11.5.8.3 Cod 74.
Both juvenile and adult cod occur throughout most of the North Sea (Figure 11.16). Cod are a demersal species and are generally found within 30-80m of the seabed at depths up to 500m (ICES, 2012c; Hedger et al. 2004). Demersal juveniles inhabit a wide variety of habitats but are often found in shallower waters than adults (Teal et al. 2009). The results of quarterly IBTS surveys show that adults are widely distributed during the colder, winter months but their range contracts during spring and summer as they retreat northwards in response to increasing temperatures in the English Channel and Southern Bight. Cod undergo an extensive spawning migration, returning to the southern North Sea during autumn (ICES 2012c).
75.
The North Sea cod stock is thought not to comprise a single distinct population but a number of sub-populations with differential rates of mixing between components (Blanchard et al. 2005; STECF 2005). There is a limited influx of young cod from the eastern English Channel into the southern North Sea and cod in the German Bight show some limited mixing with those in the Southern Bight (Horwood et al. 2006).
76. Hutchinson et al. (2001) have identified several genetically distinct populations within the southern and northern North Sea at Bergen Bank, Moray Firth, Flamborough Head and the Southern Bight. These populations appear to form units that are reproductively isolated from each other and which may be spatially distinct at least during the spawning season (ICES 2005).
77.
Preliminary Environmental Information May 2014
Information on currently active cod spawning areas in the North Sea is limited (Fox et al. 2008). Being pelagic spawners, cod spawning grounds are not substrate specific. Previous studies have recorded the presence of spawning areas in the Southern Bight (Daan 1978), in the vicinity of Flamborough (Harding and Nichols 1987) and around the southern and eastern edges of the Dogger Bank (Heessen and Rijnsdorp 1989). Van Damme et al. (2011) found yolk sac larvae at a limited number of sampling stations in the eastern sector of the southern North Sea in February (Diagram 11.3). Ichthyoplankton surveys have generally confirmed the results of these spawning studies showing hot spots of egg production around the southern and eastern edges of the Dogger Bank, in the German Bight, the Moray Firth and to the east of the Shetlands (Fox et al. 2008). The low numbers of cod eggs at sites off Flamborough Head however suggests that this area can now be considered as a historical spawning ground (Fox et al. 2008). East Anglia THREE Offshore Windfarm
Appendix 11.2 Page 43
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71 |
Page 72 |
Page 73 |
Page 74 |
Page 75 |
Page 76 |
Page 77 |
Page 78 |
Page 79 |
Page 80 |
Page 81 |
Page 82 |
Page 83 |
Page 84 |
Page 85 |
Page 86 |
Page 87 |
Page 88 |
Page 89 |
Page 90 |
Page 91 |
Page 92 |
Page 93 |
Page 94 |
Page 95 |
Page 96 |
Page 97 |
Page 98 |
Page 99 |
Page 100 |
Page 101 |
Page 102 |
Page 103 |
Page 104 |
Page 105 |
Page 106 |
Page 107 |
Page 108 |
Page 109 |
Page 110 |
Page 111 |
Page 112 |
Page 113 |
Page 114 |
Page 115 |
Page 116 |
Page 117 |
Page 118 |
Page 119 |
Page 120 |
Page 121 |
Page 122 |
Page 123 |
Page 124 |
Page 125 |
Page 126 |
Page 127 |
Page 128 |
Page 129 |
Page 130 |
Page 131 |
Page 132 |
Page 133 |
Page 134 |
Page 135 |
Page 136 |
Page 137 |
Page 138 |
Page 139 |
Page 140 |
Page 141 |
Page 142 |
Page 143 |
Page 144 |
Page 145 |
Page 146 |
Page 147 |
Page 148 |
Page 149 |
Page 150 |
Page 151