Copepods can disrupt marine fish farming
In a new research project, a fish farmer’s everyday issues come face to face with the latest research into copepods. The project, which is supported by the European Maritime and Fisheries Fund (EMFF) and others, aims to study how the laboratory results from Roskilde University can be translated into a stable, industrial outdoor production of copepod larvae year-round. This is an innovation that will ensure access to cheap feed with an optimal biochemical profile for the survival and growth of fish larvae. This is because copepods may be what can ensure a greater survival rate among young fishes, healthier adult fishes and a generally higher quality of fish from fish farms.
“Today, there is a huge global market for live feed. If this market can be disrupted by copepods, there will be a huge potential - not just financially in terms of selling copepods as live feed for fish larvae, but also in terms of farming high-quality fish and at the same time ensuring a greater diversity in the species that are being farmed,” says Benni Winding Hansen.
Since the mid-1980s, he has been researching the ecology, biology and physiology of copepods. Over the last 15 years, this research has been supplemented with application-oriented projects that optimise the industrial production of live feed.
Copepods are nature’s choice
Copepods are the most numerous multi-cellular organisms in the world, and they have a very core position in all water-based ecosystems. Except for the salmonids, all fish larvae depend on live feed, and it is precisely copepod larvae that are the primary food source in nature for fish at the larvae stage.
Copepods get their nutrition from micro-algae that contain a high content of omega-3 and omega-6 fatty acids. The copepods’ fatty acid profile is of critical importance to fish larvae, as they need just the right amount of fatty acid balance in order to develop things such as their nervous system, sensory system and pigmentation optimally.
“It always makes sense to learn from evolution, and copepods are nature’s choice. So it is natural to mass produce copepods and replace the types of live feed that are used today,” says Benni Winding Hansen.
Today, copepods play an almost inconsequential role in the ocean fish farming industry. The industry typically uses live feed based on rotifers and brine shrimp, which both belong naturally in fresh water. They are easy to use in fish farming, but they have low contents of omega-3 and omega-6 fatty acids, and this has negative consequences on the survival and development of the fish larvae, and in the end, also on the production costs.
Facts on marine fish farming
> On a global level, the vast majority of fish farming is in fresh water: Only 15% of the total production is from marine fish farming - i.e., the farming of fish species native to the oceans.
> In Denmark, the vast majority of fish farming is in fresh water too. This is mainly rainbow trout from conventional uses of dams: Danish fish farmers have a century-long tradition of focusing on precisely rainbow trout as they are cheap and relatively simple to produce.
> Despite the fact that fish farming with ocean species remains a modest part of the Danish production, it is an industry that is growing at significant rates. The prices for ocean fish are attractive and the demand far exceeds what is produced.
> The proportion of marine fish that are fish farmed exceeded 50% in 2016 on a global level according to the UN’s Food and Agriculture Organization.
> Using copepods as live feed for young fish makes it possible to farm new types of fish species in salt water - and this may reduce the stresses being put on wild fish stocks such as tuna.