The primary sampling unit (PSU) in the Belgian at sea sampling programme is vessel x trip (as a proxy for trip). A vessel x trip (PSU) for the TBB_DEF_>221 kW fleet segment is selected ad hoc or standard quota sampling is conducted (non-probability-based sampling). The vessels that are willing to take observers onboard and those that are logistically suited, are included in the vessel list, that currently contains ± 15 vessels over which the sampling will be spread. ILVO introduced 2 types of sampling: 1. Ad hoc sampling: for those strata with a lower sampling coverage (based on previous years) 2. Quota sampling: sampling effort is proportionally to the fleet effort (based on previous year) A vessel x trip (PSU) for the TBB_DEF_<=221 kW fleet segment is selected ad hoc. More than half of TBB_DEF vessels with a capacity <=221 kW flying the Belgian flag are regularly fishing for shrimp (TBB_CRU). Belgium has a derogation for sampling the TBB_CRU métier until the end of 2021. The TBB_DEF_<=221 kW vessel list proved too small to ensure random PSU selection. Therefore, ad hoc sampling of 2 euro cutters and 2 coastal vessels is carried out. The observer coordinator keeps track of the vessels in the vessel list but ILVO considers collecting non-responses and refusals on PSU (trip) level not relevant. Every other haul is sampled by an observer. For the TBB_DEF_<=221 kW fleet segment, the aim is to sample all hauls during the short trips of the coastal vessels. The crew sorts the marketable fish from the conveyor belt. In the meantime, the observer is sampling the discarded fraction of the catch by sorting all commercially important species. The total weight per species in each haul is determined and lengths are measured. When a species is extremely abundant, a smaller representative subsample (TSU) is measured. The marketable part of the catch (landings) is sampled later on in the same way as the discarded part of the catch. For selected species (depending on the area), otoliths from minimum 3 fish per cm-size class per species per area, are collected (except for 1 fish per cm-size class for cod) for age estimations. Otoliths are collected throughout the whole trip (several hauls) until the quota for otoliths is achieved. For the discarded part of the catch, otoliths are being removed on board. For the retained part (landings) of the catch, the fish are purchased. Coordination takes place within the Regional Coordination Groups (RCG NA/RCG NSE).

The primary sampling unit (PSU) in the Belgian at sea sampling programme is vessel x trip (as a proxy for trip). A vessel x trip (PSU) for the TBB_DEF_>221 kW fleet segment is selected ad hoc or standard quota sampling is conducted (non-probability-based sampling). The vessels that are willing to take observers onboard and those that are logistically suited, are included in the vessel list, that currently contains ± 15 vessels over which the sampling will be spread. ILVO introduced 2 types of sampling: 1. Ad hoc sampling: for those strata with a lower sampling coverage (based on previous years) 2. Quota sampling: sampling effort is proportionally to the fleet effort (based on previous year) A vessel x trip (PSU) for the TBB_DEF_<=221 kW fleet segment is selected ad hoc. More than half of TBB_DEF vessels with a capacity <=221 kW flying the Belgian flag are regularly fishing for shrimp (TBB_CRU). Belgium has a derogation for sampling the TBB_CRU métier until the end of 2021. The TBB_DEF_<=221 kW vessel list proved too small to ensure random PSU selection. Therefore, ad hoc sampling of 2 euro cutters and 2 coastal vessels is carried out. The observer coordinator keeps track of the vessels in the vessel list but ILVO considers collecting non-responses and refusals on PSU (trip) level not relevant. Every other haul is sampled by an observer. For the TBB_DEF_<=221 kW fleet segment, the aim is to sample all hauls during the short trips of the coastal vessels. The crew sorts the marketable fish from the conveyor belt. In the meantime, the observer is sampling the discarded fraction of the catch by sorting all commercially important species. The total weight per species in each haul is determined and lengths are measured. When a species is extremely abundant, a smaller representative subsample (TSU) is measured. The marketable part of the catch (landings) is sampled later on in the same way as the discarded part of the catch. For selected species (depending on the area), otoliths from minimum 3 fish per cm-size class per species per area, are collected (except for 1 fish per cm-size class for cod) for age estimations. Otoliths are collected throughout the whole trip (several hauls) until the quota for otoliths is achieved. For the discarded part of the catch, otoliths are being removed on board. For the retained part (landings) of the catch, the fish are purchased. Coordination takes place within the Regional Coordination Groups (RCG NA/RCG NSE).

The primary sampling unit (PSU) in the Belgian at sea sampling programme is vessel x trip (as a proxy for trip). A vessel x trip (PSU) for the TBB_DEF_>221 kW fleet segment is selected ad hoc or standard quota sampling is conducted (non-probability-based sampling). The vessels that are willing to take observers onboard and those that are logistically suited, are included in the vessel list, that currently contains ± 15 vessels over which the sampling will be spread. ILVO introduced 2 types of sampling: 1. Ad hoc sampling: for those strata with a lower sampling coverage (based on previous years) 2. Quota sampling: sampling effort is proportionally to the fleet effort (based on previous year) A vessel x trip (PSU) for the TBB_DEF_<=221 kW fleet segment is selected ad hoc. More than half of TBB_DEF vessels with a capacity <=221 kW flying the Belgian flag are regularly fishing for shrimp (TBB_CRU). Belgium has a derogation for sampling the TBB_CRU métier until the end of 2021. The TBB_DEF_<=221 kW vessel list proved too small to ensure random PSU selection. Therefore, ad hoc sampling of 2 euro cutters and 2 coastal vessels is carried out. The observer coordinator keeps track of the vessels in the vessel list but ILVO considers collecting non-responses and refusals on PSU (trip) level not relevant. Every other haul is sampled by an observer. For the TBB_DEF_<=221 kW fleet segment, the aim is to sample all hauls during the short trips of the coastal vessels. The crew sorts the marketable fish from the conveyor belt. In the meantime, the observer is sampling the discarded fraction of the catch by sorting all commercially important species. The total weight per species in each haul is determined and lengths are measured. When a species is extremely abundant, a smaller representative subsample (TSU) is measured. The marketable part of the catch (landings) is sampled later on in the same way as the discarded part of the catch. For selected species (depending on the area), otoliths from minimum 3 fish per cm-size class per species per area, are collected (except for 1 fish per cm-size class for cod) for age estimations. Otoliths are collected throughout the whole trip (several hauls) until the quota for otoliths is achieved. For the discarded part of the catch, otoliths are being removed on board. For the retained part (landings) of the catch, the fish are purchased. Coordination takes place within the Regional Coordination Groups (RCG NA/RCG NSE).

The primary sampling unit (PSU) in the Belgian at sea sampling programme is vessel x trip (as a proxy for trip). A vessel x trip (PSU) for the TBB_DEF_>221 kW fleet segment is selected ad hoc or standard quota sampling is conducted (non-probability-based sampling). The vessels that are willing to take observers onboard and those that are logistically suited, are included in the vessel list, that currently contains ± 15 vessels over which the sampling will be spread. ILVO introduced 2 types of sampling: 1. Ad hoc sampling: for those strata with a lower sampling coverage (based on previous years) 2. Quota sampling: sampling effort is proportionally to the fleet effort (based on previous year) A vessel x trip (PSU) for the TBB_DEF_<=221 kW fleet segment is selected ad hoc. More than half of TBB_DEF vessels with a capacity <=221 kW flying the Belgian flag are regularly fishing for shrimp (TBB_CRU). Belgium has a derogation for sampling the TBB_CRU métier until the end of 2021. The TBB_DEF_<=221 kW vessel list proved too small to ensure random PSU selection. Therefore, ad hoc sampling of 2 euro cutters and 2 coastal vessels is carried out. The observer coordinator keeps track of the vessels in the vessel list but ILVO considers collecting non-responses and refusals on PSU (trip) level not relevant. Every other haul is sampled by an observer. For the TBB_DEF_<=221 kW fleet segment, the aim is to sample all hauls during the short trips of the coastal vessels. The crew sorts the marketable fish from the conveyor belt. In the meantime, the observer is sampling the discarded fraction of the catch by sorting all commercially important species. The total weight per species in each haul is determined and lengths are measured. When a species is extremely abundant, a smaller representative subsample (TSU) is measured. The marketable part of the catch (landings) is sampled later on in the same way as the discarded part of the catch. For selected species (depending on the area), otoliths from minimum 3 fish per cm-size class per species per area, are collected (except for 1 fish per cm-size class for cod) for age estimations. Otoliths are collected throughout the whole trip (several hauls) until the quota for otoliths is achieved. For the discarded part of the catch, otoliths are being removed on board. For the retained part (landings) of the catch, the fish are purchased. Coordination takes place within the Regional Coordination Groups (RCG NA/RCG NSE).

The primary sampling unit (PSU) in the Belgian at sea sampling programme is vessel x trip (as a proxy for trip). A vessel x trip (PSU) for the TBB_DEF_>221 kW fleet segment is selected ad hoc or standard quota sampling is conducted (non-probability-based sampling). The vessels that are willing to take observers onboard and those that are logistically suited, are included in the vessel list, that currently contains ± 15 vessels over which the sampling will be spread. ILVO introduced 2 types of sampling: 1. Ad hoc sampling: for those strata with a lower sampling coverage (based on previous years) 2. Quota sampling: sampling effort is proportionally to the fleet effort (based on previous year) A vessel x trip (PSU) for the TBB_DEF_<=221 kW fleet segment is selected ad hoc. More than half of TBB_DEF vessels with a capacity <=221 kW flying the Belgian flag are regularly fishing for shrimp (TBB_CRU). Belgium has a derogation for sampling the TBB_CRU métier until the end of 2021. The TBB_DEF_<=221 kW vessel list proved too small to ensure random PSU selection. Therefore, ad hoc sampling of 2 euro cutters and 2 coastal vessels is carried out. The observer coordinator keeps track of the vessels in the vessel list but ILVO considers collecting non-responses and refusals on PSU (trip) level not relevant. Every other haul is sampled by an observer. For the TBB_DEF_<=221 kW fleet segment, the aim is to sample all hauls during the short trips of the coastal vessels. The crew sorts the marketable fish from the conveyor belt. In the meantime, the observer is sampling the discarded fraction of the catch by sorting all commercially important species. The total weight per species in each haul is determined and lengths are measured. When a species is extremely abundant, a smaller representative subsample (TSU) is measured. The marketable part of the catch (landings) is sampled later on in the same way as the discarded part of the catch. For selected species (depending on the area), otoliths from minimum 3 fish per cm-size class per species per area, are collected (except for 1 fish per cm-size class for cod) for age estimations. Otoliths are collected throughout the whole trip (several hauls) until the quota for otoliths is achieved. For the discarded part of the catch, otoliths are being removed on board. For the retained part (landings) of the catch, the fish are purchased. Coordination takes place within the Regional Coordination Groups (RCG NA/RCG NSE).

The primary sampling unit (PSU) in the Belgian at sea sampling programme is vessel x trip (as a proxy for trip). A vessel x trip (PSU) for the TBB_DEF_>221 kW fleet segment is selected ad hoc or standard quota sampling is conducted (non-probability-based sampling). The vessels that are willing to take observers onboard and those that are logistically suited, are included in the vessel list, that currently contains ± 15 vessels over which the sampling will be spread. ILVO introduced 2 types of sampling: 1. Ad hoc sampling: for those strata with a lower sampling coverage (based on previous years) 2. Quota sampling: sampling effort is proportionally to the fleet effort (based on previous year) A vessel x trip (PSU) for the TBB_DEF_<=221 kW fleet segment is selected ad hoc. More than half of TBB_DEF vessels with a capacity <=221 kW flying the Belgian flag are regularly fishing for shrimp (TBB_CRU). Belgium has a derogation for sampling the TBB_CRU métier until the end of 2021. The TBB_DEF_<=221 kW vessel list proved too small to ensure random PSU selection. Therefore, ad hoc sampling of 2 euro cutters and 2 coastal vessels is carried out. The observer coordinator keeps track of the vessels in the vessel list but ILVO considers collecting non-responses and refusals on PSU (trip) level not relevant. Every other haul is sampled by an observer. For the TBB_DEF_<=221 kW fleet segment, the aim is to sample all hauls during the short trips of the coastal vessels. The crew sorts the marketable fish from the conveyor belt. In the meantime, the observer is sampling the discarded fraction of the catch by sorting all commercially important species. The total weight per species in each haul is determined and lengths are measured. When a species is extremely abundant, a smaller representative subsample (TSU) is measured. The marketable part of the catch (landings) is sampled later on in the same way as the discarded part of the catch. For selected species (depending on the area), otoliths from minimum 3 fish per cm-size class per species per area, are collected (except for 1 fish per cm-size class for cod) for age estimations. Otoliths are collected throughout the whole trip (several hauls) until the quota for otoliths is achieved. For the discarded part of the catch, otoliths are being removed on board. For the retained part (landings) of the catch, the fish are purchased. Coordination takes place within the Regional Coordination Groups (RCG NA/RCG NSE).

The primary sampling unit (PSU) in the Belgian at sea sampling programme is vessel x trip (as a proxy for trip). A vessel x trip (PSU) for the TBB_DEF_>221 kW fleet segment is selected ad hoc or standard quota sampling is conducted (non-probability-based sampling). The vessels that are willing to take observers onboard and those that are logistically suited, are included in the vessel list, that currently contains ± 15 vessels over which the sampling will be spread. ILVO introduced 2 types of sampling: 1. Ad hoc sampling: for those strata with a lower sampling coverage (based on previous years) 2. Quota sampling: sampling effort is proportionally to the fleet effort (based on previous year) A vessel x trip (PSU) for the TBB_DEF_<=221 kW fleet segment is selected ad hoc. More than half of TBB_DEF vessels with a capacity <=221 kW flying the Belgian flag are regularly fishing for shrimp (TBB_CRU). Belgium has a derogation for sampling the TBB_CRU métier until the end of 2021. The TBB_DEF_<=221 kW vessel list proved too small to ensure random PSU selection. Therefore, ad hoc sampling of 2 euro cutters and 2 coastal vessels is carried out. The observer coordinator keeps track of the vessels in the vessel list but ILVO considers collecting non-responses and refusals on PSU (trip) level not relevant. Every other haul is sampled by an observer. For the TBB_DEF_<=221 kW fleet segment, the aim is to sample all hauls during the short trips of the coastal vessels. The crew sorts the marketable fish from the conveyor belt. In the meantime, the observer is sampling the discarded fraction of the catch by sorting all commercially important species. The total weight per species in each haul is determined and lengths are measured. When a species is extremely abundant, a smaller representative subsample (TSU) is measured. The marketable part of the catch (landings) is sampled later on in the same way as the discarded part of the catch. For selected species (depending on the area), otoliths from minimum 3 fish per cm-size class per species per area, are collected (except for 1 fish per cm-size class for cod) for age estimations. Otoliths are collected throughout the whole trip (several hauls) until the quota for otoliths is achieved. For the discarded part of the catch, otoliths are being removed on board. For the retained part (landings) of the catch, the fish are purchased. Coordination takes place within the Regional Coordination Groups (RCG NA/RCG NSE).

1. BTS During the BTS 62 fixed stations are fished for 30 min at 4 knots using a beam trawl as standard gear (beam length 4 m, cod-end mesh size 40 mm). Although the target species are plaice and sole, all fish and commercially important cephalopods and crustaceans are sorted, weighed and measured since 2010. Since 2009, a subsample of the catch is taken of which all epibenthic species are recorded in numbers and sample weight. The data collected during the BTS are used in analytical population studies of several species/stocks, mainly serving as tuning indices in the stock assessments leading to the fishing quota. Additionally, several other investigations are planned, such as (a) the construction of "age-length-keys" for a number of commercially important flatfish, and (b) documenting distribution and abundance of all commercial and non-commercial (bycatch) invertebrate species. 2. DYFS All 33 DYFS sampling stations are fished for approximately 30 min, with a standard shrimp beam trawl (beam length 6 m; cod-end mesh size 22 mm, no tickler chains), at 3 knots against tide. Several fish species (cod, whiting, plaice, flounder, dab, sole, brill and turbot) are hand-picked from the catches, sorted by species, weighed and measured in mm (by the in-house developed SmartFish measuring board). From 2009 onwards, the species list was extended to cover a larger range of commercial fish species (e.g. including lesser spotted dogfish, gurnards, lemon sole, horse mackerel, etc.). In this way, a total of 18 species are documented. From 2018 onwards, the species list has been extended with all elasmobranch species that are weighed and measured (by sex). The brown shrimp from the catches are first sorted into a ‘small’ and ‘large’ fraction by means of a rotating shrimp riddle (same type used on commercial shrimp trawlers). From each of these two fractions, 1-2 liter samples are taken (depending on the amount of shrimp and other organisms in the fractions). Samples are further sub-sampled in the lab to approximately 250 shrimps, which are then measured in mm using an in-house developed system.

1. BTS During the BTS 62 fixed stations are fished for 30 min at 4 knots using a beam trawl as standard gear (beam length 4 m, cod-end mesh size 40 mm). Although the target species are plaice and sole, all fish and commercially important cephalopods and crustaceans are sorted, weighed and measured since 2010. Since 2009, a subsample of the catch is taken of which all epibenthic species are recorded in numbers and sample weight. The data collected during the BTS are used in analytical population studies of several species/stocks, mainly serving as tuning indices in the stock assessments leading to the fishing quota. Additionally, several other investigations are planned, such as (a) the construction of "age-length-keys" for a number of commercially important flatfish, and (b) documenting distribution and abundance of all commercial and non-commercial (bycatch) invertebrate species. 2. DYFS All 33 DYFS sampling stations are fished for approximately 30 min, with a standard shrimp beam trawl (beam length 6 m; cod-end mesh size 22 mm, no tickler chains), at 3 knots against tide. Several fish species (cod, whiting, plaice, flounder, dab, sole, brill and turbot) are hand-picked from the catches, sorted by species, weighed and measured in mm (by the in-house developed SmartFish measuring board). From 2009 onwards, the species list was extended to cover a larger range of commercial fish species (e.g. including lesser spotted dogfish, gurnards, lemon sole, horse mackerel, etc.). In this way, a total of 18 species are documented. From 2018 onwards, the species list has been extended with all elasmobranch species that are weighed and measured (by sex). The brown shrimp from the catches are first sorted into a ‘small’ and ‘large’ fraction by means of a rotating shrimp riddle (same type used on commercial shrimp trawlers). From each of these two fractions, 1-2 liter samples are taken (depending on the amount of shrimp and other organisms in the fractions). Samples are further sub-sampled in the lab to approximately 250 shrimps, which are then measured in mm using an in-house developed system.

1. BTS During the BTS 62 fixed stations are fished for 30 min at 4 knots using a beam trawl as standard gear (beam length 4 m, cod-end mesh size 40 mm). Although the target species are plaice and sole, all fish and commercially important cephalopods and crustaceans are sorted, weighed and measured since 2010. Since 2009, a subsample of the catch is taken of which all epibenthic species are recorded in numbers and sample weight. The data collected during the BTS are used in analytical population studies of several species/stocks, mainly serving as tuning indices in the stock assessments leading to the fishing quota. Additionally, several other investigations are planned, such as (a) the construction of "age-length-keys" for a number of commercially important flatfish, and (b) documenting distribution and abundance of all commercial and non-commercial (bycatch) invertebrate species. 2. DYFS All 33 DYFS sampling stations are fished for approximately 30 min, with a standard shrimp beam trawl (beam length 6 m; cod-end mesh size 22 mm, no tickler chains), at 3 knots against tide. Several fish species (cod, whiting, plaice, flounder, dab, sole, brill and turbot) are hand-picked from the catches, sorted by species, weighed and measured in mm (by the in-house developed SmartFish measuring board). From 2009 onwards, the species list was extended to cover a larger range of commercial fish species (e.g. including lesser spotted dogfish, gurnards, lemon sole, horse mackerel, etc.). In this way, a total of 18 species are documented. From 2018 onwards, the species list has been extended with all elasmobranch species that are weighed and measured (by sex). The brown shrimp from the catches are first sorted into a ‘small’ and ‘large’ fraction by means of a rotating shrimp riddle (same type used on commercial shrimp trawlers). From each of these two fractions, 1-2 liter samples are taken (depending on the amount of shrimp and other organisms in the fractions). Samples are further sub-sampled in the lab to approximately 250 shrimps, which are then measured in mm using an in-house developed system.

1. BTS During the BTS 62 fixed stations are fished for 30 min at 4 knots using a beam trawl as standard gear (beam length 4 m, cod-end mesh size 40 mm). Although the target species are plaice and sole, all fish and commercially important cephalopods and crustaceans are sorted, weighed and measured since 2010. Since 2009, a subsample of the catch is taken of which all epibenthic species are recorded in numbers and sample weight. The data collected during the BTS are used in analytical population studies of several species/stocks, mainly serving as tuning indices in the stock assessments leading to the fishing quota. Additionally, several other investigations are planned, such as (a) the construction of "age-length-keys" for a number of commercially important flatfish, and (b) documenting distribution and abundance of all commercial and non-commercial (bycatch) invertebrate species. 2. DYFS All 33 DYFS sampling stations are fished for approximately 30 min, with a standard shrimp beam trawl (beam length 6 m; cod-end mesh size 22 mm, no tickler chains), at 3 knots against tide. Several fish species (cod, whiting, plaice, flounder, dab, sole, brill and turbot) are hand-picked from the catches, sorted by species, weighed and measured in mm (by the in-house developed SmartFish measuring board). From 2009 onwards, the species list was extended to cover a larger range of commercial fish species (e.g. including lesser spotted dogfish, gurnards, lemon sole, horse mackerel, etc.). In this way, a total of 18 species are documented. From 2018 onwards, the species list has been extended with all elasmobranch species that are weighed and measured (by sex). The brown shrimp from the catches are first sorted into a ‘small’ and ‘large’ fraction by means of a rotating shrimp riddle (same type used on commercial shrimp trawlers). From each of these two fractions, 1-2 liter samples are taken (depending on the amount of shrimp and other organisms in the fractions). Samples are further sub-sampled in the lab to approximately 250 shrimps, which are then measured in mm using an in-house developed system.