Research and Development

DEPARTMENT for ENVIRONMENT, FOOD and RURAL AFFAIRS CSG 15 Research and Development Final Project Report (Not to be used for LINK projects)

Two hard copies of this form should be returned to: Research Policy and International Division, Final Reports Unit DEFRA, Area 301 Cromwell House, Dean Stanley Street, London, SW1P 3JH. An electronic version should be e-mailed to [email protected]

Project title Salmonid migration and climate change

DEFRA project code SF0230

Contractor organisation CEFAS and location Pakefield Road Lowestoft Suffolk NR33 0HT

Total DEFRA project costs £ 726969

Project start date 01/04/99 Project end date 31/03/2004

Executive summary (maximum 2 sides A4)

The management of the salmonid fisheries is currently based upon a very limited understanding of the behaviour and distribution of salmon and sea trout in the sea and the factors affecting their migration routes, distribution and survival. Defra has the primary responsibility for scientific and policy issues relating to the effects of fisheries outside national waters on salmon originating from England and Wales. This principally involves discussions with other countries on both policy and scientific issues, and participation in the relevant activities of ICES and NASCO. Both these organisations have emphasised the need to increase our understanding of the environmental factors affecting the distribution and survival of post-smolts and adult salmonids in the estuarine and marine environments in order that we can develop methods to predict changes in stock abundance. A basic understanding of salmonid migration is also fundamental to predicting the future impact of climate change and global warming on salmonid stocks and the fisheries dependant upon them.

The key objectives of the research were to describe and model the environmental factors affecting the migration of salmonids and to investigate the effects of climate change on salmonid migration and survival both in freshwater and the sea.

The main findings of the research are as follows:

Migratory behaviour of salmonid smolts and post-smolts

 Smolt emigration in the freshwater section of the river was correlated with increasing water temperature and increasing river flows although no particular threshold was evident for either environmental parameter.

CSG 15 (9/01) 1 Project Salmonid migration and climate change DEFRA SF0230 title project code  There was a seasonal difference in the time that tagged smolts spent in freshwater section of the river before entering the estuary. Fish released later in the season spent less time in the river before emigrating into coastal waters. As a result a significant proportion of the sea trout smolts migrated out of the estuary and into coastal waters during a 10-day period that coincided with a spring tide.  Migration through the estuary was principally on a spring ebb tide and in the region of the water column with the highest flows. This is energetically the most advantageous strategy for migration and resulted in the fish being moved rapidly out into coastal waters.  The smolts were pre-adapted in freshwater to the marine environment and as a result there was no requirement to spend long periods acclimating within the estuary during one of the most critical periods in the life cycle of the sea trout.  A physiological requirement for smolts to leave freshwater and to enter the marine environment is likely to be the major stimulus initiating the emigration of sea trout smolts in spring.  In coastal waters salmon and sea trout post-smolts demonstrated active, directed swimming. Migratory behaviour was initiated when the direction of the prevailing tidal currents was suitable to assist the fish in rapid movement away from the estuary mouth and in the case of the salmon in the general direction of the principal feeding grounds in the Norwegian Sea.  The speed of migrating salmon over the ground was within the range 18-23 cm sec-1, which is similar to the migratory speeds recorded in studies on other salmon populations in UK river systems.  The physiological transformation of the emigrating fish to full smolt status was necessary for successful migration within the marine environment. Therefore any factors that operate within the freshwater environment to inhibit smoltification (e.g. contaminants or high water temperatures) or delay migration (e.g. estuarine barrages amenity constructions) will reduce the survival of the post-smolts in the marine environment.

Migratory behaviour of sea trout kelts.

 The post-spawning survival of the sea trout was relatively high and over 60% of the tagged kelts emigrated from freshwater and into the coastal zone.  Seaward migration within freshwater was predominantly nocturnal and generally occurred in conjunction with increasing river discharge and rising water temperature. Post-spawning residency within the freshwater zone was highly variable between individuals ranging from 4 days to over 2 months.  Measurements of gill ATPase activity in fish sampled soon after spawning indicated that the fish were not yet physiologically adapted to migrate into saline conditions. However, the subsequent movement through the estuary and into coastal waters was rapid and the fish showed no evidence of a requirement to acclimate to the increasing salinities. Physiological adaptation after spawning would therefore appear to be rapid prior to the onset of emigration.  Migration through the estuary was predominantly nocturnal and occurred during an ebbing tide. This ebb tide form of transport is energetically the most favourable method of movement and migration at night would reduce the level of mortality from visual predators.  Tagged trout were recorded returning to the river after a period at sea and in the case of one individual successfully spawned whilst still retaining the tag in the body cavity.  The high return rates of tagged sea trout suggests that similar techniques using electronic data storage tags would permit longer term studies such as the thermal habitat requirements of the sea trout in the marine environment.

Distribution of salmon in the sea

 Attachment methods have been developed to allow data storage tags (DSTs) to be used as part of large- scale studies to determine the distribution of salmon in relation to marine environmental conditions. Existing DSTs can be placed within the body cavities of adult salmon for long-term monitoring of marine environmental conditions although the exteriorisation of the light sensor to permit the geographical position of the fish to be calculated would be necessary.

CSG 15 (9/01) 2 Project Salmonid migration and climate change DEFRA SF0230 title project code  A non-invasive technique for monitoring cortisol levels in tagged fish was developed in order to quantify the effect of electronic tag attachment to fish and their subsequent recovery. The technique measures the levels of cortisol excreted into the water by individual tagged fish and allows the recovery rate of the fish to be assessed. The technique will be used to quantify the effects of tags on salmon prior to the long-term studies on the distribution and behaviour of salmon in the sea.  Collaborative links have been developed with international organisations through the NASCO Working Group on International Cooperative Research held in Norway to study the factors regulating populations of salmon in the sea.  CEFAS contributed to the development 0f SALSEA – A marine research strategy to determine key factors affecting salmon survival at sea presented to the EU in 2004 for funding.  Other opportunities have continued to be investigated for applying DSTs to salmon in the sea and a variety of approaches have been pursued through this project and related work programmes (e.g. MOU - SA). These have included membership of the Lotek Wireless - Ocean Technology Fund Committee (funded by Lotek Wireless) and participation in the Census of Marine Life - Pacific Ocean Salmon Tracking Program.  However, the cost research programmes has been the main factor in preventing large-scale studies on salmon in the sea.

The impact of climate change on salmonids

 A literature review was completed using the available models and scenarios of climate change and organised into a framework with which to predict the impact on the freshwater and marine environment and subsequent effects on populations of salmon and sea trout over the next 20 and 50 years.  The climatic information on which the study was based was taken principally from the UK Climatic Impacts Programme (UKCIP) Technical Report 1 and from the NOAA-CIRES Climatic Diagnostics Center and the work on the North Atlantic Oscillation (NAO) by CEFAS, Lowestoft.  In freshwater, the expected increases in winter temperature and precipitation will be greatest in NW England and in Wales; the highest increase in summer temperatures will occur in SE England where there will be a corresponding reduction in summer and annual rainfall. Warming of rivers should be less than the 1-2°C anticipated for annual mean air temperatures. However, the warming of rivers in winter will probably be more significant for salmonids than increases at other seasons. The frequency of extreme events such as droughts and floods will increase. Increasing abstraction and reduced precipitation will increase the contaminant loading in many rivers and exacerbate their impact on salmonid populations.  The warming of rivers by 1-2°C will accelerate embryonic and alevin development during the winter, and lead to earlier emergence of fry from the gravels.  The consequential effects on survival and growth of later stages will depend on a synchronous phenological advancement of food organisms, plant growth and other requirements.  Survival of eggs and alevins in upland rivers could be reduced should expected higher winter rainfall generate more frequent river spates resulting in wash-out of the embryos.  Growth rates of salmonid parr will increase significantly as the result of a temperature rise of 1-2°C providing that there is a commensurate increase in their food resources.  Faster growth could lower the mean age at which parr reach the smolt stage, increasing smolt production for a particular year-class. However, density-dependent regulation would limit overall smolt production.  Reduced river flows and lower water temperatures would inhibit or delay the emigration of smolts and their entry into coastal waters. Modifications to the timing of the entry of smolts into the marine environment have been shown to affect survival and the return of spawning adults.  Reduced flows will inhibit and delay the movement of adult spawning salmon into the freshwater environment. Increased temperatures will reduce the amount of suitable thermal habitat for returning salmon. Reproductive success and fecundity may be reduced at higher water temperatures.  Increases in river flow will facilitate upstream spawning migration and assist the movement around obstacles such as weirs and barrages.

CSG 15 (9/01) 3 Project Salmonid migration and climate change DEFRA SF0230 title project code  There are major uncertainties regarding the impact of changes in climate within the marine environment. The various models and predictions indicate either small gradual rises in sea surface temperature, no significant changes, or even slight cooling in those regions occupied by salmon.  Changes to sea surface temperature and oceanographic features such as currents may modify the distribution and abundance of key prey items of the post-smolts and adult salmon. A mis-match in prey availability during entry into the marine environment may reduce post-smolt survival and growth.  Changes in sea surface temperatures (SST) will reduce the amount of suitable thermal habitat required for the suitable growth and development of salmon in the sea.  Changes in oceanographic features such as shelf edge currents may compromise the bioenergetic requirements of the migrating fish and lower survival.

The results of the research are used to provide base-line information on the effects of environmental factors on salmon and sea trout in estuaries and the marine environment, and to develop models on the factors controlling abundance of salmonid year classes. The information derived is used to improve advice on the management of home and distant water fisheries for the benefit of Defra, EA, DETR, SOAEFD, DANI, WOAD, NASCO, ICES and EIFAC.

CSG 15 (9/01) 4 Project Salmonid migration and climate change DEFRA SF0230 title project code

Scientific report (maximum 20 sides A4)

Introduction.

The emigration of salmonid smolts through estuaries and the movements of post-smolt through coastal waters are considered to be critical stages when both salmon and sea trout may be particularly vulnerable to a range of factors such as predation and adverse environmental conditions. Kelts, which are an important component of most sea trout stocks, are also considered vulnerable to similar impacts during their post-spawning emigration within the estuarine environment and coastal waters. Mortality at this stage can therefore be high and variable, and smolt mortality may have a major effect on the relative size of salmonid year classes. For example the poor returns of the salmon and sea trout year classes in the early 1990s appear to have been related to poor survival of post-smolts. Studies on North American stocks have suggested that marine environmental factors (e.g. sea surface temperature) influence the migration routes, abundance, growth, run-timing and survival of salmon in the sea. Preliminary studies in the NE Atlantic suggest that similar processes may operate there and these will be influenced further by climatic change. Further, in terms of the life cycle of salmonids it has recently been demonstrated that the freshwater and marine environments cannot be considered in isolation. The conditions occuring in rivers and estuaries may have a significant impact on the behaviour and survival of salmonids once they emigrate into the marine environment. A better understanding of the effects of the changing environment on salmonid stocks is therefore required to ensure appropriate conservation and management measures can be taken in the future. In order to develop appropriate models, information was required on the estuarine and marine distribution and behaviour of the fish and how they are affected by environmental parameters. The management of the salmonid fisheries has been based upon a very limited understanding of the behaviour and distribution of salmon and sea trout in the sea and the factors affecting their migration routes, distribution and survival. The present study was undertaken to provide a better understanding of the effects of environmental factors on the distribution, behaviour and survival of salmonids in the sea in order to improve the management of stocks and the fisheries dependant upon them. The study also considers the potential effects of climate change on these aspects of salmonid biology.

The main scientific objectives of the research were:

1. To describe the environmental and physiological factors controlling salmon and sea trout smolt and post- smolt migration in estuaries and coastal waters. 2. To describe the environmental and physiological factors controlling sea trout kelt migration in freshwater and estuaries. 3. To model the movements of salmon and sea trout post-smolts in the marine environment in relation to environmental conditions. 4. To develop methodologies for studying the movements and distribution of adult salmon in the open ocean. 5. To investigate the influence of climate on salmon and sea trout migration and marine survival.

1. The environmental and physiological factors controlling salmon and sea trout smolt and post-smolt migration in estuaries and coastal waters.

During the spring Atlantic salmon (Salmo salar L.) and sea trout (Salmo trutta L.) smolts move seaward from the freshwater nursery streams through river estuaries and enter coastal waters. Prior to this emigration the juvenile salmon and sea trout undergo the parr-smolt transformation which, involves significant changes in their morphology, physiology and behaviour that enables them to survive their subsequent life in the sea (see McCormick & Saunders, 1987). The physiological changes involved during this period of transition include modifications to plasma ion concentrations (e.g. chloride Cl- & sodium Na+) and an increase in the activity of gill Na+K+ATPase (Hoar, 1988; Boeuf, 1993) which allows the fish to osmoregulate in saltwater.

The transition from the freshwater to the marine environment is considered to be a critical period in the life history of both species, during which time they encounter increasing salinities, variable tidal currents, variable CSG 15 (9/01) 5 Project Salmonid migration and climate change DEFRA SF0230 title project code water quality and novel prey and predators (Moore et al. 1995; Moore et al. 1998). Recent studies have also demonstrated that survival of smolts in estuarine and coastal waters can also be significantly influenced by the freshwater conditions they experienced during the parr-smolt transformation. For instance, exposure to a number of pesticides derived from intensive agriculture and aquaculture may modify the smolts physiology so that they are unable to adapt to saline conditions and therefore survival in saltwater is reduced (Waring & Moore, 2004). In addition, exposure of pre-smolts to low levels of the atrazine in freshwater inhibits migratory behaviour so that fish either do not migrate or there is a significant delay to the emigration. This has particular significance to the survival of smolts in the marine environment as previous studies have indicated that there is a very brief window of time for successful entry of smolts into the open sea (Moore et al. 1995). Smolts missing this brief window have reduced survival and return rates as adults (Hansen & Jonsson 1989).

At present the management of the salmonid fisheries is based upon a very limited understanding of the behaviour of salmon and sea trout smolts in estuaries and the distribution of post-smolts in the sea. Research is required on the physiological and environmental control of smolt migration so that impact of both anthroprogenic and natural changes within the estuarine and coastal environments (e.g. construction of barrages, poor water quality, water temperature and tidal currents) on the distribution, behaviour and survival of salmonids in the sea can be assessed in order to improve the management of stocks and the fisheries dependant upon them.

The behaviour and distribution of salmon and sea trout smolts and post-smolts have been studied in a number of river estuaries in England using telemetry and electronic tracking techniques. The present studies have principally focused on the River Fowey (movement of sea trout smolts in the estuary and coastal waters) and the River Tees (movement of salmon and sea trout in estuaries and post-smolts in coastal waters). This research builds on previous studies on the movements of salmon and sea trout smolts carried out during previous research funded by MAFF (Moore & Potter, 1994; Moore et al. 1995; Moore et al. 1996; Moore et al. 1998; Moore et al. 1998; Moore et al. 2000).

The outbreak of Foot and Mouth Disease (FMD) in 2001 prevented access to any suitable field sites in order to carry out the trapping and tagging of salmon smolts. The study on the movements of salmon smolts in estuaries and post-smolts in the marine environment was therefore delayed until 2002 when it was subsequently undertaken in the River Tees.

Movement of sea trout smolts in the estuary of the River Fowey

During the spring smolt emigration 1999 and 2000 the behaviour of 54 sea trout was studied as they moved from freshwater and migrated through the estuary. The River Fowey is a small spate river in south-west England. The river rises in Bodmin Moor and runs 35 km before entering the English Channel at Fowey. The estuary is approximately 11km in length and 0.5 km wide at the estuary mouth.

The smolts were captured in the freshwater section of the River Fowey as they emigrated seawards and tagged using miniature 300kHz acoustic transmitters developed by the CEFAS Electronics Design Unit (Moore et al. 1991). All the smolts were trapped using a fyke net during dusk or the hours of darkness. In 1999 the smolts were trapped when the mean river water temperature was 9.5 ( 1.46C) and in 2000 when the mean river water temperature was 11.4 ( 1.98C). The transmitters were implanted into the peritoneal cavity of the smolts as described in previous studies (Moore & Potter, 1994; Moore et al. 1995; Moore et al. 1996; Moore et al. 1998; Moore et al. 1998) and allowed to fully recover from the effects of anaesthesia and handling before being released back into the river. This method of transmitter attachment has been shown to have no significant effects on either the behaviour or survival of salmon smolts (Moore et al. 1991). The movements of the smolts within the river and estuary were monitored using an array of 300kHz acoustic signal relay buoys also developed by the CEFAS Electronics Design Unit (Moore et al. 1995). The buoys were positioned between the limit of tidal influence and the exit of the estuary.

In order to monitor the seasonal changes in the physiology of the migrating smolts and determine the level of adaptation of the migrating fish to the marine environment a microplate assay to measure Na+K+ ATPase CSG 15 (9/01) 6 Project Salmonid migration and climate change DEFRA SF0230 title project code activity of salmonid gill tissue was developed at the Lowestoft Laboratory in conjunction with Project S0228 – The impact of agricultural contaminants on wild salmonids. Sea trout smolts trapped in freshwater at the same time as the smolts that were tagged and released were sampled for gill tissue and blood. Samples were taken from smolts on three dates throughout the tagging study. The gill tissue was stored at -80C and the level of Na+K+ ATPase activity measured later at the Lowestoft Laboratory. The blood sample was also analysed later to measure the plasma levels of Cl- and Na+. The increase in the gill Na+K+ATPase activity and changes in plasma ion concentrations are robust physiological indicator of a smolt’s physiological transformation and its ability to tolerate the marine environment.

A total of 44 tagged sea trout smolts migrated successfully from freshwater and through the length of the estuary. The remaining 10 smolts did not migrate past the limit of the tidal influence and remained in pools within the freshwater section of the river. In general sea trout smolt emigration in the freshwater section of the River Fowey was related to both increasing water temperature and increasing river flows although no particular threshold was evident for either environmental parameter. In 2000, there was a seasonal difference in the time that tagged smolts spent in freshwater section of the River Fowey before entering the estuary and migrating into coastal waters (r=0.83; p < 0.0001). Fish that were tagged earlier in the study spent less time in freshwater before emigrating through the estuary. As a result a significant proportion of the sea trout smolts migrated out of the estuary and into coastal waters during a 10-day period that coincided with a spring tide. Similar behaviour has been reported for both salmon and sea trout smolts in the River Conwy, Wales (Moore et al. 1995; Moore et al. 1998).

Smolts sampled in freshwater at the same time as the tagged fish all had high gill Na+K+ATPase activity and significantly lower plasma chloride and sodium ion concentrations (Figure 1). The gill activity has been compared to brown trout parr sampled from the River Fowey at the same time which act as a freshwater control group. The sea trout smolts showed lower Cl- and Na+ plasma ion concentrations compared to the brown trout parr is common in smolts just prior to saltwater entry. The physiological data indicates that whilst in freshwater the sea trout smolts were already adapted to the marine environment. In addition, the levels of gill Na+K+ATPase activity in the sampled completed the parr-smolt transformation and were fully adapted to survive in the marine environment.

In both 1999 and 2000 the emigration of the sea trout smolts from freshwater and through the estuary occurred during both day and night. There was no nocturnal pattern of migration that has previously been demonstrated in sea trout from the Rivers Avon and Conwy (Moore & Potter, 1994; Moore et al. 1998) or in salmon from a number of river systems (Moore et al. 1992; Moore et al. 1995, Moore et al. 1996; Moore et al. 1998). Once the smolts migrated past the limit of tidal influence and entered the estuary the movements of the fish within the estuary were analysed using circular statistics to determine migration in relation to the tidal cycle. Analyses demonstrated that the smolts moved seawards on an ebbing tide and the mean time in the tidal cycle that fish was recorded leaving the estuary and entering coastal waters was 4h 52min after the previous high water. However, a small number of smolts were unable to migrate into the coastal zone on a single ebb tide and were subsequently moved upstream on the following flood tide. As a result of this tidal related movement a number of smolts remained within the estuary environment for periods of up to 8 days.

A number of fish (n=5) were also manually tracked from a small research vessel as they migrated through the estuary and entered coastal waters. A 300 kHz directional hydrophone was mounted on the vessel which when operated provided an indication of the position of the smolts within estuary channel and the relative position of the fish within the water column. During this period the migrating smolts were located in the mid-channel of the estuary and close to the surface where the maximum mean current speeds were measured (87  23 cm sec-1). In addition, manual tracking indicated that there was no change in the behaviour of the smolts when they moved into full saline conditions. This behaviour supports the physiological data suggesting that the smolts were already pre-adapted and did not require a period of acclimation to saltwater.

In conclusion, the migratory behaviour of the sea trout smolts in the River Fowey was similar to populations of both sea trout and salmon in other river systems in England and Wales or in salmon from a number of river

CSG 15 (9/01) 7 Project Salmonid migration and climate change DEFRA SF0230 title project code systems (Moore et al. 1992; Moore & Potter, 1994; Moore et al. 1995, Moore et al. 1996; Moore et al. 1998; Moore et al. 1998).

Cl- + Na 24 ( g

180  i

22 l m l

N 160 * 20 o a l ) P l + o i * 18 , . 140 K m M + g

16 A m

( T 120 p

P 14 r s o

* a n 100 t s 12 e o e i i n

a a 80 10 c - 1 t m . i h

8 v s 60 - i 1 a t l y 6 ) p 40 4 20 2 0 0 sea trout smolts brown trout parr

Figure 1. The changes in gill Na+K+ ATPase and plasma ion concentrations in sea trout smolts and brown trout parr from the River Fowey. * denotes significant differences between the sea trout and brown trout.

Migration through an estuary on a spring ebb tide and in the region of the water column with the highest flows is energetically the most advantageous strategy and will result in the fish being moved rapidly out into coastal waters. In addition, the pre-adaptation of the smolts in freshwater to saltwater conditions means that there is no requirement to spend long periods acclimating within the estuary during one of the most critical periods in the life cycle of the sea trout. A physiological requirement for smolts to leave freshwater and to enter the marine environment is likely to be the major stimulus initiating the emigration of sea trout smolts in spring.

The movement of salmon and sea trout smolts in coastal waters.

Previous studies in the Rivers Conwy, Avon and Test had investigated the limited movements of smolts as they migrated out of the estuary and into coastal waters (Moore et al. 2000; Holm et al. 2003). During this research, smolts were tagged and released in freshwater as described above and allowed to emigrate naturally downstream. A small research vessel was then positioned at the mouth of the estuary and a 300kHz directional hydrophone mounted to the vessel was used to detect the tagged fish and subsequently track them as they migrated into coastal waters. However, the technique was labour intensive and required that the operator was located on the outside of the vessel and exposed to the elements. As a result, the length of time that an individual fish could be monitored was short and the amount of information on the behaviour and distribution of the fish in relation to tidal currents and other environmental conditions was limited. Therefore, the CEFAS Electronic Design Unit undertook the development of a dedicated automatic coastal tracking system to study of

CSG 15 (9/01) 8 Project Salmonid migration and climate change DEFRA SF0230 title project code the long-term behaviour and distribution of post-smolts in coastal waters. In 1999, initial trials on the River Fowey indicated that further development was required to both the software and the hardware. After a further 18 months development by the Electronic Design Unit it was evident that a working system could not be produced to meet the milestones of the research. It was therefore agreed to purchase an already developed and operating coastal tracking system from VEMCO (Canada). This system together with VEMCO miniature coded acoustic transmitters and VEMCO VR2 acoustic receivers were used throughout the remaining period of the study to monitor the movements of salmonid smolts in coastal waters.

During 2002 and 2003 the movements and distribution of wild Atlantic salmon and sea trout post-smolts were studied in the coastal waters adjacent to the River Tees, north-east England. The River Tees flows from the Pennines for approximately 160 km before discharging into Tees Bay through Tees Port, a busy commercial cargo and shipping port. Outside the entrance of the of the River Tees the tidal stream flows in a south east direction during the flood tide and north west during the ebb tide. Prior to entry into the estuary and coastal waters the smolts must negotiate the River Tees Barrage at Stockton-on-Tees, which forms a physical barrier to migration and has modified the tidal cycle within the estuary below the construction. The smolts negotiate the barrage by moving over the gates at high tide or pass through the canoe slalom adjacent to the main barrage. During May and June salmon and sea trout smolts were trapped during the spring smolt emigration in the lower-most pool of the canoe slalom using a seine net and selected fish were then intraperitoneally tagged with VEMCO V8 miniature pinger acoustic transmitters. Throughout the study period, gill samples were taken from additional groups of fish to measure Na+K+ATPase activity as an indicator of saltwater adaptation and relate to the subsequent behaviour of the tagged smolts. Initially, the smolts were released immediately below the barrage at the point where the canoe slalom discharged into the estuary. However, it was immediately evident that the modification of the tidal cycle by the barrage had removed the necessary cues required to assist seaward migration in the smolts (Moore et al. 1996). Therefore for the rest of the study in both 2002 and 2003 the tagged smolts were transported in the research vessel before being released inside the estuary mouth.

The VEMCO VR28 coastal tracking system was attached to a small research vessel, which was then deployed to monitor the movements of the posts through the estuary and into Tees Bay. The VR28 system consists of a control module, 4 receiver modules, a stereo audio module and a 4 element VH41-XPD transponding hydrophone mounted on one side of the research vessel. The entire system was run through TRACK28 software on an IBM laptop computer. The tracking screen allowed for easy identification of the signal received from the pinger tag as well as giving the bearing and broadcasting the signal strength. This permitted the research vessel to remain in range of the smolt during it’s migration. GPS positions were obtained from the vessel every 2 minutes and this data provided the information on the track of the fish.

In 2002 4 salmon and 4 sea trout smolts were tracked for periods of up to 19.5 hours and over distances of up to 2.7 nautical miles until adverse weather conditions prevented further study. The direction of migration of individual fish during each track was analysed by plotting GPS positions onto an admiralty chart at exact intervals of 1 hour following the last high water. Joining each point produced a compass direction and distance for each hour the fish was tracked. Patterns of activity of the smolts was determined by placing a grid of squares (1 square = 450m2) over a chart of the Tees bay and recording from each individual smolt track the time of entry and length of time spent within each square. Both directional migration and swimming activity of the post-smolts in relation to tidal cycles and tidal streams were subsequently analysed using circular statistics (Batschelet, 1981). The data was tested to show whether the movement of the smolts was random with respect to time and state of tide using the Rayleigh test (“r” value) (Batschelet, 1981). In all post-smolts there was a strong correlation between the swimming activity of the fish and the tidal cycle. Movement throughout an entire tidal cycle occurred predominantly during the middle of the ebb tide (HW + 2.49  1.9 hours). The direction of migration of the post-smolts during the first 4 hours of the ebb tide was significantly correlated with the directional flow of the Tees bay tidal stream (Figure 2). The increase in swimming behaviour during the beginning and middle of the ebb tide ensured that the fish moved rapidly in a north-east direction away from the estuary mouth with the prevailing tidal stream current.

CSG 15 (9/01) 9 Project Salmonid migration and climate change DEFRA SF0230 title project code The gill Na+K+ATPase activity of the salmon and sea trout smolts sampled throughout the study showed a mean -1 -1 + + value of 25.4  4.8 molPi.mg protein .h . There was also an increase in gill Na K ATPase activity -1 -1 throughout the 4 week study period study from 22.16 – 30.39 molPi.mg protein .h . The levels of gill activity were within the range normally encountered in smolts that have successfully undergone the parr-smolt transformation and are fully adapted to saline conditions and survival within the marine environment.

In 2003 a further 2 salmon and 2 sea trout smolts were trapped in the canoe slalom, tagged with miniature acoustic pinger transmitters and released inside the River Tees estuary mouth. However, in all cases the fish did not move from the point of release and showed no evidence of migratory behaviour. The fish remained at the point of release throughout the study period in May. The subsequent analyses of the gills demonstrated that gill + + -1 -1 Na K ATPase activity was within the range 3-7 molPi.mg protein .h . These levels indicate that the fish may not have been physiologically adapted to marine conditions although when the fish were captured in the canoe slalom they appeared morphologically to be smolts. The reason for poor physiological adaptation to marine conditions in these smolts is not clear. However, high water temperatures during the smolt emigration are known to inhibit or reverse the parr-smolt transformation (McCormick et al. 2000). It is not known how long the smolts had been resident in the canoe slalom before they were tagged and released. A previous study has indicated that temperatures within the slalom can reach 26 C for long periods particularly when the operation is stopped and flows are reduced between the afternoon and mid-morning (Quayle and Bendall pers.comm.). In addition, exposure of juvenile salmonids to contaminants during the parr-smolt transformation can also reduce gill Na+K+ATPase activity and increase mortality once the fish transfer to saltwater (Waring & Moore, 2004).

In conclusion, salmon and sea trout smolts demonstrate active, directed swimming in coastal waters. Migratory behaviour is initiated when the direction of the prevailing tidal currents is suitable to assist the fish in rapid movement away from the estuary mouth and in the case of the salmon in the general direction of the principal adult feeding grounds in the north. The speed of migrating salmon over the ground is within the range 18-23 cm sec-1which is similar to the migratory speeds recorded in studies on other salmon populations in UK river systems (Moore et al. 1995; Holm et al. 2003). The physiological transformation of the emigrating fish to full smolt status is also necessary for successful migration within the marine environment. Any factors that operate within the freshwater environment to inhibit smoltification (e.g. contaminants or high water temperatures) or delay migration (e.g. estuarine barrages amenity constructions) will reduce the survival of the post-smolts in the marine environment.

2. The environmental and physiological factors controlling sea trout kelt migration in freshwater and estuaries.

The migratory form of the brown trout Salmo trutta L. (sea trout), are known to emigrate from freshwater and enter the marine environment at two specific periods during their life history. The initial emigration occurs at the smolt stage when the juvenile move from the freshwater nursery grounds and into coastal waters . The second emigration may occur after spawning when the adult fish having reproduced in the upper reaches of freshwater systems once again migrate as kelts to the marine feeding areas.

Figure 2. Directional migration of Atlantic salmon and sea trout smolts throughout an entire tidal cycle in the coastal waters adjacent to the River Tees. M = mean vector. T = tidal stream direction. n = number of fish observed. P1 = level of Probability obtained from the rayleigh test. P2 = level of probability obtained from the modified Rayleigh test (V test).

The behaviour of sea trout smolts in the River Fowey has been documented above, and the environmental and physiological cues initiating the movement of sea trout smolts have also been studied in a number of river systems in England and Wales (Moore and Potter 1994; Moore et al. 1998). Kelts, which are an important component of most sea trout stocks, (L'Abee-Lund et al. 1989) are also considered vulnerable to a similar range of adverse environmental conditions during their post-spawning emigration that are of concern to salmonid smolts. Changes within the estuarine environment from anthropogenic and climate change may significantly affect behaviour and survival of the fish. Mortality at this stage can therefore be high and variable, and this may have a major effect on the relative size of the repeat-spawning component of the population. However,

CSG 15 (9/01) 11 Project Salmonid migration and climate change DEFRA SF0230 title project code there is little information on the factors controlling the migratory behaviour of kelts particularly in relation to environmental conditions and the physiological status of the adult fish. Further, in terms of the life cycle of salmonids it has recently been demonstrated that the freshwater and marine environments cannot be considered in isolation. The conditions occurring in rivers and estuaries may have a significant impact on the behaviour and survival of both juvenile and adult salmonids once they emigrate into the marine environment (Fairchild et al. 2002; Waring & Moore, 2004). Therefore, a better understanding of the migratory behaviour, run-timing and residency of sea trout kelts within rivers and estuaries is essential in order to ensure appropriate conservation and management measures can be taken in the future, particularly in relation to changes in the freshwater and estuarine environments.

During 2001,2002, and 2003 the migratory behaviour of sea trout kelts was studied in the river and estuary of the River Fowey, south-west England. The research again used telemetry and tracking techniques to describe the movements of the kelts in relation to the physiological status of the fish and environmental cues initiating and controlling seaward migration and the movements of fish within the estuarine environment.

Following spawning, 45 sea trout kelts (12 males and 33 females) were caught using a combination of electro-fishing and stop-nets from pools immediatley downstream from the spawning areas in the upper reaches of the River Fowey. Individual fish were anaesthetised with 2 phenoxy ethanol (0.4 ml l-1) and miniature coded acoustic transmitters (Model V8SC-H, VEMCO Ltd, Canada) were surgically implanted into the peritoneal cavity as described for salmon smolts (Moore et al. 1991). The subsequent behaviour and movements of the tagged smolts within the freshwater and the estuary were monitored using VR2 acoustic receivers (VEMCO) positioned throughout the river catchment. Gill samples were also collected from kelts (n=5) caught at the same time as the tagged fish in order to measure the levels of Na+K+ATPase activity and determine whether the post-spawning fish were physiological adapted to survive in the marine environment.

Freshwater movements of sea trout kelts

Twenty-seven of the forty-five tagged kelts (60%) successfully migrated from the upper reaches of the River Fowey through the estaury and into coastal waters whilst nine (20%) of the tagged fish were not detected by any of the receivers throughout the study. Eight fish (18%) were detected moving past the receivers located in the freshwater reaches of the river, without subsequently being detected by any of the estuary receivers. Overall rates of successful migration were similar during each year of the study (61% in 2001 and 63% in 2002). However there was some variation in successful migration observed between male and female fish. More male fish (75%) successfully migrated into the coastal waters than female fish (58%). Daily mean flows varied greatly through out the study with recorded flows varying from between 1.7m³/s to 30.8m³/s in 2001/2002 and 3.1m³/s to 43m³/s in 2002/2003. Mean river flow during the period that the fish were moving through the system was very similar 7.8m³/s and 7.9m³/s in 2002 and 2003 respectively.

Residency of sea trout kelts within the freshwater reaches of the River Fowey ranged from between 6 and 69 days in 2001 (mean 41  23days) and between 4 and 62 days in 2002 (mean 29  31days). The level of gill Na+K+ATPase activity in sea trout kelts, sampled at the same time as the tagged fish, was within the range of 2.5 and 4.5 µmol Pi/mg Protein/h. This low level of activity suggests that at the time of tagging the post- spawning fish were not yet physiologically adapted to survive within saltwater. The fish would require a further period of residency within freshwater to obtain hypo-osmoregulatory status and this is reflected in the high

Figure 3. Movements of sea kelts through the River Fowey estuary in relation to the tidal cycle.

residency times of the fish in freshwater prior to emigrating into the estuarine environment.

A comparison of the mean time taken for the tagged kelts to reach tidal waters indicated that there was no difference between residency times of female and male fish within the freshwater sections of the river (t-test, P= 0.05). However, there was a significant difference between the size of the fish and the time that they began

CSG 15 (9/01) 13 Project Salmonid migration and climate change DEFRA SF0230 title project code to emigrate downstream after tagging and release (regression analysis: R = 0.6, P < 0.001). The larger fish migrated significantly earlier in the run than the smaller fish.

Migration in the freshwater sections of the river was nocturnal. There was no significant difference between the mean times that the fish were recorded emigrating in both years of the study. The mean time that the kelts were detected passing the freshwater receiver present throughout the two-year study was 00:21 hours.

Movements of sea trout kelts in the estuary

There continued to be a significant nocturnal component to the movement of the kelts through the upper, middle and lower portions of the estuary. In both 2002 and 2003 fish migrated through the estuary predominantly after midnight. However, there were significant differences in the mean time that fish emigrated through the middle estuary between the two study years. In 2001 and 2002 the mean times were 04:45 h and 07:57h respectively.

Migration of sea trout kelts through the estuary was predominantly on an ebbing tide (Figure 3). Time of entry into estuary waters in relation to the spring/neap tidal cycle was variable in each year occurring at all stages of the tidal cycle. The residency of the emigrating kelts within the estuary varied among individuals, although it was invariably short, with most fish moving out into coastal waters within 1-2 tidal cycles.

Return migration of tagged sea trout

Over the two year study period five kelts, which successfully emigrated into coastal waters, were again detected by the receivers in the Fowey estuary and subsequently migrated into freshwater. The first of the tagged fish to return from the groups tagged in December 2001 was a female on 21st April 2002 having spent only 89 days at sea. The second was a male sea trout that returned on the 14th June 2002 having spent a total of 145 days in coastal waters. Upstream movement through the estuary was rapid and the two fish entered freshwater after spending <16 hours and <10 hours in the tidal sections of the river respectively. The fish were subsequently detected moving past the freshwater receiver ~10 km above the tidal limit 4 and 6 days later. The female sea trout was once more recaptured after spawning on the 11th December 2002 in the very same pool it had been first caught the previous year. Fork length of the fish had increased by 5.1 cm during this period.

Of the fish tagged in 2002 three were subsequently detected as returning fish. All three of these fish were female, the first two returning in April (15th and 21st) having spent 106 and 112 days at sea respectively. While the third fish returned on 2nd June having spent 142 days in coastal waters. As in the previous year the upstream movement through the estuary and into freshwater was completed in <17 hours for all fish. Movement within freshwater occurred with all three fish moving past the freshwater receiver 12 km upstream of the tidal limit within 6 days of entering the estuary.

Upstream migration through the estuary occurred predominantly against an ebbing tide, with the mean time that fish were detected moving past the acoustic receiver in the middle estuary of HW + 3h. There was no significant diurnal pattern of migration within the estuary although the majority migrated during daylight hours. However, within freshwater, migration was again nocturnal, with the mean time that fish were recorded of 00:52.

In conclusion, the post-spawning survival of the sea trout was relatively high and over 60% of the tagged kelts emigrated from freshwater and into the coastal zone. Seaward migration within freshwater was predominantly nocturnal and generally occurred in conjunction with increasing river discharge and rising water temperature. Post-spawning residency within the freshwater zone was highly variable between individuals ranging from 4 days to over 2 months. Measurements of gill ATPase activity in fish sampled soon after spawning indicated that the fish were not yet physiologically adapted to migrate into saline conditions. However, the subsequent movement through the estuary and into coastal waters was rapid and the fish showed no evidence of a requirement to acclimate to the increasing salinities. Physiological adaptation after spawning would therefore

CSG 15 (9/01) 14 Project Salmonid migration and climate change DEFRA SF0230 title project code appear to be rapid prior to the onset of emigration. Migration through the estuary was predominantly nocturnal and occurred during an ebbing tide. This ebb tide form of transport is energetically the most favourable method of movement and migration at night would reduce the level of mortality from visual predators. Tagged trout were recorded returning to the river after a period at sea and in the case of one individual successfully spawned whilst still retaining the tag in the body cavity. The technique may also be appropriate for Atlantic salmon to determine the migratory behaviour of kelts within the freshwater and estuarine environments. In addition, the high return rates of tagged sea trout suggests that similar tagging techniques using electronic data storage tags would permit longer term studies such as the thermal conditions experienced by sea trout in the marine environment.

3. Modelling the migration routes of post-smolts in the sea

The aim of this modelling work was to investigate likely pathways for salmon migration from rivers in the UK to their initial feeding grounds, and the effects of behaviour on these pathways. The study required the use of two models: a hydrodynamic model for the prediction of a background water currents and a Lagrangian model for the prediction of the salmon transport. The hydrodynamic model produced predictions of the depth-mean flows due to the dominant semi-diurnal tidal currents throughout the migration at a resolution of approximately 8-km. These were used as input to the Lagrangian model to provide the passive transport field to which the swimming behaviour of the fish could be added. The model also used information from the coastal tracking studies to provide the swimming speeds of salmon throughout the tidal cycle.

The study comprised three main parts.

1) An investigation of the time taken to travel two pre-defined routes.

Two potential pathways were defined for transport between the south coast of England and the Sea of the Hebrides, either around the west-coast of Ireland, or through the western Irish Sea. For the section of the former route north of latitude 54.7N, an additional transport velocity of 0.3 ms-1 was imposed to simulate the Shelf Edge current. Swim speeds were varied between 0.2 and 0.5 ms-1 and the time taken to travel the predefined routes was found to be linearly and inversely proportional to the swim speed. The route around the west of Ireland was found to take marginally longer than that through the Irish Sea, by approximately 5%. For example, to reach the Sea of the Hebrides along the west of Ireland route took 77.0 (30.6) days with a swim speed of 0.2 (0.5) ms-1, as opposed to 72.1 (29.4) days for the Irish Sea route with the same swim speed. The small difference between the transport times for the two routes would suggest that factors other than transport time may control the choice of migration route. For example, differences in food supply (both timing and distribution) may result in an increased probability of survival along a particular path. Assuming a Shelf Edge residual current speed of approximately 0.3 ms-1, the total transport time between the south coast of England and the Norwegian coast was predicted to range between approximately 49 and 107 days for swim speeds of 0.5 and 0.2 ms-1 respectively.

2) An investigation of the pathway and travel time predicted if the salmon are assumed to preferentially head in a northward direction.

For this part of the study, the salmon were assumed to attempt to head in a northward direction. If they encountered land, they then moved in a different direction (following an imposed hierarchy dependent on the coastline orientation) until they could move freely northward again. The assumption was based on previous studies by Moore et al. 1991), which indicated the presence of biomagnetic material in the lateral line of salmon that would allow the fish to orientate in a preferred direction using the earth’s magnetic field. This directed swimming behaviour resulted in a transport path through the western Irish Sea, between the Outer Hebrides and mainland Scotland and then to the coast of Norway. The predicted transport times were 92 (76) days assuming a swim speed of 0.2 (0.4) ms-1.

3) An investigation of the effect of imposing selective tidal stream transport on transport times.

For the final part of the study, the salmon were assumed to swim only when the local current direction was within a defined arc of angles about the preferred direction of travel (as given by the predefined transport routes used in Part 1 of the study). For the remainder of the time, the salmon were assumed to sit on the bottom. It was found that for the same swim speed, the salmon took approximately twice as long to reach their destination. This is not unsurprising, as for the majority of the predefined transport routes, the major axes of the current ellipses are either not aligned with the route, or not particularly strong. Thus the average contribution of the tides 'felt' by the salmon during the active swimming phase is relatively weak, and the loss of swimming effort whilst the salmon are on the bottom results in an overall increase in the time taken to complete the defined route.

In conclusion, the model suggests that smolts migrating in the sea are not using a selective tidal stream transport form of migration. Instead fish continue to swim actively in a northerly direction probably being transported by the strong northerly or north-easterly surface currents and the Slope Current. It is predicted that the fish are also actively feeding during the migration. Previous studies by Holst et al. (2000) have shown that salmon tagged as smolts in Ireland and Wales and captured as post-smolts in surface trawls close to the Wyville-Thompson Ridge enter the Slope Current and are transported first north and later north-eastwards into the Norwegian Sea. A single smolt tagged in a southern England chalk stream and later recaptured in the Norwegian Sea completed the migration in ~77days, which is similar to that predicted by the model and also by recaptured tagged smolts from Ireland (39-88 days) (Holst et al. 2000).

The information from this study is being incorporated into a larger modelling exercise on the environmental control of post-smolt and adult salmon migration in the open sea currently being carried out under a Defra funded project SF0237 - Modelling the bioenergetics of Salmon migration.

4. Distribution of salmon in the sea.

In recent years, increasing concern has been expressed about the decline in abundance of the North Atlantic salmon. Run-reconstruction models (Potter et al. 1998) indicate marked declines in the abundance of both multi-sea-winter salmon and one-sea-winter salmon from European stocks of salmon. Although it is widely believed that the factors responsible for the decline in abundance have been operating in the marine phase of the life cycle, the reasons are clearly more complex. The freshwater and marine environments cannot be considered in isolation and conditions experienced by juvenile salmon in freshwater have been shown to have a significant impact on the survival of smolts during the transition to saltwater and the subsequent return of spawning adults (Waring & Moore, 2004; Fairchild et al. 2002). However, various studies have demonstrated a correlation between environmental parameters in the sea and stock numbers or survival rates of salmon (Martin & Mitchell, 1985; Friedland et al. 1993). Changes in the ocean climate resulting in modifications to the sea surface temperature and ocean currents (Reddin et al. 2000) have been suggested to be the main drivers regulating growth and survival of salmon in the sea. However, large-scale research on the distribution and abundance of salmon in the sea in relation to environmental conditions and the potential impact of further climatic change is difficult and expensive. The recent developments in electronic tag technology and in particular archival or data storage tags (DSTs) now provide an opportunity to describe both the geographical movements of salmon in the sea and their distribution in relation to sea surface temperatures (Stone et al. 1998). DSTs are microprocessor controlled data-logging tags that record information about the surroundings on internal memory and operate independently of any external recording devices. DSTs are not actively monitored but rely on the tags being recovered and returned in order to retrieve the stored information. The present generation of tags can collect environmental data such as temperature, depth, light and salinity. Information already obtained from applications of DSTs on adult salmon in coastal waters clearly shows the potential importance of these tags for studies of salmon in the sea (Sturlaugsson & Thorisson,1997).

The principal purpose of the study was therefore to develop methodologies, which would form the basis for future large-scale tagging studies using DSTs to describe the environmental distribution of salmonids in the sea.

CSG 15 (9/01) 16 Project Salmonid migration and climate change DEFRA SF0230 title project code These methods included assessing the most suitable methods of attaching tags to salmonids and identifying appropriate experimental sites for the trapping and release of salmonids. A further objective of the work was to develop and maintain close links with other international organisations deploying DST technology to study migratory fish (Pacific and Atlantic species) in order to extend and develop the work on UK salmonids.

Previous studies on the movement and distribution of smolts in estuaries and coastal waters have used electronic tags that are surgically implanted into the peritoneal cavity of the fish (Moore et al. 1995, Holm et al.2003). This method has been shown to have a minimal impact on growth and swimming behaviour in juvenile salmon (Moore et al, 1991). Alternative methods such as external attachment of tags to the salmon may effect growth, swimming behaviour and infection at the point of attachment. However, surgically implanting tags within the body cavity may effect the measurement of light, which is used for estimating the geographic location of the fish and temperature, which is used to measure the sea surface temperature in the vicinity of the fish. A study was therefore carried out to assess and compare the light and temperature recordings of a tag implanted inside salmon compared to external light and water temperature. Four adult salmon (mean length 69 ± 4 cms) were anaesthetised and Lotek Marine Technologies Ltd 100 Series Archival Tags were surgically implanted into the body cavities. The tag, developed at CEFAS, incorporates pressure (depth), temperature and light sensors. The light sensor allows an estimation of day length and time of local noon, which can be used to determine geographic location. A similar tag was attached externally to the dorsal fin of the fish using absorbable sutures. Light and temperature recordings were taken over a 22-day period. The results indicated that there were no significant differences between the measured temperatures between the internal and external tag. The mean temperature of the internal tag was 12.3 ± 1.2 °C compared to 12.2 ± 1.1 °C for the external tag. In addition, the light sensor was also sensitive to changes in light intensity whilst in the body cavity. However, the recorded light levels were significantly lower than the ambient levels and it is therefore unlikely that the light levels would be sufficient to calculate the geographic position of the fish in the Norwegian Sea. In conclusion, the existing DSTs could be placed within the body cavities of adult salmon for long-term monitoring of marine environmental conditions although the exteriorisation of the light sensor would be necessary.

DST technology can provide important information on the geographic distribution of salmon in the sea in relation to oceanographic features such as sea surface temperature. However, electronic tags are simply biological tools and the method of attachment to the fish must have no long-term effect on the behaviour or survival of the adult salmon throughout their migration within the marine environment. Therefore, prior to any field-based study using DSTs on salmon, the suitability and the long-term effects of the tag on the fish should be quantified. Previously, laboratory studies have been carried out to examine the effects of tag attachment on a range of behavioural and physiological parameters including swimming performance (Thorstad et al. 2000), feeding behaviour (Adams et al. 1998) and blood chemistry (Martinelli et al., 1998). An additional problem with telemetry studies is obtaining a quantitative assessment of when the fish have recovered from the tagging protocols and accurate data can start to be recorded which represents the natural behaviour of wild individuals.

One method that has been used to assess the impact of tags and recovery rates in tagged fish is to monitor plasma cortisol levels as a measure of stress (Jepsen et al. 2001). Generally when fish are exposed to a stressor, primary stress responses are induced. These include an increase in the release of the catecholamines adrenaline and noradrenaline and corticotropin-releasing hormone (CRH) is released by the hypothalamus, which is the initiating hormone in the response of the hypothalamic-pituitary-interrenal axis to stress. CRH in turn stimulates the production of adrenocorticotrophic hormone (ACTH), which subsequently affects the release of steroid hormones, principally cortisol, from the interrenal tissue. Secondary stress responses are subsequently induced by this increase in circulating levels of catecholamines and cortisol. The elevated plasma cortisol may significantly affect natural behaviour in fish and modify feeding behaviour, swimming performance and social interactions with conspecifics (Gregory and Wood, 1999). Physiological parameters such as growth (Barton et al. 1987; Pickering et al. 1991) or reproductive status (Pankhurst and Van der Kraak 1997) may also be affected, as well as lowered immunity (Pickering and Pottinger 1989). Measuring cortisol however, normally requires that a blood sample is taken from the fish and the subsequent handling of the fish during the sampling can in turn further modify plasma cortisol levels (Barton & Iwama, 1991).

Therefore, a non-invasive technique for monitoring cortisol levels in tagged fish was developed in order to quantify the effect of electronic tags on fish and their subsequent recovery. The technique measures the levels of cortisol excreted into the water by individual tagged fish and allows the recovery rate of the fish to be assessed. Although the technique was developed to assess the effects of DSTs on salmon in the sea, the initial research was carried out on freshwater species carp, (Cyprinus carpio L.) and roach (Rutilus rutilus L.) as insufficient adult salmon were available at the Lowestoft Laboratory.

The carp and roach tagged with miniature dummy acoustic transmitters responded to the surgical implantation of the tags with an immediate (1-4 h) increase in the release of cortisol into the water. These levels were significantly higher than the control groups (no tagging) and the sham-operated group (anaesthetic and handling only). Mean levels of released cortisol in carp were 0.94 ngl-1  0.07 (control); 1.1 ngl-1  0.1 (sham tagged); 1.7 ngl-1  0.23 (tagged). Mean levels of released cortisol in roach were 8.12 ngl-1  1.42 (control); 6.6 ngl-1  1.15 (sham tagged); 11.45 ngl-1  1.81 (tagged). In both species cortisol returned to baseline levels within 24hours of tag-insertion, and remained at baseline level for the duration of the experiment (Figure 4). In addition, there was no chronic stress response to the long-term presence of a tag in the body cavity. Although the technique was developed using the carp and roach it is applicable to a wide range of freshwater and marine fish species. It is recommended that prior to any study using DSTs to describe the distribution and behaviour of salmon in the sea that this technique is used to determine the long-term effects of tagging and the recovery of the fish.

There remain a number of problems and limitations with the use of DSTs to study the distribution and behaviour of salmon in the sea. Firstly, the DSTs that provide information on the geo-location of salmon are still too large to be attached to emigrating wild smolts. A further, major limitation is that imposed by the absence of an effective mechanism to recover tags and retrieve the stored data. Return rates to rivers are generally less than 2-5% and returns from a target fishery (not a popular option) could be as low. This would mandate a huge release of DSTs that are still relatively expensive (> US$ 600) in order to recover a few tags. Therefore, it was not possible to identify a release site where it was cost-effective to tag fish with DSTs. Although, there are a number of small temperature loggers that would provide information on the distribution of fish in relation to sea surface temperature, returns are still poor.

Collaborative links have continued to be developed with international organisations through the NASCO Working Group on International Cooperative Research held in Norway. Eight research proposals were formulated which were considered to address the main problems regarding salmon in the sea. A research programme entitled: Application of electronic tag technology to determine the marine distribution of salmon was developed by CEFAS and included within the proposals. A further research proposal entitled: The Bioenergetics of smolt migration in the marine environment was also formulated by CEFAS at the WG and this has now been further developed by CEH Wallingford and is currently being funded by DEFRA. In 2002 NASCO established the International Co-operative Salmon Research Board (IARSB) to set research priorities to investigate problems facing salmon in the sea and to seek funding for large-scale international projects. CEFAS has participated actively in this process and has supported, among other things, the use of DSTs on salmon. In 2003, biologists from Ireland, UK and Norway organised a workshop at the Institute of Marine Research, Bergen to bring together scientists working on problems facing salmon at sea, establish an overall marine research strategy and identify common or overlapping araes of interest between the organisations carrying out research on salmon in the sea. The result of the workshop was a document SALSEA – A marine research strategy to determine key factors affecting salmon survival at sea. A research programme entitled: The influence of freshwater contaminants on the marine survival of Atlantic salmon was developed by CEFAS and included within the strategy. The document will be presented to the EU in 2004 and progress with the research will be dependent upon the availability of suitable funds.

6 Control Sham-operated Tagged 5 * ) l * *

m * / ** * *

* l o s

i 3 t r o c

e 2 t a w 1

0 16 24 0 1 2 4 6 8 10 12 24 34 48 72 68 40 36 -8 - 1 2 3 Time (h)

Figure 4. The levels of excreted cortisol and recovery time of freshwater carp tagged intraperitoneally with electronic tags. * indicate significant differences between the treatment groups.

Other opportunities have continued to be investigated for applying DSTs to salmon in the sea and a variety of approaches have been pursued through this project and related work programmes (e.g. MOU - SA). These have included membership of the Lotek Wireless - Ocean Technology Fund Committee (funded by Lotek Wireless) and participation in the Census of Marine Life - Pacific Ocean Salmon Tracking Program. However, in all cases the cost of the programmes and the poor return rates of the tagged fish have prevented funding of large-scale studies on salmon in the sea.

The 3rd Conference on Fish Telemetry in Europe

The 3rd Conference on Fish Telemetry in Europe was organised by CEFAS and held at the University of East Anglia. The aim of the conference was to integrate the scientific knowledge of both aquatic scientists and engineers who were actively involved with the development and application of telemetry techniques to biological studies and management of fisheries. The Conference increased the opportunities for CEFAS to collaborate with international organisations on studies on salmon in the sea. The conference was attended by 120 delegates from 21 countries and supported by CEFAS, the European Union, Defra, the Environment Agency and Norwich County Council. The Proceedings of the Conference were edited and published by CEFAS with the agreement of the Defra Customer.

5. The impact of climate change on salmonids

It is now generally agreed that the climate is changing in many regions of the world. Surface climate is warming at the rate of about 0.15C per decade and has been doing so since the 1970s. The world is now about 0.6C warmer than a hundred years ago. The three warmest years have been – in decreasing order – 1997, 1995

CSG 15 (9/01) 19 Project Salmonid migration and climate change DEFRA SF0230 title project code and 1990. The UK climate is also warming. The 1990s have so far been about 0.5C warmer than the 1961-90 average and four of the five warmest years in the 340-year Central England temperature series have occurred since 1988.

Climate change will have a significant impact upon both the freshwater and marine environments in and around the UK. In order to manage and conserve populations of salmon and sea trout it is necessary to understand the implications of climate change and modifications to the weather patterns to both the freshwater and marine environments. Therefore, a literature-based study on the possible effects of changes in climate on salmonid populations and the ecosystems inhabited by them has been completed. The objectives of the study were:

1. To collate the various models and scenarios of climate change and organise a framework within which to predict the impact on the freshwater and marine environment and subsequent effects on populations of salmon and sea trout over the next 20 and 50 years. 2. To review the available scientific literature so as to assess and predict the effects of the expected climate change on a range of population parameters including:- reproduction and fecundity, embryo survival and emergence, juvenile carrying capacity of freshwater habitat, smolt production, smolt emigration, marine migration and distribution, spawning migration of adults in freshwater, prey abundance and distribution in the freshwater and marine environments. 3. To review the impact of climate change on other environmental factors that regulates salmonid populations (i.e. contaminants, abstraction and other anthropogenic interactions).

The climatic information on which the study was based was taken principally from the UK Climatic Impacts Programme (UKCIP) Technical Report 1 (Hulme & Jenkins, 1998), a DETR commissioned scientific study by the Climatic Research Unit, (University of East Anglia) and the Hadley Centre for Climate Prediction and Research, (Meteorological Office). The report describes four possible alternative scenarios of climate change for the UK, which are relevant to the freshwater environment. These are called UKCIP98 climate scenarios and are derived from the HADCM2 model of global warming rates for different emission levels of greenhouse gases and are termed : Low, Medium-low, Medium-high and High. These climate scenarios span a range of greenhouse gas emissions and different climate sensitivities from low sensitivity (1.5C temperature rise) to high sensitivity (4.5C temperature rise). The UKCIP report presents the study in the form of UK maps and for each scenario and climatic variable estimated changes are given as mean values for each of three 30-year periods centred on the 2020s, 2050s and 2080s. During the present study only the first two periods have been examined in relation to the potential impact on salmonid populations. The predicted changes in the mean summer temperatures and mean summer precipitations for the UK produced by the UK Climatic Impacts Programme (UKCIP) Technical Report 1 are shown in Figures 5 &6. A small amount of additional information was also extracted from the Summary for Policymakers (SPM, January 2001), based on the 3rd Assessment Report of Working Group 1 of the Intergovernmental Panel on Climate Change (IPCC). The climatic information, which was relevant to the marine environment was derived from the NOAA-CIRES Climatic Diagnostics Center and the work on the North Atlantic Oscillation (NAO) by Dr R.R. Dickson (CEFAS, Lowestoft).

Figure 5. Change in mean summer mean temperature (with respect to the 1961-90 mean) for thirty-year periods centred on the 2020s, 2050s and 2080s and for the four UKCIP98 scenarios. Background fields are interpolated from the full HadCM2 grid, while the highlighted numbers show the change for each HadCM2 land gridbox over the UK (from Hulme and Jenkins, 1998)

Figure 6. Change in mean summer precipitation (with respect to the 1961-90 mean) for thirty-year periods centred on the 2020s, 2050s and 2080s and for the four UKCIP98 scenarios. Background fields are interpolated from the full HadCM2 grid, while the highlighted numbers show the change for each HadCM2 land gridbox over the UK (from Hulme and Jenkins, 1998).

The principal findings of the literature study were as follows:

Freshwater environment

CSG 15 (9/01) 22 Project Salmonid migration and climate change DEFRA SF0230 title project code  The expected increases in winter temperature and precipitation will be greatest in NW England and in Wales; the highest increase in summer temperatures will occur in SE England where there will be a corresponding reduction in summer and annual rainfall. Warming of rivers should be less than the 1-2°C anticipated for annual mean air temperatures. However, the warming of rivers in winter will probably be more significant for salmonids than increases at other seasons. The frequency of extreme events such as droughts and floods will increase. Increasing abstraction and reduced precipitation will increase the contaminant loading in many rivers and exacerbate their impact on salmonid populations.  The warming of rivers by 1-2°C will accelerate embryonic and alevin development during the winter, and lead to earlier emergence of fry from the gravels.  The consequential effects on survival and growth of later stages will depend on a synchronous phenological advancement of food organisms, plant growth and other requirements.  Survival of eggs and alevins in upland rivers could be reduced should expected higher winter rainfall generate more frequent river spates resulting in wash-out of the embryos.  Growth rates of salmonid parr will increase significantly as the result of a temperature rise of 1-2°C providing that there is a commensurate increase in their food resources.  Faster growth could lower the mean age at which parr reach the smolt stage increasing smolt production for a particular year-class. However, density-dependent regulation would limit overall smolt production.  Reduced river flows and lower water temperatures would inhibit or delay the emigration of smolts and their entry into coastal waters. Modifications to the timing of the entry of smolts into the marine environment have been shown to affect survival and the return of spawning adults.  Reduced flows will inhibit and delay the movement of adult spawning salmon into the freshwater environment. Increased temperatures will reduce the amount of suitable thermal habitat for returning salmon. Reproductive success and fecundity may be reduced at higher water temperatures.  Increases in river flow will facilitate upstream spawning migration and assist the movement around obstacles such as weirs and barrages.

Marine environment

 There are major uncertainties regarding the impact of changes in climate within the marine environment. The various models and predictions indicate either small gradual rises in sea surface temperature, no significant changes, or even slight cooling in those regions occupied by salmon.  Changes to sea surface temperature and oceanographic features such as currents may modify the distribution and abundance of key prey items of the post-smolts and adult salmon. A mis-match in prey availability during entry into the marine environment may reduce post-smolt survival and growth.  Changes in sea surface temperatures (SST) will reduce the amount of suitable thermal habitat required for the suitable growth and development of salmon in the sea.  Changes in oceanographic features such as shelf edge currents may compromise the bioenergetic requirements of the migrating fish and lower survival.

The report recommends a number of areas for further research to extend our understanding of the impact of changes in climate on salmonid populations. These are:

 The impact of changes in river temperatures on salmonid spawning behaviour and reproduction  The impact of estuarine water temperatures on salmonid migration  The impact of changes in river flows on juvenile salmonid population dynamics and stocking practices  The effects of sea surface temperatures on salmonid prey abundance and distribution.  The effects of changes in sea surface temperature on marine productivity as a means of predicting recruitment in salmonid stocks.

These areas of work have been proposed for further funding by Defra.

CSG 15 (9/01) 23 Project Salmonid migration and climate change DEFRA SF0230 title project code All the objectives of the research have been met except the organisation of the workshop on Climate Change and the Impact on Salmonid Fisheries. The organisation of the workshop was discussed with the Climatic Research Unit (CRU) at the University of East Anglia. Since proposing the idea of the Workshop, a report entitled Climate Change Scenarios for the United Kingdom had been published jointly by CRU and the Hadley Centre for Climate Prediction and Research (HCCPR) at the Met. Office. A further updated report by HCCPR was also in press. CRU suggested that a workshop at this time might be inappropriate as the majority of the data that we would require to model climate change on salmonids is contained within the two reports. The Reports were circulated within CEFAS and the EA for comment and these formed the basis for the subsequent literature review outlined above and the full report entitled The potential impacts of climate change on Atlantic salmon and seatrout.

Discussion

The seaward emigration of salmon and sea trout smolts is a dynamic, active process initiated after the fish has physiologically transformed to survive in saline conditions and together with favourable environmental conditions (river flow and temperature) is motivated to move away from the freshwater environment. Migration through the estuary is generally nocturnal and rapid using the ebb tide cycle to move in the most energetically favourable manner. Emigrating during the night also reduces the level of predation pressure on the smolts from a number of common predators. The peak movement of smolts out into coastal waters occurs during a brief 5-10 day period which is considered to be important to the subsequent survival of the smolts and the successful return of spawning adults. The environmental factors regulating the population during this time is not fully understood although sea surface temperature, availability of suitable prey and favourable coastal currents may all play an important role. In coastal waters, salmon smolts continue to migrate in a directed manner and continual swimming against all tidal currents ensures that the fish migrate rapidly to the initial feeding grounds. The adult sea trout kelt exhibits similar migratory behaviour to the smolts in both the freshwater and estuarine environments. Movement through the estuary is rapid and again there is no period of acclimation required to survive in the increasing salinity. Pre-adaptation to the marine environment is an important factor controlling the timing and successful entry into the marine environment of both smolts and kelts. Adverse conditions in freshwater will therefore have an influence on the survival of the fish once they migrate to sea. In particular, exposure of smolts to contaminants in freshwater has been shown to inhibit or delay their seaward migration and reduce the ability of the remaining migrants to adapt to saline conditions (see Final Report S0228- Impact of agricultural contaminants on salmonid populations). Kelts exposed to contaminants within freshwater will also show low survival in the marine environment and consideration should be given to the freshwater history of both salmon and sea trout kelts when considering the potential contribution of the multi-spawning component of the stock to the overall population dynamics.

At present the data storage tag technology is not adequate for extensive studies throughout the marine phase of the life cycle in order to describe the distribution of salmon in relation to environmental change. There needs to be a reduction in both the size and the cost of the tags to allow studies on the movements and behaviour of salmon smolts and post-smolts during the period when they first enter the sea. However, rapid advances are being made in miniaturisation and the continuation of international collaborative research will allow proposals to be developed on the marine phase of the salmon and the factors regulating populations in the sea.

Although it is accepted that the climate is changing there is still a great deal of disagreement on the rate and extent of the predicted changes. The impact on the marine environment has been the most difficult to predict with scenarios suggesting both a cooling and a warming of the environment. Within this variable framework it is difficult to predict the potential effect on the marine phase of the salmon and sea trout. In freshwater, although there is general agreement there will be a general increase in water temperature over the UK it is more difficult to assess the impacts at a catchment scale which is required to determine the potential effect of climate change on salmonid populations in the future.

Further research is now required on the factors affecting the distribution and migratory behaviour of salmonids in both the freshwater and marine environments. Specifically:

1. Investigate the impact of expected changes in freshwater river flows and temperatures expected to result from the predicted climate change scenarios on juvenile salmonid production in rivers in England and Wales.

2. Determine the abundance and distribution of the autumn migrant component of the salmonid populations in rivers and estuaries in order to assess their relative contribution to smolt production and determine the effects on current stock assessment and management practices.

3. Determine the habitat requirements of returning salmon within estuaries and the environmental and physiological factors controlling successful entry into freshwater, particularly in context of environmental perturbation and advise on management requirements.

4. Investigate the thermal habitat requirements of adult salmon in freshwater and the relationship between water temperatures and spawning migration, and determine management approaches that will mitigate the impact of any changes to the freshwater environment on salmon populations.

5. Investigate whether interannual differences in the recruitment of adult salmon can be accounted for by the composition and quality of the available prey in the open ocean, and determine how results could improve stock management.

References.

Adams, N.S., Rondorf, D.W., Evans, S.D. & Kelly, J.E. (1998). Effects of surgically and gastrically implanted radio transmitters on growth and feeding behaviour of juvenile Chinook salmon. Transactions of the American fisheries Society 127, 128- 136.

Barton, B.A. & Iwama, G.K. (1991). Physiological changes in fish from stress in aquaculture with emphasis on the response and effects of corticosteroids. Annual Review of Fish Diseases 1, 3-26.

Barton, B.A., C.B. Schreck, and L.D. Barton. (1987). Effects of chronic cortisol administration and daily acute stress on growth, physiological conditions, and stress responses in juvenile rainbow trout. Diseases of Aquatic Organisms 2, 173 185.

Fairchild, W.L., Brown, S.B. & Moore, A. (2002). Effects of freshwater contaminants on marine survival in Atlantic salmon. NPAFC Technical report No. 4. 30-32.

Friedland, K.D., Reddin, D.G. & Kocik, J.F. (1993). Marine survival of North American and European Atlantic Salmon: effects of growth and environment. ICES Journal of Marine Science 50, 481-192.

Gregory, T.R. & Wood, C.M. (1999). The effects of chronic plasma cortisol elevation on the feeding behaviour, growth, competitive ability and swimming performance of juvenile rainbow trout. Physiological and Biochemical Zoology, 72(3), 286-295.

Holm, M., Holst, J.C., Hansen, L.P., Jacobsen, J.A., Ó'Maoiléidigh, N. and Moore, A. (2003). Migration and distribution of Atlantic salmon post-smolts in the North Sea and North East Atlantic. In: Salmon at the Edge (Edited by D. Mills)Blackwell Science Ltd. Oxford pp7-23.

Holst, J.C., Shelton, R., Holm, M. & Hansen, L.P. (2000). Distribution and possible migration routes of post- smolt Atlantic salmon in the north-east Atlantic. In: The Ocean Life of the Atlantic salmon: environmental and biological factors influencing survival (Edited by D. Mills) Fishing News Books, Blackwell Science Ltd. Oxford pp 65-74.

CSG 15 (9/01) 25 Project Salmonid migration and climate change DEFRA SF0230 title project code Hulme, M. & Jenkins, G.J. (1998). Climate Change Senarios for the UK: Scientific Report. UKCIP Technical Report No. 1, Climatic Research Unit, Norwich, 80 pp.

Jepsen, N., Davis, L. E., Schreck, C. B., Siddens, B. (2001). The Physiological Response of Chinook Salmon Smolts to Two Methods of Radio-Tagging. Transactions of the American Fisheries Society, 130(3), 495-500.

Martin, J.H.A. & Mitchell, K.A. (1985). Influence of sea temperature upon the numbers of returning grilse and milti-sea-winter Atlantic salmon (Salmo salar L.) caught in the vicinity of the River Dee (Aberdeenshire). Canadian Journal of Fisheries and Aquaculture Science 42, 1513-1521.

Martinelli, T.L., Hansel, H.C. & Shively, R.S. (1998). Growth and physiological responses to surgical and gastric radio transmitter implantation techniques in sub-yearling Chinook salmon (Oncorhynchus tshawytscha). Hydrobiologie 371/372, 79-87.

Moore, A. & Scott, A. (1988). Observations of recently emerged sea trout, Salmo trutta L., fry in a chalk stream, using a low light underwater camera. Journal of Fish Biology 33, 959-960.

Moore, A. Freake, S.M. & Thomas, I.M. (1990). Magnetic particles in the lateral line of the Atlantic salmon. Philosophical Transactions of the Royal Society of London B. 329, 11-15.

Moore, A. Russell, I.C. & Potter, E.C.E. (1990). The effects of intraperitoneally implanted dummy acoustic transmitters on the physiology and behaviour of Atlantic salmon parr. Journal of Fish Biology 37, 713-721.

Moore, A., Russell, I.C. & Potter, E.C.E. (1990) Preliminary results from the use of a new technique for tracking the estuarine movements of Atlantic salmon smolts. Aquaculture and Fisheries Management 21, 369- 371.

Moore, A., Potter, E.C.E. and Buckley, A.A.(1992). Estuarine behaviour of migrating Atlantic salmon smolts. In: Wildlife Telemetry. (Eds. I.G. Priede and S.M. Swift), Ellis Horwood, Chichester, pp 390-399.

Moore, A. & Potter, E.C.E. (1993). Surveying and Tracking Salmon in the Sea. Atlantic Salmon Trust Blue Book. Pitlochry, Scotland.

Moore, A. & Potter, E.C.E. (1994) The movements of sea trout smolts through the estuary of the River Avon, Southern England. Fisheries Management and Ecology 1, 1-14.

Moore, A., Potter, E.C.E., Milner, N.J. & Bamber, S. (1995). The migratory behaviour of wild Atlantic salmon smolts in the estuary of the River Conwy, North

Moore, A., Stonehewer, R., Kell, L.T., Challiss, M.J., Ives, M. Russell, I.C. Riley, W.D. & Mee, D.M. (1996). The movements of emigrating salmonid smolts in relation to the Tawe barrage, Swansea. In: Barrages: Engineering Design & Environmental Impacts. (N. Burt & J. Watts eds.) HR Walingford Ltd. John Wiley & Sons Ltd. pp. 409-417.

Moore, A. et al. (1998). The migratory behaviour of wild sea trout (Salmo trutta L.) smolts in the estuary of the River Conwy, North Wales. Aquaculture 168, 57-68.

Moore, A. et al. (1998). The migratory behaviour of wild Atlantic salmon (Salmo salar L.) smolts in the River Test and Southampton Water. Hydrobiology 371/372, 295-304.

Moore, A., Lacroix, G.L. & Sturlaugsson, J. (2000). Tracking Atlantic salmon post-smolts in the sea. In: The Ocean Life of the Atlantic salmon: environmental and biological factors influencing survival (Edited by D. Mills) Fishing News Books, Blackwell Science Ltd. Oxford pp 49-65.

CSG 15 (9/01) 26 Project Salmonid migration and climate change DEFRA SF0230 title project code Moore, A., Scott, A.P., Lower, N., Katsiadaki, I. & Greenwood, L. (2003). The effects of 4-nonylphenol and atrazine on Atlantic salmon (Salmo salar L.) smolts. Aquaculture 222, 253-263

Pankhurst, N.W. and G. Van Der Kraak. (1997). Effects of stress on reproduction and growth of fish. In: Fish stress and health in Aquaculture. (G.K. Iwama, J. Sumpter, A.D. Pickering and C.B. Schreck, Eds). Society for Experimental Biology Seminar Series, 62; Cambridge University Press, Cambridge UK. pp. 73-95

Pickering, A.D. and Pottinger, T.G. (1989). Stress responses and disease resistance in salmonid fish: effect of chronic elevation of plasma cortisol. Fish Physiology and Biochemistry, 7, 253-258.

Pickering, A.D., Pottinger, T.G., Sumpter, J.P., Carragher, J.F., Le Bail, P.Y. (1991). Effects of acute and chronic stress on the levels of circulating growth hormone in the rainbow trout, Oncorhynchus mykiss. General And Comparative Endocrinology 83, 86-93.

Potter, E.C.E., Hansen, L.P., Gudbergsson, G., Crozier, W.C., Erkinaro, J., Insulander, C., MacLean, J., O’Maolileidigh, N.S. & Prusov, S. (1998). A method for estimating preliminary conservation limits for salmon stocks in the NASCO-NEAC area. International Council for the Exploration of the Sea, CM1998/T:17.

Thorstad, E.B., Økland, F., and Finstad, B. (2000). Effects of telemetry transmitters on swimming performance of adult Atlantic salmon. Journal of Fish Biology 57, 531-535.

Stone, G.S., Tausig, H.C. & Schubel, J.R. (eds). (1998). Marine Animal Telemetry Tags. New England Aquarium, Aquatic Forum Series, Report 98-3, Boston.

Sturlaugsson, J. & Thorisson, K. (1997). Migratory pattern of homing Atlantic salmon (Salmo salar L.) in coastal waters of West Iceland, recorded by data storage tags. International Council for the Exploration of the Sea CM. 1997/CC:09.

PUBLICATIONS, REPORTS AND CONFERENCE PRESENTATIONS Scientific publications and reports

Moore, A., Lacroix, G.L. & Sturlaugsson, J. (2000). Tracking Atlantic salmon post-smolts in the sea. In: The Ocean Life of the Atlantic salmon: environmental and biological factors influencing survival (Edited by D. Mills) Fishing News Books, Blackwell Science Ltd. Oxford pp 49-65.

Holm, M., Holst, J.C., Hansen, L.P., Jacobsen, J.A., Ó'Maoiléidigh, N. and Moore, A. (2003). Migration and distribution of Atlantic salmon post-smolts in the North Sea and North East Atlantic. In: Salmon at the Edge (Edited by D. Mills)Blackwell Science Ltd. Oxford pp7-23.

Advances in Fish Telemetry. (2000). Proceedings of 3rd Conference on Fish Telemetry in Europe. (Edited by A. Moore & I. Russell). CEFAS Publications 264 p. Dare, P. & Moore, A. The impact of climate change on salmonids. CEFAS Publications. N. Lower, N., Moore, A., Scott, A.P. & Ellis, T. (2004). A non-invasive method to assess the impact of electronic tag attachment techniques on stress levels in fish. Journal of Fish Biology (In press). Anonymous (2004) SALSEA – A marine research strategy to determine key factors affecting salmon survival at Sea. NASCO IASRB.

Scientific papers submitted or in preparation.

CSG 15 (9/01) 27 Project Salmonid migration and climate change DEFRA SF0230 title project code Moore, A. & Bendall, B. Comparisons between the migratory behaviour of sea trout kelts and smolts. Journal of Fish Biology.

Moore, A. Quayle, V., Bendall, B., D. Goldsmith, D. & Bush, R. The coastal migratory behaviour of salmon and sea trout post-smolts. Journal of Fish Biology.

Moore, A., Russell, I.C., Ives, M., Lower, N. & Cook, A. Physiological and environmental cues involved in sea trout smolt migration. Journal of Fish Biology.

Moore, A. Bendall, B. & Quayle, V.A. The post-spawning movements of migratory brown trout (Salmo trutta L.). Journal of Fish Biology.

Conference presentations and posters

Invited Keynote Speaker: Moore, A. The influence of a changing environment on salmon migration 4th Telemetry Conference in Europe, Trondheim, Norway, 2001.

Paper presentation: Moore, A., Russell, I.C., & Cook, A. The movements of sea trout smolts in the estuary and coastal waters of the River Fowey. 4th Telemetry Conference in Europe, Trondheim, Norway, 2001.

Poster presentation: N. Lower, N., Moore, A., Scott, A.P. & Ellis, T. A non-invasive method to assess the impact of electronic tag attachment techniques on stress levels in fish. 5th Telemetry Conference in Europe, Ustica, Italy, 2003.

Paper presentation: Bendall, B., Moore, A. & Quayle, V.A. The post-spawning movements of migratory brown trout (Salmo trutta L.). 5th Telemetry Conference in Europe, Ustica, Italy, 2003. Please press enter

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