The Big Picture

Could recent developments in aquaculture lead the way to sustainable fisheries?

Capt. Steve Dougherty October 1, 2012

With populations of game fish collapsing worldwide and the demand for fresh seafood showing no signs of diminishing, major change is needed or the world’s oceans will soon be devoid of life.

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With incredible growth rates, dolphin are ideal candidates for aquaculture. Photo: doughertyphotos.com

The ocean’s ecosystems are incredibly complex and healthy populations of all members of the food chain are essential to a balanced web of life. Remove one and the entire chain could collapse. This is why fisheries protection and management are a lot more complex than we think. While it would be nice to harvest unlimited numbers of grouper and snapper year round, we really need to look at the big picture concerning these and all other highly sought after species.

Unfortunately, even the best state and federal management practices can’t completely rebuild drastically diminished fish stocks. Recreational fishermen are relied upon to be stewards of the sea, even though it’s not hook and line weekend warriors that are truly at fault for endangering entire populations of fish. Rather, it’s indiscriminate commercial fishing practices that support the world’s insatiable appetite for fresh seafood that are truly to blame. Additionally, those who enjoy consuming fresh fish are a bigger part of the problem than enthusiastic anglers looking to bend a rod. And with the earth’s population growing exponentially, the next 50 years will test the sea’s inhabitants to levels never before imagined, with pollution and over-fishing the most dangerous elements.

One way to eliminate some of the pressure is with aquaculture or aqua farming, which is the successful cultivation of desirable aquatic organisms in an effort to supply world populations with fresh, consumer-safe seafood. In addition to providing nutrition, aquaculture supports families worldwide as technologies and practices continue to develop. Currently, aquaculture yields over 50 percent of the world’s seafood consumption, with the Food and Agriculture Organization’s 2012 report on World Fisheries revealing an amazing production of 128 million tons of fish for human consumption.

However, aquaculture has received a host of negative press thanks to poor governance, questionable management practices, and feed conflicts just to name a few. Thankfully, a team of scientists, students, research assistants and interns at the University of Miami’s Rosenstiel School of Marine and Atmospheric Science are paving the way as they continue to experiment with environmentally friendly and economically viable aquaculture procedures at their experimental hatchery.

Historically, the problem with fish farming hasn’t been the ability to spawn or raise fish through larval stages, rather what to feed them and how to deal with their waste. In aquaculture, the efficiency of an animal converting feed mass into body mass is referred to as the food conversion ratio. While the food conversion ratio depends on the species being farmed, current data shows that the average global food conversion ratio for all aquaculture is approximately 1.5.

Using fishmeal and fish oil for aquaculture is the most natural and efficient use of these commodities and science has shown that the reduction fishing industry, if well managed, can continue to support the growth of the global aquaculture industry. Essentially, the amount of small pelagics harvested from the sea for reduction into fishmeal and fish oil remains relatively unchanged year-to-year. The growth of aquaculture will simply result in a greater share of the FM/FO going towards aquaculture and not being used for terrestrial animals such as swine and poultry.

With a goal of reshaping commercial harvesting and fisheries management without harming the natural ecosystem, the team at UM is utilizing emerging technologies and research to successfully introduce hatchery reared game fish to offshore aquaculture farms around the globe. Their state of the art facility on Virginia Key features maturation and larval rearing tanks with specialized filter systems, egg collection devices, chillers and UV sterilization systems.

It all started with cobia, which are one of the most ideal candidates for aquaculture. With quality meat and a high growth rate, cobia have been effectively spawned in captivity and reared from fingerlings to adults. The team at UM is also working with pompano and blackfin tuna, although their latest endeavor is the most exciting.

Highly recognized by their brilliant coloration, dolphin have extremely high growth rates, spawn naturally year round, produce incredible table fare and are perhaps the greatest candidate for large scale fish farming. Like with all captive species, the research must examine maturation, spawning and grow out, while also considering nutrition, disease prevention and physiology.

The dream started in September 2011 when research assistants Ron Hoenig and John Stieglitz—two avid anglers—caught and transferred a bull dolphin and several cows to the facility at UM. Led by Dr. Daniel Benetti, the team has been able to successfully rear larval dolphin from the broodstock, with females spawning in captivity nearly every other day, year round. The fertilized eggs are captured and transferred to separate tanks, while at the same time the team also cultivates plankton and brine shrimp for sustainable feed for the larval fish. As the game fish grow in captivity they are transitioned from a live plankton diet to a pelletized diet, partially comprised of fishmeal and oil, while mature broodstock fish receive a diet of sardines and squid. As research continues, new techniques will be revealed for increasing feeding efficiency through the development of sustainable diets which are tailored to specific species and life stages, thereby allowing for reduced food conversion ratios and more efficient use of animal and plant protein sources.

As the fingerlings and broodstock grow day by day, researchers continue to study their energy use in an effort to develop sustainable feed that’s also economically feasible. One of the major problems associated with dolphin aquaculture is that they have strict water quality requirements that are hard to match in captivity. Fortunately, the UM experimental hatchery gets some of their water directly from the source. Situated on the shore of Virginia Key, the tanks are supplied fresh ocean water from nearby Bear Cut. On a large-scale model, offshore cage technology continues to develop and provides ideal oceanic conditions for the aquaculture of countless dolphin.

University of Miami is leading the way in aquaculture research and development as they respond to the growing demand of seafood without degrading the environment. Involving science and technology, sustainable seafood practices are viable options and are already shaping the future.

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