This study focus on juvenile Seriola rivoliana, also known as kampachi or almaco jack. Photo courtesy of Ocean Era /Global Aquaculture Advocate

Testing diets without fishmeal and fish oil for kampachi

UNITED STATES
Tuesday, August 25, 2020, 05:00 (GMT + 9)

Results show potential for drastically reduced footprint for carnivorous finfish production

Reliance on marine-sourced fishmeal and fish oil is a primary limiting factor in the growth, profitability, and sustainability of the marine finfish aquaculture industry. For the species kampachi (almaco jack, Seriola rivoliana), several alternative ingredients have proven successful as partial replacements of fishmeal or fish oil – an important biological proof – but few ingredients meet the range of criteria necessary for commercialization.

In addition to reliable nutritional quality, successful alternative diets must be palatable to the species in question, must not alter the quality of the final product for consumers, and must be affordable. Despite several research-scale successes, commercial Seriola production in 2020 still utilizes diets primarily based on fishmeal and oils derived from wild-caught forage fish.

View of flow-through tank system used in this study at Ocean Era facilities in Kona, Hawai’i.

Through the U.S. National Oceanic and Atmospheric Administration (NOAA) Saltonstall-Kennedy Grant Program, Ocean Era (formerly Kampachi Farms), Aquatic Feed Technologies and the F3 Future of Fish Feed team have worked together to create fish-free feeds for S. rivoliana that not only yielded competitive performance but were formulated with ingredients that are both abundant and cost-effective. Specifically, ingredients of interest were byproducts from the natural spirulina pigment market, low-cost poultry meal, and Veramaris™ algae oil. Poultry meal used in these diets was all pet-food grade (PFG).

The scope of the grant involved three separate grow-out trials for S. rivoliana from 2018 to 2020, with diet formulae evolving based on the results, and this article focuses on the results of the final trial in the series.

This material is based upon work supported by NOAA under contract number NA18NMF4270208. Any opinions, findings, conclusions or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the views of NOAA.

Photo: courtesy Monterey Bay Aquarium Seafood Watch

Study setup

The study was conducted in April 2020 at Ocean Era (Hawaii, USA) with 480 juvenile S. rivoliana randomly distributed into sixteen 4-ton tanks to initiate a comparative grow-out trial. The four treatments included a commercial control diet, and three fishmeal-free formulations with a shared base of pet-food grade poultry meal, wheat, soy protein concentrate and corn protein. One diet was identical to a formulation that had proven successful in the preceding Trial 2 (PM+FO); one diet replaced all fish oil in that formula with a blend of canola, flax, and Veramaris™ algae oils (PMnoFO); and one incorporated spirulina as a primary protein (PM+Spiru). Complete formulations are open access, available through the F3 Feed Innovation Network.

Diets were randomly assigned to each experimental tank in quadruplicate; tanks were originally stocked at 30 fish per tank and culled to 15 fish per tank at the start of Month 2, as dictated by density limitations. Fish were 145 days post-hatch at trial start, averaging 282 grams. Total trial duration was three months. Prior to trial start, all fish were held on a different commercial yellowtail feed in order to minimize any acclimation bias for the experimental feeds; all fish were subject to a diet change at trial start, including the Control fish (from one commercial diet to the Control commercial diet).

Kampachi Farms placed an offshore cage system growing Almaco jack (Seriola rivoliana). The company calls the project Velella Epsilon, and it is slated to operate in the southeastern waters of the Gulf of Mexico for six to nine months. (Photo courtesy of Kampachi Farms /Courtesy Global Aquaculture Alliance)

Fish were initially fed twice daily, switching to once daily when they reached approximately 1-kg average weight. Every four weeks, all fish were anaesthetized, weighed and measured (fork length). The biological feed conversion ratio (FCR) was calculated based on feed consumption and weight gain over the four-week intervals.

At trial completion, three fish from each tank (12 per treatment) were randomly selected for processing. Whole fish were weighed for total body weight, then viscera were removed and weighed separately to calculate viscerosomatic index, VSI (relationship between fish body weight and liver weight). Each fish was filleted, then right and left fillets (ribs on) were weighed separately, and the combined fillet weight was compared to whole fish weight to obtain percent yield. All fish were filleted by the same person to account for technique variation.(Continued...)

Authors: Helen Meigs, MAS Frederick Barrows, Ph.D. Neil Anthony Sims, M.Sc. Kelly Alfrey, B.S. / Global Aquaculture Advocate | Read the rest of the story by clicking the link here

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