Rockfishes of the genus Sebastes are trophically important in most nearshore environments of the west coast of North America, and support important commercial and recreational fisheries. Though the 72 northeast Pacific species have drumming muscles along their swim bladders, little is known about sound production in the genus. Sounds produced by nearshore rockfish were recorded using fixed hydrophones and underwater video in aquaria, and acoustical dataloggers in the field. Sounds were analyzed from six species: Sebastes nebulosus, S. atrovirens, S.carnatus, S. chrysomelas, S. caurinus, and S.maliger. These six species are closely related, mostly bottom dwelling species with similar drumming musculature. No sounds were recorded from twelve other species in response to diver harassment or agonistic interactions. All the sound production observed was close range, agonistic and relatively quiet (estimated source level 122 dB re 1uPa). Sounds were recorded at all times of the day in the field, presumably from S. nebulosus. While courtship type behavior was observed and video-recorded for only two species, no sounds were produced during courtship. Analysis of the sounds (duration, number of pulses, pulse rate, peak frequency, interpulse interval) from the six species showed considerable overlap between call characteristics, although S. carnatus and S. chrysomelas produced some longer calls with more pulses than the other species. It appears that these agonistic sounds are designed for short-range communication and that they are not species-specific.

The aim of this master thesis was test, comapre and observe the best density of rotifers (Brachionus plicatilis) for growth and survival of zander (Sander lucioperca) larvae stage in the recirculation aquatic systém (RAS). The secondary experiment tests initial feeding of zander by dint of rotifers and consequently by mix of rotifers and artemia. Main experiment observe effect of different density of rotifers on survive and growth of zander. Other observe parameters such as Fulton´s coeficient, total lenght of fish, weight of fish, etc. Fish was divided into 4 groups with different density of feeding and the control group without feeding. Rotifers has been used in density of 2, 6, 10 and 20 pieces per larva. The best growth in "D" group has been compensate by lower surviving. On the other hand the best ratio of survive has been observe in "C" group, which showed lower growth. The optimal rate of growth and survive has been declared in "B" group, which were feed with dose of 6 pieces rotifers for larva. In the second experiment were observe body changes of zander after initial feeding by rotifers folowed with feeding mix of rotifers and artemia. There were observe successful fulfillment of gas bladder and deformation of fish body and spinal after 40 days of keeping larvae in RAS. In the end of experiment there were also observe defirmations body - for example missing lower jaw, upper jaw or both of them. Spinal deformities occured in the form of scoliosis, lordosis, kyphosis and zig zag distortion. The experiment has shown that unsuccessfully filled gas bladder is closely related to the formation of deformitiy in the zander. Another negative factor that affects the filling of the gas bladder is grease on the surface of the water level, so I recommend installing the grease trap in the fill phase of the gas bladder.

Extensive use of the organophosphate diazinon has led to its accumulation in aquatic environments and negative effects on fish health. Most studies focus on the effects of short term exposure to high levels of organophosphate pesticides. This research was conducted to assess the effect of chronic sub-lethal exposure to 0, 0.01, and 0.1 mg/L diazinon for 15 and 30 days on blood parameters and histopathological damage in alligator gar, Atractosteus spatula. Fish exposed to either concentration were motionless, produced excess mucous, had lighter skin color, and had skin lesions. Blood indices of red blood cells, leukocytes and hematocrit values significantly decreased but there was no significant change in mean cell volume. Hemoglobin values significantly increased in fish exposed to the low dose for 15 days, but significantly decreased for the other exposure doses and times. On the contrary, mean corpuscular hemoglobin, and mean corpuscular hemoglobin concentration values significantly increased in fish exposed to both concentrations and duration times. Leukocyte differentials showed significant decreases in lymphocytes with significant increases of monocytes in fish exposed to the high dose in both exposure times. The most frequent biomarker for exposure to organophosphate pesticides is the inhibition of cholinesterase (ChE). Diazinon significantly reduced plasma ChE activity in a dose-dependent manner, with 62% and 72% in the low and high concentrations for 30 days, respectively. Plasma ChE could be determined from peripheral blood samples and did not require sacrifice of the fish. Fish exposed to either diazinon concentration or duration time developed histopathological changes in skin, gills, liver, and kidney tissues. The skin lesions were on the head and body, and progressed into deep ulcerations. The histopathological changes in the liver included hepatic vacuoles, swollen hepatocytes, steatosis, aggregation of macrophages, necrosis, and hepatic fibrosis. Also, exposed fish demonstrated vacuolar degeneration in the hematopoietic tissues of the kidney. Gills showed epithelial hyperplasia in the secondary lamellae. In conclusion, long term exposure to sub-lethal concentrations of diazinon induced significant changes in hematological indices and histopathological alteration in various tissues. Plasma ChE can be used to monitor diazinon exposure in wild gar populations.