Octopus aquaculture describes the captive-raising of octopuses and commercial sale of their meat. A complex and labor-intensive form of farming, octopus aquaculture is being driven by strong market demand in the Mediterranean and in South American and Asian countries. [1] Annual global demand for octopus more than doubled from 1980 to 2019, from roughly 180,000 to about 370,000 tons. [2] The supply of octopus has been constrained by overfishing in many key fisheries [3] and proponents of farming suggest human-induced culturing could help restock natural populations. [4] Opponents of the nascent industry argue that cephalopod intelligence and emotional capacity, as well as the solitary and carnivorous character of octopuses, make them particularly ill-suited to intensive, captive breeding. Commercial sale may stimulate market demand, hastening rather than offsetting the decline in wild stocks. [5] An announcement that a Spanish firm would begin octopus aquaculture as early as 2022 prompted ethical and scientific controversy.
Octopuses live short lives, grow quickly and mature early [6] and they typically reach 2 to 3 kg, high weights for an invertebrate. Octopuses are 75 to 90% muscle at their total live weight, [7] basically a pure protein food with very little fat. In nature there is little overlap between successive generations, [8] which makes them sensitive to changing environmental conditions. [9] It is currently difficult to culture the early life stages of octopus and maintain high survival rates for their paralarvae, [10] mainly because of high mortality rates by poor zoo-technical conditions or equipment, and also because of conspecific cannibalism. [11] A requirement for live and high-quality food is another constraint: crab zoea [12] or rotifer are necessary, since Artemia, microalgae, or pellets is insufficient. These difficulties have limited the development of fully closed life cycle octopus hatchery systems. In 2021, Nueva Pescanova Group located in Spain, announced that they had achieved many generations of Octopus vulgaris by culture; [13] the conditions octopuses are to be kept in, type of food, and killing techniques were not disclosed. [5]
The aquaculture potential of several octopuses species has been investigated in recent years, including Octopus maya (red octopus), [15] Octopus bimaculoides (California two-spot octopus), [16] Octopus ocellatus (now re-named Amphioctopus fangsiao ) [17] , Octopus mimus (changos octopus), [18] Enteroctopus megalocyathus (Patagonian red octopus) [19] and Robsonella fontaniana. [20]
The common octopus, Octopus vulgaris, appears to be the most serious candidate for aquaculture in terms of its biological and market potential. [21] It has a worldwide distribution in tropical, subtropical and temperate waters. It is a benthic species occurring from the coastal line to the outer edge of the continental shelf, at depths to 200 m and in very diverse marine habitats. [22] The common octopus is easily adapted to captive conditions and has a rapid growth rate of 5% body weight per day. [21] It also has a high feed conversion rate with 30–60% of ingested food being incorporated in its own weight, [23] [24] and a high fecundity of 100,000–500,000 eggs per female. [23]
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. [24] Above its optimal thermal range, growth and food intake decrease, and above 23 °C loss in weight and increased mortality has been recorded. [24] 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. [24]
Crustaceans, such as crabs and lobster are an important dietary constituent of both natural and captive populations of octopus. [25] 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. [24] Cephalopods, such as octopus and squids, show low lipid digestibility as a result of low lipid requirements. Consequently, a large component of the fish feed will not be taken up. [26] Crustacean diets are favored possibly as a result of their high protein relative to lipid levels. [24]
Whether octopus farming is profitable depends in large part on how much it costs to maintain a steady supply of crustaceans. [25] 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. [25]
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. [27]
The bottleneck currently hindering the commercial development of octopus aquaculture is the difficulty of rearing octopus during their early paralarva stage. [28] [29] Paralarva is the name given to the larva of cephalopods. [10] Paralarvae are small, less than 3 millimetres at hatching, with a long planktonic life stage. Current rearing techniques are inadequate, resulting in very high mortality rates. [30] 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. [1] [28] However the survival and settlement rates of the paralarvae is typically low in such studies, highlighting the difficulties in raising octopus paralarvae. Maintaining high survival rates for paralarvae appears to be the main factor limiting the development of a fully closed life cycle octopus hatchery system. [31]
To achieve both profitable and environmentally sustainable results, much research has been focused on paralarval rearing. [29] 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. [31] 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. [27] Research in these areas is promising. [27]
Many people believe that it is unethical to be farming octopuses, with the main reasons being that octopuses and other cephalopods are shown to be intelligent animals and that they are solitary.
Mariculture or marine farming is a specialized branch of aquaculture involving the cultivation of marine organisms for food and other animal products, in enclosed sections of the open ocean, fish farms built on littoral waters, or in artificial tanks, ponds or raceways which are filled with seawater. An example of the latter is the farming of marine fish, including finfish and shellfish like prawns, or oysters and seaweed in saltwater ponds. Non-food products produced by mariculture include: fish meal, nutrient agar, jewellery, and cosmetics.
An octopus is a soft-bodied, eight-limbed mollusc of the order Octopoda. The order consists of some 300 species and is grouped within the class Cephalopoda with squids, cuttlefish, and nautiloids. Like other cephalopods, an octopus is bilaterally symmetric with two eyes and a beaked mouth at the center point of the eight limbs. The soft body can radically alter its shape, enabling octopuses to squeeze through small gaps. They trail their eight appendages behind them as they swim. The siphon is used both for respiration and for locomotion, by expelling a jet of water. Octopuses have a complex nervous system and excellent sight, and are among the most intelligent and behaviourally diverse of all invertebrates.
Shellfish is a colloquial and fisheries term for exoskeleton-bearing aquatic invertebrates used as food, including various species of molluscs, crustaceans, and echinoderms. Although most kinds of shellfish are harvested from saltwater environments, some are found in freshwater. In addition, a few species of land crabs are eaten, for example Cardisoma guanhumi in the Caribbean. Shellfish are among the most common food allergens.
Mysida is an order of small, shrimp-like crustaceans in the malacostracan superorder Peracarida. Their common name opossum shrimps stems from the presence of a brood pouch or "marsupium" in females. The fact that the larvae are reared in this pouch and are not free-swimming characterises the order. The mysid's head bears a pair of stalked eyes and two pairs of antennae. The thorax consists of eight segments each bearing branching limbs, the whole concealed beneath a protective carapace and the abdomen has six segments and usually further small limbs.
A freshwater prawn farm is an aquaculture business designed to raise and produce freshwater prawns or shrimp for human consumption. Freshwater prawn farming shares many characteristics with, and many of the same problems as, marine shrimp farming. Unique problems are introduced by the developmental life cycle of the main species.
Broodstock, or broodfish, are a group of mature individuals used in aquaculture for breeding purposes. Broodstock can be a population of animals maintained in captivity as a source of replacement for, or enhancement of, seed and fry numbers. These are generally kept in ponds or tanks in which environmental conditions such as photoperiod, temperature and pH are controlled. Such populations often undergo conditioning to ensure maximum fry output. Broodstock can also be sourced from wild populations where they are harvested and held in maturation tanks before their seed is collected for grow-out to market size or the juveniles returned to the sea to supplement natural populations. This method, however, is subject to environmental conditions and can be unreliable seasonally, or annually. Broodstock management can improve seed quality and number through enhanced gonadal development and fecundity.
Cephalopod intelligence is a measure of the cognitive ability of the cephalopod class of molluscs.
A fish hatchery is a place for artificial breeding, hatching, and rearing through the early life stages of animals—finfish and shellfish in particular. Hatcheries produce larval and juvenile fish, shellfish, and crustaceans, primarily to support the aquaculture industry where they are transferred to on-growing systems, such as fish farms, to reach harvest size. Some species that are commonly raised in hatcheries include Pacific oysters, shrimp, Indian prawns, salmon, tilapia and scallops.
The giant Pacific octopus, also known as the North Pacific giant octopus, is a large marine cephalopod belonging to the genus Enteroctopus. Its spatial distribution includes the coastal North Pacific, along Mexico, The United States, Canada, Russia, Eastern China, Japan, and the Korean Peninsula. It can be found from the intertidal zone down to 2,000 m (6,600 ft), and is best adapted to cold, oxygen-rich water. It is the largest octopus species, based on a scientific record of a 71-kilogram (157-pound) individual weighed live.
The common octopus is a mollusc belonging to the class Cephalopoda. Octopus vulgaris is one of the most studied of all octopus species, and also one of the most intelligent. It ranges from the eastern Atlantic, extends from the Mediterranean Sea and the southern coast of England, to the southern coast of South Africa. It also occurs off the Azores, Canary Islands, and Cape Verde Islands. The species is also common in the Western Atlantic.
Enteroctopus megalocyathus, also known as Patagonian red octopus (EN), Pulpo del sur (Chile) and Pulpo colorado (Argentina); is a medium-sized octopus, and the type species for the genus Enteroctopus.
Enteroctopus magnificus, also known as the southern giant octopus, is a large octopus in the genus Enteroctopus. It is native to the waters off Namibia and South Africa.
Sepioteuthis lessoniana, commonly known as the bigfin reef squid, glitter squid or oval squid, is a species of loliginid squid. It is one of the three currently recognized species belonging to the genus Sepioteuthis. Studies in 1993, however, have indicated that bigfin reef squids may comprise a cryptic species complex. The species is likely to include several very similar and closely related species.
Cobia, a warm water fish, is one of the more suitable candidates for offshore aquaculture. Cobia are large pelagic fish, up to 2 metres (6.6 ft) long and 68 kilograms (150 lb) in weight. They are solitary fish except when spawning, found in warm-temperate to tropical waters.
Octopus tetricus, the gloomy octopus or the common Sydney octopus, is a species of octopus from the subtropical waters of eastern Australia and New Zealand. O.tetricus belongs to the Octopus vulgaris species group and is a commercially prized species. All species within the O. vulgaris group are similar in morphology. The English translation of O. tetricus (Latin) is 'the gloomy octopus'.
Pinnoctopus cordiformis is a species of octopus found around the coasts of New Zealand. It is one of the most common species of octopus in the country.
Octopus maya, known colloquially as the Mexican four-eyed octopus, is a shallow water octopus that can be found in the tropical Western Atlantic Ocean. It is common to sea grass prairies and coral formations. The species was initially discovered in an octopus fishery in Campeche Mexico, where its close external resemblance to Octopus vulgaris led to its mistaken grouping with the other species. O. maya makes up 80% of octopus catch in the Yucatán Peninsula, while O. vulgaris makes up the remaining 20%.
Octopus insularis is a species of octopus described in 2008 from individuals found off the coast of Brazil, with a potentially much larger range.
Octopus sinensis is a mollusk belonging to the class Cephalopoda. Octopus sinensis is a well-known shallow-water benthic octopus species found in the coastal, temperature waters of South Korea, China, and Japan, with the species name, sinensis being Latin for Chinese. Octopus sinensis is closely related to the Atlantic and Mediterranean common octopus, Octopus vulgaris. Because of the morphological similarities, O. sinensis was considered synonymous with Octopus vulgaris until 2017. Octopus sinensis are carnivores that prey upon on many shallow-water animals such as crustaceans and mollusks.