Raising squid can be challenging. Fortunately, a team of researchers from the Okinawa Institute of Science and Technology Graduate University in Japan has found a way to reduce mortality rates of squid in farms.
Squid is a popular seafood enjoyed around the world for its taste and versatility in cooking. It can be grilled, seared, boiled, braised, and even eaten raw. Furthermore, it is nutritious, as it is a great source of protein and other essential nutrients, such as zinc, vitamin B12, and phosphorus. Also, it is low in calories and fat, making it a healthy option for many diets.
Most of the world’s squid supply comes from wild fisheries. Unfortunately, overfishing and climate change have caused wild squid populations to decline significantly. In Japan alone, the wild squid population has collapsed by 90% since the 1980s. So, to prevent further decline and ensure the sustainability of squid populations, people have been trying to raise squid in aquaculture.
However, raising squid in aquaculture presents several challenges. For example, squid are highly sensitive to changes in water flow and are vulnerable to diseases. As a result, high mortality rates and low egg-hatching rates are commonly observed in squid aquaculture.
Recently, a team of researchers from the Okinawa Institute of Science and Technology Graduate University in Japan has discovered a new threat in squid aquaculture—Ikanecator primus gen. et sp. nov. This newly identified parasitic copepod infects squid eggs. It secretes enzymes that degrade the eggs’ protective gelatinous layer, resulting in the premature hatching or death of the squid. Fortunately, the researchers have found an eco-friendly solution to the parasite—peracetic acid (PAA).
According to the researchers, PAA is widely known for its antifungal, antibacterial, antiviral, and antiparasitic properties, which is why it is commonly used in various industries for disinfection and sterilization purposes. It is also eco-friendly, as it breaks down into harmless by-products, such as water, acetate, and carbon dioxide. So, the researchers experimented with various concentrations of a PAA-based solution to determine whether the chemical could eliminate I. primus without harming squid eggs. This solution contained 14% PAA, 6% hydrogen peroxide (H2O2), 40%–50% acetic acid, 30%–40% water, and less than 1% 1-hydroxyethlidene-1,1-diphosphonic acid.
Based on the results of their experiments, the researchers identified a concentration of 500 μl/L of the PAA-based solution (70 mg/L PAA and 30 mg/L H₂O₂) as the most effective in eliminating I. primus without harming squid eggs. It can exterminate all the parasites from infected egg clutches within only two minutes. Also, it can improve the survival of squid embryos and increase the size of hatchlings.
“These findings suggest that PAA holds a great potential as inhibitor and controller of parasitic copepod infections and for overall health management in cephalopod culture,” said the researchers.
Hopefully, the discovery can help advance squid aquaculture so the global demand for squid can be met without compromising wild squid populations.