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.
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