Defense Date
5-1-2026
Document Type
Thesis
Degree Type
Master of Science
Degree Name
Marine Science
First Advisor
Andrew Bauman
Second Advisor
Fraser Januchowski-Hartley
Third Advisor
Brock Bergseth
Keywords
Fish Behavior, MPA Management, Fear Effects, Philippines
Abstract
Predator avoidance behaviors have recently gained more attention in scientific research, but relatively few studies have examined how protection levels in marine protected areas (MPAs) influence fish escape responses. This thesis aimed to assess fear-based proxy metrics of behavior across a gradient of protection from large, isolated, well-enforced MPAs to small MPAs with lower levels of compliance. Specifically, I analyzed flight initiation distance (FID) and minimum approach distance (MAD) of target and non-targeted species, and evaluated whether they were affected by protection level, total length, depth, family, group size, or pre-flight behavior.
FID measures the closest distance between an observer and target animal with the intent of provoking a flight response, whereas MAD is the closest distance between the observer and target animal without intentionally provoking flight. FID decreased with higher protection levels, mainly influenced by protection level, total length, and family. Depth and group size had little impact. FID was lower if fish were feeding before flight, but pre-flight behavior showed little variation across protection levels. MAD was lower in protected sites, such as pristine areas and MPAs, with no differences among them. Protection level, family, and depth primarily affected MAD, followed by group size and total length. Similar to FID, MAD was lower when fish were feeding prior to approach.
While protection level, total length, and pre-flight activity showed similar effects on MAD and FID, the results for family, depth, and group size differed. Overall, I demonstrate that protection levels significantly influence fish wariness and illustrate the potential of behavioral metrics for guiding management of key species in MPAs. The differing results for some covariates suggest each metric may be better suited for certain MPAs. FID is more responsive in systems where spearfishing on SCUBA is prohibited. In systems where spearfishing on SCUBA is legal, MAD may be more responsive to human predation. This is the first comparison of both metrics across a protection gradient, and further research is encouraged to refine these metrics.
NSUWorks Citation
Sofia Ella El-Rass. 2026. Comparing Fish Behavior Metrics in Philippine Marine Protected Areas. Master's thesis. Nova Southeastern University. Retrieved from NSUWorks, . (239)
https://nsuworks.nova.edu/hcas_etd_all/239.