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82 J. FISH. RES. BOARD CAN., VOL. 33(1), 1976 Ta,eLE 2. Percentage of thrombocytes, lymphocytes, and heterophils in the blood. Hours after Thrombocytes (~) Lymphocytes (~) Heterophils (~) treat- Treatment ment N ?C se N X se N X se Control 0 9 1.7 0.5 9 89.2 2.l 9 9.1 2.0 Shocked 0 7 4.0 1.8 7 88.1 2.6 7 7.9 2.4 Shocked l 6 0.5 0.3 6 93.7 1.1 6 5.8 2.9 Shocked 3 7 0.7 0.3 7 93.0 2.4 7 6.3 2.1 Shocked 6 8 0.1 0.1 R 95.6 0.7 8 4.3 0.8 Control 6 12 0.8 0.2 12 92.6 0.9 12 6.6 0.9 W ~~ r ~ ~ ~~ J a 200 r A` 4 ~ ``~ ~ 'b ,~--~_ ,o N IOOr~---~-~_ _ `n GI ~, _ w _ J j i5 5~ EC IS $EC m zoo - Y r ~°- O o ',1 _ V7 Q _ ~ _ 4'~ a ItI 1.~L11_L1.11,1..LLL1_ 1 I 11 1 1 1 1 1 I I I I I I I I J O IO 20 90 60 90 120 150 tas sEC. O 1020 40 60 90 120 150 TIME (MINI Ftc. 4. Buccal pressure expressed as percentage of preshock levels in two trout (open circles, solid line; triangles, and dashed line) shocked twice for 15 s each time (upper panel); and (lower panel) one trout (triangles, dashed line) shocked for 45 s. In both panels the clots and broken line represent un- shocked fish. The curves are interrupted at the time of shocking because data were not collected during periods of electrode activation (arrows) for the treated fish. Discussion It is evident that capturing trout by electro- shock elicits a general stress response lasting several hours. Handling alone has been shown to be a stressor in fishes (Donaldson and McBride 1967; Wedemeyer 1969, 1972; Stevens 1972). That hematocrit value did not reflect the change in erythrocytes noted by Bouck and Ball (1966) and Kraiukhin and Smirnova (1966) is perhaps attributable to the small numbers of samples for this determination. Androgen levels were not markedly affected by shocking, but reproductive success of populations might be influenced if eggs or fry were shocked (Godfrey 1957; and Marriott 1973). There appears to be a close parallel between the stress induced by electroshock and that in- deed by hypoxia and/or severe muscular activity. "The responses of the physiological processes examined are most likely dependent on severity and duration of the stressor. The rapid increase in breathing amplitude after electric shock and the return to baseline values after the electric shock follow a pattern similar to that in fish with an oxygen debt and the paying off of that debt as discussed by Heath (1973). Ventilatory and circulatory rates work in concert with amplitude (stroke volume) to supply oxygen to the tissues. Our data do not indicate an effect of electroshock on the rate component of the system. Phis is con- trary to reports on visual counts ]Wade by Hauck (1949), Bodrova and Kraiukhin (1958), Kraiu- khin and Smirnova (1966), and Kynard and Lons- dale (1975). We found in all treatments, how- ever, that the electroshocked fish responded by changing the amplitude but not frequency of breathing. The variability in these factors in fish under various environmental conditions (Spitzer et al, 1969) may account for these differences in response. The rapidity of lactate increase in the shocked fish apparently reflects the severity of the period of anaerobic muscular activity. The recovery of lactic acid levels in the blood was somewhat similar to that noted in rainbow trout after mus- cular exercise (Black et al. 1960) and confirms reports of lactate increase due to shocking (John- son et al. 1956; Caillouet ]967). The degree of oxygen debt incurred during shocking may have been small, however, as indicated by the more than tenfold, but more gradual increase in lactate in cutthroat trout (S. clarki) subjected to severe hypoxia by Heath and Pitchard (1965). Muscular exertion also elicited a steady increase in blood glucose levels for the first 12 h during recovery; resting levels had been regained 12 h later (Black et al. 1960). Asphyxiation can also lead to steadily elevating glucose levels, as shown by Chavin and Young (1970) in goldfish. 1n the