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Korwin-Kossakowski M.,Stanislaw Sakowicz Inland Fisheries Institute
Reviews in Fish Biology and Fisheries | Year: 2012

The paper presents differences in the distribution of hatching gland cells, and the location of egg envelope digestion, the significance of hatching movements, and the ways larvae escape from egg envelopes. A review of the literature on the hatching orientation of 34 fish species is compared. No correlation was seen between hatching orientation and egg diameter or newly hatched larva length, nor newly hatched larvae length ratio to egg diameter. Photographs of twelve freshwater species present the moment of hatching either head first or tail first. Some differences were shown in swelling between eggs incubated in commercial hatchery and developed in natural conditions, as well as possible effect of these differences on hatching. © 2011 Springer Science+Business Media B.V.

Korwin-Kossakowski M.,Stanislaw Sakowicz Inland Fisheries Institute
Journal of Fish Biology | Year: 2014

Preservation in 30% ethanol and freezing to a temperature of -20±2° C is an appropriate method for measurement of fish eggs, larvae and juveniles. Egg diameter of the common carp Cyprinus carpio increased insignificantly by 1·32% after preservation compared with live size. The total length (LT) of 1 day post-hatching (dph) larvae as well as the standard length (LS) of 16 dph larvae of C. carpio increased significantly (2·95 and 1·50%, respectively) after preservation. Egg diameter as well as the LT of 1 dph larvae of barbel Barbus barbus increased significantly after preservation, by 1·74 and 1·96%, respectively over their original size. The standard length (LS) of 14 dph larvae of B. barbus as well as juveniles of B. barbus, crucian carp Carassius carassius, common nase Chondrostoma nasus and tench Tinca tinca decreased significantly after preservation (-0·56 to -5·54%), whereas their body mass increased significantly (11·46-18·57%). Preserved eggs of C. carpio and B. barbus were hard, round and transparent. The larvae and juveniles of examined fishes, preserved in frozen ethanol, were straight, flexible and easily measurable after 60 days. Integrity of body surface and fins, as well as preservation of colours were much better in larvae or juveniles frozen and thawed only once than in specimens frozen and thawed thrice. Cooling in 30% ethanol to a temperature of 6±2° C and freezing in water to a temperature of -20±2° C are not appropriate preservation methods for eggs and larvae of C. carpio (1 and 16 dph). © 2014 The Fisheries Society of the British Isles.

Myszkowski L.,Stanislaw Sakowicz Inland Fisheries Institute
Journal of Fish Biology | Year: 2013

In a 40 day experiment, barbel Barbus barbus juveniles were fed a dry diet continuously, or food was withheld for 2, 5 or 10 days, and then resumed feeding. Improved feed utilization efficiency allowed fish deprived of food for 2 or 5 days to fully compensate for body mass loss. Short-term food deprivation as a method of preventing negative effects of overfeeding in intensive rearing of juvenile B. barbus is proposed. © 2012 The Author. Journal of Fish Biology © 2012 The Fisheries Society of the British Isles.

Studies were carried out on the effect of initial size summer pikperch fry, Stizostedion lucioperca, (two size groups), water temperature (22 and 24°C), and food type (zooplankton or artificial feeds) upon the results of rearing in controlled conditions. Weight and total length of the fish at the beginning of the experiment amounted respectively to 0.25 ± 0.06 g and 32.9 ± 2.7 mm (group S), 0.53 ± 0.06 g 39.4 ± 1.6 mm (group L). No significant effect of the initial fish size and water temperature on fish survival and losses due to cannibalism was bserved in fish which fed on zooplankton (p > 0.05). Statistical analysis revealed significant effect of initial fish size (p = 0.0011) as well as water temperature (p = 0.0001) on the survival in the groups of fish reared on artificial food. These fish attained bigger size (body weight and length) than fish in the control group (feeding on live zooplankton) (p < 0.05). Temperature had no effect on growth rate of the fish, those reared on artificial as well as natural food.

Napiorkowska-Krzebietke A.,Stanislaw Sakowicz Inland Fisheries Institute
Archives of Polish Fisheries | Year: 2014

Phytoplankton changes in canals were described in light of communities in chosen lakes of the Konin lakes system, and links were identified between these changes and water quality assessments based on different biological indexes. Seasonal phytoplankton studies were performed in the Warta-Goplo (WG) and Konin Power Plant (EK) canals. 258 and 223 taxa from six divisions were identified that comprised a maximum biomass of 13.4 mg dm-3 in the EK canal and 9.3 mg dm-3 in the WG canal. The communities in the canals were co-dominated by diatoms, cryptomonads, and chlorophytes. Blooms of the cyanobacteria Microcystis aeruginosa and Aphanizomenon flos-aquae were only noted in the WG canal. The phytoplankton in the EK canal and Lake OElesinskie were closely similar. Consistent water quality assessments were obtained with the saprobic system (moderately polluted and good quality), while the results of the algal genus pollution index indicated there was a high degree of pollution. Classifications using the Shannon-Weaver and indexes (IT) indicated the water quality in the EK canal was good, while in the WG canal the water had low levels of pollution and was at a poor ecological potential. Classification modifications based on the Shannon-Weaver index permit assessing canal water quality analogously to the saprobity index. Using these indexes is proposed as a phytoplankton-based alternative to multi-metric assessments of ecological status or potential in small rivers, streams, and canals. The possibility of performing comprehensive, five-degree classifications was confirmed, thus, permitting the recommendation of this method for water quality assessments.

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