Growth of juvenile Red Abalone (Haliotis rufescens) fed different seaweed-based diets

Author

Quinn C. Wulffson, Humboldt State UniversityFollow

Graduation Date

Fall 2020

Document Type

Thesis

Program

Master of Science degree with a major in Natural Resources, option Fisheries

Committee Chair Name

Rafael Cuevas Uribe

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

Brian Tissot

Third Committee Member Affiliation

HSU Faculty or Staff

Subject Categories

Fisheries

Abstract

The rise of abalone aquaculture has mitigated most of the global demand placed on wild stocks of abalone; however, the current production of abalone relies heavily on naturally harvested kelp. The continued reliance on wild kelp as a feed source further contributes to the disappearance of kelp forests throughout coastal ecosystems. This study aims to better understand how juvenile red abalone Haliotis rufescens grow and utilize nutrients from three diets: a control diet of naturally harvested bull kelp Nereocystis luetkeana, a formulated commercial diet (ABKelp^®), and Pacific dulse Palmaria mollis produced using Integrated Multi-Trophic Aquaculture (IMTA). Juvenile abalone greater than 10 mm were reared in a recirculating quarantine system from October 2^nd, 2019 to March 23^rd, 2020. Each diet treatment had nine replicates with data on weight, shell length and shell depth collected monthly. A mixed-effects model ANOVA indicated that diet treatments had a significant effect on abalone weight (F_2,24=49, P < 0.05), length (F_2,24=61.7, P < 0.05) and depth (F_2,24=43.2, P < 0.05). Abalone grew significantly larger on both macroalgal diets (bull kelp and Pacific dulse) as compared with the formulated feed. Dulse produced the largest abalone; however, post-hoc pairwise comparisons revealed that abalone in the dulse and bull kelp treatments were not significantly different from one another in terms of final average weight, shell length, and shell depth. Abalone fed dulse had significantly higher weight gain per day and body weight to shell length ratios than the other two treatments. Amino acid profiling demonstrated that the formulated feed had the highest concentration of essential amino acids, but that tissue from abalone fed dulse had the highest protein nitrogen content and amino acids. Fatty acid analysis showed a seasonal increase in Eicosapentaienoic acid (EPA (20:5n3)) for dulse. It is suggested that juvenile red abalone have the potential to biosynthesize Clupanodonic acid (22:5n3) from EPA but may not have the ability to convert it into Docosahexaenoic acid, or DHA (22:6n3), as is seen in other members of the Haliotis genus. It is speculated that the formulated fed abalone would have exhibited greater growth and consumption had the presentation of the feed been in a more compressed form. This study further emphasizes the benefits of IMTA cultured algae as a feed source for juvenile red abalone and a sustainable alternative to wild harvest kelp.

Citation Style

Transactions of the American Fisheries Society

Recommended Citation

Wulffson, Quinn C., "Growth of juvenile Red Abalone (Haliotis rufescens) fed different seaweed-based diets" (2020). Cal Poly Humboldt theses and projects. 436.
https://digitalcommons.humboldt.edu/etd/436