Biological Sciences, Santa Barbara City College pipeline center for sustainability

Biology 130: Methods in Field Biology

Field Technique:  Abalone Size Frequency

TA for the day write-up

From: Black Abalone Monitoring at Channel Islands National Park 2008 - 2010

During the timed or defined-area searches, typically one observer searches for abalone by carefully inspecting crevices and cavities among boulders, and checking under kelp or other canopy-forming seaweeds. Abalone are identified to species, shell lengths are measured with vernier calipers or estimated if an accurate measurement is not possible, and the nearest neighbor distance is recorded using five spatially descriptive categories (touching, < 10 cm, 10-100 cm, 1-5 m, >5 m). Aggregation sizes (number of abalone within one meter of an other) are generally noted as well. Shell size serves as a proxy for age giving us a picture of the population structure. Nearest neighbor distance and aggregation size give us insight to the theory that abalone aggregate naturally and we hope it serves as an indication of spawning potential, since, as broadcast spawners, their reproductive options increase with proximity to other abalone. There may be other Allee Effects from aggregation such as an increased ability to capture drift kelp.

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Revised 26 January, 2015
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