UK fisheries laboratories send observers to sea to record the quantity of fish discarded and retained by fishing vessels. This sampling is intended to provide estimates of discards of the main commercial species. It is only possible to sample a small proportion of fishing trips in this way. For this reason the sampling effort tends to be focused on those fisheries which are of relatively large scale, and which usually involve some discarding. There are a large number of fisheries which are small in scale and/or involve little or no discarding, which are not routinely sampled. These include many shellfish fisheries, fisheries for pelagic species such as mackerel and herring, and in particular inshore fisheries involving vessels less than 10 metres in length. Vessels in this latter category form the majority of the UK fishing fleet. As a result, estimates of discards given as weight per vessel may not be representative. Estimates of discards by UK vessels for some important fish stocks are given for 1998 to 2007 (where available), and numbers of fishing vessels registered in the UK over the same period are given in the following tables.
Tonnes Species Cod Haddock Whiting Plaice Sole Vessels Sco EWN Sco EWN Sco EWN EWN EWN 1998 10,287 — 35,134 — 8,861 — — — 1999 2,991 — 35,270 — 15,563 — — — 2000 4,141 — 39,745 — 16,211 — — — 2001 4,440 — 86,297 — 8,869 — — — 2002 1,519 — 32,196 — 8,315 — — — 2003 1,086 — 18,555 — 5,931 — — — 2004 1,266 430 12,834 371 5,765 2,023 547 33 2005 1,169 604 7,412 168 5,547 683 122 1 2006 1,671 581 14,671 310 4,457 1,385 351 37 2007 11,892 221 24,671 322 3,383 541 136 37
Tonnes Species Cod Haddock Whiting 1998 289 4,801 4,232 1999 62 4,060 2,015 2000 410 6,875 4,831 2001 139 6,087 1,561 2002 110 7,151 1,257 2003 27 3,649 1,283 2004 56 4,072 2,445 2005 45 2,677 828 2006 322 4,453 647 2007 1,107 3,405 312
Under 10 metres 10 metres+ Total 1997 2,436 6,022 8,458 1998 2,244 6,027 8,271 1999 2,123 5,916 8,039 2000 2,049 5,769 7,818 2001 2,006 5,715 7,721 2002 1,805 5,773 7,578 2003 1,684 5,412 7,096 2004 5,394 1,628 7,022 2005 5,134 1,582 6,716 2006 5,203 1,549 6,752 2007 5,236 1,527 6,763