ICES Advice 2007, Book 9 - Widely Distributed and Migratory Stocks

9 WIDELY DISTRIBUTED AND MIGRATORY STOCKS 1

9.1 Ecosystem overview 2

9.1.1 Bottom topography, substrates, and circulation 2

9.1.2 Hydrography 2

9.1.3 Plankton 4

9.1.4 Distribution of widely distributed and migratory fish species 5

9.1.5 Feeding and school behaviour 10

9.1.6 Potential environmental influences 11

9.1.7 References 12

9.2 The human impact on the ecosystem 14

9.2.1 Fishery effects on benthos and fish communities 14

9.3 Assessments and advice 16

9.3.1 Assessments and advice regarding fisheries 16

9.3.2 Special requests 21

9.3.2.1 NEAFC request concerning the spatial and temporal extent of deepwater fisheries in the Northeast Atlantic and a preliminary evaluation of areas closed to fishing by NEAFC by e.g. using VMS data 21

9.3.2.2 NEAFC request on evaluation of assessment methods for blue whiting and Norwegian . Spring-Spawning (Atlanto-Scandian) herring 22

9.3.2.3 EC request on evaluation of management plan for NEA mackerel 25

9.3.2.4 NEAFC request to continue to provide all available new information on distribution of vulnerable habitats in the NEAFC Convention Area and fisheries activities in and in the vicinity of such habitats. 28

9.3.2.5 NEAFC request to evaluate the use and quality of VMS data and records of catch and effort to be received from NEAFC in order to provide information on the spatial and temporal extent of current deep-water fisheries in the NE Atlantic 37

9.3.2.6 NEAFC request to develop suitable criteria for differentiating fisheries into possible management types (e.g. directed deep-water fisheries, by-catch fisheries etc.) and to apply these criteria to categorise individual fisheries 39

9.3.2.7 NEAFC request to compile data on documented historical or present spawning/aggregation areas of blue ling in the NEAFC Convention area (including November update 40

9.3.2.8 NEAFC request to consider co-ordination of existing deep-sea surveys. The evaluation may also include recommendations for the development of new surveys if it is considered to be appropriate 43

9.3.2.9 EC request on evaluation of management plan for western horse mackerel 49

9.3.2.10 EC request on Black Sea eel 54

9.3.2.11 EC request on the Draft EU Guidelines for Eel Management Plans (EC regulation n°1100/2007) 56

9.4 Stock Summaries 63

9.4.1 Hake – Northern stock (Division IIIa, Subareas IV, VI and VII and Divisions VIIIa,b,d 63

9.4.2 Northeast Atlantic Mackerel (combined Southern, Western and North Sea spawning components) 74

9.4.3 Western horse mackerel (Trachurus trachurus) (Divisions IIa, IVa, Vb, VIa,, VIIa-c, e-k, VIIIa-e) 88

9.4.4 Blue whiting combined stock (Subareas I-IX, XII and XIV) 98

9.4.5 Norwegian spring-spawning herring 113

9.4.6-8 Nephrops Advice - Please Refer to ICES Advice 2006 – Book 9 122

9.4.9 European Eel 123