Results of a survey of the freshwater salmonid habitat. of sub-reaches within the Owenmore River System

Transcription

1 Results of a survey of the freshwater salmonid habitat of sub-reaches within the Owenmore River System 2007 By Elvira de Eyto, Russell Poole, Joseph Cooney, Davy Sweeney and Michael Hughes A report prepared for Shell E&P Ireland Limited by The Marine Institute and the North Western Regional Fisheries Board The North Western Regional Fisheries Board Bord Iascaigh Reigiúnach an Iarthuaiscirt

2 Executive Summary Planning permission was granted during 2004 by Mayo County Council for the development of a gas terminal at Bellagelly South, Bellanaboy Bridge, and associated peat deposition site at Srahmore and Attavally, Bangor-Erris, Co Mayo. A condition (Condition No. 29 of Pl ) in the subsequent An Bord Pleanála decision relating to the necessity for a baseline salmonid study was included in a list of conditions for the development. A survey in 2007 followed on from those carried out in 2004 and 2005, and included fish stock assessment of the Bellanaboy subcatchment and the littoral zone of Carrowmore Lake in the vicinity of Bellanaboy. Habitat type was classified and quantified using aerial photographic surveys and a Geographic Information System (GIS) was used in analysis of this dataset. A combination of habitat quantification and estimation of fish biomass has allowed for the estimation of the potential smolt output for the Bellanaboy River and downstream lacustrine habitat. Salmon fry (0+ age) were recorded at all 10 sites in the survey of the Bellanaboy subcatchment, which is a significant improvement over Trout were also recorded at all 10 sites. 0+ salmon densities increased at all sites except site 5 over trout densities increased at 5 sites over 2005 levels. Numbers of salmon and trout were generally low in the seine net catches in Carrowmore lake, where the most abundant species in 2007 was 3-spine stickleback. Standing crop estimates for 0+ and 1+ salmon were and 1177 fish for the Bellanaboy subcatchment, and trout for the same area. The 0+ salmon estimate is the highest recorded in the three years this survey has been carried out and is almost three times higher than the 2005 estimate. These high numbers will hopefully be reflected in a large smolt run in CONTENTS 1. Introduction 1 2. Site Description 1 3. Fish Stock Survey Methods Results Bellanaboy Carrowmore lake 6 4. Production Estimate Discussion Acknowledgements References 25

3 1. INTRODUCTION Planning permission was granted during 2004 by Mayo County Council for the development of a gas terminal at Bellagelly South, Bellanaboy Bridge, and associated peat deposition site at Srahmore and Attavally, Bangor-Erris, Co Mayo. A condition (Condition No. 29 of Pl ) in the subsequent An Bord Pleanála decision relating to the necessity for a baseline salmonid study was included in a list of conditions for the development. The North Western Regional Fisheries Board (NWRFB) and the Marine Institute (MI) were contracted by Shell E&P Ireland Limited to undertake a baseline assessment of the salmonid habitat in the Owenmore catchment, adjacent to the proposed development area. The scope and degree of monitoring for the study was agreed during consultations with Shell in Further agreement in relation to an annual audit of the fish stocks pre, during and post construction phase of the development was also reached. This report outlines the results of the 2007 audit surveys of the Bellanaboy River and Carrowmore Lake, and their subsequent analysis with reference to those undertaken during 2004 and Owing to inclement weather conditions in 2007, the survey was restricted to the sites in the Bellanaboy subcatchments and in Carrowmore lake. It was not possible to fish the larger Munhin and Owenmore rivers, as water levels were constantly high throughout the season. 2. SITE DESCRIPTION The Shell gas terminal development is located in north County Mayo in the Owenmore catchment. The development consists of the construction and operation of a gas terminal which is located principally in the Bellanaboy sub-catchment of Carrowmore Lake (Figure 2.1). A peat deposition site is located to the south approximately 12 km away. The peat deposition area is a significant undertaking in its own right and is located adjacent to sensitive fisheries habitat of the Munhin and Owenmore Rivers. Both Carrowmore Lake and the Owenmore River are renowned for the quality spring salmon, grilse and sea trout angling that they provide, as a recently produced Fisheries Catchment Management Plan has examined (NWRFB 2004). The construction of this terminal and peat deposition area represents a considerable industrial development in a sensitive location from the perspective of the fisheries resource located in close proximity to it. The Bellanaboy River is the largest sub-catchment of Carrowmore Lake and contains important spawning and nursery areas salmon and trout. The river also hosts a population of Brook Lamprey Lampetra planeri, an Annex species under the EU 1

4 Habitats Directive. Carrowmore Lake is a candidate Special Area of Conservation. The Munhin River is the outflow river from Carrowmore Lake and consists of deeper, low gradient channel that is more significant in terms of migrating salmonids rather than a productive juvenile habitat, although the presence of indigenous brown trout and eel populations would also be expected. It is occasionally fished by anglers and ownership is held privately Bellanaboy Carrowmore lake Munhin Owenmore 2007 Figure 2.1. Shell site survey locations in the Carrowmore sub-catchment of the Owenmore River System, NW Mayo. 2

5 3. FISH STOCK SURVEY 3.1 Methods A description of the work programme, details of the site, and an introduction to the project methodology can be found in Poole et al. (2004; 2005). The sites surveyed in each year changed somewhat (Fig. 2.1) with the largest number of sites being surveyed in In 2007, 10 sites in the Bellanaboy catchment and 5 sites in Carrowmore lake were surveyed (Table 3.1). Table 3.1. Site locations of fishing surveys in the Bellanaboy River and Carrowmore Lake, 2007 Method Site number Site name X coord Y coord Electrofished (backpack) 1 Knocknaleabhar, Miungerroon North Knocknaleabhar, Miungerroon North, Aghhos Aghoos u/s Bellinaboy bridge Muingingaun d/s Bellinaboy bridge u/s of shell security cabin Muigingaun beside carey's house Ruddy's farm house Muingingaun Meenanark bridge Draft net 1 Bungurra south side Bungurra north side South of pier Paradise bay In Bellanaboy river Electrofishing The core task to be completed during the 2007 audit was for a revisiting of sites electro fished during 2004 and 2005, in order that a recalculation of the potential smolt output from the catchment could be made and to assess the level of spawning and recruitment in the Bellanaboy river. All of the sites surveyed during 2004 were re-fished between the 27 th September and the 8 th October Quantitative electrofishing was used to assess fish stocks in the stream and river sites. All sites were electro-fished from bottom to top, three times, using a 12-volt Safari Research 550D backpack electrofisher. The three fishing depletion method was used at each site with stunned fish being netted out and retained in bins of freshwater. All the catches from each fishing were held separately in the bins of water, until all 3

6 fishings at each site were complete. The fish were then identified, counted and measured, (fork length ± 1mm) and returned to the water. The length of each site, and five random widths, were measured, to quantify the area fished. Length frequency distributions of salmon and trout were determined for all the sites fished. The length range for each age class was estimated from length frequency histograms. Salmon and trout population estimates and population densities (± 95% C.I.) for 0+ and 1+ age classes were calculated for each site using the Zippin method (1958). Minimum numbers (n/m 2 ) were used where it was not possible to obtain an estimated density. Seine Netting The lake littoral area was also surveyed again using beach seine netting in order to provide further quantification of the utilisation of littoral lakeshore area by juvenile salmonids, for which only limited data is generally available. Five draft net locations were fished on the 23 October Netting took place during daylight hours. The net was 60m long and 3m deep and was constructed from 9mm (6mm bar) No 210/24 knotless nylon. There was a 'bulge' built into the middle section. The top rope was 10mm nylon with 100mm floats fitted at 0.5 metre intervals. The bottom rope was 0.5kg/m lead rope. The net was set by loading onto a deck fitted to the stern of a lake boat. One operator remained on the shore holding one end of a 10m rope attached to the head rope of the net. The boat was then rowed in a semi-circle allowing the net to unfurl over the transom. The distance rowed was judged so that the end of the net was approximately 10m from the shore. Both ends of the net were then hauled together, tightening the net into a circle and hauled to the shore. The net was hauled slowly, with frequent pauses, to allow water to pass through the fine mesh without the bottom of the net rising to allow fish to escape. The fish were eventually gathered into the bulge of the net in shallow water. Fish were then transferred to bins for identification and measurement. The full sweep of the net enclosed approximately 950 m 2. It is believed that fish tend to ignore a boat until it comes within 2 or 3 m (Pierce et al. 1990), so we assumed that evasion or other movements into or out of the enclosed area during setting of the seine were negligible. Catch per unit effort (CPUE) was calculated as the total number of fish of each species per haul of the net at each site and inshore fish 4

7 density was calculated as the number of fish divided by the total area covered by the net when fully deployed (950m 2 ) (Matthews et al. 1997). 3.2 Results In addition to salmon Salmo salar, and brown trout, Salmo trutta, four other fish species were recorded. These were three-spine stickleback Gasterosteus aculeatus, minnow Phoxinus phoxinus, eel Anguilla anguilla, and brook lamprey Lampetra planeri. Summary statistics for the lengths of fish captured are given in Appendix I Bellanaboy River Summary length statistics are presented for all fish species captured in Appendix I and length frequency distributions showed two age classes for salmon (Figure 3.1) and three age classes for trout (Figure 3.1) and the length at age breakdowns are given for salmon and trout in Table 3.2. These length ranges were used for separating each age class when estimating population density and biomass. Salmon Table 3.3 gives the catch and density data for salmon and also presents the details for each fishing. Salmon were recorded at all sites. Salmon fry (0+ age) were recorded at all sites in the survey, which is a significant improvement over 2005, when they were absent from 3 sites. 0+ densities ranged from 0.05/m 2 to 0.53 /m 2. One year old (1+ age) salmon were absent from four sites, but were present at relatively low densities at the others, ranging from 0.01 /m 2 to 0.06 /m 2. Trout Table 3.4 gives the catch and density data for trout and also presents the details for each fishing. Trout were recorded at all 10 sites. Trout fry (0+ age) densities were highest at sites 1, 8 and 10 and lowest at sites 4, 6 and 7. The highest density was recorded at site 10 (0.79 fish m -2 ). Densities of 1+ trout were generally low, ranging from 0.01 fish/m 2 to 0.05 fish/m 2. Two year old trout were recorded at six sites, which was significantly more sites than in 2005 (2 sites). The length frequency distribution (Fig. 3.1) confirms a fry dominated population typical of a small troutspawning stream. It is likely that as the trout grow larger there is a movement downstream into deeper pools and Carrowmore Lake. Other Species Brook lamprey, three-spine stickleback, eel and minnow were recorded in the Bellanaboy River (Table 3.5). Figures 4.1 & 4.2 show the length frequency distributions and the summary statistics are given in Appendix I. 5

8 Comparison between 2004, 2005 and 2007 The densities of 0+ and 1+ salmon are given in Table 3.6 and Figure 3.3 for 2004, 2005 and densities increased at all sites except site 5 over densities were, on average, 0.12/m 2 in 2004, 0.11/m 2 in 2005 and increased to 0.23/m 2 in densities stayed very similar to those of 2004, with an average of 0.04/m 2 across all sites in 2004 and In contrast, 2005 had slightly lower average density of 0.02/m 2. The densities of 0+ and 1+ trout are given in Table 3.7 and Figure 3.3 for both 2004 and densities increased at 5 sites over 2005 levels. 0+ trout densities were on average 0.38/m 2 in 2004, 0.35/m 2 in 2005 and 0.29/m 2 in While 1+ densities were roughly similar to those found in 2005 and 2004 (average densities across sites were 0.09/m 2 in 2004, 0.02/m 2 in 2005 and 0.03/m 2 in 2007), it is perhaps more significant that like the 0+ trout and 0+ salmon, 1+ trout were found at all 10 sites Carrowmore Lake Beach seine samples were taken on Carrowmore L. in October 2007, which was somewhat later than in Three species of fish were recorded, salmon (Salmo salar), trout (Salmo trutta) and three-spine stickleback (Gasterosteus aculeatus). Minnow were not recorded on this occasion. Summary catch data for 2007 is presented for each species captured in the beach seine in Table 3.8 and length frequency distributions in 3.4. Summary length statistics are given in Appendix I. The catch per unit effort and the estimated density (no./m 2 ) are given in Table 3.9 along with those of 2004 and 2005 for comparison. Numbers of salmon and trout were generally low in the seine net catches. The most abundant species in 2007 was 3-spine stickleback. Density/m 2 of all three species were roughly similar to those recorded in 2005, although there were slightly more trout. The main conclusion to be drawn is that the littoral zone continues to be inhabited by salmonids, which is reassuring. Although the overall numbers of salmonids obtained from the seine netting passes were relatively low when compared with Mathews et al. (1997), the Carrowmore Lake basin is principally a large extensive littoral zone in its own right. Therefore, when the whole extent of the lake littoral area is considered it is possible that it provides a significant proportion of the productive habitat for juvenile salmonids relative to the total habitat area generally available in the catchment. 6

9 Table 3.2. Lengths for each age class of trout and salmon at each site on the Bellanaboy River, Carrowmore system for the shell survey in Site Salmon 0+ (cm) Salmon 1+ (cm) Trout 0+ (cm) Trout 1+ (cm) Trout 2+ (cm) 1. Knocknaleabhar, Miungerroon North <8.9 >9.0 < > Knocknaleabhar, Miungerroon North <8.9 >9.0 <8.9 >9.0 na 3. Aghoos <8.9 >9.0 < > u/s Bellinaboy bridge <8.9 >9.0 < > Muingingaun <8.9 na < > d/s Bellinaboy bridge <8.9 >9.0 < > u/s of shell security cabin <8.9 >9.0 < > Muigingaun beside carey's house <8.9 >9.0 < na 9. Ruddy's farm house Muingingaun <8.9 na < > Meenanark bridge <8.9 na < na 7

10 Table 3.3 Catches of Salmon for each fishing and population density (+/- 95%CI) estimate for each site on the Bellanaboy River in the Carrowmore system for the shell survey, Site Area Age Class Count 1 Count 2 Count 3 Pop. Den No. / Sq.m +/- 95% CI S 0+* S 1+* S S 1+* S S 1+* S S S S S S 1+* S S 1+* S S S S S 0+* S *Refers to sites where it was only possible to get a minimum population density per m 2 8

11 Table 3.4. Catches of trout for each fishing and population density (+/- 95%CI) estimate for each site on the Bellanaboy River, in the Carrowmore system, Site Area Age Class Count 1 Count 2 Count 3 Pop. Den No. / Sq.m +/- 95% CI T T 1+* T 2+* T 0+* T 1+* T T T T 2+* T T T 2+* T T 1+* T T 0+* T 1+* T 2+* T 0+* T 1+* T 2+* T T 1+* T T T 1+* T 2+* T T 1+* T * Refers to sites where it was only possible to get a minimum population density per m 2 9

12 Table 3.5. Estimates of Lamprey, Stickleback, Eel, Minnow for 10 sites on the Bellanaboy river electrofished in Site number Lamprey Stickleback Eel Minnow 1 Pop. Den No. / Sq.m /-95% CI Min Est 2 Pop. Den No. / Sq.m /-95% CI Min Est 3 Pop. Den No. / Sq.m /-95% CI Min Est 4 Pop. Den No. / Sq.m /-95% CI Min Est Pop. Den No. / Sq.m /-95% CI Min Est Pop. Den No. / Sq.m /-95% CI 0.31 Min Est Pop. Den No. / Sq.m /-95% CI Min Est Pop. Den No. / Sq.m /-95% CI 0.41 Min Est 9 Pop. Den No. / Sq.m /-95% CI 2.46 Min Est Pop. Den No. / Sq.m /-95% CI 0.12 Min Est 10

13 Table 3.6. Comparison of 2004, 2005 and 2007 salmon densities in the Bellanaboy River Site Age No/m 2 +/- 95% ci No/m 2 +/- 95% ci No/m 2 +/- 95% ci 1 S S S S S S S S S S S S S S S S S S S

14 Table 3.7. Comparison of 2004, 2005 and 2007 trout densities in the Bellanaboy River Site Age No/m 2 +/- 95% ci No/m 2 +/- 95% ci No/m 2 +/- 95% ci 1 T T T T T T T T T T T T T T T T T T T T

15 Table 3.8. Survey results of draft netting on Carrowmore, October Site GPS GPS Species Age Total Number Length Salmon Salmon 1+ 2 >13.0 Trout <9.3 Trout Stickleback Trout 0+ 1 <9.3 Trout Stickleback Salmon 0+ 7 <8.2 Salmon 1+ 3 >8.3 Trout 0+ 8 <8.7 Trout 1+ 5 <13.2 Trout 2+ 3 >13.3 Stickleback Salmon 1+ 5 >10.8 Trout Stickleback Salmon 1+ 3 >11.3 Trout Stickleback 1 13

16 Table 3.9. Catch per unit effort (CPUE) and estimated density (No./m 2 ) of fish species captured in Carrowmore lake, 2004, 2005 and Species Number of hauls CPUE Density No./m 2 September 2004 Salmon Trout Stickleback Minnow November 2004 Salmon Trout Stickleback July 2005 Salmon Trout Stickleback Minnow October 2007 Salmon Trout Stickleback

17 Bellanaboy Salmon Number of Fish Length Interval (cm) Bellanaboy Trout Number of Fish Length Interval (cm) Bellanaboy Eel Number of Fish Length Interval (cm) Figure 3.1. Length frequency distributions for salmon, trout and eel in the Bellanaboy sub-catchment,

18 Bellanaboy Stickleback Number of Fish Bellanaboy Minnow 30 Number of Fish Length Interval (cm) Length Interval (cm) Bellanaboy Lamprey Number of Fish Length Interval (cm) Figure 3.2. Length frequency distributions for stickleback, minnow and lamprey in the Bellanaboy sub-catchment,

19 fish per m2 fish per m Salmon densities/m Site 1+ Salmon densities/m Site fish per m 2 fish per m Trout densities/m Site 1+ Trout densities/m Site Figure 3.3. Salmon and trout 0+ and 1+ densities from 10 sites in the Bellanaboy river in 2004, 2005 and

20 Carrowmore Lake Salmon 4 Number of Fish Length Interval (cm) Carrowmore Lake Trout Number of Fish Number of Fish Length Interval (cm) Carrowmore Lake Stickleback Length Interval (cm) Figure 3.4. Length frequency distributions for salmon, trout and stickleback in Carrowmore Lake,

21 4. PRODUCTION ESTIMATE Electrofishing surveys are usually carried out to determine juvenile salmonid stock levels throughout a catchment. Comparisons of densities can be made between sites within the catchment and with sites surveyed in other systems to assess the status of the stocks. However, this type of information provides little indication of the relative importance of individual sub-catchments within the system in terms of juvenile production. The potential contribution of any sub-catchment will largely be dictated by its size, suitability for spawning and nursery function together with the actual stock densities recorded. As representative sites within typical habitat types, or zones, were electrofished in the Bellanaboy, it was possible to estimate total juvenile salmonid production for the system in 2007, and compare that with values calculated for 2004 and The possibility that movement of fish occurs between the river and Carrowmore Lake, particularly at the late 0+ age, makes it difficult to carryout accurate estimates of smolt production. Details of the methodology for the calculation of the production estimates for the Bellanaboy catchment can be found in Poole et al. (2004). In summary, fish densities from electrical fishing surveys were multiplied by area estimates quantified from the Fisheries GIS providing a production estimate in numbers of 0+ and 1+ salmon and trout for the fluvial habitat in the Bellanaboy catchment. Fluvial habitat was stratified into stream units based on a combination of stream order and gradient and after visual assessment of the river was carried out. Average fish densities from each electrical fishing site (for production areas with greater than one site) were allocated to each production area as appropriate (Figure 4.1). There were small differences in calculations between 2005 and 2007, in particular, 2007 does not include an estimate for area 4, as it was not fished, but it does include a salmon estimate for area 5, which was not included in 2005 as no salmon were recorded in that year. However, we did find salmon in area 5 in Table 4.1 quantifies the habitat area available for the salmonid production estimates in the Bellanaboy catchment. The electrical fishing sites used for the quantification of the salmon and trout estimates are also indicated. Calculation of the wetted area for catchment tributaries was obtained from shape files from the aerial photography and also from a national study (McGinnity et al. 2003). These areas are identified in Figure 4.1. Figure 4.2 contains a breakdown of the production areas within the Bellanaboy catchment, including the location of the electrical fishing sites referred to in table 4.1. A breakdown of the standing crop estimates for the catchment, by species and by year class, can be found in Tables 4.2 to 4.6. Table 4.7 provides a comparison of the total standing crop estimate for 2004, 2005 and Table 4.8 provides the results of the smolt production estimate for the upper catchment during 2005, 2006 and Values for the upper catchment are calculated by assuming a survival rate of 27.5% for 1+ parr found in area 1, 2, 3 and 5 of the Bellanaboy catchment of the preceding year. A modelled estimate obtained for the same area in McGinnity et al. (1999), is also included. 19

22 Due to the higher fish densities recorded during the electrical fishing surveys in 2007, the relevant production estimates are significantly higher than those obtained for 2005, but are still lower than those calculated for However, it should be noted that the very high production estimate of 0+ salmon in 2007 should manifest itself in high numbers of 1+ fish in 2008, and subsequently high smolt production for the system in Table 4.1. Quantification of the habitat in the Bellanaboy sub-catchment (2007) Area trout Site ID Area salmon Site ID Location (m²) (m²) Area 1 (Muingerron North) Area 2 (Aghoos - Bellanaboy) ,3,4,6,7, ,3,4,6,7, Area 3 (Muingingaun) ,8, ,8,9 Area 4 (Below Sheep Bridge) n.a n.a. Area 5 (Muingerron South) Total Figure 4.1. Electrical fishing site locations including identification of the production area and models used in estimates. 20

23 Figure 4.2. The extent of the habitat designated for salmon and trout production in the Bellanaboy sub-catchment. This map was drawn in 2005, when it was thought that site 10 (area 5) was not a salmon production area. This was found to be untrue in 2007, so area 5 was included in salmon estimates for

24 Table 4.2. Standing crop estimates of 0+ salmon in the Bellanaboy sub-catchment, using 2007 electrofishing data. Location Area (m²) Density (no. fish/m²) Estimate O+ (No.) Area 1 (Muingerron North) Area 2 (Aghoos - Bellanaboy) Area 3 (Muingingaun) Area 4 (Below Sheep Bridge) Area 5 (Muingerron South) Table 4.3. Standing crop estimates of 1+ salmon in the Bellanaboy sub-catchment, using 2007 electrofishing data. Location Area (m²) Density (No. fish/m²) Estimate 1+ (No.) Area 1 (Muingerron North) Area 2 (Aghoos - Bellanaboy) Area 3 (Muingingaun) Area 4 (Below Sheep Bridge) Area 5 (Muingerron South) Table 4.4. Standing crop estimates of 0+ trout in the Bellanaboy sub-catchment, using 2007 electrofishing data. Location Area (m²) Density (No. fish/m²) Estimate 0+ (No.) Area 1 (Muingerron North) Area 2 (Aghoos - Bellanaboy) Area 3 (Muingingaun) Area 4 (Below Sheep Bridge) Area 5 (Muingerron South)

25 Table 4.5. Standing crop estimates of 1+ trout in the Bellanaboy sub-catchment, using 2007 electrofishing data. Location Area (m²) Density (No. fish/m²) Estimate 1+ (No.) Area 1 (Muingerron North) Area 2 (Aghoos - Bellanaboy) Area 3 (Muingingaun) Area 4 (Below Sheep Bridge) Area 5 (Muingerron South) Table 4.6. Standing crop estimates of 2+ trout in the Bellanaboy sub-catchment, using 2007 electrofishing data. Location Area (m²) Density (No. fish/m²) Estimate = 2+ trout (No.) Area 1 (Muingerron North) Area 2 (Aghoos - Bellanaboy) Area 3 (Muingingaun) Area 4 (Below Sheep Bridge) Area 5 (Muingerron South) Table 4.7. A comparison of standing crop estimates for trout and salmon in the Bellanaboy sub-catchment, excluding lower gradient habitat below Sheep Bridge, during 2004 and 2005 (Area 1,2, 3 and 5). Year Sal. 0+ Sal. 1+ Trout 0+ Trout 1+ Trout =

26 Table 4.8. Salmon smolt production estimates for the upper Bellanaboy subcatchment using 1+ fish estimates from 2004, 2005 and 2007 and assuming a survival of 27.5%. Location McGinnity et al. Upper Bellanaboy Discussion Carrowmore Lake is an internationally renowned spring salmon and grilse fishery. The construction of a major industrial enterprise within its catchment area promoted the current study, which is funded by Shell E&P Ireland, so that a better understanding of the temporal and spatial dynamics of the fisheries resource in the areas adjacent to the development could be undertaken. This report covers sampling undertaken in 2007 and is a follow-on from the surveys reported on in 2004 and Assessing the productive capacity of any catchment of significant size is confounded by various dynamics including the extent of the annual spawning escapement, recruitment success for particular species and year classes, and habitat related aspects such as water quality, flood events and seasonal droughts. The movement of fish stocks in and out of the study reach can also confound our understanding of the relative importance of sub-reaches within large catchments which may contain both lacustrine and fluvial habitat areas. This report goes some way towards answering and quantifying these questions for the purposes of providing a comprehensive assessment and baseline study of the fisheries adjacent to the proposed gas terminal. The significantly higher salmon fry densities recorded in the Bellanaboy catchment during 2007 when compared with 2004 and 2005 is very reassuring. Recorded densities were almost double those recorded in 2004 and treble those recorded in We would assume that this should be evident in higher number of 1+ fish in 2008, and hence a high smolt output in As we are missing data from 2006, it is difficult to calculate survival of salmon between 0+ and 1+ age classes. Survival of fry to parr was approximately 12 % which is significantly lower than that recorded in the Srahrevagh river in the neighbouring Burrishoole catchment in 2002/2003 (de Eyto. pers. comm). Nevertheless, even presuming this low figure of 12 % and applying it to the data, we would assume a 1+ density of 1428 in 2008 and a potential smolt output of 392 in While this would be higher than the previous two years, it is nevertheless still significantly lower than that predicted for 2005, and every effort must be made to ensure the continued successful spawning and recruitment of salmon in the upper Bellanaboy catchment. 24

27 The seine netting survey in Carrowmore Lake was also completed during 2007 and several new areas were fished. Although 2007 densities have again proved lower than reported for studies carried out in the littoral zones of other lakes, the extensive littoral area in Carrowmore Lake ensures that the total likely smolt output is large when compared with the river habitat in the catchment. The opportunity to carry out stock assessment in the lower gradient habitat, in the Munhin River and the Bellanaboy catchment in 2005 provided useful information and it was unfortunate that we were unable to resurvey them in While the quantification value of the electrofishing results from these bigger sites is low, they are useful to confirm large of small (or absent) numbers of age classes marks the third year of these surveys, and it is anticipated that this annual assessment will continue for several more years in order to fully quantify the productive capacity of the fisheries resource in this catchment. This will be particularly informative given the drift net fishing ban implemented in 2007, which should theoretically mean that more adults can return to spawn. This should be evident in high numbers of 0+ fish in 2008, and hence higher smolt production capacity in However, this can only happen if there is suitable spawning and nursery habitat in the streams and rivers. Therefore, this baseline data collected since 2004 will prove very valuable is assessing how much more smolt production the catchment can sustain. It will also provide a valuable support and source of information for managers from the environmental perspective, especially during the ongoing construction and subsequent operation of the Shell development in to the future. Fish surveys provide one biotic index for assessing the ecological quality of river systems, and the results presented here indicate that the quality in the Bellanaboy catchment remains high enough to support populations of salmon and trout at the current time. The increase in the 0+age salmon was also encouraging. 6. Acknowledgements The authors would like to acknowledge the staff of the North Western Regional Fisheries Board and the staff and bursary students of the Marine Institute for their assistance with the surveys and Compass Informatics for the provision of the aerial photography and wetted area analysis. 7. References Dillane, M., de Eyto, E., O'Hea, B., Poole, R. & Whelan, K. (2004). Electrofishing survey of the Newport, Owengarve, Owenmore, Owenduff, Glenamoy and Carrowmore systems 2002, 2003 & 2004, with reference to previous 25

28 surveys. Internal Report to the North Western Regional Fisheries Board. 129pp. Matthews, M.A., Poole, W.R., Dillane, M.G. & Whelan K.F.. (1997). Juvenile recruitment and smolt output of brown trout (Salmo trutta L.) and Atlantic salmon (Salmo salar L.) from a lacustrine system in western Ireland. Fisheries Research, 31; McGinnity, P., O Hea, B., Gallagher, T., Mills, P., Steinberg, H., Fitzmaurice, P., Delanty, K., Ó Maoileidigh, N., Mitchell, S., & Kelly, A. (1999). A GIS supported estimate of natural Atlantic Salmon smolt production for the river catchments of northwest Co. Mayo, Ireland. MRM Final Report for Contract No. 97.IR.MR.015. McGinnity, P., Gargan, P., Roche, W., Mills, P. & McGarrigle, M. (2003). Quantification of the freshwater salmon habitat in Ireland using data interpreted in a GIS platform. Irish Freshwater Fisheries, Ecology and Management Series No.3., ISSN , Central Fisheries Board. NWRFB, (2005). An examination of the causes and factors related to the recent eutrophication of Carrowmore Lake. Internal Report, Ballina. O Grady, M A review of fish stocks in Lough Conn 1978 to Dublin. Central Fisheries Board. Pierce, C.L., Rasmussen, J.B. & Leggett, W.C., (1990). Sampling littoral fish with a seine: Corrections for variable capture efficiency. Can. J. Fish. Aquat. Sci., 47: Poole, R., Kennedy, B., O'Hea, B. & Dillane, M. (2004).A baseline survey of the freshwater salmonid habitat of sub-reaches within the Owenmore River System. North Western Regional Fisheries Board, Ballina. Commissioned Report by Shell E&P Ireland Ltd. Poole, R., de Eyto, E. Kennedy, B. and Dillane, M. (2005). Results of a survey of the freshwater salmonid habitat of sub-reaches within the Owenmore River system. North Western Regional Fisheries Board, Ballina. Commissioned Report by Shell E&P Ireland Ltd. Zippin, C. (1958). The removal method of population estimation. J. Wildl. Mgmt., 22;

29 Appendix 1. Lengths of all fish species captured in the Bellanaboy River and in Carrowmore Lake, Salmon Trout Stickleback Minnow Lamprey Eel Bellanaboy n Mean Median Min Max StdErr Carrowmore n Mean Median Min Max StdErr