The Danish research vessel Dana is used for the Danish participation in the International Bottom Trawl Survey (IBTS), which has the purpose of annually monitoring fish species. Internationally, each nation surveys part of the area, with some overlap in coverage and depth stratification, in a coordinated sampling design.

The IBTS is conducted twice a year in the first and fourth quarters as a depth-stratified survey. The strata are based on sub-divisions and depth layers. Each year the necessary stations are randomly selected before the beginning of the international trawl surveys, from a list of clear haul data. These stations are a stratified randomly selected sub-sample of the possible trawl tracks.

The standard haul is a 30-minutes haul with a towing speed of 3 knots. Trawling only takes place during daylight, defined as the time between 15 minutes past sunrise and 15 minutes before sunset.

Period

Quarter 1

Activity

Here is shown a map with the survey activity. The map shows both valid and invalid stations, a station can be deemed invalid if the haoul could not be conducted within the guilines of the survey manual

Trawl Stations

Each trawl stations consists a haul of 30 minutes where all the catch documented, including litter. Biological samples to determine e.g. stock, age matuity are taken from individual fish.

CTD Stations

CTD (Conductivity - Temperature - Depth), are measured trough the water column, and used to calculate e.g. the oxygen and salinity content, key environmental variables for life in the ocean.

CTD Results

Here is shown a map the results of the CTD measurments at the bottom. The heatmap is made with linear interpolation between measurments, and can be seen as the general trend in the monment of the survey

Bottom oxygen

Bottom temperature

Bottom salinity

Catch Overview

Below is a table with the total catche and catches for selected species, in wiegth and numbers. The numbers are in some instances calculated based on representative subsampling of some abundant species. The maps illustrates for biodiveity the number of different species cougt on each station, and for CPUE (catch per unit effort) the catch in numbers standadized to a unit effort of one hour of hauling.


	Weight (kg)	Number	Min. Length (mm)	Max. Length (mm)
Total Catch	9803.3	268110
Haddock	1879.4	12771	110	620
Whiting	1714.1	10629	100	450
Herring	1184.6	12144	85	345
Cod	327.4	216	110	1150
Plaice	103.9	447	120	420

CPUE

CPUE (catch per unit effort) shown as the catch in Numbers rasied to to pr hour of hauling

CPUE for Selected Species

CPUE (catch per unit effort) shown as the catch in Numbers rasied to to pr hour of hauling. The dots indicates the stations, and red dots indicates that a species where not found at all in that station. The scale is different between plots

Cod

Plaice

Whiting

Haddock

Herring

Biodiversity

Shown is the Number of species cought by station

Length Distributions

Here is shown the length distribution For the 10 most abundant comercieal species cought during the survey, allocated to each ship. The black line represents the average length distribution of the 5 years previus surveys.

Norway pout

Common dab

Haddock

Herring

Whiting

Grey gurnard

Mackerel

Sprat

Plaice

Lemon sole

All species Caught

The table below is an overview of all the different species cought in the survey, devided into the different ices areas covered by the surve.

Area - 20


Latin name	English name	Weight (kg)	Number	Min. Length (mm)	Max. Length (mm)
Callionymus lyra	Common dragonet	0.1	1	250	250
Cancer pagurus	Edible crab	2.5	10	88	130
Clupea harengus	Herring	6.7	675	85	235
Gadus morhua	Cod	1.6	2	210	520
Gasterosteus aculeatus	Three-spined stickleback	0.0	4	60	60
Hippoglossoides platessoides	American plaice	0.6	13	120	230
Hyperoplus lanceolatus	Greater sandeel	0.1	1	225	225
Limanda limanda	Common dab	3.8	69	120	260
Merlangius merlangus	Whiting	1.7	35	100	390
Microstomus kitt	Lemon sole	0.2	1	260	260
Pleuronectes platessa	Plaice	1.2	16	120	240
Sprattus sprattus	Sprat	5.0	778	60	135
Squalus acanthias	Spurdog	0.0	1	140	140

Area - 4A


Latin name	English name	Weight (kg)	Number	Min. Length (mm)	Max. Length (mm)
Aequipecten opercularis	Queen scallop	0.1	2
Alloteuthis subulata	European common squid	14.4	4322	20	80
Amblyraja radiata	Starry ray	18.8	45	280	470
Anarhichas lupus	Catfish	11.7	4	420	920
Argentina	Silver smelts	18.0	459	80	250
Brosme brosme	Tusk	0.6	1	410	410
Callionymus lyra	Common dragonet	0.0	1	100	100
Callionymus maculatus	Spotted dragonet	0.1	17	70	130
Cancer pagurus	Edible crab	1.0	1	181	181
Capros aper	Boarfish	0.1	2	100	140
Chelidonichthys cuculus	Red gurnard	42.8	266	170	330
Clupea harengus	Herring	1050.4	8698	120	345
Cyclopterus lumpus	Lumpfish	7.9	2	400	420
Eledone cirrhosa	Horned octopus	2.5	23
Enchelyopus cimbrius	Four-bearded rockling	0.3	5	170	260
Engraulis encrasicolus	Anchovy	0.3	19	120	160
Eutrigla gurnardus	Grey gurnard	581.7	4290	140	430
Gadiculus argenteus	Silvery pout	2.0	207	40	130
Gadus morhua	Cod	280.2	158	160	1150
Glyptocephalus cynoglossus	Witch	17.3	56	210	510
Hippoglossoides platessoides	American plaice	61.3	1593	60	300
Hippoglossus hippoglossus	Atlantic halibut	2.3	1	590	590
Illex coindetii	Southern shortfin squid	130.6	1593	50	220
Lepidorhombus whiffiagonis	Megrim	7.6	13	250	520
Leucoraja naevus	Cuckoo ray	5.3	7	340	530
Limanda limanda	Common dab	459.0	7329	120	320
Lithodes maja	Norway king crab	8.1	27	29	169
Loligo	Loligo sp	4.3	1351	20	60
Loligo forbesii	Northern squid	26.5	379	20	300
Loligo vulgaris	European squid	2.2	5	90	370
Lophius piscatorius	Angler fish	121.3	52	150	950
Lycodes gracilis	Vahls eelpout	0.0	1	150	150
Maurolicus muelleri	Pearlside	0.0	6	40	70
Melanogrammus aeglefinus	Haddock	1519.0	9620	110	550
Merlangius merlangus	Whiting	1413.4	7643	110	450
Merluccius merluccius	Hake	39.1	231	170	530
Micromesistius poutassou	Blue whiting	0.0	1	190	190
Microstomus kitt	Lemon sole	25.4	143	140	400
Molva molva	Ling	6.0	7	390	660
Mullus surmuletus	Striped red mullet	1.3	8	130	380
Mustelus asterias	Starry smooth-hound	30.1	16	480	990
Mustelus mustelus	Smooth hound	10.4	9	440	860
Myxine glutinosa	Hagfish	0.0	2	300	320
Nephrops norvegicus	Norway lobster	2.9	93	18	63
Phycis blennoides	Greater forkbeard	0.0	1	160	160
Pleuronectes platessa	Plaice	32.1	108	210	400
Pollachius pollachius	Pollack	4.8	1	760	760
Pollachius virens	Saithe	185.3	73	380	1040
Pomatoschistus spp.	Sand gobies	0.0	3	30	50
Raja brachyura	Blonde ray	1.6	2	420	490
Raja clavata	Thornback ray	3.4	1	780	780
Rossia macrosoma	Stout bobtail squid	0.4	20
Sardina pilchardus	Pilchard	3.2	168	90	260
Scomber scombrus	Mackerel	38.9	571	160	410
Scyliorhinus canicula	Lesser-spotted dogfish	12.4	17	200	660
Sebastes viviparus	Redfish	1.6	59	90	140
Squalus acanthias	Spurdog	0.4	1	470	470
Todaropsis eblanae	Lesser flying squid	3.8	51	40	140
Trachurus trachurus	Horse mackerel	1.1	17	110	370
Trisopterus esmarkii	Norway pout	1396.6	179375	70	210
Trisopterus minutus	Poor-cod	3.2	69	110	230

Area - 4B


Latin name	English name	Weight (kg)	Number	Min. Length (mm)	Max. Length (mm)
Aequipecten opercularis	Queen scallop	0.1	2
Agonus cataphractus	Pogge	0.0	1	120	120
Alloteuthis subulata	European common squid	34.7	9853	20	90
Amblyraja radiata	Starry ray	6.6	14	270	470
Ammodytes marinus	Lesser sandeel	1.9	486	70	165
Argentina	Silver smelts	0.0	2	140	140
Callionymus maculatus	Spotted dragonet	0.0	4	90	110
Cancer pagurus	Edible crab	1.6	2	168	175
Chelidonichthys cuculus	Red gurnard	3.0	25	160	320
Clupea harengus	Herring	127.4	2771	135	255
Crystallogobius linearis	Crystal goby	0.0	1	40	40
Cyclopterus lumpus	Lumpfish	7.5	5	240	400
Eledone cirrhosa	Horned octopus	0.0	1
Engraulis encrasicolus	Anchovy	0.2	17	120	150
Eutrigla gurnardus	Grey gurnard	446.5	4625	130	360
Gadus morhua	Cod	45.6	56	110	880
Glyptocephalus cynoglossus	Witch	4.0	17	270	390
Hippoglossoides platessoides	American plaice	53.8	1504	110	280
Hippoglossus hippoglossus	Atlantic halibut	3.7	2	540	580
Hyperoplus lanceolatus	Greater sandeel	0.0	1	290	290
Illex coindetii	Southern shortfin squid	4.3	347	30	200
Leucoraja naevus	Cuckoo ray	1.6	3	300	510
Limanda limanda	Common dab	529.2	7514	100	320
Liparis liparis	Sea snail	0.0	1	70	70
Lithodes maja	Norway king crab	13.3	20	53	113
Loligo forbesii	Northern squid	2.2	14	40	240
Loligo vulgaris	European squid	0.2	1	180	180
Lophius piscatorius	Angler fish	1.5	5	100	360
Melanogrammus aeglefinus	Haddock	360.5	3151	150	620
Merlangius merlangus	Whiting	299.0	2951	120	390
Merluccius merluccius	Hake	0.4	1	390	390
Microstomus kitt	Lemon sole	24.6	178	170	390
Mullus surmuletus	Striped red mullet	0.3	8	130	150
Mustelus asterias	Starry smooth-hound	6.4	8	530	790
Mustelus mustelus	Smooth hound	1.8	2	590	640
Myoxocephalus scorpius	Sculpin	0.9	4	170	290
Platichthys flesus x Pleuronectes platessa		0.1	1	250	250
Pleuronectes platessa	Plaice	70.7	323	140	420
Pollachius virens	Saithe	0.3	2	270	280
Raja montagui	Spotted Ray	1.0	2	430	430
Sardina pilchardus	Pilchard	0.3	22	100	130
Scomber scombrus	Mackerel	75.4	1709	160	220
Scophthalmus maximus	Turbot	3.2	4	320	370
Scyliorhinus canicula	Lesser-spotted dogfish	11.6	16	210	670
Sprattus sprattus	Sprat	0.1	6	90	145
Squalus acanthias	Spurdog	2.6	9	220	710
Todaropsis eblanae	Lesser flying squid	0.1	2	70	100
Trachinus draco	Greater weever fish	0.9	5	280	340
Trachurus trachurus	Horse mackerel	0.5	13	110	270
Trisopterus esmarkii	Norway pout	15.0	1547	80	180
Trisopterus minutus	Poor-cod	0.0	1	170	170

Quarter 3

Activity

Trawl Stations

Each trawl stations consists a haul of 30 minutes where all the catch documented, including litter. Biological samples to determine e.g. stock, age matuity are taken from individual fish.

CTD Stations

CTD (Conductivity - Temperature - Depth), are measured trough the water column, and used to calculate e.g. the oxygen and salinity content, key environmental variables for life in the ocean.

CTD Results

Bottom oxygen

Bottom temperature

Bottom salinity

Catch Overview


	Weight (kg)	Number	Min. Length (mm)	Max. Length (mm)
Total Catch	26346.7	1207174
Herring	8053.8	421132	65	315
Whiting	5164.2	104537	40	410
Haddock	2140.3	67531	70	450
Plaice	337.6	2472	100	490
Cod	42.3	104	80	650

CPUE

CPUE (catch per unit effort) shown as the catch in Numbers rasied to to pr hour of hauling

CPUE for Selected Species

Cod

Plaice

Whiting

Haddock

Herring

Biodiversity

Shown is the Number of species cought by station

Length Distributions

Sprat

Herring

Whiting

Haddock

Common dab

Horse mackerel

Norway pout

Grey gurnard

Mackerel

Plaice

All species Caught

The table below is an overview of all the different species cought in the survey, devided into the different ices areas covered by the surve.

Area - 20


Latin name	English name	Weight (kg)	Number	Min. Length (mm)	Max. Length (mm)
Ammodytes marinus	Lesser sandeel	0.3	34	70	195
Callionymus lyra	Common dragonet	0.1	2	180	200
Cancer pagurus	Edible crab	0.2	1	106	106
Chelidonichthys lucerna	Tub gurnard	0.4	2	250	260
Echiichthys vipera	Lesser weever	0.0	2	90	110
Eutrigla gurnardus	Grey gurnard	42.0	338	140	310
Gadus morhua	Cod	3.0	1	650	650
Gymnammodytes semisquamatus	Smoothed sandeel	8.1	754	140	195
Hyperoplus lanceolatus	Greater sandeel	11.2	328	145	330
Limanda limanda	Common dab	120.0	1340	120	300
Loliginidae		7.9	87	50	250
Merlangius merlangus	Whiting	6.1	101	70	230
Microstomus kitt	Lemon sole	1.4	8	210	270
Mullus surmuletus	Striped red mullet	0.1	1	180	180
Pleuronectes platessa	Plaice	77.4	638	130	450
Scomber scombrus	Mackerel	11.1	48	220	380
Scophthalmus maximus	Turbot	0.4	1	260	260
Scyliorhinus canicula	Lesser-spotted dogfish	0.8	1	600	600
Solea solea	Sole	0.3	3	220	230
Trachinus draco	Greater weever fish	14.5	76	190	400
Trachurus trachurus	Horse mackerel	4.9	22	240	360

Area - 4B


Latin name	English name	Weight (kg)	Number	Min. Length (mm)	Max. Length (mm)
Aequipecten opercularis	Queen scallop	1.7	39
Agonus cataphractus	Pogge	0.0	1	140	140
Alloteuthis subulata	European common squid	7.4	1276	20	120
Amblyraja radiata	Starry ray	11.2	26	80	460
Ammodytes marinus	Lesser sandeel	1.6	107	140	190
Anarhichas lupus	Catfish	3.8	1	720	720
Arnoglossus laterna	Scaldfish	0.0	3	100	120
Buglossidium luteum	Solenette	0.2	16	80	120
Callionymus lyra	Common dragonet	1.2	33	100	240
Cancer pagurus	Edible crab	39.9	53	75	203
Chelidonichthys lucerna	Tub gurnard	4.1	15	150	450
Clupea harengus	Herring	6193.6	134285	65	315
Echiichthys vipera	Lesser weever	4.9	181	80	160
Eledone cirrhosa	Horned octopus	0.1	2	40	40
Enchelyopus cimbrius	Four-bearded rockling	0.9	28	130	230
Eutrigla gurnardus	Grey gurnard	545.3	6423	100	390
Gadus morhua	Cod	34.8	81	80	600
Glyptocephalus cynoglossus	Witch	1.2	4	280	400
Gymnammodytes semisquamatus	Smoothed sandeel	27.5	1776	155	205
Hippoglossoides platessoides	American plaice	49.2	920	100	270
Homarus gammarus	European lobster	4.7	7	74	114
Hyperoplus lanceolatus	Greater sandeel	19.6	683	160	320
Illex coindetii	Southern shortfin squid	5.3	89	60	210
Leucoraja naevus	Cuckoo ray	0.5	2	330	380
Limanda limanda	Common dab	1660.9	24829	100	350
Liparis montagui	Montague’s seasnail	0.0	1	30	30
Lithodes maja	Norway king crab	3.2	10	33	110
Loliginidae		4.9	542	30	100
Loligo forbesii	Northern squid	12.8	108	40	360
Loligo vulgaris	European squid	2.6	9	150	300
Lophius piscatorius	Angler fish	9.4	5	200	660
Lumpenus lampretaeformis	Snake blenny	0.0	1	330	330
Melanogrammus aeglefinus	Haddock	2140.2	67530	70	450
Merlangius merlangus	Whiting	3306.0	81405	40	410
Merluccius merluccius	Hake	29.0	28	260	890
Microstomus kitt	Lemon sole	115.8	915	150	350
Molva molva	Ling	0.4	1	440	440
Mullus surmuletus	Striped red mullet	0.3	4	160	220
Mustelus asterias	Starry smooth-hound	12.5	4	870	1040
Mustelus mustelus	Smooth hound	2.5	1	890	890
Myoxocephalus scorpius	Sculpin	0.6	6	130	220
Nephrops norvegicus	Norway lobster	5.9	183	23	57
Pasiphaea	Pasiphaea	7.1	4	810	890
Pecten maximus	Great scallop	0.1	1
Platichthys flesus	Flounder	0.9	4	270	290
Pleuronectes platessa	Plaice	215.5	1389	120	490
Pollachius pollachius	Pollack	4.9	7	380	510
Pollachius virens	Saithe	13.8	16	340	510
Raja clavata	Thornback ray	4.7	3	500	750
Raja montagui	Spotted Ray	15.0	17	410	550
Rossia macrosoma	Stout bobtail squid	0.0	1
Sardina pilchardus	Pilchard	0.0	2	140	140
Scomber scombrus	Mackerel	306.8	1628	200	380
Scophthalmus maximus	Turbot	16.8	21	200	480
Scophthalmus rhombus	Brill	3.2	10	240	340
Scyliorhinus canicula	Lesser-spotted dogfish	52.1	72	390	670
Sebastes	Rockfishes	0.1	1	140	140
Solea solea	Sole	0.2	2	210	240
Sprattus sprattus	Sprat	3802.3	425570	45	145
Squalus acanthias	Spurdog	0.3	2	300	330
Syngnathidae	Pipefishes and seahorses	0.0	1	120	120
Todarodes sagittatus	European flying squid	0.5	3	160	170
Todaropsis eblanae	Lesser flying squid	0.5	5	90	160
Trachinus draco	Greater weever fish	0.2	3	180	250
Trachurus trachurus	Horse mackerel	17.8	179	30	350
Trisopterus esmarkii	Norway pout	34.1	8180	50	190
Trisopterus luscus	Bib	0.1	1	210	210
Trisopterus minutus	Poor-cod	0.6	18	120	200

Area - 4C


Latin name	English name	Weight (kg)	Number	Min. Length (mm)	Max. Length (mm)
Aequipecten opercularis	Queen scallop	0.1	2
Agonus cataphractus	Pogge	0.0	1	120	120
Alloteuthis subulata	European common squid	23.5	3154	20	140
Alosa fallax	Twaite shad	0.6	1	420	420
Ammodytes marinus	Lesser sandeel	1.8	232	105	165
Anguilla anguilla	Eel	5.3	3	740	810
Arnoglossus laterna	Scaldfish	0.0	2	120	120
Buglossidium luteum	Solenette	0.1	7	80	110
Callionymus lyra	Common dragonet	0.5	15	100	210
Cancer pagurus	Edible crab	29.1	81	50	192
Cerastoderma edule	Common cockle	24.7	197	160	270
Chelidonichthys cuculus	Red gurnard	0.4	3	210	250
Chelidonichthys lucerna	Tub gurnard	7.0	15	220	520
Clupea harengus	Herring	1860.2	286847	70	265
Dicentrarchus labrax	Bass	32.4	21	380	710
Echiichthys vipera	Lesser weever	48.7	2209	60	180
Engraulis encrasicolus	Anchovy	1.2	41	120	180
Entelurus aequoreus	Snake pipefish	0.0	1	380	380
Eutrigla gurnardus	Grey gurnard	15.0	150	140	370
Gadus morhua	Cod	4.5	22	80	350
Galeorhinus galeus	Tope	52.5	4	1400	1490
Homarus gammarus	European lobster	14.2	25	56	145
Hyperoplus lanceolatus	Greater sandeel	100.6	4786	145	285
Lepidorhombus whiffiagonis	Megrim	0.2	1	240	240
Limanda limanda	Common dab	235.9	3725	100	270
Loliginidae		12.6	514	30	130
Loligo	Loligo sp	0.2	40	20	80
Loligo forbesii	Northern squid	6.5	83	30	260
Loligo vulgaris	European squid	0.4	1	250	250
Melanogrammus aeglefinus	Haddock	0.0	1	140	140
Merlangius merlangus	Whiting	1852.1	23030	40	330
Microstomus kitt	Lemon sole	9.1	89	70	310
Mullus surmuletus	Striped red mullet	64.2	735	130	920
Mustelus asterias	Starry smooth-hound	267.2	105	610	1120
Mustelus mustelus	Smooth hound	15.2	8	650	920
Myoxocephalus scorpius	Sculpin	0.5	5	120	220
Pholis gunnellus	Butter fish	0.1	4	120	180
Platichthys flesus	Flounder	1.3	4	280	390
Pleuronectes platessa	Plaice	44.7	445	100	430
Raja brachyura	Blonde ray	5.7	4	310	720
Raja clavata	Thornback ray	15.0	8	380	750
Raja montagui	Spotted Ray	6.4	7	230	730
Sardina pilchardus	Pilchard	108.0	6093	90	140
Scomber scombrus	Mackerel	291.0	1549	200	380
Scophthalmus maximus	Turbot	3.6	7	190	410
Scophthalmus rhombus	Brill	0.7	2	250	320
Scyliorhinus canicula	Lesser-spotted dogfish	142.3	309	320	680
Solea solea	Sole	0.5	6	190	210
Sprattus sprattus	Sprat	504.0	96659	45	145
Trachurus trachurus	Horse mackerel	1167.4	11825	30	280
Trisopterus luscus	Bib	111.9	920	130	270
Trisopterus minutus	Poor-cod	182.3	609	80	1080
Zeus faber	John dory	1.6	6	230	250

Danish International Bottom Trawl Survey

Period

Quarter 1

Activity

Trawl Stations

CTD Stations

CTD Results

Bottom oxygen

Bottom temperature

Bottom salinity

Catch Overview

CPUE

CPUE for Selected Species

Cod

Plaice

Whiting

Haddock

Herring

Biodiversity

Length Distributions

Norway pout

Common dab

Haddock

Herring

Whiting

Grey gurnard

Mackerel

Sprat

Plaice

Lemon sole

All species Caught

Area - 20

Area - 4A

Area - 4B

Quarter 3

Activity

Trawl Stations

CTD Stations

CTD Results

Bottom oxygen

Bottom temperature

Bottom salinity

Catch Overview

CPUE

CPUE for Selected Species

Cod

Plaice

Whiting

Haddock

Herring

Biodiversity

Length Distributions

Sprat

Herring

Whiting

Haddock

Common dab

Horse mackerel

Norway pout

Grey gurnard

Mackerel

Plaice

All species Caught

Area - 20

Area - 4B

Area - 4C