Hi Daniel,

I know of no such study comparing survival during the smolt stage. You may, however, read chapter 11.5.2 in Jonsson & Jonsson (2011).There you will find examples of mortality of sympatric hatchery and wild salmonids in rivers. Furthermore, I may speculate a little over your question. I do know that wild smolts may change their behaviour from night-time to day-time migration and school downstream with released hatchery smolts (Hansen & Jonsson 1985). This has been called ‘the pied-piper-effect which most probably will influence their survival. For instance, survival of anadromous brown trout increases in presence of many salmon smolts (Jonsson & Jonsson 2009) and a similar effect may ocur in Atlantic salmon when the number of smolts is increased by a fry release. The migratory routes and feeding areas of hatchery and wild smolts in the Atlantic Ocean are similar (Hansen et al. 1993, Jonsson et al. 1993). Thus, there appears to be no reason to expect that the migratory route of released fry will differ from that of wild salmon. There may, however, be reason to believe that their behaviour during competition and towards competitors can be different. The survival of hatchery fish is often lower than that of wild conspecifics (e.g. Jonsson et al. 2003), and there is a difference in competitive behavior between sea ranched and wild salmon on the spawning grounds (Fleming et al. 1996, 1997). Hatchery salmon are less evasive and more risk prone (Berejikian 1995), they behave differently in the river during refuge use (Griffiths & Armstrong 2002) and return migration (Jonsson et al. 1990, Økland et al. 1995). Possibly, this difference is established during the first couple of months during hatchery rearing as part of a behavioural syndrome (Andriaenssens et al. 2013). Thus, if you release alevins, their behavior should be wild like. If you release one summer old parr, on the other hand, they may behave differently during competition and against predators. Their migration behaviour, on the other hand, should be similar to that of wild conspecifics.

References

Andriaenssens, B. & Johnsson, J.I. (2013) Natural selection, plasticity and the emergence of a behavioural syndrome in the wild. -Ecology Letters 16: 47-55.

Berejikian, B.A. (1995) The effect of hatchey and wild ancestry and experience on the relative ability of steelhead trout fry (Oncorhynchus mykiss) to avoid a benthic predator. Can J Fish Aquat Sci 52: 2476-2482.

Fleming, I.A., B. Jonsson, M.R. Gross & A. Lamberg, A. (1996) An experimental study of the reproductive behaviour and success of farmed and on wild Atlantic salmon (Salmo salar) - Journal ofApplied Ecology 33: 893-905.

Fleming, I.A., A. Lamberg, A. & B. Jonsson (1997) Effects of early experience on the reproductive performance of Atlantic salmon. -  Behavioural Ecology 8: 470-480.

Griffiths, S.W. & Armstrong, J.D. (2002) Rearing conditions influence refuge use among over-wintering Atlantic salmon juveniles. J Fish Biol 60: 363-369.

Hansen, L.P. & B. Jonsson (1985) Downstream migration of reared smolts of Atlantic salmon (Salmo salar L.) in the River Imsa. - Aquaculture 45: 237-248.

Hansen, L.P., N. Jonsson & B. Jonsson (1993) Oceanic migration of homing Atlantic salmon. - Anim. Behav. 45: 927-941.

Jonsson, B. & Jonsson, N. (2009) Migratory timing, marine survival and growth of anadromous brown trout Salmo trutta in the River Imsa, Norway. Journal of Fish Biology 74: 621-638.

Jonsson, B & Jonsson, N. (2011) Ecology of Atlantic salmon and brown trout: Habitat as a template for life histories. Fish and Fisheries Series 33, Springer, Dordrecht, The Netherlands, 708 pp.

Jonsson, N., L.P. Hansen & B. Jonsson (1993) Migratory behaviour and growth of hatchery-reared post-smolt Atlantic salmon Salmo salar L. - J. Fish Biol. 42: 435-443.

Jonsson, N., Jonsson, B. & Hansen, L.P. (2003) Marine survival and growth of sea ranched and wild Atlantic salmon. - Journal of Applied Ecology 40: 900-911.

Økland, F., T.G. Heggberget & B. Jonsson (1995) Migratory behaviour of wild and farmed Atlantic salmon during spawning. - Journal Fish Biology 46: 1-7.

The first question is whether the fry will be marked, and if you are planning on operating a smolt trap to capture downstream migrating fish. I would suspect the fry will re-distribute, and wait a year or so to smolt and migrate towards the ocean. If you used a smolt trap and the fry were marked (eg adipose fin clip, etc), then you could compare smolt migration among the two groups, and also look at fry migration vs smolt migration.

Daniel, perhaps Peake's 1997 TAFS 126:707-714, may interest you, also check out my paper on smolting juvenile steelhead during migration, they have a similar life history to Atlantics. See my RG page - Plumb et al 2006 NAJFM 26:438-452.

Cheers,

JP

Thank you for your answers! To clearify, my question is weather or not smolts released as fry (that is hatched in a hatchery) behave differently than smolts hatched in the river. . 

Dear Daniel,

You may be interested in our recent review of Scottish information comparing returns of Atlantic salmon stocked as hatchery reared smolts and compared with wild-reared fish: http://www.gov.scot/Resource/0047/00476498.pdf . See also the references referred to in that report.

Regards

John