Open Government Licence (OGL)

Fishing - King scallop assessment areas in Scotland

Marine Scotland Information NMPi icon

For the purposes of Marine Scotland Science’s (MSS) stock assessments, the king scallop (Pecten maximus) grounds around Scotland are divided into assessment areas (previously known as ‘Management areas’) which are defined on the basis of ICES (International Council for the Exploration of the Sea) statistical rectangles.  As in previous assessments, rectangle 40E4 is divided into two data components, one from the east side of the Mull of Kintyre and one from the west side.  This allows for a clearer distinction between the West of Kintyre and Clyde scallop stocks.

Haddock - spawning grounds - North Sea (Gonzalez-Irusta and Wright 2016)

Marine Scotland Information NMPi icon

What is it: 

The spawning grounds of haddock (Melanogrammus aeglefinus) layer has been generated to identify the likely distribution of haddock spawning in the North Sea and West of Scotland, taking account of certain environmental influences. The map key refers to mean values, where a value of 0 indicates ‘low’ prediction of preference as a spawning ground and a value of 1 as a ‘high’ prediction of preference.  

This layer updates the existing (Coull et al., 1998) spawning map for haddock (Melanogrammus aeglefinus) also available on NMPi, by providing finer granularity to the likely haddock spawning areas. The Coull et al., (1998) maps have been used for more than a decade to ensure that appropriate protection is afforded to sensitive areas from disturbance.

The model used to create the layers was designed for use at a regional level and above.

More Information: 

Data was obtained from two surveys; the North Sea International Bottom Trawl Survey (NS-BTS) and the Scottish West Coast Bottom Trawl Survey (SWC-IBTS) to assess the abundance of haddock in spawning stage (HSS) (2009 – 2015). The importance of environmental influences on spawning distribution was then examined using General Additive Models (GAMs). Environmental variables such as water depth, distance to coast, springtide (tidal currents), sediment type, temperature and salinity were considered.

An optimum temperature for spawning of 7⁰C was evident for North Sea and west of Scotland regions. Spawning haddock preferred high salinity waters in the northern North Sea and shelf edge waters to the west of Scotland. They tended not to aggregate on mud-rich sediments, which was associated with a split in the main spawning areas between the east and west North Sea. The distribution of spawning haddock from this study indicated a shift in the spawning grounds compared to historic reports. By identifying the physical characteristics and persistent use of spawning grounds, the present study provides a guide for future marine developments and an aid to discussions about the utility of spawning closures.

This output serves as an update to the existing (Coull et al., 1998) spawning map for haddock (Melanogrammus aeglefinus) also available on NMPi, by providing finer granularity to the likely haddock spawning areas.

Publication DOI: https://doi.org/10.1016/j.fishres.2016.05.028

Cod - spawning grounds - North Sea (Gonzalez-Irusta and Wright 2016)

Marine Scotland Information NMPi icon

What is it: 

The spawning grounds of Atlantic cod (Gadus morhua) layer has been generated to identify the likely distribution of Atlantic cod spawning in the North Sea, taking account of certain environmental influences. The map key classifies Atlantic cod spawning areas as ‘recurrent’, ‘occasional’, ‘rare’ and ‘unfavourable’.

This layer updates the existing (Coull et al., 1998) spawning map for Atlantic cod (Gadus morhua) also available on NMPi, by providing finer granularity to the likely Atlantic cod spawning areas. The Coull et al., (1998) maps have been used for more than a decade to ensure that appropriate protection is afforded to sensitive areas from disturbance.

The model used to create the layers was designed for use at a regional level and above.

More Information: 

Data was obtained from the North Sea International Bottom Trawl Survey (NS-BTS) (2009-2014) to assess the abundance of cod in spawning stage (CSS). The importance of environmental influences on spawning distribution was then examined using General Additive Models (GAMs). Environmental variables such as depth, slope, distance to coast, springtide (tidal currents), sediment type, temperature and salinity were considered.

Cod were found to prefer areas with temperatures around 5–7°C for spawning and there was a general preference for high salinity waters. Seabed conditions also affected spawning distribution with cod selecting coarse sand and avoiding areas of very high tidal flow. The model prediction was compared with the distribution of cod aggregations during the spawning season reported by fishing boats. Seventy per cent of the aggregations were located in areas classified as occasional or recurrent spawning grounds. The predicted distribution confirmed the widespread occurrence of spawning in the North Sea and showed good agreement with recent and past studies of cod egg distribution, suggesting that nearly all major historical areas of spawning still appear in use today. However, the study also found that the recent recovery of spawning-stock biomass was not uniform across the stock, being centered in the northwest subarea.

This output serves as an update to the existing (Coull et al., 1998) spawning map for Atlantic cod (Gadus morhua) also available on NMPi, by providing finer granularity to the likely Atlantic cod spawning areas.

Publication DOI: https://doi.org/10.1093/icesjms/fsv180

Whiting - spawning grounds - North Sea (Gonzalez-Irusta and Wright 2017)

Marine Scotland Information NMPi icon

What is it: 

The spawning grounds of whiting (Merlangius merlangus) layer has been generated to identify the likely distribution of whiting spawning in the North Sea, taking account of certain environmental influences, with due regard for possible density dependent effects on distribution. The map key refers to the ‘Index of Persistence’ of whiting spawning, where a value of 0 means that that the cell was not classified as suitable for any year during the study period and a value of 1 means that the cell was classified as suitable for all the years studied.

This layer updates the existing (Coull et al., 1998) spawning map for whiting (Merlangius merlangus) also available on NMPi, by providing finer granularity to the likely whiting spawning areas. The Coull et al., (1998) maps have been used for more than a decade to ensure that appropriate protection is afforded to sensitive areas from disturbance.

The model used to create the layers was designed for use at a regional level and above.

More Information: 

Data was obtained from the North Sea International Bottom Trawl Survey (NS-BTS) (2009-2015) to assess the abundance of whiting in spawning stage (WSS). The importance of environmental influences on spawning distribution was then examined using General Additive Models (GAMs). Environmental variables such as depth, distance to coast, springtide (tidal currents), sediment type, temperature, salinity and current velocity were considered. Whiting showed high plasticity in spawning ground selection with extensive areas of the North Sea appearing suitable across the study period. Nevertheless, a divide between two centres of persistent spawning aggregation was found consistent with the boundary described in previous studies. In addition to aggregations suggested by past egg surveys, another spawning area off the north east Scottish coast was identified. The study identified springtide as a key physical determinant of whiting spawning distribution, which may be linked to the need for larvae to be advected offshore.

Contrary to past studies, peak abundance of whiting was found around 125 m bottom depth, although there may have been differences in physical preferences related to the region of the North Sea studied. The persistence of some spawning aggregations of whiting indicates the need for marine spatial planning to consider the potential impact of marine developments in these areas.

This output serves as an update to the existing (Coull et al., 1998) spawning map for whiting (Merlangius merlangus) also available on NMPi, by providing finer granularity to the likely whiting spawning areas.

Publication DOI: https://doi.org/10.1016/j.fishres.2017.07.005

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