Why is There No Commercial Mahi-mahi Aquaculture Yet?

Mahimahi (Coryphaena hippurus), also known as Dorado or Dolphinfish, is a tropical oceanic predator. In the U.S., it is a prized sportfishing species with an annual recreational landing of approximately 5,000 tonnes in recent years; and it is in even higher demand commercially, leading the U.S. to import 25,000 tonnes in 2013 (1). Keep in mind these numbers are for the U.S. alone.

One of the reasons wild stocks have been able to endure this fishing pressure is the remarkable growth and reproductive capabilities of this species. Juveniles have been shown to gain roughly 30 grams a day in laboratory settings, and grow up to 9.5 kg in the first year (2,3). Perhaps more importantly, they reach sexual maturity in just 4 to 5 months in the wild and spawn up to 180 days of the year (4)!

The market, the growth rates, and the success in captive spawning are all there; so why is there no mahimahi aquaculture? The Achilles heel for C. hippurus thus far is their natural aggression: larval rearing can be challenging due to high rates of cannibalism at early life stages, followed by territorial bloodlust as they reach maturity. They start earning the moniker “dolphinfish” at a young age, exhibiting the ability to jump impressively high out of things (tanks) or into things (walls).

At Kampachi Farms we strive to allay this aggression by creating cohorts of single sex mahi. The sex of several other marine fish species can be determined by unique temperature fluctuations near time of spawning, and anecdotal evidence suggests this can be applied to mahi. By defining the ideal water temperature and timing/duration of exposure, we could provide a noninvasive, economical method of producing all-male cohorts. This would be ideal for aquaculture as male mahi aggression is naturally lower in the absence of females, and the overall growth rate of males is higher as they invest less energy in reproduction.

While mahi may be excellent restaurant fare, they are also incredibly useful for ecological research. The same biological features that make this a promising species for commercial production – exceptionally high metabolism, low age at reproduction – make a convenient proxy to illustrate the effects of environmental changes on marine finfish. The University of Miami has used their renowned C. hippurus spawning program in myriad studies since the Deepwater Horizon oil spill to observe the developmental effects this event may have had on pelagic fish species (spoiler: oil is not great for fish). Since mahi progress through their developmental stages so quickly, it is an ideal species in which to study toxicology. For instance, certain levels of embryonic exposure to crude oil may prove nonlethal, but may impact cardiac function and energy demands of the fish later in life (5,6). Similarly, mahi have been used to illustrate the metabolic and behavioral impacts of ocean acidification (7). This knowledge can be applied to past and future scenarios to better understand long term impacts of anthropogenic activity on fish population fitness.

Wild mahi have thus far proven robust to fishing pressure, but the world needs ever more seafood. Optimizing aquaculture of this species can increase availability, alleviate pressure on wild stocks, as well as provide invaluable knowledge for resource management in the face of a changing environment.

More mahi for all!

References:

1. NMFS Recreational Fisheries Statistics Queries (2013). National Oceanic and Atmospheric Association.  [online] Available at: https://www.st.nmfs.noaa.gov/st1/recreational/queries/ [Accessed 21 Nov. 2017].
2. Hagood, R.W., Rothwell, G.N., Swafford, M., Tosaki, M. (1981) Preliminary report on the aquaculture development of the dolphin fish, Coryphaena hippurus (Linnaeus).  J. WorldMaricult. Soc., 12(1), pp.135–139.
3. Kraul, S. (1989) Review and current status of the aquaculture potential for the mahimahi, Coryphaena hippurus. Advances in Tropical Aquaculture, Workshop at Tahiti, French Polynesia, 20 Feb-4 Mar 1989.
4. McBride, R.S., Snodgrass, D.J., Adams, D.H., Rider, S.J. and Colvocoresses, J.A. (2012) An indeterminate model to estimate egg production of the highly iteroparous and fecund fish, dolphinfish (Coryphaena hippurus). Bulletin of Marine Science, 88(2), pp.283-303.
5. Esbaugh, A.J., Mager, E.M., Stieglitz, J.D., Hoenig, R., Brown, T.L., French, B.L., Linbo, T.L., Lay, C., Forth, H., Scholz, N.L. and Incardona, J.P. (2016) The effects of weathering and chemical dispersion on Deepwater Horizon crude oil toxicity to mahi-mahi (Coryphaena hippurus) early life stages. Science of the Total Environment, 543, pp.644-651.
6. Pasparakis, C., Mager, E.M., Stieglitz, J.D., Benetti, D. and Grosell, M. (2016) Effects of Deepwater Horizon crude oil exposure, temperature and developmental stage on oxygen consumption of embryonic and larval mahi-mahi (Coryphaena hippurus). Aquatic Toxicology, 181, pp.113-123.
7. Pimentel, M., Pegado, M., Repolho, T. and Rosa, R. (2014) Impact of ocean acidification in the metabolism and swimming behavior of the dolphinfish (Coryphaena hippurus) early larvae. Marine biology, 161(3), pp.725-729.

Velella Epsilon: Pioneering Offshore Aquaculture in the Gulf of Mexico

As part of a national initiative to increase U.S. aquaculture production in the next four years, Kampachi Farms has been awarded a grant in partnership with Florida Sea Grant to trial a new Velella net pen pilot project in the Gulf of Mexico.   

Kampachi Farms has successfully deployed smaller Aquapod™ demonstration fish pens off the coast of Kona, Hawaii. The Velella Beta-test was awarded one of TIME Magazine’s 25 Best Inventions of the Year, and was featured on a National Geographic special hosted by Dr. Robert Ballard. The Velella Beta-test and the Velella Gamma project were both also highly popular with the local Kona fishing community, as the net pen arrays acted as Fish Aggregating Devices (FADs), and proved to be exciting dive sites for snorkel tours.    

In 2016, NOAA Fisheries finalized a Rule that would allow commercial aquaculture operations to be permitted in U.S. federal waters in the Gulf. However, no applications have been received for such projects yet, according to Jess Beck-Stimpert, an aquaculture coordinator with NOAA Fisheries.

“This demonstration pen would therefore be the only permitted structure in Gulf waters,” said Beck-Stimpert.

One of the major barriers to commercially expanding open ocean aquaculture in the Gulf of Mexico has been its arduous permitting process.

Neil Anthony Sims, CEO for Kampachi Farms stated, “The primary goal of the demonstration project is to help the local communities in the Gulf of Mexico to understand the ancillary benefits that offshore aquaculture can bring to fisheries and to recreational tourism.”

Kampachi Farms also intends to start discussions with State and Federal agencies and the local community about pioneering an application for a commercial aquaculture permit in the Gulf of Mexico. The Velella Epsilon will use a SUBflex submersible net pen system (made by GiliOcean Technology), on a single-point mooring, which allows the net pens to pivot as the current direction changes. The project will also encourage recreational and charterboat fishermen to use the pen as a FAD, or Fish Aggregating Device. As part of the Sea Grant project, this process, and the community response, will be documented as a reference for future applicants.

Sims explained, “Once the Velella Epsilon has demonstrated the technology and benefits of offshore aquaculture to the local communities, then we will engage them in the discussions about how this industry might move forward. We will also work with the various agencies to identify areas needing further regulation or clarification of agency requirements, or areas where we could eliminate any redundancies. And, we will make our documentation on this process readily available for future aquaculture industry applicants to use as a template.”

For more information on previous Velella Project Trials see our Research Page.  

Fertilized Kyphosus Eggs: moving culture of high-value herbivorous reef fish closer to reality

Kampachi Farms’ Research Team recently obtained fertilized eggs from our tank-reared nenue (rudderfish, Kyphosus vaigiensis). To our knowledge, this is the first captive-reared spawn ever obtained of any Kyphosidae family.

Kampachi Farms – along with many others in aquaculture research - have pursued enhanced sustainability by formulating "vegetarian" diets for carnivorous fish, such as our much-loved Cabo Kampachi™. However, few have focused on the potential for growing a high-quality herbivorous marine fish. Herbivorous fish are less widely appreciated, but in Hawaii a local reef herbivore, the nenue (rudderfish; a member of the Kyphosidae family), has always been prized as a food fish. These seaweed-grazers have a fantastically efficient ruminant-like gut, which allows them to digest and utilize macroalgae(seaweed, or ‘limu’, in Hawaiian). Cultured nenue could therefore potentially be grown on a highly sustainable and economical diet including macroalgae, agricultural byproducts and other plant-based materials. Perhaps most importantly, the fish tastes great and is very nutritious.

Learn more about our various research projects.

Business Insider Interview: Next Generation Research at Kampachi Farms

Recently, a member of our accomplished research team, Julien Stevens, was interviewed by Seafood Source - a leading online publication for global seafood industry news.

If you're a Seafood Source member, you can find the Business Insider article here.

You can also check out a pdf version of the article.