Abstract
An evidence-based understanding of the distribution of fish spawning and nursery grounds, and other ecologically important fish habitats is required to allow scientific advisors and regulators to better manage human activities in our seas. For example, many offshore wind farm developments are currently subject to seasonal restrictions in order to minimise disruption from anthropogenic noise, particularly the sounds associated with pile driving, on spawning fish and to protect egg and larval stages. Similarly, there is more conservative management and regulation of some human activities that operate in areas of seabed considered important or potentially important to key life-history stages, for example in relation to the spawning grounds of herring Clupea harengus.
Such management actions have implications for developers in terms of both cost and delivery of projects. Consequently, it is essential that the provenance of data on spawning and nursery grounds is understood to ensure that its interpretation within Environmental Impact Assessments and regulatory decision-making is appropriately applied. This report describes the sources, spatial and temporal coverage and limitations of the data, including where there are data gaps. Using the maps in isolation may result in misrepresentations of the data, so in all cases the supporting rationale should also be considered.
Lee & Ramster (1981) compiled an atlas of the seas around the British Isles, in which the spawning grounds of several commercial fish were illustrated. Subsequently, a collaborative project between the national fisheries laboratories (Cefas and the then Fisheries Research Services, Scotland), with the UK Offshore Operator’s Association (UKOOA), the Scottish Fishermen’s Association (SFF) and the National Federation of Fishermen’s Organisations (NFFO) aimed to provide broad scale maps of the sensitive habitats of marine fish in UK waters (Coull et al., 1998). This report aimed to assist in the environmental impact assessment process, and included maps indicating the main spawning and nursery grounds for 14 commercially important species: herring, cod Gadus morhua, haddock Melanogrammus aeglefinus, whiting Merlangius merlangus, saithe Pollachius virens, Norway pout Trisopterus esmarki, blue whiting Micromesistius poutassou, mackerel Scomber scombrus, sprat Sprattus sprattus, sandeels (Ammodytidae), plaice Pleuronectes platessa, lemon sole Microstomus kitt, sole Solea solea and Norway lobster Nephrops norvegicus.
Coull et al. (1998) correctly acknowledged that “spawning distributions are under continual revision. It follows that these maps should not be seen as rigid, unchanging descriptions of presence or absence”. Since these maps were produced there have been further ichthyoplankton surveys in some areas, and there are now other fish species for which there is an interest in the location of ‘critical habitats’.
This report aims to update some of these maps with more recent data, and so highlighting some of the evidence for their selection, and to provide a first attempt at identifying some of the ecologically important habitats for some other fish species, including some species of conservation importance (e.g. OSPAR, 2008) that have been considered in marine planning. It is important to note that such data are not available for all fish species, and many coastal, continental shelf, and shelf edge waters are still to be surveyed for ichthyoplankton and juveniles.
In addition to eight of the highly mobile species included within Coull et al. (1998), it was considered that existing groundfish surveys could assist in the preliminary spatial description of the nursery grounds for some other species of commercial and/or conservation importance, including spurdog Squalus acanthias, tope Galeorhinus galeus, common skate Dipturus batis-complex, thornback ray Raja clavata, spotted ray Raja montagui, undulate ray Raja undulata, ling Molva molva, hake Merluccius merluccius, anglerfish Lophius piscatorius and horse mackerel Trachurus trachurus.
The summary report is based on a report provided to Defra1 , and comprises two main sections. Section 2 provides an overview of the data collation for the species, including a summary of available fishery-independent trawl surveys and ichthyoplankton surveys. This section also includes a discussion on the limitations and caveats of these data (e.g. issues on gear selectivity, the timings and locations of surveys, and taxonomic identification in surveys) and the users of the GIS data are encouraged to use this information to assist in the interpretation of distribution data. Section 3 provides more detailed information on the derived data layers for the various species.