Results & Discussion

3. Results & Discussion

WRT surveyed 24 semi-quantitative and one quantitative sites on the River Fowey in September. Weather and general survey conditions were dry and very warm which resulted in extremely low river levels and increased water temperatures. It should also be noted that summer 2022 was the driest since 1995, as well as the second hottest year on record. As with previous years, surveyors kept a close eye on river water temperatures to ensure surveying did not proceed if water temperatures exceeded 18°C, in accordance with Environment Agency guidance.

As in previous years, the 2022 catchment survey demonstrates that the River Fowey catchment can support excellent salmonid spawning and the importance of large, main river stem and larger tributary spawning sites for salmon reproduction, whereas trout rely on important, generally smaller side tributaries. There were three excellent classification sites for salmon in 2022, along with three good sites. Salmon fry were absent from ten of the 24 sites, however, most of these sites are historically absent of salmon, mainly due to obstructions and poor or unsuitable habitat. Trout fry were far more productive with four excellent classification sites along with eight good classification sites, with only one site being absent of trout fry.

As in previous years salmon spawning was sporadic with varied results and although most of the main river sites did hold salmon fry of varying numbers some of the side tributaries also held salmon fry to excellent to poor numbers. In contrast, most of the trout fry were present in largest numbers in the tributaries of the Fowey with all of the excellent sites being within the Warleggan. A total of 390 salmon (183 in 2021) and 500 trout (688 in 2021) were caught across all sites which included the number of salmon and trout parr caught at each semi-quantitative site, but these do not have any formal classification associated.

Figure 8 Total catch for salmon and trout fry derived from semi-quantitative data (including total number of fry per survey site), River Fowey 2022

Figure 9 Semi-quantitative salmon fry classification, River Fowey 2022

Figure 10 Semi-quantitative trout fry classification, River Fowey 2022

Figure

11 Quantitative salmon fry classification, River Fowey 2022

Figure 12 Quantitative salmon parr classification, River Fowey 2022

Figure 13 Quantitative trout fry classification, River Fowey 2022

Figure 14 Quantitative trout parr classification, River Fowey 2022

Main River Fowey

Although most of the salmon spawning occurred on the main River Fowey, recruitment did vary at each site. There were two excellent classifications that were achieved at Golitha Draynes and Rivermead (31 and 24 fry, respectively). Lawarne LDAC achieved a good classification with 20 fry, Trago Two Foot achieved a fair classification with 9 fry and The Nether and DS Bodithial Bridge both achieved poor classifications with 3 and 1 fry, respectively. Both Leskernick Hill and Glynn US Parkway were absent of salmon and although this is historically the case for Leskernick Hill, as it is situated near the headwaters of the catchment, Glynn US Parkway is far lower down in the catchment. It has been noted that the habitat was potentially not optimal to hold fry at the Glynn site and more situated to parr life stage as shown in the five parr recorded at time of surveying. It would be worth considering if there was habitat more suitable to fry close to this site to see if it could perform better as hydrogeomorphological process can alter the characteristics of sites over time.

Through the Water for Growth Project several structures, such as Trekeivesteps Gauging Station and Bodmin Parkway Bridge, have undergone works to improve fish passage and it is encouraging that salmon are managing to migrate high up the main river system. However, there are still some barriers present on the main river, if solutions could be agreed upon at these sites it would potentially further improve access for more salmon to migrate higher up the system. By increasing the ability for salmon to successfully

migrate freely through the River Fowey, it is hoped more salmon fry will be recorded at sites in the upper catchment.

Trout followed a similar trend, and although no excellent sites were recorded, Leskernick Hill was the only site to achieve a good classification with 17 trout fry. The remaining sites achieved two fair, four poor and one absent classification. Usually when one species (trout or salmon) is in lower abundance the other tends to dominate and although this is the case for some sites on the main river there are some sites which have lower classifications for each. This may indicate that there is limited quality habitat available for either species to utilise and more investigation to find the limiting factors would help direct future works in the catchment.

Warleggan

Salmon fry were absent from all semi-quantitative sites on the Warleggan. This is usually the case for Castle Dewey, which historically has not produced salmon and is a tributary of the Warleggan and a smaller stream possibly suited more to brown trout. Temple Tor higher up on the river also has habitat more suited to brown trout spawning. Both Barleysplat Wood and Whiterail Bridge produced salmon fry in the 2021 surveys, albeit in low numbers but the 2022 surveys were both absent of salmon fry. Historically, both sites can be sporadic in salmon fry presence and could possibly be the fry are either displaced or there were few spawning success the previous year, so fry could be limited. Salmon were still present at both sites with parr being recorded. Trout fry abundance remained constant from 2021 to the 2022 surveys with all semi-quantitative site classifications remining the same. In contrast, Trengoffe Wood (the fully quantitative site) achieved good classifications for both salmon and trout fry with 60.07 and 22.87 fish per 100m2 respectively and 8.19 and 17.06 parr per 100m2 respectively. Although trout fry density has decreased slightly from the 2021 survey, this is likely due to the increase in salmon fry which increased from a fair to a good classification. The increase in salmon fry in 2022 is very encouraging and shows that there is optimal habitat present for all life stages from fry to parr as demonstrated in the 2021 excellent parr classification. Moreover, this site was piloted for aboricultural interventions which involved hinge cutting willow stands into the banks, creating added refuge and improving the shade regime on riffle areas by crown lifting certain trees. It appears both trout and salmon have responded well to this intervention with increases of both species and could be replicated at other sites to increase salmon recruitment. In addition, through the Water for Growth Project, work was undertaken at Trengoffe Gauging Station to increase fish passage efficiency at this site which has improved the access for salmon and other migratory species to the available habitat upstream.

St Neot

Salmon recruitment on the St Neot was relatively good with varying classifications at each site Pengelly Bridge/Kitesnest Woods was the most productive site achieving an excellent

classification with 42 fry being recorded which was also a slight increase in individuals from the 2021 surveys. Lampen Lane was the next highest producing site with a good classification and 12 salmon fry recorded and although direct comparisons with the 2021 survey are not possible as this survey followed a fully-quantitative methodology, historical data does suggest that salmon can be present in good numbers at this site. It is encouraging that salmon fry and parr are present throughout most of the length of the St Neot, which supports that fish are able to migrate freely throughout. More so, work has been done through the Water for Growth project which has improved passage at Craigshill Wood Gauging station and the removal of a large trash screen close to the village of St Neot. This would have significantly improved passage for migrating salmonids and it is hoped to be highlighted in the annual surveys going forward. Furthermore, various arboricultural interventions have been conducted on the St Neot and supported by other sites such as Trengoffe Woods on the Warleggan have shown to benefit both salmon and trout.

However, it must be noted that there is a local hatchery which do release fish into the St Neot, with these surveys conducted after stocking of fry. It is difficult to determine if the salmon fry and parr recorded are stocked fish or hatched fish from returning adults. Either way it still highlights that there is high quality habitat present along the St Neot that is being utilised by salmonid species and is not a limiting factor for recruitment. Overall, trout recruitment on the St Neot was relatively low with Carnglaze being the only site achieving a good classification with 14 fry which was an increase from the fair classification achieved in 2021. Lampen Lane, Pengelly Bridge/Kitesnest Wood and S&J all achieved fair classifications which was a decrease from the 2021 surveys. Overall, the St Neot varied in performance for both salmon and trout but does support that not only do fish have free passage to migrate the entire length of available river but there is sufficient quality habitat available for both species and highlights the St Neot being an important tributary of the Fowey catchment.

Cardinham Water

Salmon fry were present on the Cardinham Water, but recruitment varied between all three sites. US Glynn was the highest scoring site of a good classification with 15 fry being recorded and is the highest classification that has been achieved since 2018. Fletchers Bridge achieved a poor classification with two fry recorded and although this is not directly comparable to the 2021 fully-quantitative survey, both years did produce low numbers of salmon fry. Millpool was absent of salmon fry but historically has not produced fry, which could support that there is either a lack of suitable habitat for salmon or that the site is situated too high in the catchment. Through the Water for Growth Project, a number of barriers have been highlighted on the Cardinham Water which could be a limiting factor for successful spawning. Similarly to salmon, trout recruitment also varied from each site with Millpool achieving the highest classification of good (19 fry), which is the same classification as last year and historically similar to other years. Both

Fletchers Bridge and US Glynn achieved fair classifications with five and eight fry recorded respectively and is historically similar to other years classifications.

Trenant Stream, Bodithial Stream, Deviock Stream, (including Clinic Viaduct and Cabilla Wood)

A number of smaller tributaries were surveyed which usually only contain trout did produce varying results. The Trenant Caravan Park achieved a poor classification with two fry being recorded, a slight decrease from the 2021 surveys, however, five salmon parr were recorded. The site provides sub-optimal fry habitat, there is limited land on this particular landowners river section. It would benefit including a new survey site above this particular site to determine how far salmon are reaching the length of the Trenant Stream. Cabilla Wood achieved a poor classification with one salmon fry being recorded, and although this is a smaller stream which is more suited to trout, it is easy for salmon to access if not able to access quality habitat on the main river. Historic data does support that small numbers of salmon fry do get recorded on this river, which suggests that if this river is utilised by salmon and it is likely that it is one of a pair of spawning fish due to the few salmon being present. All three remaining sites; Clinick Viaduct, Bodithial Stream and Deviock Stream, were all absent of salmon fry which is usually the case for these where historic data shows no salmon ever recorded here, apart from Deviock Stream which did have salmon fry present in 2011, 2012 and 2013 but not since. Although these three sites did not produce any or large numbers of salmon, all three produced relatively good classifications of trout with one excellent and two good classifications being produced which again follows the same trend as historic data.

In addition, through the Water for Growth Project, work has been undertaken on the Trenant to improve fish passage through the removal of a dilapidated pipe culvert bridge located in the upper reaches of the river. Although it is unlikely salmon will spawn this far upstream, this will help other migratory species and help to re-naturalise this river section. Trout fry recruitment was good on the Trenant Stream with both the Caravan Park and Pipe Bridge site achieving good classifications with 18 and 21 fry recorded, respectively. As mentioned, the very most upper reaches of the river are more suited to trout but does not mean that salmon will not migrate just below this section where habitat is more varied.

4. Recommendations

The WRT EF surveys are undertaken to gain an understanding year on year recruitment of salmon and trout, but they have slightly different habitat preferences, and one species will often dominate over the other where the other has limited or no presence. There will be natural annual variations in populations, and this is to be expected depending on the success of recruitment of a species. Therefore, management strategies need to be considered for each species, hence a conservation strategy for both salmon and trout.

The strategy for restoration and conservation of sites suggested here broadly follows the “Defend, Repair, Attack” (DRA) concept (Table 10) developed by Ronald Campbell of the Tweed Foundation, and has, in the past, been applied locally in the Exe catchment by the River Exe and Tributaries Association project. The fry productivity of the rivers is assessed by a combination of historic semi-quantitative electric fishing results. These results are then applied in context of existing plans (e.g. Salmon Action Plan, habitat walkover surveys and genetic data) to produce assessments and recommendations for each subcatchment of the river. These sub-catchments are classified according to three levels: Defend, Repair, and Attack.

Despite the DRA strategy being a useful tool to identify and prioritise works in catchments, the requirements of waterbodies can rarely be quite so clear cut. The coloured arrow in Table 10 represents the continuum of the three strategies and the goal for each waterbody; to move all the Tamar sites from their current position to somewhere in the Defend category, or to ensure they remain in this status if fish stocks are already good.

5. Acknowledgements

Westcountry Rivers Trust would like to thank all landowners who gave us permission to undertake surveys on the River Fowey catchment. We would also like to thank the Fowey Rivers Association and the Environment Agency.