Octopus aquaculture

) The aquaculture potential of several octopuses species has been investigated in recent years, including Octopus maya (red octopus), Octopus bimaculoides (California two-spot octopus), Octopus ocellatus (now renamed Amphioctopus fangsiao), Octopus mimus (changos octopus), Enteroctopus megalocyathus (Patagonian red octopus) and Robsonella fontaniana. The common octopus, Octopus vulgaris, appears to be the most serious candidate for aquaculture in terms of its biological and market potential. The common octopus is easily adapted to captive conditions and has a rapid growth rate of 5% body weight per day. It also has a high feed conversion rate with 30–60% of ingested food being incorporated in its own weight, and a high fecundity of 100,000–500,000 eggs per female. == Temperature ==

There is an optimum temperature at which a cold-blooded species does best in terms of growth, survival and food intake. The common octopus is sensitive to temperature, with an optimum range for commercial growth of 16–21 °C. Above its optimal thermal range, growth and food intake decrease, and above 23 °C loss in weight and increased mortality has been recorded. A narrow thermal band can mean seasonality in growth due to seasonal variations in water temperatures. The incorporation of temperature control mechanisms, such as in the use of closed or onshore farming systems, can reduce seasonal variances in production. == Nutrition ==

Crustaceans, such as crabs and lobster are an important dietary constituent of both natural and captive populations of octopus. Fish are not as important. Fish-based diets have been shown to provide both lower growth rates and food conversion to growth ratios in captive octopus. This may be because of high lipid levels in fish flesh. Crustacean diets are favored possibly as a result of their high protein relative to lipid levels. Whether octopus farming is profitable depends in large part on how much it costs to maintain a steady supply of crustaceans. Economic profitability can be maximized without significantly compromising biological productivity by incorporating a mix of fish and crustacean-based feed strategies. García García and Cerezo Velverde (2006) found a feeding regime of one day of crab followed by three days of fish can reduce the cost of producing one kg of octopus by a predicted value of €2.96. == Juveniles ==

Commercial aquaculture so far has been confined to starting with young juveniles caught in the wild, weighing about 750 g. In Spain, these juveniles are purchased from local fishermen and transferred to offshore floating sea cages. There they are fattened with bycatch (fish, molluscs and crabs) for several months until a commercial size, about 3 kilograms, is reached. However, acquiring juveniles in this way, from the wild, further increases the fishing pressure on octopus stocks that are already managed badly, possibly producing cascades in marine ecosystems. A cost analysis of this practice found that over 40% of total costs went into acquiring the juveniles. The profitability of this approach is low, depending as it does on fishing and the supply of sub-adults, a costly and highly variable process. == Paralarva ==

The bottleneck currently hindering the commercial development of octopus aquaculture is the difficulty of rearing octopus during their early paralarva stage. Results vary when octopus paralarvae are fed different combinations of prey. The best results have been with a mix of brine shrimp and other living prey, such as crab zoeae. To achieve both profitable and environmentally sustainable results, much research has been focused on paralarval rearing. In 2005, scientists from the principal research groups in the field concluded the key factor affecting paralarval mortality is nutrition, making nutritional research the highest priority. There is "no reason not to believe that the aquacultural rearing of octopus will be of great economic potential" as soon as the rearing technology and nutritional issues have been addressed. Research in these areas is promising. ==Ethical complications==

There is growing opposition to farming octopuses due to ethical and environmental concerns. Octopuses are recognized as intelligent, sentient, and naturally solitary animals. Critics argue that confining these creatures in cramped tanks would cause immense distress, potentially leading to aggression and cannibalism. Additionally, as carnivores, farmed octopuses would require fish as feed, putting further pressure on already strained marine ecosystems. Environmental concerns include potential pollution, threats to local wildlife, and high energy and water consumption. In response to these issues, in 2024, Washington and California banned octopus farming. Subsequently, a bipartisan bill was introduced in Congress to ban octopus farming nationwide and prohibit imports of farmed octopus. This legislative action reflects a growing global movement against the practice, with numerous NGOs, experts, and members of the public voicing opposition to proposed octopus farming projects. In the UK, animal charity the RSPCA and think tank The Food Policy Institute are opposed to octopus farming and asking that British MPs pay close attention to any potential commercial developments. == References ==