ICES Advice 2008, Book 9 - Widely Distributed and Migratory Stocks

9 WIDELY DISTRIBUTED AND MIGRATORY STOCKS 1

9.1 Ecosystem overview 1

9.1.1 Continental shelf and Pelagic Zone 1

9.1.1.1 Surface circulation and hydrography 1

9.1.1.2 Recent oceanographic trends 2

9.1.1.3 Plankton 3

9.1.1.4 Distribution of pelagic species 5

9.1.1.5 Feeding and school behaviour 9

9.1.1.6 Potential environmental influences 10

9.1.1.7 References 10

9.1.2 Oceanic and deep sea area 14

9.1.2.1 Bottom topography, substrates, and circulation 14

9.1.2.2 Physical and chemical oceanography (temperature, salinity, nutrients) 15

9.1.2.3 Broad-scale climate and oceanographic features and drivers 16

9.1.2.4 Benthos, larger invertebrates (cephalopods, crustaceans, etc.), biogenic habitat taxa 16

9.1.2.5 Fish community 18

9.1.2.6 Birds and mammals 19

9.1.2.7 The major environmental impacts on the ecosystem dynamics 20

9.1.2.8 References 20

9.2 The human impact on the ecosystem 21

9.2.1 Fishery effects on benthos and fish communities 21

9.2.2 References 22

9.3 Assessments and advice 23

9.3.1 Assessments and advice regarding fisheries 23

9.3.1.1 Widely distributed and migratory stocks 23

9.3.1.2 Deep water species 30

9.3.2 Special requests 43

9.3.2.1 EC request on evaluation of long-term management of the NEA mackerel stock and fishery 43

9.3.2.2 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 62

9.3.2.3 NEAFC request to identify vulnerable marine ecosystems and definitions and assessment of fishing activates that may cause significant adverse impacts on such ecosystems 67

9.3.2.4 NEAFC request to evaluate the use and quality of VMS data and records of catch and effort to be received from NEAFC 71

9.3.2.5 NEAFC request to compile data on documented historical or present spawning aggregation areas of blue ling in the NEAFC Convention area 82

9.3.2.6 NEAFC request to develop suitable criteria for differentiating fisheries 92

9.3.2.7 Irish request on management plan for blue whiting and stock structure 93

9.3.2.8 Irish request regarding the long-term management for Northeast Atlantic mackerel 99

9.3.2.9 EC, Faroe Islands, Iceland Norway request on long-term management of blue whiting 100

9.3.2.10 Norway EC Faroe Islands request regarding the management of mackerel in the Northeast Atlantic 102

9.3.2.11 EC request to ICES on evaluation of applications of exemption from the obligation to submit Eel Management Plans 117

9.4 Stock Summaries 121

9.4.1 Hake – Northern stock (Division IIIa, Subareas IV, VI and VII and Divisions VIIIa,b,d 121

9.4.2 Northeast Atlantic Mackerel (combined Southern, Western and North Sea spawning components) 132

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

VIIIa-e) 149

9.4.4 Blue whiting combined stock (Subareas I-IX, XII and XIV) 165

9.4.5 Norwegian spring-spawning herring 181

9.4.6 Northeast Atlantic spurdog 192

9.4.7 Northeast Atlantic porbeagle 196

9.4.8 Northeast Atlantic basking shark 201

9.4.9 European Eel 205

9.4.10 Ling (Molva molva) in all areas 212

9.4.10.1 Ling in Divisions I and II 214

9.4.10.2 Ling in Subdivision Va 217

9.4.10.3 Ling Subarea Vb 221

9.4.10.4 Ling in Divisions IIIa and Iva, and in Subareas VI, VII, VIII, IX, XII, and XIV 224

9.4.11 Blue ling (Molva dypterygia) in all areas 232

9.4.11.1 Blue ling in Subdivisions Va and XIV 235

9.4.11.2 Blue ling in Subdivisions Vb, VI, and VII 239

9.4.11.3 Blue ling in other areas (Subdivisions I, II, IIIa, IVa, VIII, IX, and XII) 248

9.4.12 Tusk (Brosme brosme) in all areas 255

9.4.12.1 Management unit I and II (Arctic) 258

9.4.12.2 Tusk in Division Va (Iceland) 264

9.4.12.3 Tusk in Divisions IIIa, Iva, Vb, VI, VII, VIII, IX, XII, and XIV (other areas) 269

9.4.12.4 Tusk in Division VIb (Rockall) 271

9.4.12.5 Tusk in Divisions IIIa, IV, Vb, VIa, VII, VIII, IX, and XIIb 274

9.4.13 Greater Silver Smelt 284

9.4.13.1 Greater silver smelt in Subdivision Va 128

9.4.13.2 Greater silver smelt in other areas (Subdivisions I, II, IIIa, IV, Vb, VI, VII, VIII, IX, X, XII, and XIV) 131

9.4.14 Orange Roughy 294

9.4.15 Roundnose grenadier 303

9.4.15.1 Roundnose grenadier in Division IIIa 305

9.4.15.2 Roundnose grenadier in subareas VI and VII and in Divisions Vb and XIIb 309

9.4.15.3 Roundnose grenadier on the Mid-Atlantic ridge 316

9.4.15.4 Roundnose grenadier in all other areas 320

9.4.16 Black scabbard fish 321

9.4.17 Greater forkbeard 327

9.4.18 Alfonsinos/Golden eye perch (Beryx spp.) 329

9.4.19 Red (=blackspot) seabream 331

9.4.20 Portuguese dogfish and leafscale gulper shark in the North East Atlantic (ICES Areas I-XIV) 339

9.4.21 Kitefin shark in the Northeast Atlantic (ICES Areas I-XIV) 344