Graduation Date
Fall 2024
Document Type
Thesis
Program
Master of Science degree with a major in Natural Resources, option Fisheries
Committee Chair Name
Jose Marin Jarrin
Committee Chair Affiliation
HSU Faculty or Staff
Second Committee Member Name
Andre Buchheister
Second Committee Member Affiliation
HSU Faculty or Staff
Third Committee Member Name
Tomothy Muligan
Third Committee Member Affiliation
HSU Faculty or Staff
Keywords
Northern California, Surfperch, MPAs, Marine Protected Areas, Humboldt County, Redtail surfperch, Silver surfperch
Subject Categories
Fisheries
Abstract
The sandy beach surf zone (SBSZ) represents an ecologically, economically, and culturally important marine habitat around the world. Despite its significance, the SBSZ has been historically underrepresented in marine and coastal ecology research. This in turn has caused many inshore marine species that prefer this habitat to be largely ignored. Two particular species, the Redtail surfperch Amphistichus rhodoterus and the Silver surfperch Hyperprosopon ellipticum, have not been well studied in the PNW region . There are merely three studies conducted on the Redtail surfperch in the Pacific Northwest region and the Silver surfperch has received even less research attention with only two studies conducted in the region. Therefore, this study provides more information on Redtail and Silver surfperch by examining these species while assessing the effectiveness of Marine Protected Areas (MPAs). To carry out this objective I analyzed the catch, length, weight, age, growth, and sex ratios across two MPAs and two reference sites, as well as examining variations among years (2020-2022) in Humboldt County, in Northern California. Data was collected using two different sampling methods, hook-and-line and seining, to ensure juveniles and adults were included in the analysis. A total of 290 Redtail surfperch were caught, including 16 by seine and 274 by hook-and-line. The catch consisted of 12.5% juveniles and 87.5% adults, with adults consisting of 32.29% females and 55.21% males. Hook-and-line catch for redtail surfperch ranged from 0 to 37 individuals per day, with total lengths ranging from 7.2 to 38.5 cm, weights from 5 to 880 g, and ages from 0 to 7 years. A total of 162 Silver surfperch were caught, 89 by seine and 73 by hook-and-line. The catch consisted of 30.52% juveniles and 69.48% adults, with adults comprising 22.08% females and 47.4% males. Hook-and-line catch for Silver surfperch ranged from 0 to 19 per day, seine catch ranged from 0 to 155 individuals per tow, with total lengths ranging from 5.4 to 23.6 cm, weights from 2 to 220 g, and ages from 0 to 5 years. Redtail surfperch were found to be larger and older at more remote northern sites, possibly due to reduced fishing pressure and steeper beach slopes that allowed larger fish to be accessible to fishers. Conversely, Silver surfperch were smaller at northern beaches, suggesting their importance as nursery habitats. Redtail surfperch displayed significant interannual variation in catch, total length, weight, and age, with 2021 having longer, heavier, and older fish, and 2022 having a higher catch than 2020. Silver surfperch also exhibited similar patterns, with fish in 2021 and 2022 being longer, heavier, and older than those in 2020, as well as exhibiting a higher 2022 hook-and-line catch and 2021 seine catch compared to 2020. However, no significant MPA effect was detected for either species, potentially due to the high mobility of surfperch, small size of MPAs, lack of fishing pressure outside of MPAs, and limited public awareness and enforcement of MPA boundaries. This study is one of the first detailed assessments of Redtail and Silver surfperch in Humboldt County and northern California, and the first to include age and growth. The results of this study suggest the Redtail and Silver Surfperch Humboldt vary spatially and temporally, potentially influenced by local and regional environmental and anthropogenic factors. These results highlight the need for increased sampling and future monitoring of these species to improve management and better understand surfperch movement and MPA residency. It also emphasizes the importance of public outreach and enforcement to enhance MPA effectiveness.
Citation Style
AFS
Recommended Citation
Angell, Noah G., "Studying redtail and silver surfperch in sandy beach surf zones with MPAs in Humboldt County, California, USA" (2024). Cal Poly Humboldt theses and projects. 2264.
https://digitalcommons.humboldt.edu/etd/2264
