Hopkins Marine Station Student Paper

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Title: Intramuscular anesthesia in yellowfin tuna (Thunnus albacares), bonito (Sarda chiliensis), and pacific mackerel (Scomber japonicus), its viability and effects on blood parameters
Student Author(s): Rollins, Meghan
Faculty Advisor(s): Block, Barbara
Pages: 41
Location: Final Papers Biology 175H
Date: June 1998
Abstract: This project focused on the development of an anesthetic regimen in yellowfin tuna (Thunnus albacares), bonito (Sarda chiliensis), and Pacific mackerel (Scomber japonicus), while monitoring effects on blood chemistry and hematology. Anesthesia was induced with a combination of ketamine and medetomidine, and compared to MS-222 (3-amino benzoic acid ethyl ester). Ketamine and medetomidine were injected into the red muscle of fish, while MS-222 was applied by immersing a fish in a drug and seawater solution. Effects of anesthesia were monitored and blood samples were taken. Blood was then analyzed for hematocrit, hemoglobin, enzymes, metabolites and ions. Survivorship between the species varied, with yellowfin tuna at 0% survival and bonito the highest at 50% survival. A trend relating an increase in time of the anesthetic induction period to decreasing metabolic rate was noted. Additionally, time until recovery from anesthesia was found to increase with the ratio of ketamine to medetomidine in yellowfin tuna, but was found to decrease with the ratio of the two drugs in bonito. Anesthesia was found to have no effect on average yellowfin tuna hematocrit (mean level = 33.4 + or - 2.2). However, a positive relationship between yellowfin tuna hematocrit and medetomidine dose was noted (r^2 = 0.82729). A negative relationship between bonito hematocrit and the ratio of ketamine to medetomidine was also present. A significant increase in ions (calcium, chloride, potassium and sodium) and some enzymes (aspartate aminotransferase and creatine phosphokinase) was noted in yellowfin and was most likely due to the high levels of activity associated with anesthesia induction. Further studies into this form of intramuscular anesthesia are needed, both to better determine the feasibility of usage of the drugs in yellowfin tuna, and to ascertain an ideal anesthetic dose in bonito and mackerel.