Beach seining using a 30m fine-mesh net to capture fish in littoral areas

Transcription

1 Preliminary Synopsis of the WFD Surveillance Monitoring Fish Stock Surveys at selected Transitional Water Bodies in the Eastern River Basin District, October Introduction Fish stock surveys were conducted on the Avoca Estuary, Broad Lough, Broadmeadow Estuary, Rogerstown Estuary, Upper Liffey Estuary, Lower Liffey Estuary and the Tolka Estuary in the Eastern River Basin District (ERBD), as part of the programme of surveillance monitoring for the Water Framework Directive, between the 4 Th and the 15 Th of October 2010 (Table 1). Table 1. Transitional water bodies surveyed in the ERBD, 4 th to 15 th of October Transitional Water Body Date of survey Avoca Estuary 04/10/2010 to 05/10/2010 Broad Lough 05/10/2010 to 07/10/2010 Broadmeadow Estuary 07/10/2010 to 08/10/2010 Rogerstown Estuary 11/10/2010 to 12/10/2010 Liffey Estuary, Upper 12/10/2010 to 14/10/2010 Liffey Estuary, Lower 12/10/2010 to 15/10/2010 Tolka Estuary 12/10/2010 to 15/10/ Methods Current work in the UK indicates the need for a multi-method approach (using various ting techniques) to sampling fish in estuaries. This approach has been adopted by the Research and Development section of Inland Fisheries Ireland as the standard method for sampling fish in transitional waters for the Water Framework Directive. Sampling methods include: seining using a 30m fine-mesh to capture fish in littoral areas ing ( m s) in open water areas s set overnight in selected areas 1.3 Results A total of 30 fish species (sea trout are included as a separate variety of trout) were recorded in the seven water bodies surveyed within the ERBD during The total number of each fish species captured with each sampling technique is given for each water body surveyed in Tables 2 to 5. 1

2 1.3.1 Avoca Estuary The Avoca Estuary (Plate 1) is located in Arklow, Co. Wicklow. It is situated within an industrialised area and has banks which are either walled, or are steep with heavy tree cover. As a result, access for beach seining was quite difficult. A total of 11 fish species (sea trout are included as a separate variety of trout) were recorded in the Avoca Estuary during the WFD survey in 2010 (Table 2). Flounder (97) was the most abundant species, followed by thick lipped grey mullet (31) and sand goby (21). Plate 1. Hauling a in the Avoca Estuary Broad Lough Broad Lough is located just north of Wicklow Town in Co. Wicklow. It can be divided into two distinct sections. The upper section is relatively shallow and free of anthropogenic changes, whilst the lower section has been modified to accommodate small and large boat traffic. A total of 16 fish species (sea trout are included as a separate variety of trout) were recorded in Broad Lough during the WFD survey in 2010 (Table 2). Sand goby (175) was the most abundant species, followed by flounder (60) and sand smelt (52) Broadmeadow Estuary Broadmeadow Estuary (Plate 2) is located between Swords and Malahide in North Co. Dublin. The entire estuary is shallow with firm, gently sloping shores. A total of 12 fish species were recorded in 2

3 Broadmeadow Estuary during the WFD survey in 2010 (Table 3). Sand goby (1,755) was the most abundant species, followed by sprat (139) and flounder (29). Plate 2. Deploying a beam in Broadmeadow Estuary Rogerstown Estuary Rogerstown Estuary is located between Rush and Donabate in north Co. Dublin. A total of 18 fish species were recorded in Rogerstown Estuary during the WFD survey in 2010 (Table 3). Sand goby (950) was the most abundant species, followed by lesser sand eel (87) and thick-lipped grey mullet (40) Liffey Estuary, Upper and Lower The Liffey Estuary is located in Dublin City centre and extends from Islandbridge to the navigational lighthouses marking the shipping lane into Dublin Port. The Liffey Estuary is divided into two water bodies (Upper Liffey Estuary and Lower Liffey Estuary) and both sections are heavily industrialised. Various challenges existed in sampling these water bodies, including piers, docks, marine traffic, walled banks and submerged physical waste. The Upper Liffey Estuary (Plate 3) had a higher proportion of freshwater species due to its upstream location. Species diversity was relatively low with only nine fish species being recorded during the WFD survey in 2010 (Table 4). Sand goby (13) was the most abundant species, followed by flounder (9) and three-spined stickleback (9). The Lower Liffey Estuary had a much higher species diversity 3

4 with a total of 17 fish species being recorded (Table 4). Thick-lipped grey mullet (1078) was the most abundant species, followed by sand goby (24) and flounder (9). Plate 3. Seine ting on the Upper Liffey Estuary Tolka Estuary The Tolka Estuary is located between Clontarf and the north Dublin Docks. It is adjacent to the Lower Liffey Estuary and, as such, is also influenced by heavy urbanisation and industrialisation. A total of 14 fish species were recorded during the WFD survey in 2010 (Table 5). Sand goby (50) was the most abundant species, followed by thick-lipped grey mullet (37) and cod (37). 4

5 Table 2. Number of each fish species captured with each sampling technique in the Avoca Estuary and Broad Lough in the ERBD, October 2010 Scientific Name Common Name Avoca Estuary (3) (8) Broad Lough Ammodytes tobianus Lesser sandeel Anguilla anguilla European eel Atherina presbyter Sand smelt Aspitrigla cuculus Red gurnard Chelon labrosus Thick-lipped grey mullet Ciliata mustela Five-bearded rockling Crenilabrus melops Corkwing wrasse Dicentrarchus labrax European seabass Gadus morhua Cod Gasterosteus aculeatus Three-spined stickleback Labrus bergylta Ballan wrasse Lampetra fluviatilis River lamprey Limanda limanda Dab Melanogrammus aeglefinus Haddock Merlangius merlangus Whiting Myoxocephalus scorpius Short-spined sea scorpion Pholis gunnellus Gunnel (Butterfish) Platichthys flesus Flounder Pleuronectes platessa Plaice Pollachius pollachius Pollack Pomatoschistus minutus Sand goby Rutilus rutilus Roach Salmo trutta Brown trout Salmo trutta Sea trout Scophthalmus rhombus Brill Scyliorhinus canicula Lesser spotted dogfish Spinachia spinachia Fifteen-spined stickleback Sprattus sprattus Sprat Syngnathus acus Greater pipefish Taurulus bubalis Long-spined sea scorpion (6) 5

6 Table 3. Number of each fish species captured with each sampling technique in Broadmeadow and Rogerstown Estuaries in the ERBD, October 2010 Scientifc Name Common Name Broadmeadow Estuary (6) (6) Rogerstown Estuary (7) Ammodytes tobianus Lesser sandeel Anguilla anguilla European eel Atherina presbyter Sand smelt Aspitrigla cuculus Red gurnard Chelon labrosus Thick-lipped grey mullet Ciliata mustela Five-bearded rockling Crenilabrus melops Corkwing wrasse Dicentrarchus labrax European seabass Gadus morhua Cod Gasterosteus aculeatus Three-spined stickleback Labrus bergylta Ballan wrasse Lampetra fluviatilis River lamprey Limanda limanda Dab Melanogrammus aeglefinus Haddock Merlangius merlangus Whiting Myoxocephalus scorpius Short-spined sea scorpion Pholis gunnellus Gunnel (Butterfish) Platichthys flesus Flounder Pleuronectes platessa Plaice Pollachius pollachius Pollack Pomatoschistus minutus Sand goby Rutilus rutilus Roach Salmo trutta Brown trout Salmo trutta Sea trout Scophthalmus rhombus Brill Scyliorhinus canicula Lesser spotted dogfish Spinachia spinachia Fifteen-spined stickleback Sprattus sprattus Sprat Syngnathus acus Greater pipefish Taurulus bubalis Long-spined sea scorpion (6) 6

7 Table 4. Number of each fish species captured with each sampling technique in the Upper and Lower Liffey Estuary in the ERBD, October 2010 Scientific Name Common Name Upper Liffey Estuary (1) (2) (1) Lower Liffey Estuary (2) Ammodytes tobianus Lesser sandeel Anguilla anguilla European eel Atherina presbyter Sand smelt Aspitrigla cuculus Red gurnard Chelon labrosus Thick-lipped grey mullet Ciliata mustela Five-bearded rockling Crenilabrus melops Corkwing wrasse Dicentrarchus labrax European seabass Gadus morhua Cod Gasterosteus aculeatus Three-spined stickleback Labrus bergylta Ballan wrasse Lampetra fluviatilis River lamprey Limanda limanda Dab Melanogrammus aeglefinus Haddock Merlangius merlangus Whiting Myoxocephalus scorpius Short-spined sea scorpion Pholis gunnellus Gunnel (Butterfish) Platichthys flesus Flounder Pleuronectes platessa Plaice Pollachius pollachius Pollack Pomatoschistus minutus Sand goby Rutilus rutilus Roach Salmo trutta Brown trout Salmo trutta Sea trout Scophthalmus rhombus Brill Scyliorhinus canicula Lesser spotted dogfish Spinachia spinachia Fifteen-spined stickleback Sprattus sprattus Sprat Syngnathus acus Greater pipefish Taurulus bubalis Long-spined sea scorpion (2) (3) 7

8 Table 5. Number of each fish species captured with each sampling technique in the Tolka Estuary in the ERBD, October 2010 Scientific Name Common Name (3) Tolka Estuary Ammodytes tobianus Lesser sandeel Anguilla anguilla European eel Atherina presbyter Sand smelt Aspitrigla cuculus Red gurnard Chelon labrosus Thick-lipped grey mullet Ciliata mustela Five-bearded rockling Crenilabrus melops Corkwing wrasse Dicentrarchus labrax European seabass Gadus morhua Cod Gasterosteus aculeatus Three-spined stickleback Labrus bergylta Ballan wrasse Lampetra fluviatilis River lamprey Limanda limanda Dab Melanogrammus aeglefinus Haddock Merlangius merlangus Whiting Myoxocephalus scorpius Short-spined sea scorpion Pholis gunnellus Gunnel (Butterfish) Platichthys flesus Flounder Pleuronectes platessa Plaice Pollachius pollachius Pollack Pomatoschistus minutus Sand goby Rutilus rutilus Roach Salmo trutta Brown trout Salmo trutta Sea trout Scophthalmus rhombus Brill Scyliorhinus canicula Lesser spotted dogfish Spinachia spinachia Fifteen-spined stickleback Sprattus sprattus Sprat Syngnathus acus Greater pipefish Taurulus bubalis Long-spined sea scorpion Further work A more detailed report will be available in early 2011 once all fish have been processed and data analyzed. 8