Early weaning of cuttlefish (Sepia officinalis, L.) with frozen grass shrimp (Palaemonetes varians) from the first day after hatching

Abstract

AbstractThe suitability of early weaning cuttlefish usingfrozen grass shrimp, and its effects on growth andmortality was determined in a 50-day experiment.Three food groups were used. One group (C) wasfed with live prey until 25th DAH and weanedwith frozen prey until the end of the experiment.In the other two groups, weaning started at thefifth DAH (W5) and first DAH (W1), also withfrozen diet. Significant differences were foundbetween C and the remaining treatments (P <0.05) for mean wet weight (MWW), instantaneousgrowth rate (IGR), biomass (B) and mortality atthe 25th and the 50th DAH. Despite the lowergrowth (~1/3 of the achieved with live food) andhigher mortality (3% obtained by C versus 23% inthe W1 and W5 groups), C cuttlefish presented asimilar weight gain tendency to W1 and W5groups after weaning. This is the first record ofearly acceptance (at the first DAH) of frozen foodby cuttlefish hatchlings. These differences could berelated with digestive enzymes of cuttlefish andprey, changes in nutritional composition andamount of captured prey, etc. Future researchshould also address the effects of this early wean-ing on cuttlefish life cycle.Keywords: cuttlefish, Sepia officinalis, grassshrimp, Palaemonetes varians, early weaning, fro-zen foodIntroductionThe European cuttlefish (Sepia officinalis) is one ofthe most well-known cephalopods (Boletzky1983). During the last years, research on cuttle-fish has focused on its introduction as a new spe-cies for aquaculture. This is due to the biologicaland economical characteristics that this speciesdisplay, which have the potential for industrialculture. The most important are the short lifecycles and the fast growth rates which implylower production periods and associated costs. Onthe other hand, the inability to grow cephalopodson an inexpensive and storable prepared diet hasbeen identified as a bottleneck (Sykes, Domingues,Correia & Andrade 2006).Like in most finfish species, the first stage cul-ture of this species is known as the most problem-atic. This is due to the dependence on live feeds(Domingues, Sykes & Andrade 2001; Domingues,Bettencourt & Guerra 2006; Sykes, Domingues A Castro 1991; Lee, Forsy-the, DiMarco, DeRusha & Hanlon 1991; Castro,DiMarco, DeRusha & Lee 1993) demonstrated poorresults in growth, survival and promoted cannibal-ism [e.g. 67.5% and 22.5% survival rates for pel-lets and surimi respectively (Castro et al. 1993)].Domingues, Dimarco, Andrade and Lee (2005) con-firmed the possibility of rearing cuttlefish with pre-pared foods. Nevertheless, these authors reportedextremely low growth rates when compared with