Scientific survey report
Danish Baltic International Trawl Survey
2023
The Danish research vessels Dana and Havfisken are used for the
Danish participation in the Baltic International Trawl Survey (BITS),
which, since 1982, has had the purpose of annually monitoring cod and
other species.
Internationally, each nation surveys part of the area, with some
overlap in coverage and depth stratification, in a coordinated sampling
design. After agreement between countries a common standard trawl gear
and standard sampling procedures were implemented in 2000, resulting in
the consistent coverage of the western and central Baltic Sea.
The BITS 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.
All data can be found in the ICES DATRAS database (https://datras.ices.dk/Data_products/Download/Download_Data_public.aspx) and details about the survey design and survey standardization before 2000 can be found in the ICES BITS manual (Anon. 2000).
Period
Quarter 1
Activity
Here is shown a map with the survey activity for both vessls. 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.
Bongo Stations
Each bongo stationsions in conducted with a set of three bongonets,
with net sizes 150, 300 and 500 micrometers. These are used for the
registartion of fishlarvey, plankton abundance and jelly 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. If any CTD stations are not plotted data has not yet been precessed
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 | 61082.2 | 1766053 | ||
| Sprat | 13972.1 | 1029210 | 40 | 165 |
| Herring | 12360.9 | 359782 | 70 | 300 |
| Cod | 10633.0 | 46919 | 50 | 800 |
| Plaice | 4752.3 | 77872 | 50 | 440 |
| Sole | 10.2 | 61 | 100 | 340 |
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
Sole
Sprat
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.
Sprat
Herring
Common dab
Plaice
Flounder
Cod
Whiting
Haddock
Norway pout
Mackerel
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) |
|---|---|---|---|---|---|
| Alloteuthis subulata | European common squid | 0.2 | 22 | ||
| Arnoglossus laterna | Scaldfish | 0.3 | 31 | 80 | 150 |
| Callionymidae | Dragonets | 10.3 | 536 | 70 | 220 |
| Callionymus lyra | Common dragonet | 1.4 | 37 | 120 | 210 |
| Callionymus maculatus | Spotted dragonet | 0.1 | 8 | 100 | 150 |
| Clupea harengus | Herring | 303.7 | 9662 | 85 | 270 |
| Enchelyopus cimbrius | Four-bearded rockling | 0.0 | 1 | 170 | 170 |
| Eutrigla gurnardus | Grey gurnard | 2.6 | 83 | 80 | 350 |
| Gadus morhua | Cod | 33.2 | 439 | 90 | 800 |
| Hippoglossoides platessoides | American plaice | 51.1 | 2751 | 70 | 190 |
| Hippoglossus hippoglossus | Atlantic halibut | 0.6 | 1 | 390 | 390 |
| Limanda limanda | Common dab | 89.3 | 1859 | 70 | 290 |
| Lophius piscatorius | Angler fish | 0.1 | 1 | 180 | 180 |
| Lumpenus lampretaeformis | Snake blenny | 0.2 | 11 | 210 | 290 |
| Melanogrammus aeglefinus | Haddock | 133.0 | 3363 | 110 | 200 |
| Merlangius merlangus | Whiting | 315.7 | 7309 | 90 | 310 |
| Microstomus kitt | Lemon sole | 4.3 | 70 | 90 | 250 |
| Myoxocephalus scorpius | Sculpin | 0.3 | 4 | 120 | 220 |
| Nephrops norvegicus | Norway lobster | 4.3 | 94 | ||
| Platichthys flesus | Flounder | 18.9 | 89 | 120 | 380 |
| Pleuronectes platessa | Plaice | 118.1 | 2612 | 70 | 280 |
| Pomatoschistus spp. | Sand gobies | 0.0 | 4 | 90 | 100 |
| Scomber scombrus | Mackerel | 0.1 | 2 | 190 | 200 |
| Scophthalmus rhombus | Brill | 3.2 | 7 | 260 | 350 |
| Sprattus sprattus | Sprat | 0.6 | 168 | 55 | 145 |
| Trisopterus esmarkii | Norway pout | 46.2 | 4867 | 90 | 130 |
Area 21
| Latin name | English name | Weight (kg) | Number | Min. Length (mm) | Max. Length (mm) |
|---|---|---|---|---|---|
| Agonus cataphractus | Pogge | 0.0 | 2 | 130 | 140 |
| Alloteuthis subulata | European common squid | 0.2 | 25 | ||
| Alosa fallax | Twaite shad | 0.2 | 1 | 280 | 280 |
| Amblyraja radiata | Starry ray | 2.7 | 8 | 170 | 530 |
| Ammodytes tobianus | Sandeel | 0.0 | 1 | 105 | 105 |
| Argentina sphyraena | Lesser silver smelt | 0.1 | 6 | 130 | 140 |
| Arnoglossus laterna | Scaldfish | 1.3 | 143 | 70 | 170 |
| Brama brama | Rays bream (pomfret) | 1.0 | 1 | 450 | 450 |
| Buglossidium luteum | Solenette | 0.2 | 21 | 70 | 140 |
| Callionymus lyra | Common dragonet | 2.8 | 79 | 100 | 230 |
| Callionymus maculatus | Spotted dragonet | 5.8 | 651 | 50 | 150 |
| Cancer pagurus | Edible crab | 6.3 | 11 | 100 | 180 |
| Chelidonichthys lucerna | Tub gurnard | 2.7 | 11 | 240 | 350 |
| Clupea harengus | Herring | 1427.7 | 87356 | 70 | 280 |
| Eledone cirrhosa | Horned octopus | 0.1 | 1 | ||
| Enchelyopus cimbrius | Four-bearded rockling | 2.3 | 98 | 100 | 230 |
| Engraulis encrasicolus | Anchovy | 0.3 | 23 | 100 | 150 |
| Entelurus aequoreus | Snake pipefish | 0.0 | 2 | 490 | 530 |
| Eutrigla gurnardus | Grey gurnard | 104.7 | 2301 | 70 | 320 |
| Gadus morhua | Cod | 59.7 | 912 | 90 | 710 |
| Glyptocephalus cynoglossus | Witch | 1.6 | 27 | 100 | 330 |
| Hippoglossoides platessoides | American plaice | 116.0 | 8695 | 60 | 320 |
| Illex coindetii | Southern shortfin squid | 0.1 | 1 | ||
| Labrus bergylta | Ballan wrasse | 0.0 | 1 | 150 | 150 |
| Limanda limanda | Common dab | 1563.1 | 37375 | 90 | 310 |
| Lithodes maja | Norway king crab | 0.8 | 1 | 120 | 120 |
| Loligo forbesii | Northern squid | 0.0 | 1 | ||
| Lumpenus lampretaeformis | Snake blenny | 4.8 | 307 | 150 | 300 |
| Melanogrammus aeglefinus | Haddock | 291.8 | 7129 | 120 | 260 |
| Merlangius merlangus | Whiting | 1005.4 | 26667 | 70 | 320 |
| Merluccius merluccius | Hake | 3.8 | 35 | 80 | 330 |
| Microstomus kitt | Lemon sole | 4.5 | 53 | 130 | 310 |
| Molva molva | Ling | 0.1 | 1 | 250 | 250 |
| Mullus surmuletus | Striped red mullet | 0.1 | 2 | 130 | 150 |
| Myoxocephalus scorpius | Sculpin | 12.8 | 137 | 80 | 280 |
| Myxine glutinosa | Hagfish | 0.1 | 3 | 250 | 270 |
| Nephrops norvegicus | Norway lobster | 139.4 | 4411 | ||
| Pandalus borealis | Northern pink shrimp | 57.1 | 0 | ||
| Petromyzontinae | Lampreys | 0.0 | 1 | 210 | 210 |
| Pholis gunnellus | Butter fish | 0.1 | 8 | 130 | 200 |
| Platichthys flesus | Flounder | 218.5 | 1185 | 100 | 410 |
| Pleuronectes platessa | Plaice | 1165.3 | 17923 | 60 | 410 |
| Pomatoschistus spp. | Sand gobies | 0.4 | 66 | 50 | 100 |
| Raja clavata | Thornback ray | 5.4 | 5 | 300 | 700 |
| Scomber scombrus | Mackerel | 183.8 | 3275 | 170 | 290 |
| Scophthalmus maximus | Turbot | 1.6 | 5 | 220 | 280 |
| Scophthalmus rhombus | Brill | 11.1 | 20 | 160 | 510 |
| Scyliorhinus canicula | Lesser-spotted dogfish | 0.6 | 1 | 550 | 550 |
| Solea solea | Sole | 5.0 | 33 | 190 | 340 |
| Spinachia spinachia | Ten spined stickleback | 0.0 | 3 | 130 | 300 |
| Sprattus sprattus | Sprat | 776.0 | 51679 | 60 | 155 |
| Squalus acanthias | Spurdog | 0.1 | 1 | 270 | 270 |
| Symphodus melops | Corkwing | 0.0 | 10 | 40 | 70 |
| Syngnathidae | Pipefishes and seahorses | 0.0 | 1 | 140 | 140 |
| Trachinus draco | Greater weever fish | 5.8 | 87 | 150 | 370 |
| Trachurus trachurus | Horse mackerel | 2.3 | 24 | 120 | 380 |
| Trisopterus esmarkii | Norway pout | 14.5 | 1532 | 90 | 140 |
| Trisopterus minutus | Poor-cod | 0.1 | 3 | 140 | 180 |
Area 22
| Latin name | English name | Weight (kg) | Number | Min. Length (mm) | Max. Length (mm) |
|---|---|---|---|---|---|
| Agonus cataphractus | Pogge | 0.8 | 40 | 70 | 180 |
| Amblyraja radiata | Starry ray | 1.1 | 2 | 350 | 470 |
| Ammodytes tobianus | Sandeel | 0.0 | 2 | 85 | 160 |
| Anguilla anguilla | Eel | 0.2 | 1 | 510 | 510 |
| Arctica islandica | Ocean quahaug | 450.7 | 0 | ||
| Arnoglossus laterna | Scaldfish | 0.7 | 71 | 40 | 140 |
| Asterias rubens | Common starfish | 9.6 | 0 | ||
| Buglossidium luteum | Solenette | 0.0 | 1 | 50 | 50 |
| Callionymus lyra | Common dragonet | 0.6 | 27 | 90 | 190 |
| Cancer pagurus | Edible crab | 0.4 | 1 | ||
| Clupea harengus | Herring | 475.0 | 32270 | 75 | 280 |
| Crangon crangon | Common shrimp | 0.0 | 3 | ||
| Enchelyopus cimbrius | Four-bearded rockling | 0.3 | 6 | 180 | 240 |
| Engraulis encrasicolus | Anchovy | 5.6 | 1008 | 80 | 130 |
| Eutrigla gurnardus | Grey gurnard | 6.8 | 109 | 140 | 310 |
| Gadus morhua | Cod | 72.1 | 1856 | 90 | 680 |
| Gasterosteus aculeatus | Three-spined stickleback | 1.1 | 530 | 40 | 80 |
| Gobius niger | Black goby | 0.2 | 16 | 70 | 110 |
| Hippoglossoides platessoides | American plaice | 22.0 | 750 | 50 | 290 |
| Hyperoplus lanceolatus | Greater sandeel | 0.1 | 3 | 210 | 210 |
| Labrus bergylta | Ballan wrasse | 0.0 | 1 | 80 | 80 |
| Limanda limanda | Common dab | 2443.6 | 56777 | 50 | 300 |
| Lumpenus lampretaeformis | Snake blenny | 3.3 | 369 | 80 | 330 |
| Melanogrammus aeglefinus | Haddock | 17.3 | 285 | 160 | 230 |
| Merlangius merlangus | Whiting | 245.4 | 7437 | 60 | 290 |
| Merluccius merluccius | Hake | 0.3 | 2 | 280 | 280 |
| Microstomus kitt | Lemon sole | 1.2 | 6 | 170 | 320 |
| Mullus surmuletus | Striped red mullet | 0.0 | 1 | 150 | 150 |
| Myoxocephalus scorpius | Sculpin | 32.8 | 402 | 80 | 290 |
| Pholis gunnellus | Butter fish | 0.1 | 10 | 90 | 190 |
| Platichthys flesus | Flounder | 220.7 | 1144 | 80 | 440 |
| Pleuronectes platessa | Plaice | 2632.1 | 49428 | 50 | 430 |
| Pomatoschistus spp. | Sand gobies | 0.6 | 135 | 40 | 110 |
| Sardina pilchardus | Pilchard | 0.2 | 23 | 110 | 120 |
| Scomber scombrus | Mackerel | 2.7 | 39 | 200 | 230 |
| Scophthalmus maximus | Turbot | 10.8 | 24 | 210 | 430 |
| Scophthalmus rhombus | Brill | 0.1 | 1 | 180 | 180 |
| Solea solea | Sole | 4.6 | 23 | 140 | 340 |
| Spinachia spinachia | Ten spined stickleback | 0.0 | 1 | 130 | 130 |
| Sprattus sprattus | Sprat | 1074.7 | 111797 | 40 | 155 |
| Symphodus melops | Corkwing | 0.1 | 2 | 130 | 130 |
| Syngnathidae | Pipefishes and seahorses | 0.0 | 1 | 320 | 320 |
| Trachinus draco | Greater weever fish | 0.5 | 5 | 180 | 280 |
| Trachurus trachurus | Horse mackerel | 0.0 | 10 | 40 | 150 |
| Trisopterus minutus | Poor-cod | 0.3 | 12 | 120 | 160 |
| Zoarces viviparus | Eelpout | 4.2 | 167 | 70 | 250 |
Area 23
| Latin name | English name | Weight (kg) | Number | Min. Length (mm) | Max. Length (mm) |
|---|---|---|---|---|---|
| Agonus cataphractus | Pogge | 0.0 | 1 | 110 | 110 |
| Anguilla anguilla | Eel | 0.4 | 1 | 550 | 550 |
| Arnoglossus laterna | Scaldfish | 0.1 | 4 | 90 | 140 |
| Callionymus lyra | Common dragonet | 0.0 | 1 | 170 | 170 |
| Callionymus maculatus | Spotted dragonet | 0.0 | 2 | 100 | 120 |
| Cancer pagurus | Edible crab | 1.2 | 2 | 130 | 175 |
| Clupea harengus | Herring | 49.8 | 4019 | 80 | 280 |
| Ctenolabrus rupestris | Goldsinny | 0.0 | 1 | 110 | 110 |
| Enchelyopus cimbrius | Four-bearded rockling | 0.2 | 4 | 220 | 230 |
| Eutrigla gurnardus | Grey gurnard | 0.5 | 4 | 220 | 280 |
| Gadus morhua | Cod | 924.0 | 2119 | 90 | 680 |
| Hippoglossoides platessoides | American plaice | 0.3 | 6 | 170 | 260 |
| Hyperoplus lanceolatus | Greater sandeel | 0.1 | 3 | 180 | 200 |
| Limanda limanda | Common dab | 372.3 | 4113 | 70 | 300 |
| Melanogrammus aeglefinus | Haddock | 6.2 | 30 | 170 | 410 |
| Merlangius merlangus | Whiting | 117.9 | 2423 | 90 | 340 |
| Merluccius merluccius | Hake | 0.2 | 1 | 310 | 310 |
| Microstomus kitt | Lemon sole | 0.2 | 1 | 240 | 240 |
| Molva molva | Ling | 2.8 | 1 | 740 | 740 |
| Mytilus edulis | Blue mussel | 102.6 | 0 | ||
| Platichthys flesus | Flounder | 51.6 | 205 | 140 | 420 |
| Pleuronectes platessa | Plaice | 326.1 | 2060 | 90 | 420 |
| Pomatoschistus spp. | Sand gobies | 0.0 | 1 | 90 | 90 |
| Scophthalmus maximus | Turbot | 3.2 | 6 | 210 | 370 |
| Scophthalmus rhombus | Brill | 15.5 | 21 | 210 | 530 |
| Scyliorhinus canicula | Lesser-spotted dogfish | 0.4 | 1 | 490 | 490 |
| Solea solea | Sole | 0.4 | 4 | 100 | 270 |
| Sprattus sprattus | Sprat | 19.0 | 1182 | 80 | 165 |
| Trisopterus minutus | Poor-cod | 0.0 | 1 | 160 | 160 |
| Zoarces viviparus | Eelpout | 0.1 | 4 | 120 | 260 |
Area 24
| Latin name | English name | Weight (kg) | Number | Min. Length (mm) | Max. Length (mm) |
|---|---|---|---|---|---|
| Agonus cataphractus | Pogge | 0.1 | 4 | 100 | 160 |
| Alosa fallax | Twaite shad | 0.1 | 1 | 260 | 260 |
| Clupea harengus | Herring | 1007.9 | 19877 | 90 | 300 |
| Cyclopterus lumpus | Lumpfish | 0.5 | 2 | 160 | 180 |
| Enchelyopus cimbrius | Four-bearded rockling | 0.2 | 3 | 200 | 250 |
| Gadus morhua | Cod | 532.6 | 6711 | 90 | 470 |
| Gasterosteus aculeatus | Three-spined stickleback | 0.0 | 3 | 60 | 60 |
| Gobius niger | Black goby | 0.1 | 1 | 150 | 150 |
| Hippoglossoides platessoides | American plaice | 0.1 | 1 | 230 | 230 |
| Hyperoplus lanceolatus | Greater sandeel | 1.1 | 62 | 170 | 205 |
| Limanda limanda | Common dab | 191.7 | 2936 | 70 | 310 |
| Lumpenus lampretaeformis | Snake blenny | 0.0 | 1 | 220 | 220 |
| Merlangius merlangus | Whiting | 20.2 | 194 | 90 | 380 |
| Myoxocephalus scorpius | Sculpin | 6.4 | 72 | 140 | 270 |
| Mytilus edulis | Blue mussel | 283.2 | 0 | ||
| Platichthys flesus | Flounder | 304.1 | 1688 | 130 | 440 |
| Pleuronectes platessa | Plaice | 283.3 | 3661 | 60 | 440 |
| Pollachius virens | Saithe | 0.3 | 1 | 320 | 320 |
| Pomatoschistus spp. | Sand gobies | 0.0 | 1 | 40 | 40 |
| Saduria entomon | Saduria | 0.0 | 4 | ||
| Scophthalmus maximus | Turbot | 5.2 | 19 | 180 | 340 |
| Scophthalmus rhombus | Brill | 0.6 | 2 | 270 | 300 |
| Solea solea | Sole | 0.2 | 1 | 270 | 270 |
| Sprattus sprattus | Sprat | 114.5 | 6968 | 70 | 165 |
| Zoarces viviparus | Eelpout | 0.5 | 7 | 150 | 310 |
Area 25
| Latin name | English name | Weight (kg) | Number | Min. Length (mm) | Max. Length (mm) |
|---|---|---|---|---|---|
| Agonus cataphractus | Pogge | 0.1 | 3 | 160 | 180 |
| Alosa fallax | Twaite shad | 77.9 | 533 | 230 | 360 |
| Clupea harengus | Herring | 8458.7 | 190452 | 120 | 300 |
| Cyclopterus lumpus | Lumpfish | 5.0 | 19 | 140 | 190 |
| Enchelyopus cimbrius | Four-bearded rockling | 9.0 | 150 | 90 | 310 |
| Engraulis encrasicolus | Anchovy | 1.3 | 266 | 100 | 180 |
| Gadus morhua | Cod | 7052.5 | 27431 | 50 | 600 |
| Gasterosteus aculeatus | Three-spined stickleback | 7.1 | 3012 | 30 | 70 |
| Hyperoplus lanceolatus | Greater sandeel | 2.2 | 139 | 125 | 200 |
| Limanda limanda | Common dab | 0.4 | 3 | 190 | 260 |
| Lumpenus lampretaeformis | Snake blenny | 0.0 | 1 | 300 | 300 |
| Melanogrammus aeglefinus | Haddock | 0.1 | 2 | 160 | 220 |
| Merlangius merlangus | Whiting | 20.8 | 102 | 160 | 420 |
| Merluccius merluccius | Hake | 0.3 | 1 | 350 | 350 |
| Myoxocephalus scorpius | Sculpin | 98.0 | 590 | 120 | 330 |
| Mytilus edulis | Blue mussel | 56.0 | 0 | ||
| Palaemon adspersus | Pink shrimp(nei) | 0.0 | 6 | ||
| Perca fluviatilis | Perch | 0.1 | 1 | 200 | 200 |
| Platichthys flesus | Flounder | 8322.8 | 42841 | 140 | 370 |
| Pleuronectes platessa | Plaice | 215.9 | 2066 | 150 | 380 |
| Pomatoschistus spp. | Sand gobies | 0.1 | 46 | 30 | 50 |
| Saduria entomon | Saduria | 2.3 | 824 | ||
| Scomber scombrus | Mackerel | 55.1 | 150 | 190 | 490 |
| Scophthalmus maximus | Turbot | 18.1 | 61 | 190 | 360 |
| Sprattus sprattus | Sprat | 11875.7 | 851342 | 75 | 160 |
| Trachurus trachurus | Horse mackerel | 0.1 | 5 | 130 | 160 |
| Zoarces viviparus | Eelpout | 0.4 | 7 | 200 | 320 |
Area 26
| Latin name | English name | Weight (kg) | Number | Min. Length (mm) | Max. Length (mm) |
|---|---|---|---|---|---|
| Alosa fallax | Twaite shad | 22.2 | 51 | 240 | 390 |
| Clupea harengus | Herring | 638.2 | 16148 | 155 | 255 |
| Enchelyopus cimbrius | Four-bearded rockling | 3.3 | 38 | 110 | 290 |
| Engraulis encrasicolus | Anchovy | 0.0 | 4 | 120 | 140 |
| Gadus morhua | Cod | 1959.0 | 7452 | 80 | 670 |
| Gasterosteus aculeatus | Three-spined stickleback | 0.1 | 14 | 30 | 60 |
| Macoma balthica | Baltic macoma | 0.0 | 0 | ||
| Mytilus edulis | Blue mussel | 0.0 | 0 | ||
| Platichthys flesus | Flounder | 1216.6 | 6468 | 170 | 390 |
| Pleuronectes platessa | Plaice | 11.4 | 122 | 150 | 280 |
| Scophthalmus maximus | Turbot | 0.1 | 1 | 200 | 200 |
| Scyphozoa | Scyphozoans | 0.1 | 0 | ||
| Sprattus sprattus | Sprat | 111.5 | 6073 | 85 | 150 |
Quarter 4
Activity
Here is shown a map with the survey activity for both vessls. 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.
Bongo Stations
Each bongo stationsions in conducted with a set of three bongonets,
with net sizes 150, 300 and 500 micrometers. These are used for the
registartion of fishlarvey, plankton abundance and jelly 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. If any CTD stations are not plotted data has not yet been precessed
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 | 39066.3 | 1009324 | ||
| Herring | 10479.7 | 267625 | 65 | 295 |
| Plaice | 6015.8 | 94422 | 40 | 430 |
| Sprat | 5789.1 | 404326 | 10 | 165 |
| Cod | 5198.1 | 36130 | 30 | 670 |
| Sole | 86.8 | 586 | 110 | 400 |
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
Sole
Sprat
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.
Sprat
Herring
Common dab
Plaice
Cod
Whiting
Flounder
Haddock
Horse mackerel
Grey gurnard
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) |
|---|---|---|---|---|---|
| Arnoglossus laterna | Scaldfish | 0.2 | 15 | 110 | 140 |
| Callionymus lyra | Common dragonet | 0.4 | 11 | 110 | 230 |
| Callionymus maculatus | Spotted dragonet | 0.1 | 9 | 100 | 110 |
| Cancer pagurus | Edible crab | 1.7 | 2 | 170 | 176 |
| Clupea harengus | Herring | 0.4 | 9 | 160 | 215 |
| Enchelyopus cimbrius | Four-bearded rockling | 0.1 | 2 | 180 | 240 |
| Eutrigla gurnardus | Grey gurnard | 3.2 | 75 | 80 | 240 |
| Gadus morhua | Cod | 8.7 | 44 | 90 | 550 |
| Hippoglossoides platessoides | American plaice | 5.0 | 120 | 100 | 260 |
| Limanda limanda | Common dab | 69.5 | 642 | 120 | 250 |
| Melanogrammus aeglefinus | Haddock | 200.5 | 1114 | 210 | 290 |
| Merlangius merlangus | Whiting | 61.7 | 477 | 180 | 370 |
| Merluccius merluccius | Hake | 1.4 | 9 | 180 | 450 |
| Microstomus kitt | Lemon sole | 0.8 | 10 | 160 | 230 |
| Nephrops norvegicus | Norway lobster | 4.4 | 126 | ||
| Platichthys flesus | Flounder | 0.0 | 1 | 130 | 130 |
| Pleuronectes platessa | Plaice | 213.5 | 2023 | 130 | 320 |
| Scomber scombrus | Mackerel | 1.3 | 5 | 250 | 370 |
| Scophthalmus rhombus | Brill | 0.3 | 1 | 270 | 270 |
| Solea solea | Sole | 0.5 | 3 | 230 | 300 |
| Sprattus sprattus | Sprat | 0.1 | 9 | 110 | 135 |
| Squalus acanthias | Spurdog | 46.5 | 14 | 740 | 1030 |
| Trachurus trachurus | Horse mackerel | 0.1 | 4 | 90 | 130 |
| Trisopterus esmarkii | Norway pout | 1.8 | 66 | 90 | 170 |
| Trisopterus minutus | Poor-cod | 0.1 | 2 | 130 | 160 |
Area 21
| Latin name | English name | Weight (kg) | Number | Min. Length (mm) | Max. Length (mm) |
|---|---|---|---|---|---|
| Agonus cataphractus | Pogge | 0.2 | 10 | 60 | 160 |
| Alloteuthis subulata | European common squid | 8.1 | 4302 | ||
| Amblyraja radiata | Starry ray | 0.6 | 1 | 450 | 450 |
| Ammodytes marinus | Lesser sandeel | 0.7 | 53 | 115 | 195 |
| Argentina sphyraena | Lesser silver smelt | 0.1 | 18 | 70 | 150 |
| Arnoglossus laterna | Scaldfish | 4.2 | 551 | 60 | 150 |
| Buglossidium luteum | Solenette | 0.8 | 69 | 70 | 130 |
| Callionymidae | Dragonets | 4.6 | 619 | 70 | 160 |
| Callionymus lyra | Common dragonet | 15.9 | 510 | 40 | 220 |
| Callionymus maculatus | Spotted dragonet | 15.9 | 2024 | 70 | 160 |
| Cancer pagurus | Edible crab | 51.4 | 84 | 90 | 190 |
| Chelidonichthys lucerna | Tub gurnard | 0.7 | 3 | 110 | 350 |
| Chelon labrosus | Thick lipped mullet | 0.0 | 1 | 140 | 140 |
| Ciliata mustela | Five-bearded rockling | 0.1 | 1 | 190 | 190 |
| Clupea harengus | Herring | 379.3 | 14228 | 75 | 295 |
| Ctenolabrus rupestris | Goldsinny | 0.1 | 10 | 30 | 140 |
| Enchelyopus cimbrius | Four-bearded rockling | 3.3 | 131 | 120 | 270 |
| Engraulis encrasicolus | Anchovy | 0.2 | 8 | 130 | 180 |
| Entelurus aequoreus | Snake pipefish | 0.1 | 2 | 470 | 490 |
| Eutrigla gurnardus | Grey gurnard | 79.2 | 1500 | 60 | 330 |
| Gadus morhua | Cod | 91.5 | 887 | 90 | 540 |
| Glyptocephalus cynoglossus | Witch | 1.2 | 17 | 150 | 270 |
| Gobius niger | Black goby | 0.8 | 73 | 50 | 150 |
| Hippoglossoides platessoides | American plaice | 181.3 | 10685 | 60 | 240 |
| Homarus gammarus | European lobster | 2.1 | 2 | 95 | 123 |
| Hyperoplus lanceolatus | Greater sandeel | 0.6 | 43 | 140 | 260 |
| Illex coindetii | Southern shortfin squid | 0.2 | 6 | ||
| Labrus bergylta | Ballan wrasse | 0.1 | 5 | 80 | 140 |
| Limanda limanda | Common dab | 2249.4 | 55752 | 50 | 270 |
| Loligo forbesii | Northern squid | 0.9 | 4 | ||
| Loligo vulgaris | European squid | 11.9 | 22 | ||
| Lophius piscatorius | Angler fish | 0.8 | 1 | 360 | 360 |
| Lumpenus lampretaeformis | Snake blenny | 2.2 | 182 | 100 | 290 |
| Lycodes gracilis | Vahls eelpout | 0.0 | 2 | 120 | 150 |
| Melanogrammus aeglefinus | Haddock | 138.3 | 1421 | 130 | 280 |
| Merlangius merlangus | Whiting | 1259.1 | 19489 | 60 | 330 |
| Merluccius merluccius | Hake | 25.6 | 218 | 60 | 500 |
| Microstomus kitt | Lemon sole | 14.3 | 229 | 100 | 310 |
| Molva molva | Ling | 0.7 | 2 | 410 | 470 |
| Mullus surmuletus | Striped red mullet | 0.6 | 11 | 100 | 260 |
| Myoxocephalus scorpius | Sculpin | 9.7 | 97 | 100 | 310 |
| Nephrops norvegicus | Norway lobster | 85.3 | 2928 | 28 | 68 |
| Pandalus borealis | Northern pink shrimp | 5.3 | 1023 | ||
| Pholis gunnellus | Butter fish | 0.1 | 6 | 100 | 200 |
| Platichthys flesus | Flounder | 68.9 | 391 | 90 | 380 |
| Pleuronectes platessa | Plaice | 935.0 | 15151 | 80 | 430 |
| Pollachius virens | Saithe | 0.3 | 1 | 300 | 300 |
| Pomatoschistus spp. | Sand gobies | 0.6 | 96 | 50 | 110 |
| Raja clavata | Thornback ray | 10.9 | 4 | 590 | 850 |
| Scomber scombrus | Mackerel | 63.4 | 302 | 220 | 400 |
| Scophthalmus maximus | Turbot | 1.1 | 3 | 210 | 350 |
| Scophthalmus rhombus | Brill | 18.5 | 53 | 140 | 460 |
| Scyliorhinus canicula | Lesser-spotted dogfish | 1.2 | 1 | 660 | 660 |
| Sepiolidae | Bobtail squids | 0.1 | 5 | ||
| Solea solea | Sole | 26.4 | 216 | 150 | 400 |
| Spinachia spinachia | Ten spined stickleback | 0.0 | 1 | 380 | 380 |
| Sprattus sprattus | Sprat | 129.6 | 9868 | 60 | 165 |
| Squalus acanthias | Spurdog | 408.3 | 137 | 220 | 1120 |
| Symphodus melops | Corkwing | 0.1 | 3 | 100 | 150 |
| Syngnathus acus | Great pipefish | 0.0 | 1 | 320 | 320 |
| Taurulus bubalis | Sea scorpion | 0.0 | 1 | 40 | 40 |
| Trachinus draco | Greater weever fish | 839.0 | 13930 | 100 | 350 |
| Trachurus trachurus | Horse mackerel | 7.6 | 584 | 50 | 200 |
| Trisopterus esmarkii | Norway pout | 6.4 | 684 | 40 | 170 |
| Trisopterus minutus | Poor-cod | 0.4 | 17 | 130 | 140 |
| Zeugopterus punctatus | Topknot | 0.0 | 3 | 90 | 90 |
Area 22
| Latin name | English name | Weight (kg) | Number | Min. Length (mm) | Max. Length (mm) |
|---|---|---|---|---|---|
| Acipenser oxyrinchus | Atlantic sturgeon | 2.9 | 1 | 790 | 790 |
| Agonus cataphractus | Pogge | 0.1 | 7 | 120 | 160 |
| Alosa fallax | Twaite shad | 0.2 | 1 | 310 | 310 |
| Ammodytes marinus | Lesser sandeel | 0.0 | 2 | 180 | 180 |
| Anguilla anguilla | Eel | 1.1 | 3 | 340 | 650 |
| Arnoglossus laterna | Scaldfish | 1.3 | 103 | 50 | 160 |
| Callionymidae | Dragonets | 0.2 | 4 | 190 | 230 |
| Callionymus lyra | Common dragonet | 0.3 | 10 | 100 | 220 |
| Cancer pagurus | Edible crab | 3.0 | 6 | 114 | 180 |
| Chelidonichthys lucerna | Tub gurnard | 0.3 | 4 | 200 | 220 |
| Clupea harengus | Herring | 319.4 | 22415 | 65 | 280 |
| Ctenolabrus rupestris | Goldsinny | 0.2 | 15 | 50 | 110 |
| Enchelyopus cimbrius | Four-bearded rockling | 1.0 | 26 | 140 | 280 |
| Engraulis encrasicolus | Anchovy | 0.1 | 8 | 110 | 180 |
| Eutrigla gurnardus | Grey gurnard | 10.2 | 158 | 80 | 330 |
| Gadus morhua | Cod | 97.3 | 4572 | 70 | 350 |
| Gasterosteus aculeatus | Three-spined stickleback | 0.0 | 3 | 40 | 60 |
| Gobius niger | Black goby | 3.1 | 313 | 50 | 140 |
| Hippoglossoides platessoides | American plaice | 7.6 | 149 | 70 | 300 |
| Homarus gammarus | European lobster | 1.2 | 1 | 125 | 125 |
| Hyperoplus lanceolatus | Greater sandeel | 0.1 | 7 | 170 | 220 |
| Labrus bergylta | Ballan wrasse | 0.1 | 5 | 70 | 110 |
| Limanda limanda | Common dab | 2476.8 | 51580 | 50 | 320 |
| Lumpenus lampretaeformis | Snake blenny | 2.3 | 213 | 100 | 270 |
| Melanogrammus aeglefinus | Haddock | 1.1 | 8 | 220 | 290 |
| Merlangius merlangus | Whiting | 279.7 | 5735 | 70 | 310 |
| Merluccius merluccius | Hake | 0.2 | 1 | 320 | 320 |
| Microstomus kitt | Lemon sole | 1.4 | 7 | 220 | 290 |
| Mullus surmuletus | Striped red mullet | 0.4 | 3 | 130 | 250 |
| Myoxocephalus scorpius | Sculpin | 19.2 | 213 | 100 | 260 |
| Nephrops norvegicus | Norway lobster | 0.0 | 2 | 33 | 34 |
| Petromyzon marinus | Sea lamprey | 0.1 | 1 | 360 | 360 |
| Pholis gunnellus | Butter fish | 0.1 | 8 | 110 | 200 |
| Platichthys flesus | Flounder | 113.6 | 847 | 100 | 380 |
| Pleuronectes platessa | Plaice | 2573.4 | 47599 | 50 | 380 |
| Pomatoschistus spp. | Sand gobies | 1.1 | 124 | 40 | 130 |
| Scophthalmus maximus | Turbot | 28.3 | 84 | 120 | 380 |
| Scophthalmus rhombus | Brill | 7.3 | 28 | 110 | 360 |
| Solea solea | Sole | 46.6 | 301 | 110 | 400 |
| Sprattus sprattus | Sprat | 539.9 | 43755 | 60 | 150 |
| Syngnathidae | Pipefishes and seahorses | 0.0 | 1 | 300 | 300 |
| Trachinus draco | Greater weever fish | 3.8 | 48 | 160 | 350 |
| Trachurus trachurus | Horse mackerel | 26.1 | 1639 | 70 | 190 |
| Zoarces viviparus | Eelpout | 2.6 | 92 | 100 | 260 |
Area 23
| Latin name | English name | Weight (kg) | Number | Min. Length (mm) | Max. Length (mm) |
|---|---|---|---|---|---|
| Anguilla anguilla | Eel | 1.8 | 3 | 600 | 740 |
| Arnoglossus laterna | Scaldfish | 0.5 | 43 | 60 | 140 |
| Buglossidium luteum | Solenette | 0.1 | 11 | 60 | 130 |
| Callionymus lyra | Common dragonet | 0.2 | 7 | 150 | 180 |
| Callionymus maculatus | Spotted dragonet | 0.1 | 13 | 80 | 110 |
| Cancer pagurus | Edible crab | 2.2 | 3 | ||
| Carcinus maenas | Common shore crab | 1.2 | 0 | ||
| Chelidonichthys lucerna | Tub gurnard | 0.6 | 1 | 390 | 390 |
| Clupea harengus | Herring | 7.9 | 238 | 65 | 295 |
| Crangon crangon | Common shrimp | 0.0 | 31 | ||
| Ctenolabrus rupestris | Goldsinny | 0.1 | 23 | 30 | 100 |
| Enchelyopus cimbrius | Four-bearded rockling | 0.1 | 3 | 130 | 220 |
| Engraulis encrasicolus | Anchovy | 0.2 | 26 | 80 | 130 |
| Eutrigla gurnardus | Grey gurnard | 9.0 | 84 | 60 | 350 |
| Gadus morhua | Cod | 74.4 | 329 | 70 | 670 |
| Gobius niger | Black goby | 0.1 | 11 | 70 | 110 |
| Hippoglossoides platessoides | American plaice | 5.6 | 111 | 110 | 310 |
| Limanda limanda | Common dab | 565.2 | 7439 | 50 | 300 |
| Merlangius merlangus | Whiting | 42.5 | 566 | 70 | 330 |
| Merluccius merluccius | Hake | 0.1 | 2 | 190 | 200 |
| Microstomus kitt | Lemon sole | 0.3 | 1 | 290 | 290 |
| Mullus surmuletus | Striped red mullet | 0.0 | 2 | 120 | 120 |
| Myoxocephalus scorpius | Sculpin | 1.0 | 12 | 120 | 260 |
| Mytilus edulis | Blue mussel | 447.5 | 0 | ||
| Neogobius melanostomus | Round goby | 3.0 | 66 | 50 | 190 |
| Pholis gunnellus | Butter fish | 0.0 | 1 | 150 | 150 |
| Platichthys flesus | Flounder | 57.4 | 310 | 60 | 380 |
| Pleuronectes platessa | Plaice | 537.1 | 3626 | 40 | 410 |
| Pomatoschistus spp. | Sand gobies | 0.0 | 26 | 40 | 70 |
| Scomber scombrus | Mackerel | 1.7 | 9 | 230 | 310 |
| Scophthalmus maximus | Turbot | 1.9 | 5 | 200 | 370 |
| Scophthalmus rhombus | Brill | 4.9 | 15 | 170 | 400 |
| Solea solea | Sole | 10.2 | 48 | 170 | 400 |
| Sprattus sprattus | Sprat | 9.4 | 571 | 55 | 165 |
| Symphodus melops | Corkwing | 0.3 | 24 | 50 | 150 |
| Syngnathidae | Pipefishes and seahorses | 0.0 | 1 | 160 | 160 |
| Trachinus draco | Greater weever fish | 3.0 | 45 | 160 | 260 |
| Trachurus trachurus | Horse mackerel | 0.3 | 40 | 70 | 120 |
| Zoarces viviparus | Eelpout | 0.2 | 8 | 160 | 200 |
Area 24
| Latin name | English name | Weight (kg) | Number | Min. Length (mm) | Max. Length (mm) |
|---|---|---|---|---|---|
| Agonus cataphractus | Pogge | 0.8 | 46 | 70 | 180 |
| Arnoglossus laterna | Scaldfish | 0.0 | 2 | 60 | 60 |
| Buglossidium luteum | Solenette | 0.5 | 96 | 60 | 110 |
| Carcinus maenas | Common shore crab | 2.3 | 0 | ||
| Clupea harengus | Herring | 25.6 | 1222 | 90 | 295 |
| Ctenolabrus rupestris | Goldsinny | 0.1 | 25 | 30 | 100 |
| Enchelyopus cimbrius | Four-bearded rockling | 1.8 | 46 | 120 | 240 |
| Eutrigla gurnardus | Grey gurnard | 0.0 | 2 | 80 | 90 |
| Gadus morhua | Cod | 51.2 | 1795 | 70 | 450 |
| Gasterosteus aculeatus | Three-spined stickleback | 0.0 | 1 | 50 | 50 |
| Gobius niger | Black goby | 0.0 | 6 | 70 | 90 |
| Hyperoplus lanceolatus | Greater sandeel | 0.8 | 49 | 165 | 210 |
| Limanda limanda | Common dab | 198.3 | 3606 | 60 | 330 |
| Lumpenus lampretaeformis | Snake blenny | 0.4 | 28 | 110 | 300 |
| Merlangius merlangus | Whiting | 5.3 | 153 | 80 | 290 |
| Myoxocephalus scorpius | Sculpin | 6.1 | 81 | 110 | 270 |
| Mytilus edulis | Blue mussel | 144.9 | 0 | ||
| Neogobius melanostomus | Round goby | 1.5 | 78 | 50 | 170 |
| Platichthys flesus | Flounder | 252.4 | 1454 | 40 | 390 |
| Pleuronectes platessa | Plaice | 1615.6 | 25007 | 60 | 410 |
| Pomatoschistus spp. | Sand gobies | 0.6 | 456 | 30 | 70 |
| Scomber scombrus | Mackerel | 0.2 | 1 | 280 | 280 |
| Scophthalmus maximus | Turbot | 24.4 | 90 | 160 | 340 |
| Scophthalmus rhombus | Brill | 1.4 | 2 | 300 | 410 |
| Solea solea | Sole | 3.1 | 18 | 150 | 370 |
| Sprattus sprattus | Sprat | 1.5 | 91 | 95 | 155 |
| Symphodus melops | Corkwing | 0.0 | 2 | 80 | 80 |
| Syngnathus rostellatus | Lesser pipefish | 0.0 | 4 | 160 | 180 |
| Trachurus trachurus | Horse mackerel | 0.1 | 7 | 90 | 130 |
| Zoarces viviparus | Eelpout | 3.1 | 58 | 100 | 330 |
Area 25
| Latin name | English name | Weight (kg) | Number | Min. Length (mm) | Max. Length (mm) |
|---|---|---|---|---|---|
| Alosa fallax | Twaite shad | 36.1 | 152 | 250 | 350 |
| Anguilla anguilla | Eel | 1.0 | 3 | 310 | 700 |
| Clupea harengus | Herring | 9747.0 | 229514 | 105 | 270 |
| Cyclopterus lumpus | Lumpfish | 1.7 | 5 | 140 | 210 |
| Enchelyopus cimbrius | Four-bearded rockling | 13.3 | 256 | 30 | 320 |
| Engraulis encrasicolus | Anchovy | 0.6 | 36 | 100 | 170 |
| Gadus morhua | Cod | 4874.9 | 28503 | 30 | 640 |
| Gasterosteus aculeatus | Three-spined stickleback | 1.6 | 961 | 30 | 70 |
| Gobiidae | True gobies | 0.0 | 9 | 30 | 40 |
| Hyperoplus lanceolatus | Greater sandeel | 0.0 | 1 | 235 | 235 |
| Limanda limanda | Common dab | 0.4 | 5 | 170 | 210 |
| Merlangius merlangus | Whiting | 6.8 | 25 | 200 | 360 |
| Myoxocephalus quadricornis | Fourhorn sculpin | 0.1 | 1 | 180 | 180 |
| Myoxocephalus scorpius | Sculpin | 115.4 | 722 | 90 | 320 |
| Mytilus edulis | Blue mussel | 0.3 | 28 | ||
| Neogobius melanostomus | Round goby | 0.1 | 1 | 190 | 190 |
| Pholis gunnellus | Butter fish | 0.1 | 3 | 190 | 200 |
| Platichthys flesus | Flounder | 448.2 | 2112 | 170 | 400 |
| Pleuronectes platessa | Plaice | 141.3 | 1016 | 60 | 360 |
| Pomatoschistus spp. | Sand gobies | 0.0 | 30 | 30 | 50 |
| Saduria entomon | Saduria | 8.2 | 3991 | ||
| Scomber scombrus | Mackerel | 0.1 | 1 | 220 | 220 |
| Scophthalmus maximus | Turbot | 45.8 | 149 | 160 | 400 |
| Scyphozoa | Scyphozoans | 20.3 | 0 | ||
| Sprattus sprattus | Sprat | 5108.6 | 350031 | 10 | 160 |
| Zoarces viviparus | Eelpout | 0.5 | 12 | 140 | 290 |