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Deep-sea fish are highly contaminated with organochlorine compounds(OCs), which are persistent man-made chemicals. Because it is very difficult to maintain these fish alive for toxicological experiments, the real impact of such contamination remains unknown. By analysing liver samples of the deep-sea grenadier Coryphaenoides rupestris (200 - 2600 meter depth), we first observed signs of an oxidative impact linked to OCs' metabolism. The activity of the phase 1 detoxification cytochrome P4501A (CYP1A) enzyme was positively correlated to OCs loads and antioxidant enzymes activities (catalase, superoxide dismutase). Still, the magnitude of CYP1A induction was fairly low compared to the huge contamination. We then developed the precision-cut liver slices (PCLS) technology to study more in-depth the oxidative impact of OCs' metabolism on living liver cells of C. rupestris. Two shallow fish (Salmo salar, Dicentrarchus labrax) were also chosen as basis for comparison. Hyperbaric cylinders were used to investigate in this comparative study the effects of the high hydrostatic pressure (typical of the deep-sea) on the response of liver cells of these fish to contaminants, their pro- and anti-oxidant status and that of heat shock proteins (also known to participate in a general stress response to toxicants). Apart from the obtention of the first-ever data on living deep-sea fish liver cells, we found a striking pressure-dependent reduction of CYP1A induction in each species, suggesting that deep-sea fish might be less prone to the oxidative impact of OCs metabolism in their environment (a feature that might explain their high OCs loads)., (BIOL 3) -- UCL, 2011

In the Northeast Atlantic fishery for roundnose grenadier Coryphaenoides rupestris, discards account for about 30% of the catch in weight. Data on discards are scarce; however, length distributions and discard rates appear to be relatively stable from year to year. In contrast, landings data available since 1990 show that the average pre-anal fin length has decreased from 20.7 cm in 1990 to 15.2 cm in 2008, resulting in a 58% reduction of the mean individual weight (850 g in 2008) and an increasing occurrence of overlapping class sizes between landings and discards in recent years. For stock assessment, the method of separable virtual population analysis (SVPA) was used. However, because of the lack of discard data for many of the years covered by the study, the catch data used as input to the assessment model had to be reconstructed from the available information (landings, discards, fishing effort and bathymetric distribution of the stock) using two methods. The first method relied on the assumption that the recent length distributions of discards were applicable to the earlier years (1990-1997). It resulted in unrealistic bimodal length distributions, suggesting a change in discarding practices through time, with larger individuals being discarded in the early days. The second method, based on the fishing effort and length distribution by depth strata, produced unimodal distributions for the whole period and confirmed that the average length of discarded fish was higher in the early days of the fishery. In both cases, the estimates of biomass follow parallel trends, suggesting a strong decline in the population. The available information and methods are discussed.

In the Northeast Atlantic fishery for roundnose grenadier Coryphaenoides rupestris, discards account for about 30% of the catch in weight. Data on discards are scarce; however, length distributions and discard rates appear to be relatively stable from year to year. In contrast, landings data available since 1990 show that the average pre-anal fin length has decreased from 20.7 cm in 1990 to 15.2 cm in 2008, resulting in a 58% reduction of the mean individual weight (850 g in 2008) and an increasing occurrence of overlapping class sizes between landings and discards in recent years. For stock assessment, the method of separable virtual population analysis (SVPA) was used. However, because of the lack of discard data for many of the years covered by the study, the catch data used as input to the assessment model had to be reconstructed from the available information (landings, discards, fishing effort and bathymetric distribution of the stock) using two methods. The first method relied on the assumption that the recent length distributions of discards were applicable to the earlier years (1990-1997). It resulted in unrealistic bimodal length distributions, suggesting a change in discarding practices through time, with larger individuals being discarded in the early days. The second method, based on the fishing effort and length distribution by depth strata, produced unimodal distributions for the whole period and confirmed that the average length of discarded fish was higher in the early days of the fishery. In both cases, the estimates of biomass follow parallel trends, suggesting a strong decline in the population. The available information and methods are discussed.

In the Northeast Atlantic fishery for roundnose grenadier Coryphaenoides rupestris, discards account for about 30% of the catch in weight. Data on discards are scarce; however, length distributions and discard rates appear to be relatively stable from year to year. In contrast, landings data available since 1990 show that the average pre-anal fin length has decreased from 20.7 cm in 1990 to 15.2 cm in 2008, resulting in a 58% reduction of the mean individual weight (850 g in 2008) and an increasing occurrence of overlapping class sizes between landings and discards in recent years. For stock assessment, the method of separable virtual population analysis (SVPA) was used. However, because of the lack of discard data for many of the years covered by the study, the catch data used as input to the assessment model had to be reconstructed from the available information (landings, discards, fishing effort and bathymetric distribution of the stock) using two methods. The first method relied on the assumption that the recent length distributions of discards were applicable to the earlier years (1990-1997). It resulted in unrealistic bimodal length distributions, suggesting a change in discarding practices through time, with larger individuals being discarded in the early days. The second method, based on the fishing effort and length distribution by depth strata, produced unimodal distributions for the whole period and confirmed that the average length of discarded fish was higher in the early days of the fishery. In both cases, the estimates of biomass follow parallel trends, suggesting a strong decline in the population. The available information and methods are discussed.

French deepwater fish exploitation (500 m) began off the West coast of the British Isles in 1973. It further developed in the 1980s, and intensified in the 1990s. In 1997, the French fleet comprised 49 boats, and since 1995 has landed yearly about 19,500 t of deepwater fish species, of which, the grenadier Coryphaenoides rupestris (Macrouridae) has been the most abundant. Discard data were sampled on-board by observers on French high sea trawlers from 1995 to 1997. Eight species were identified as totally landed, 43 non-commercial species as totally discarded and only one, the grenadier, as both landed and discarded. The mean discarding rate by haul was 48.5% in weight, whereas the mean grenadier discarding rate was 21.2%; these rates increased with depth. Discard species composition and discard quantities varied with depth, and depended on the specific composition of the fish communities, species abundance and their length-frequency distribution. The latter, established for grenadier and Alepocephalus bairdii (Aiepocephalidae), assumes a bathymetric ontogenic migration. Annual discards of the fishery accounted for about 17,500 t in 1996 and 1997, but the results are quite uncertain.

French deepwater fish exploitation (500 m) began off the West coast of the British Isles in 1973. It further developed in the 1980s, and intensified in the 1990s. In 1997, the French fleet comprised 49 boats, and since 1995 has landed yearly about 19,500 t of deepwater fish species, of which, the grenadier Coryphaenoides rupestris (Macrouridae) has been the most abundant. Discard data were sampled on-board by observers on French high sea trawlers from 1995 to 1997. Eight species were identified as totally landed, 43 non-commercial species as totally discarded and only one, the grenadier, as both landed and discarded. The mean discarding rate by haul was 48.5% in weight, whereas the mean grenadier discarding rate was 21.2%; these rates increased with depth. Discard species composition and discard quantities varied with depth, and depended on the specific composition of the fish communities, species abundance and their length-frequency distribution. The latter, established for grenadier and Alepocephalus bairdii (Aiepocephalidae), assumes a bathymetric ontogenic migration. Annual discards of the fishery accounted for about 17,500 t in 1996 and 1997, but the results are quite uncertain.

French deepwater fish exploitation (500 m) began off the West coast of the British Isles in 1973. It further developed in the 1980s, and intensified in the 1990s. In 1997, the French fleet comprised 49 boats, and since 1995 has landed yearly about 19,500 t of deepwater fish species, of which, the grenadier Coryphaenoides rupestris (Macrouridae) has been the most abundant. Discard data were sampled on-board by observers on French high sea trawlers from 1995 to 1997. Eight species were identified as totally landed, 43 non-commercial species as totally discarded and only one, the grenadier, as both landed and discarded. The mean discarding rate by haul was 48.5% in weight, whereas the mean grenadier discarding rate was 21.2%; these rates increased with depth. Discard species composition and discard quantities varied with depth, and depended on the specific composition of the fish communities, species abundance and their length-frequency distribution. The latter, established for grenadier and Alepocephalus bairdii (Aiepocephalidae), assumes a bathymetric ontogenic migration. Annual discards of the fishery accounted for about 17,500 t in 1996 and 1997, but the results are quite uncertain.

This document describes the Spanish deep-sea fishery performed in international waters on the Hatton Bank and proximities (NE Atlantic) during the period 1996-2000. This is a multi-species fishery, carried out by stern bottom trawlers, mainly between June and September, in depths mainly between 800 m to 1600 m. The importance of the fishing activity in this area is increasing notably. This fishery has been monitored since the beginning in 1996, with the collaboration of the fishing industry, by means of a scientific observer programme. The observers on board provide data on catches, discards, location and depth, haul by haul. Length samples of the main species and biological material are also collected. The species composition of the catches is presented. In terms of weight, the roundnose grenadier (Coryphaenoides rupestris) and the bairdii smoothhead (Alepocephalus bairdii) are the most important species in the catches. Other less important species are the Portuguese dogfish (Centroscymnus coelolepis) and the blue ling (Molva dypterygia). In addition to the total catch, the composition of the retained catch and the discard are studied. For the main retained species, the dressing types are described and the conversion coefficients are presented. The length distribution of the catches and the discards, length-weight relationships and other biological aspects of some of the main species are analysed.

Catch Per Unit Effort (CPUE) trends of the main target species of the deep-sea fishery were recorded for one sample trawler in two areas to the west of the British Isles, from 1993 to 1997. Considered species were the orange roughy (Hoplostethus atlanticus), the roundnose grenadier (Coryphaenoides rupestris), the black scabbard fish (Aphanopus carbo) and two squalid sharks: the Portuguese dogfish (Centroscymnus coelolepis) and the leafscale gulper shark (Centrophorus squamosus). Two sources of data have been used: the catch and effort database of IFREMER and the personal logbooks of the skipper from the sample trawler. The personal logbooks indicate the catch per haul, whereas the IFREMER database provides the catch and effort per day and statistical rectangle. From the personal logbooks, the time spent on deep-sea species can be known and CPUE corrected for the depth. These corrected CPUE allow to take into account the changes of the fishing strategy and the variations of the fish abundance according to depth. Both, the life strategies of the exploited species and the fishing strategy of the trawler are very important to consider the CPUE as abundance indices.

Age is a necessary parameter used in population dynamics to assess the state of exploited resources. This parameter is poorly known for most deep-sea species (depth > 400 m). This work focused on age estimation from otoliths of Alepocephalus bairdii (Alepocephalidae), Coryphaenoides rupestris (Macrouridae), Helicolenus dactylopterus (Sebastidae) and Hoplostethus atlanticus (Trachichthyidae), which French fishery exploitation, off the west coasts of the British Isles, began the late 1980's. Considering otolith growth zones as annual, the four species all show high longevity: 38, 54, 43 and 130 years, respectively, together with slow growth. The differences in growth between sex were estimated and difficulties in accurately estimating the age were highlighted and showed the need to standardise and validate age estimation. The ages currently estimated for deep-sea fish must be used with caution.

Catch Per Unit Effort (CPUE) trends of the main target species of the deep-sea fishery were recorded for one sample trawler in two areas to the west of the British Isles, from 1993 to 1997. Considered species were the orange roughy (Hoplostethus atlanticus), the roundnose grenadier (Coryphaenoides rupestris), the black scabbard fish (Aphanopus carbo) and two squalid sharks: the Portuguese dogfish (Centroscymnus coelolepis) and the leafscale gulper shark (Centrophorus squamosus). Two sources of data have been used: the catch and effort database of IFREMER and the personal logbooks of the skipper from the sample trawler. The personal logbooks indicate the catch per haul, whereas the IFREMER database provides the catch and effort per day and statistical rectangle. From the personal logbooks, the time spent on deep-sea species can be known and CPUE corrected for the depth. These corrected CPUE allow to take into account the changes of the fishing strategy and the variations of the fish abundance according to depth. Both, the life strategies of the exploited species and the fishing strategy of the trawler are very important to consider the CPUE as abundance indices.

Age is a necessary parameter used in population dynamics to assess the state of exploited resources. This parameter is poorly known for most deep-sea species (depth > 400 m). This work focused on age estimation from otoliths of Alepocephalus bairdii (Alepocephalidae), Coryphaenoides rupestris (Macrouridae), Helicolenus dactylopterus (Sebastidae) and Hoplostethus atlanticus (Trachichthyidae), which French fishery exploitation, off the west coasts of the British Isles, began the late 1980's. Considering otolith growth zones as annual, the four species all show high longevity: 38, 54, 43 and 130 years, respectively, together with slow growth. The differences in growth between sex were estimated and difficulties in accurately estimating the age were highlighted and showed the need to standardise and validate age estimation. The ages currently estimated for deep-sea fish must be used with caution.

Age is a necessary parameter used in population dynamics to assess the state of exploited resources. This parameter is poorly known for most deep-sea species (depth > 400 m). This work focused on age estimation from otoliths of Alepocephalus bairdii (Alepocephalidae), Coryphaenoides rupestris (Macrouridae), Helicolenus dactylopterus (Sebastidae) and Hoplostethus atlanticus (Trachichthyidae), which French fishery exploitation, off the west coasts of the British Isles, began the late 1980's. Considering otolith growth zones as annual, the four species all show high longevity: 38, 54, 43 and 130 years, respectively, together with slow growth. The differences in growth between sex were estimated and difficulties in accurately estimating the age were highlighted and showed the need to standardise and validate age estimation. The ages currently estimated for deep-sea fish must be used with caution.

Catch Per Unit Effort (CPUE) trends of the main target species of the deep-sea fishery were recorded for one sample trawler in two areas to the west of the British Isles, from 1993 to 1997. Considered species were the orange roughy (Hoplostethus atlanticus), the roundnose grenadier (Coryphaenoides rupestris), the black scabbard fish (Aphanopus carbo) and two squalid sharks: the Portuguese dogfish (Centroscymnus coelolepis) and the leafscale gulper shark (Centrophorus squamosus). Two sources of data have been used: the catch and effort database of IFREMER and the personal logbooks of the skipper from the sample trawler. The personal logbooks indicate the catch per haul, whereas the IFREMER database provides the catch and effort per day and statistical rectangle. From the personal logbooks, the time spent on deep-sea species can be known and CPUE corrected for the depth. These corrected CPUE allow to take into account the changes of the fishing strategy and the variations of the fish abundance according to depth. Both, the life strategies of the exploited species and the fishing strategy of the trawler are very important to consider the CPUE as abundance indices., Les Captures Par Unité d’Effort (CPUE) des principales espèces cibles de la pêcherie récente de l’étage moyen du talus continental ont été suivies dans deux secteurs géographiques à l’ouest des Iles britanniques, de 1993 à 1997, pour un bateau témoin. Les espèces choisies sont l’empereur (Hoplostethus atlanticus), le grenadier de roche (Coryphaenoides rupestris), le sabre noir (Aphanopus carbo) et deux requins de la famille des Squalidae: le pailona commun (Centroscymnus coelolepis) et le squale chagrin de l’Atlantique (Centrophorus squamosus). Deux sources de données ont permis de réaliser ce suivi: la base statistique IFREMER et les cahiers de bords personnels du patron de pêche du bateau témoin. Cette dernière source d’information indique la capture par trait contrairement à la base statistique qui donne la capture par rectangle statistique. Elle permet de connaître précisément le temps de pêche alloué à la capture de ces espèces mais aussi d’estimer des CPUE corrigées de l’effet profondeur, c’est-à-dire de tenir compte de la stratégie de pêche du navire et des variations d’abondance en fonction de la profondeur. Ces deux aspects sont importants pour interpréter de façon pertinente les CPUE en tant qu’indice d’abondance.

Catch Per Unit Effort (CPUE) trends of the main target species of the deep-sea fishery were recorded for one sample trawler in two areas to the west of the British Isles, from 1993 to 1997. Considered species were the orange roughy (Hoplostethus atlanticus), the roundnose grenadier (Coryphaenoides rupestris), the black scabbard fish (Aphanopus carbo) and two squalid sharks: the Portuguese dogfish (Centroscymnus coelolepis) and the leafscale gulper shark (Centrophorus squamosus). Two sources of data have been used: the catch and effort database of IFREMER and the personal logbooks of the skipper from the sample trawler. The personal logbooks indicate the catch per haul, whereas the IFREMER database provides the catch and effort per day and statistical rectangle. From the personal logbooks, the time spent on deep-sea species can be known and CPUE corrected for the depth. These corrected CPUE allow to take into account the changes of the fishing strategy and the variations of the fish abundance according to depth. Both, the life strategies of the exploited species and the fishing strategy of the trawler are very important to consider the CPUE as abundance indices., Les Captures Par Unité d’Effort (CPUE) des principales espèces cibles de la pêcherie récente de l’étage moyen du talus continental ont été suivies dans deux secteurs géographiques à l’ouest des Iles britanniques, de 1993 à 1997, pour un bateau témoin. Les espèces choisies sont l’empereur (Hoplostethus atlanticus), le grenadier de roche (Coryphaenoides rupestris), le sabre noir (Aphanopus carbo) et deux requins de la famille des Squalidae: le pailona commun (Centroscymnus coelolepis) et le squale chagrin de l’Atlantique (Centrophorus squamosus). Deux sources de données ont permis de réaliser ce suivi: la base statistique IFREMER et les cahiers de bords personnels du patron de pêche du bateau témoin. Cette dernière source d’information indique la capture par trait contrairement à la base statistique qui donne la capture par rectangle statistique. Elle permet de connaître précisément le temps de pêche alloué à la capture de ces espèces mais aussi d’estimer des CPUE corrigées de l’effet profondeur, c’est-à-dire de tenir compte de la stratégie de pêche du navire et des variations d’abondance en fonction de la profondeur. Ces deux aspects sont importants pour interpréter de façon pertinente les CPUE en tant qu’indice d’abondance.

Age is a necessary parameter used in population dynamics to assess the state of exploited resources. This parameter is poorly known for most deep-sea species (depth > 400 m). This work focused on age estimation from otoliths of Alepocephalus bairdii (Alepocephalidae), Coryphaenoides rupestris (Macrouridae), Helicolenus dactylopterus (Sebastidae) and Hoplostethus atlanticus (Trachichthyidae), which French fishery exploitation, off the west coasts of the British Isles, began the late 1980's. Considering otolith growth zones as annual, the four species all show high longevity: 38, 54, 43 and 130 years, respectively, together with slow growth. The differences in growth between sex were estimated and difficulties in accurately estimating the age were highlighted and showed the need to standardise and validate age estimation. The ages currently estimated for deep-sea fish must be used with caution.