Date of Award

8-2006

Level of Access

Open-Access Thesis

Degree Name

Master of Science (MS)

Department

Marine Bio-Resources

Advisor

John Riley

Second Committee Member

Michael Peterson

Third Committee Member

Michael Moore

Abstract

Two test systems were developed to evaluate the influence of draw-length and tissue compliance on entanglement-induced epidermal abrasion in humpback (Megaptera novaeangliae) and right whale (Eubalaena glacialis) tissue samples. Under straight pull abrasion tests an adult right whale fluke required 3.7 times the load and 15 times the draw-length of a right whale calf flipper to induce epidermal failure while a humpback fluke was intermediate between these extremes. Epidermal thickness did not appear to be the cause of this difference in abrasion resistance. Epidermal thickness averaged 8.0k0.2 mm for the calf flipper, 4.9k0.4 rnrn for the humpback fluke, and 5.1k0.1 mm for the right whale fluke. It is unknown whether the difference in abrasion resistance is a function of species (right vs. humpback whale), age (adult vs. calf), or body region (fluke vs. flipper). Repeated tests with different line materials (new and used float vs. sink) did not show a significant difference in the rate of epidermal abrasion. However, line diameter does appear to influence tissue abrasion rates. Thinner (6.4 mm diameter) lines cut substantially deeper than thicker (9.5 mm diameter) lines under similar loads and draw-lengths. Tests with the oscillatory abrasion system revealed that draw-lengths that exceed the tissue compliance limit resulted in substantially increased rates of tissue abrasion. Draw-lengths below the compliance limit did not penetrate the epidermis while those exceeding the compliance limit deeply cut into the underlying dermis. In actual entanglement situations, the relative draw-length to tissue compliance ratio may be the critical component that determines if the line will cut into the body or benignly press against the skin. Investigations into the potential for reducing line modulus to allow lines to stretch with flexure of the body and thus minimize sliding relative to the skin may be beneficial in reducing the mortality associated with entanglement injuries.

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