Assessment of culture density and prey availability for the management of cannibalism in paralarvae of Patagonian red octopus Enteroctopus megalocyathus

Abstract

The Patagonian red octopus Enteroctopus megalocyathus (Gould, 1852) is a merobenthic cephalopod that inhabits the coasts of Chile from the Los Lagos region (41°lat. S) to the Strait of Magellan (56º lat. S) in the South Eastern Pacific (Ibáñez et al., 2009); it can also be found in the coasts of Argentina from the Gulf of San Matías (41ºlat. S), to the Strait of Magellan (56º lat.S) in the South Atlantic (Ré, 1998). It is one of the two octopus species of commercial importance in Chile, being exploited by artisanal fishing. Recently, the life cycle of E. megalocyathus under captivity has been completed, and its culture was possible until commercial size (Farías et al., 2016;. The culture of this species shown its high growth rate, reaching commercial size in 2.5 years after hatching with a weight of 2.5 to 3 kg (Uriarte et al., 2019). The paralarval stage lasts between 90 to 114 days , after an embryonic development of 135 to 172 days, depending on the temperature

Performance Parameters of Paralarvae and Postparalarvae Rearing of Patagonian Red Octopus, Enteroctopus megalocyathus, under Experimental Conditions

“…According to the characterization of Dan et al [40], the AL/ML ratio < 1.0 is typical of planktonic life, while AL/ML > 1.0 indicates the transition to benthic life. On the other hand, the paralarvae produced between 2012 and 2016 had less arm-length development than the paralarvae of the 2017-2021 period, which could be associated with both genetic variability and the progressive standardization of the E. megalocyathus paralarvae culture [11,12,22].…”

“…juvenile crabs. A density of five paralarvae L −1 , and 10 prey paralarva −1 day −1 was used, according to [11]. The experiment ended at 15 DAH and growth rate, survival and whole-body fatty acid composition were evaluated.…”

“…The studies based in controlled culture under optimized conditions have led to discover important characteristics of its life cycle including (1) moderate fecundity between 1,000 and 5,000 eggs per female [2]; however, in suboptimal food availability conditions for female breeders (75% of the daily ration), it was observed that the biochemical composition of the clutches was maintained but fecundity decreased to 4.1% in relation to females fed 100% of the daily ration [5]; (2) embryonic development takes between 150 and 176 days depending on the rearing temperature within the range of 10-16°C [6,7]; (3) the complete paralarvae development takes about 90 days, growing from 10 mm at hatching to 30 mm at settlement [2]; however, it has been documented that Octopus vulgaris paralarvae can increase their weight by 2.9% at the end of the paralarval period if the Artemia diet is replaced by a zooplankton diet [8]. Research on the E. megamegalocyathus paralarvae rearing has mainly concentrated on the first 6 weeks after hatching due to the high mortality observed afterward, mainly attributed to poor nutrition with Artemia [9,10], and stressful culture conditions [11,12]. The management of prey to feed paralarvae has been highlighted as a critical point in octopus farming [8,10,13,14].…”

The effectiveness and impact of disinfection with chlorine on embryos and early hatchlings of two Western Pacific octopus species

“…On two occasions, A. fangsiao juveniles that hatched overnight and remained in the same system until the morning were observed to cannibalize unhatched late Naef stage embryos, resulting in their death shortly after. Cannibalism in the early hatchling stage, including sibling cannibalism, was previously described for paralarvae from Robsonella fontaniana (Miranda et al, 2011) and E. megalocyathus (Espinoza et al, 2019(Espinoza et al, , 2021 and was primarily attributed to overcrowding and food availability. While this behavior does not explain the early decline in embryonic survival and the severity on later Naef stage embryos cannot entirely be assessed, this behavior should be considered in artificial rearing unit designs, i.e., having an overflowing system that removes newly hatched juveniles from unhatched embryos.…”