Jerzy Janusz - Academia.edu (original) (raw)
Papers by Jerzy Janusz
Acta Ichthyologica et Piscatoria
Sea Fisheries institute-Gdynia and [nstitu te of lch thyology, Szczecin Over the years 1970 and 1... more Sea Fisheries institute-Gdynia and [nstitu te of lch thyology, Szczecin Over the years 1970 and 1974 there were carried out studies on the prevalence of the Clave/la adunca (Str�m, 1762) parasite on the cod (Gadus morhua L.) from North west Atlantic (Labrador and New Founland fishing grounds). The growth rate and condition of 4454 cod specimens was studied. The length-weight relationship, condition. and growth paramctcr5 of infested and non-infested fishes were calculated. The calculations hawc shown that young fishes infested by Clave/la adunca parasite had higher average weight and condition than noninfosted ones of the same length. On the other hand, older infested fishes (above 6 years of life) had average weight and condition lower than noninfcsted specimens. The author's own attempt to explain this paradoxal phenomenon is presented.
Acta Ichthyologica et Piscatoria
The studies of the infestation state of the cod (Gadus morhua L.) by the Clavell,a adunca (Strjl!... more The studies of the infestation state of the cod (Gadus morhua L.) by the Clavell,a adunca (Strjl!m, 1762) parasite were carried out in North Atlantic waters over the years 1970, 1974 and 1975. Totally 7168 cod specimens have been subjected to detailed ichthyological analysis, 4454 cods originating from Labrador and New Founland fishing grounds and 2714 from Spitsbergen Island fishing grounds. The results of observations of the parasite occurrence on the particular parts of cod body are presented in the work. The observations of differences in body-build proportions of female parasite and forms of bullae originating from different locations of attachment to the host were made as well. By the use of Student's test t the significance of differences in infestation of cods from different regions was estimated, Jerzy Janusz Clavella uncinata (Muller, 177 6). Female is an invasive form attaching itself to a host by the means of bulla. It is occurring mainly in the gill cavity, on the fins, and in an anal {egion. It takes food through the mouth organ placed on the end of mobile cephalothorax and devours host's blood and slime.
Acta Ichthyologica et Piscatoria
Infection levels of six fish species-representing the fam ily Nothoteniidae-with external parasit... more Infection levels of six fish species-representing the fam ily Nothoteniidae-with external parasite Eubrachiella antar ctica (Quidor, 1906) (Copepoda) were studied in the season of 1978/79. The prevalence and the intensity of infection of indi vidual fish species on different fishing grounds of the Atlantic sector of Antarctic were determined. In addition the density analysis of the parasite occurrence on different parts of fish body was carried out as well as the relationship between the in fection parameters and the body length of the studied fish spe cies.
Fisheries Research, 1997
Aspects of pollock biology, including growth and mortality rates are presented, based on 4 years ... more Aspects of pollock biology, including growth and mortality rates are presented, based on 4 years (1991-1994) sampling of Polish commercial catches in the international waters of the Okhotsk Sea. To estimate stock dynamics, production models were fitted using Russian CPUE data, 1985-1993. The length of fish in the catches ranged from 23 to 65 cm, with a dominant mode of 35-45 cm. Fish aged 2-22 years were recorded, with fish 4-8 years old dominating the catch. The mean age and length of the exploited fish were stable in the period analyzed. The von Bertalanffy's growth curves fitted to males and females separately showed a significantly higher asymptotic length for females. Specimens with gonads at the spawning stage were found in the catches, suggesting that the spawning ground is nearby. Biomass estimates for the most recent years were about 10 million tons, and mean fishing mortality was 0.19. The natural mortality value obtained by the Pauly (1980) formula was 0.2. The optimum catch levels, resulting from production models, slightly exceed 2 million tons, and the optimum fishing mortalities are in the range 0.27-0.30. This is consistent with the F-0.1 value from the yield per recruit analysis. 0 1997 Elsevier Science B.V.
mar-eco.no
Roundnose grenadier was successfully exploited over underwater domes, distributed in the southern... more Roundnose grenadier was successfully exploited over underwater domes, distributed in the southern part of the Reykjanes Ridge and northern part of the Mid-Atlantic Ridge. This exploitation, as well as field Polish research in 1985, 1986 and 1997, has revealed biologically variable populations. However, their abundance was fairly stable under changing small-scale and large-scale environmental conditions, but was decreasing rapidly as a result of heavy commercial exploitation, which was accompanied by decreasing fish size. Roundnose grenadier has formed "resident" populations over various underwater domes. These populations tended to disperse and most probably move deeper as a result of few days of trawling. Morphological and genetic relations between these populations are not clear.
Acta Ichthyologica et Piscatoria, 1986
Sea Fisheries Institute Gdynia Infestation of five chaenichthyid species with Eubrachiella gaini ... more Sea Fisheries Institute Gdynia Infestation of five chaenichthyid species with Eubrachiella gaini (Copepoda Parasitica) was studies in the Atlantic sector of Antarctica in 1978/1979. A total of 6321 fish individuals were examined in detail. Invasion incidence and intensity of each species is presented and related to the fishing areas visited. Frequency of the parasite's occurrence on various parts of the host's body is analysed. An attempt is made to relate the degree of infestation to fish body, length in the fish species studied.
Acta Ichthyologica et Piscatoria
Sea Fisheries institute-Gdynia and [nstitu te of lch thyology, Szczecin Over the years 1970 and 1... more Sea Fisheries institute-Gdynia and [nstitu te of lch thyology, Szczecin Over the years 1970 and 1974 there were carried out studies on the prevalence of the Clave/la adunca (Str�m, 1762) parasite on the cod (Gadus morhua L.) from North west Atlantic (Labrador and New Founland fishing grounds). The growth rate and condition of 4454 cod specimens was studied. The length-weight relationship, condition. and growth paramctcr5 of infested and non-infested fishes were calculated. The calculations hawc shown that young fishes infested by Clave/la adunca parasite had higher average weight and condition than noninfosted ones of the same length. On the other hand, older infested fishes (above 6 years of life) had average weight and condition lower than noninfcsted specimens. The author's own attempt to explain this paradoxal phenomenon is presented.
Acta Ichthyologica et Piscatoria
The studies of the infestation state of the cod (Gadus morhua L.) by the Clavell,a adunca (Strjl!... more The studies of the infestation state of the cod (Gadus morhua L.) by the Clavell,a adunca (Strjl!m, 1762) parasite were carried out in North Atlantic waters over the years 1970, 1974 and 1975. Totally 7168 cod specimens have been subjected to detailed ichthyological analysis, 4454 cods originating from Labrador and New Founland fishing grounds and 2714 from Spitsbergen Island fishing grounds. The results of observations of the parasite occurrence on the particular parts of cod body are presented in the work. The observations of differences in body-build proportions of female parasite and forms of bullae originating from different locations of attachment to the host were made as well. By the use of Student's test t the significance of differences in infestation of cods from different regions was estimated, Jerzy Janusz Clavella uncinata (Muller, 177 6). Female is an invasive form attaching itself to a host by the means of bulla. It is occurring mainly in the gill cavity, on the fins, and in an anal {egion. It takes food through the mouth organ placed on the end of mobile cephalothorax and devours host's blood and slime.
Acta Ichthyologica et Piscatoria
Infection levels of six fish species-representing the fam ily Nothoteniidae-with external parasit... more Infection levels of six fish species-representing the fam ily Nothoteniidae-with external parasite Eubrachiella antar ctica (Quidor, 1906) (Copepoda) were studied in the season of 1978/79. The prevalence and the intensity of infection of indi vidual fish species on different fishing grounds of the Atlantic sector of Antarctic were determined. In addition the density analysis of the parasite occurrence on different parts of fish body was carried out as well as the relationship between the in fection parameters and the body length of the studied fish spe cies.
Fisheries Research, 1997
Aspects of pollock biology, including growth and mortality rates are presented, based on 4 years ... more Aspects of pollock biology, including growth and mortality rates are presented, based on 4 years (1991-1994) sampling of Polish commercial catches in the international waters of the Okhotsk Sea. To estimate stock dynamics, production models were fitted using Russian CPUE data, 1985-1993. The length of fish in the catches ranged from 23 to 65 cm, with a dominant mode of 35-45 cm. Fish aged 2-22 years were recorded, with fish 4-8 years old dominating the catch. The mean age and length of the exploited fish were stable in the period analyzed. The von Bertalanffy's growth curves fitted to males and females separately showed a significantly higher asymptotic length for females. Specimens with gonads at the spawning stage were found in the catches, suggesting that the spawning ground is nearby. Biomass estimates for the most recent years were about 10 million tons, and mean fishing mortality was 0.19. The natural mortality value obtained by the Pauly (1980) formula was 0.2. The optimum catch levels, resulting from production models, slightly exceed 2 million tons, and the optimum fishing mortalities are in the range 0.27-0.30. This is consistent with the F-0.1 value from the yield per recruit analysis. 0 1997 Elsevier Science B.V.
mar-eco.no
Roundnose grenadier was successfully exploited over underwater domes, distributed in the southern... more Roundnose grenadier was successfully exploited over underwater domes, distributed in the southern part of the Reykjanes Ridge and northern part of the Mid-Atlantic Ridge. This exploitation, as well as field Polish research in 1985, 1986 and 1997, has revealed biologically variable populations. However, their abundance was fairly stable under changing small-scale and large-scale environmental conditions, but was decreasing rapidly as a result of heavy commercial exploitation, which was accompanied by decreasing fish size. Roundnose grenadier has formed "resident" populations over various underwater domes. These populations tended to disperse and most probably move deeper as a result of few days of trawling. Morphological and genetic relations between these populations are not clear.
Acta Ichthyologica et Piscatoria, 1986
Sea Fisheries Institute Gdynia Infestation of five chaenichthyid species with Eubrachiella gaini ... more Sea Fisheries Institute Gdynia Infestation of five chaenichthyid species with Eubrachiella gaini (Copepoda Parasitica) was studies in the Atlantic sector of Antarctica in 1978/1979. A total of 6321 fish individuals were examined in detail. Invasion incidence and intensity of each species is presented and related to the fishing areas visited. Frequency of the parasite's occurrence on various parts of the host's body is analysed. An attempt is made to relate the degree of infestation to fish body, length in the fish species studied.