atlantic Salmon (WGNAS). ICES Scientific Reports, 2: 21. International Council for the Exploration of the Sea. DOI 10.17895/

Robertson, M. (ed), [13 authors], Gregory, S. D., [15 authors] (2019) Working Group on North Atlantic Salmon (WGNAS). ICES Scientific Reports, 1: 16. International Council for the Exploration of the Sea. DOI 10.17895/

Gregory, S.D., Henderson, W., Smee, E. & P. Cassey (2014) Eradications of vertebrate pests in Australia: A review and guidelines for future best practice. PestSmart Toolkit publication, Invasive Animals Cooperative Research Centre, Canberra, Australia


Gregory, S.D. (2010) Demographic Allee effects: empirical evidence and detection. PhD thesis, Universite Paris-Sud XI, France

Gregory, S.D. (2006) Interspecific overlap in resource and space use of the endemic Santiago Rice rat and the invasive Black rat on Santiago, Galápagos. MSc thesis, University of Oxford, UK

Selected oral and poster presentations

See my recent presentations at:

Orangutan persistence under global change; conservation needs (15min). Society for Conservation Biology Annual Meeting 2011, Auckland, New Zealand

Bat roost dynamics (15min). Society for Conservation Biology Annual Meeting 2009, Beijing, China

Bats and Allee effects (1hr). Fete de la science 2009, University of Paris XI, France

Bats and Allee effects (15min). PhD Student Conference 2009, University of Paris XI, France

Bats and Allee effects (45min). Ecology in English course 2009, University of Paris XI, France

Demographic Allee effects; What are they and how common are they? (15min). Student Conference for Conservation Science 2009, University of Cambridge, UK

A prickly case of coexistence?  Or a blunt case of competition?  (poster). Student Conference of Conservation Science 2007, University of Cambridge, UK

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