Thesis

Effects of intraperitoneal implantation of ultrasonic transmitters on the feeding activity, growth, tissue reaction, and survival of adult white seabass (Atractoscion nobilis)

Biotelemetry studies assume that vital biological processes are unaffected by the attachment method and presence of the transmitter. I examined the effects surgically implanted transmitters (representing 0.2-0.9 % of body weight) had on feeding activity, growth, tissue reaction, and survival of 70 adult white seabass, Atractoscion nobilis, (72.5-120.4 em total length) over a 451-day period. On day 97 (expected transmitter life), analysis of growth in standard length revealed no significant difference among fish exposed only to handling and anesthesia (controls), surgery but no implanted transmitter (sham-surgery), dummy transmitters surgically implanted (dummy-surgery), and functional transmitters surgically implanted (active-surgery). However, during this period active-surgery fish gained significantly less weight than sham-surgery fish. No significant difference in growth occurred among control, sham-surgery, and dummy-tagged fish over the remaining 354 days of the study. Differences in feeding activity of fish among the four treatment groups were significant during 12 recorded feeding trials over the first 32 days, but were likely influenced by the behavior of a few dominant individuals .. Incision healing was complete after 97 days, with light necrosis at the insertion points of sutures. All transmitters were completely encapsulated by fibrous connective tissue within 97 days. No gross morphological differences were observed in the tissue encapsulating dummy or active transmitters, and no fish expelled transmitters through the body wall, via the intestinal tract, or incision site over the 451 day study period. Two mortalities occurred during the study when sham-surgery fish died on day 17 and 41. My results show that with the described surgical procedures, intraperitoneal implantation provides a suitable technique for future biotelemetry studies on adult white seabass.

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