Marine Institute Open Access Repository >
Marine Institute Community of Research Publications >
Survey Reports >
Acoustic Surveys >
Please use this identifier to cite or link to this item:
|Title: ||Celtic Sea Herring Acoustic Survey, Cruise Report 2009|
|Authors: ||Saunders, R|
|Keywords: ||Celtic Sea|
|Issue Date: ||2009|
|Publisher: ||Marine Institute|
|Citation: ||Saunders, R., O’Donnell, C., Campbell, A., Lynch, K. & Wall, D. "Celtic Sea Herring Acoustic Survey, Cruise Report 2009", Marine Institute 2009|
|Series/Report no.: ||FSS Survey Series;2009/03|
|Abstract: ||In the southwest of Ireland and the Celtic Sea (ICES Divisions VIIaS, g & j), herring are an important commercial species to the pelagic and polyvalent fleet. The local fleet is composed of dry hold polyvalent vessels and a small number of purpose built Refrigerated seawater vessels (RSW). The stock is composed of both autumn and winter
spawning components and the fishery targets pre-spawning and spawning aggregations.
The Irish commercial fishery has historically taken place within 1-20 nmi (nautical miles) of the coast and focused on aggregated schools within the spawning cycle.
In recent years the larger RSW vessels have actively targeted offshore summer feeding
aggregations in the south Celtic Sea. In VIIj, the fishery traditionally begins in mid
September and is concentrated within several miles of the shore including many bays
and inlets. The VIIaS fishery peaks towards the year end in December, but may be
active from mid October depending on location. In VIIg, along the south coast herring are targeted from October to January at a number of known spawning sites and surrounding areas. Overall, the protracted spawning period of the two components extends
from October through to January, with annual variation of up to 3 weeks. Spawning
occurs in successive waves in a number of well known locations including large
scale grounds and small discreet spawning beds. The stock structure and discrimination of herring in this area has been investigated
recently. Hatfield et al. (2007) has shown the Celtic Sea stock to be fairly discrete.
However, it is known that fish in the eastern Celtic Sea recruit from nursery areas in the Irish Sea, returning to the Celtic Sea as young adults (Brophy et al. 2002; Molloy et al., 1993). The stock identity of VIIj herring is less clear, though there is evidence that they have linkages with VIIb and VIaS (ICES, 1994; Grainger, 1978). Molloy (1968) identified possible linkages between young fish in VIIj and those of the Celtic Sea herring. For the purpose of stock assessment and management divisions VIIaS, VIIg and VII j have been combined since 1982. For a period in the 1970s and1980s, larval surveys were conducted for herring in this area. However, since 1989, acoustic surveys have been carried out, and currently are the only tuning indices available for this stock. In the Celtic Sea and VIIj, herring acoustic surveys have been carried out since 1989, and this survey represents the 18th in the overall acoustic series or the fourth in the modified time series. The geographical confines of the annual 21 day survey have been modified in recent years to include areas to the south of the main winter spawning grounds in an effort to
identify the whereabouts of winter spawning fish before the annual inshore spawning
migration. Spatial resolution of acoustic transects has been increased over the entire
south coast survey area. The acoustic component of the survey has been further complimented by detailed hydrographic and marine mammal and seabird work programs
first initiated during this survey in 2004.|
|Description: ||Use the URI link below to search the Marine Institute Data Discovery Catalogue for datasets relevant to this report.|
|Appears in Collections:||Acoustic Surveys|
Items in the Marine Institute Open Access Repository are protected by copyright, with all rights reserved, unless otherwise indicated.