Fish Hatchery Management - fisheries & aquaculture

360 FISH HA'TCHERY MANAGEMENTTABLE 39. CLASSIFICATION OF THE BEHAVIORAL CHANGES THAT OCCUR IN FISHES'fC)DURING ANES'THESIA. LEVE,LS OT ANE,STHESIA CONSIDEREI) VAI-UABL!]FISHERIES WORK ARE ITALICIZED. (SOURCE: McFARLAND ll)(i0)DEFINABL!] LEVELS OF ANESTHESIASTATE PLANE WORD EqUIVALENTS BEHAVIORAL RESPONSTS OF FISHIIilUIIVNormalLight sedationDeep sedationPartial loss ofequilibriumTotal loss ofequi libriumLoss of reflexreactiait!Medullary collapseReactive to external stimuli, equilibriumand muscle tone normal.Slight loss of reaction to external stimuli(visual and tactile).No reaction to external stimuli exceptstrong pressure; slight decreased opercularrate.Partial loss of muscle tone; reaction onlyonly to very strong tactile and vibrationalstimuli; rheotaxis present, butswimming capabilities seriously disrupted;increased opercular rate.Total loss of muscle tone; reaction only todeep pressure stimuli; opercular ratedecreased below normal.Total loss of reactivity; respiratory ratevery slow; heart rate slow.Respiratory movements cease, followedseveral minutes later by cardiac arrest.Carrying CapacityThe weight of fish that can be safely transported in a distribution unitdepends on the efficiency of the aeration system, duration of the haul, watertemperature, fish size, and fish species.If environmental conditions are constant, the carrying capacity of a distributionunit depends upon fish size. Fewer pounds of small fish can betransported per gallon of water than of large fish. It has been suggestedthat the maximum permissible weight of trout in a given distribution tankis directly proportional to their length. Thus, if a tank can safely hold 100pounds of 2-inch trout, it could hold 200 pounds of 4-inch trout, and 300pounds of 6-inch trout.Reported loading rates for fishes vary widely among hatcheries, andmaximum carrying capacities of different types of transportation units havenot been determined.Fish loadings have been calculated and reported inconsistently. In theinterests of uniform reporting by fish culturists, it is suggested that loadingdensities be calculated by the water-displacement method. This is based on