"Gueguen (2001)" . "2001"^^ . "2001"^^ . "Gueguen, F. 2001. La crevette rose du large Parapenaeus longirostris en Guyane fran\u00E7aise. Bulletin de la Soci\u00E9t\u00E9 Zoologique de France, 126(4): 331-349." . . "Two species of deep-water shrimps have been the target of the traditional fisheries of the continental slope of French Guiana (Western-Central Atlantic) since 1988: the orange shrimp Solenocera acuminata Perez Farfante and Bullis, 1973 (Solenoceridae), only caught during the night at a depth of about 200 m; and the scarlet prawn Plesiopenaeus edwardsianus (Johnson, 1867) (Aristeidae), widely distributed from 400 to 900 m and exploited during the daytime and at night near 700 m, where the species has a peak abundance. The major aspects of the biology of these species have been recently published. Moreover, the deep-water rose shrimp Parapenaeus longirostris (Lucas, 1846) (Penaeidae) is caught as secondary species with the orange shrimp S. acuminata. In spite of the commercial interest of P. longirostris, only a few notes dealing with the distribution and the morphology of this shrimp have been published, probably due to its minor importance to fisheries in French Guiana. In order to establish some aspects of the biology of Parapenaeus longirostris in French Guiana (i.e. the bathymetric and geographic distributions, abundance, sex ratio, day-night activity, size frequency distributions, and a detailed study of morphometric relationships of the species), a total of 60 bottom trawls were carried out at bottom depths ranging from 100 to 500 m on the Guianese continental slope. A first scientific survey was conducted in February 1981 with a shrimp trawler (23 m long, 565 horsepower) using single bottom trawls (headline length 20.7 m, vertical opening 1.0 m, and 22.5 mm mesh cod-end liner); a total of 24 tows were carried out during the daytime. An additional 36 bottom trawls were made at night during four scientific surveys conducted from August 1990 through July 1991; the shrimp trawler (23 m long, 500 horsepower) was equipped with a double bottom trawl (size of each trawl: headline length 19.8 m, vertical opening 0.9 m, and 22.5 mm mesh cod-end liner). For each tow, catches of Parapenaeus longirostris were first weighted and mean catch rates (g/h/trawl) were calculated for four arbitrary 100 m depth levels (from 100 to 500 m). Then, in order to establish the sex ratio and size frequency distributions, males and females were separately measured for carapace length (the linear distance between the post-orbital margin and the median posterior edge of the carapace). The study was completed with morphometric relationships, and length and weight measurements were made (carapace length excluding rostrum, total length including rostrum, tail length, rostrum length, total weight, tail weight, and head weight). The results obtained were first plotted graphically two by two, and regression coefficients describing the various morphometric relationships were calculated using a power model for length-weight relations and a linear model for weight-weight and length-length relations (except for rostrum length plotted against carapace length, described with a power model). The deep-water rose shrimp Parapenaeus longirostris is distributed in the entire Mediterranean, in western Atlantic waters (from Massachusetts to French Guiana), and in the eastern Atlantic (from southern coast of Portugal to Namibia). It is one of the most important commercial species of the Mediterranean (coasts of Spain, France and Italy), of Portugal, and of the southern part of the Gulf of Guinea. The major results obtained during this study on the biology of this deep-water shrimp in French Guiana are as follows. Parapenaeus longirostris is distributed in muddy sand grounds of the Guianese continental slope at depths ranging from 200 to 280 m (bottom temperatures from 10 to 16[degree]C). This result is in agreement with several works showing that the species is mainly distributed at bottom temperatures ranging from 9 to 16[degree]C. In terms of biomass, mean catch rates obtained in the day time are about 1650 g/h/net, while mean catches obtained at night reach only 250 g/h/net; this suggests that day-night activity of the Penaeidae P. longirostris is well-pronounced [-] the species is mostly active during the day and probably borrows into the sediment during the night. In contrast, most shrimps of the family Solenoceridae are exclusively active during the night, e.g. Solenocera membranacea in the Mediterranean Sea and Solenocera acuminata in French Guiana. All samples observed show a great predominance of females (about 95%), but this phenomenon is probably linked to the existence of a sexual dimorphism in sizes: analysis of size frequency distributions of P. longirostris indicates that maximum carapace lengths of captures are about 33 mm (total length 140 mm) for females and only about 22 mm (total length 95 mm) for males. This means that the number of small specimens, that is to say males, is highly underestimated because of the selectivity of the net. Similar results have already been observed by several authors for different families of deep-water shrimps, e.g. Aristeus antennatus, Aristeus antillensis and Plesiopenaeus edwardsianus (family Aristeidae), or Solenocera acuminata (family Solenoceridae). The relationship between rostrum length and carapace length in P. longirostris is not described by a linear model, but there is a positive allometric growth in rostrum; a similar relationship has been established for Nematocarcinus gracilipes on the west African coast. In contrast, many deep-water shrimps of the family Aristeidae are characterized by a negative allometric growth of the rostrum, e.g. Aristeus antennatus in the Mediterranean Sea, or Aristeus antillensis and Plesiopenaeus edwardsianus in the western central Atlantic (French Guiana); this phenomenon is probably linked to reproduction." . "Gueguen (2001)" . . . "Two species of deep-water shrimps have been the target of the traditional fisheries of the continental slope of French Guiana (Western-Central Atlantic) since 1988: the orange shrimp Solenocera acuminata Perez Farfante and Bullis, 1973 (Solenoceridae), only caught during the night at a depth of about 200 m; and the scarlet prawn Plesiopenaeus edwardsianus (Johnson, 1867) (Aristeidae), widely distributed from 400 to 900 m and exploited during the daytime and at night near 700 m, where the species has a peak abundance. The major aspects of the biology of these species have been recently published. Moreover, the deep-water rose shrimp Parapenaeus longirostris (Lucas, 1846) (Penaeidae) is caught as secondary species with the orange shrimp S. acuminata. In spite of the commercial interest of P. longirostris, only a few notes dealing with the distribution and the morphology of this shrimp have been published, probably due to its minor importance to fisheries in French Guiana. In order to establish some aspects of the biology of Parapenaeus longirostris in French Guiana (i.e. the bathymetric and geographic distributions, abundance, sex ratio, day-night activity, size frequency distributions, and a detailed study of morphometric relationships of the species), a total of 60 bottom trawls were carried out at bottom depths ranging from 100 to 500 m on the Guianese continental slope. A first scientific survey was conducted in February 1981 with a shrimp trawler (23 m long, 565 horsepower) using single bottom trawls (headline length 20.7 m, vertical opening 1.0 m, and 22.5 mm mesh cod-end liner); a total of 24 tows were carried out during the daytime. An additional 36 bottom trawls were made at night during four scientific surveys conducted from August 1990 through July 1991; the shrimp trawler (23 m long, 500 horsepower) was equipped with a double bottom trawl (size of each trawl: headline length 19.8 m, vertical opening 0.9 m, and 22.5 mm mesh cod-end liner). For each tow, catches of Parapenaeus longirostris were first weighted and mean catch rates (g/h/trawl) were calculated for four arbitrary 100 m depth levels (from 100 to 500 m). Then, in order to establish the sex ratio and size frequency distributions, males and females were separately measured for carapace length (the linear distance between the post-orbital margin and the median posterior edge of the carapace). The study was completed with morphometric relationships, and length and weight measurements were made (carapace length excluding rostrum, total length including rostrum, tail length, rostrum length, total weight, tail weight, and head weight). The results obtained were first plotted graphically two by two, and regression coefficients describing the various morphometric relationships were calculated using a power model for length-weight relations and a linear model for weight-weight and length-length relations (except for rostrum length plotted against carapace length, described with a power model). The deep-water rose shrimp Parapenaeus longirostris is distributed in the entire Mediterranean, in western Atlantic waters (from Massachusetts to French Guiana), and in the eastern Atlantic (from southern coast of Portugal to Namibia). It is one of the most important commercial species of the Mediterranean (coasts of Spain, France and Italy), of Portugal, and of the southern part of the Gulf of Guinea. The major results obtained during this study on the biology of this deep-water shrimp in French Guiana are as follows. Parapenaeus longirostris is distributed in muddy sand grounds of the Guianese continental slope at depths ranging from 200 to 280 m (bottom temperatures from 10 to 16[degree]C). This result is in agreement with several works showing that the species is mainly distributed at bottom temperatures ranging from 9 to 16[degree]C. In terms of biomass, mean catch rates obtained in the day time are about 1650 g/h/net, while mean catches obtained at night reach only 250 g/h/net; this suggests that day-night activity of the Penaeidae P. longirostris is well-pronounced [-] the species is mostly active during the day and probably borrows into the sediment during the night. In contrast, most shrimps of the family Solenoceridae are exclusively active during the night, e.g. Solenocera membranacea in the Mediterranean Sea and Solenocera acuminata in French Guiana. All samples observed show a great predominance of females (about 95%), but this phenomenon is probably linked to the existence of a sexual dimorphism in sizes: analysis of size frequency distributions of P. longirostris indicates that maximum carapace lengths of captures are about 33 mm (total length 140 mm) for females and only about 22 mm (total length 95 mm) for males. This means that the number of small specimens, that is to say males, is highly underestimated because of the selectivity of the net. Similar results have already been observed by several authors for different families of deep-water shrimps, e.g. Aristeus antennatus, Aristeus antillensis and Plesiopenaeus edwardsianus (family Aristeidae), or Solenocera acuminata (family Solenoceridae). The relationship between rostrum length and carapace length in P. longirostris is not described by a linear model, but there is a positive allometric growth in rostrum; a similar relationship has been established for Nematocarcinus gracilipes on the west African coast. In contrast, many deep-water shrimps of the family Aristeidae are characterized by a negative allometric growth of the rostrum, e.g. Aristeus antennatus in the Mediterranean Sea, or Aristeus antillensis and Plesiopenaeus edwardsianus in the western central Atlantic (French Guiana); this phenomenon is probably linked to reproduction." .