CONFIRMED: SMAST DFO PhD Dissertation Defense presented by Christopher Rillahan on January 7th
Department of Fisheries Oceanography "Application of optical and acoustic technologies to improve the understanding of fish behavior, ecology, and stock assessment." By: Christopher Rillahan Advisor: Dr. Pingguo He Committee Members Dr. Kevin D. E. Stokesbury, Dr. Steven X. Cadrin, Dr. Theodore Castro-Santos, and Dr. Kresimir Williams Tuesday January 7th, 2025 11:00 AM SMAST West 204 706 S. Rodney French Blvd, New Bedford and via Zoom Abstract: Marine species inhabit an extensive underwater environment that is largely inaccessible to humans. Consequently, we have relied on various technologies to study and manage the commercial and recreational species we depend on. Over the past century, there have been rapid advancements in optical and acoustic technology, which have coincided with an increased need for effective fisheries management. The ability to observe fish during the capture process has shed light on the role of fish behavior and the potential bias it introduces into fisheries data. Due to insufficient knowledge of most systems, scientific surveys and stock assessment models have traditionally relied on simplified assumptions about fish behavior. While it has been understood that fish have well-developed sensory systems, mobility, and complex life histories, the lack of information has limited their use in gear catchability, survey design, and assumptions about spatial and temporal population dynamics. This dissertation examines the use of optical and acoustic technology to address these limitations, improving the interpretative power of survey data and reducing potential bias. Baited remote underwater video systems (BRUVS) were employed in Chapter II to examine the role of a species' life history in the performance of traditional survey gears (e.g., fish pots and demersal otter trawls). The spatial distribution of black sea bass (Centropristis striata), a structure-oriented species, in Buzzards Bay was observed to vary depending on the survey gear. Conversely, scup (Stenotomus chrysops), a habitat-agnostic species, exhibited similar patterns across survey methods. Video observations of black sea bass documented an increasing affinity for structured habitats during the summer and fall. This shift in the spatial distribution of black sea bass dramatically affected the trawl survey data. Catch data from the spring trawl survey generally corresponded to the video and pot data with respect to the spatial distribution and population structure of both black sea bass and scup. Conversely, the fall trawl survey data starkly contrasted with the two other surveys, with few adult black sea bass catches. The lack of catch is presumably due to the shifting residence of black sea bass to rocky habitats, which are not sampled by the trawl and, therefore, unavailable to the survey. The shifting availability between the spring and fall trawl surveys presents an inaccurate picture of black sea bass abundance in Buzzards Bay....... ************ Join Zoom Meeting https://umassd.zoom.us/j/91787205979 Note: Meeting passcode required, email contact below to receive ************** To request the full abstract, Zoom passcode, or for any other questions, please email Callie Rumbut at c.rumbut@umassd.edu
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