Introduction
The development of artificial diets for rearing Atlantic bluefin tuna (ABT) is crucial for several reasons. Overall, it will support sustainability, economic viability, and reduced environmental impact in tuna aquaculture. This trial aimed to establish a benchmark of artificial ABT feeding with readily available commercial diets on the European market, for future studies and diet improvement, focusing on artificial weaning and feeding of ABT.
Material & Methods
Over 12 weeks, an ABT feeding trial was conducted at the Instituto Oceanográfico de Murcia (IEO). Two Skretting artificial feeds, Gemma Silk (GS) and Magro, were assessed across three ABT rearing stages: Weaning, pre-ongrowing phases 1 and 2. Weaning occurred between 23-41 days post hatch (dph) when ABT larvae were introduced to GS at 23 dph, taking 9 days for full weaning from sea bream (Sparus Aurata L.) yolk sac larvae. In pre-ongrowing phase 1 (41-84 dph), a 50:50 GS and Magro diet was supplied, followed by exclusive Magro feeding in pre-ongrowing phase 2 (84-106 dph).
Results & Discussion
The application of Skretting commercial start feeding diets, resulted in expected survival rates during weaning, ranging from 26% to 37% across replicas, in the range of previous weaning experiments. Pre-ongrowing phase 1 had the highest specific growth rate with 8.1 versus 3.8 in pre-ongrowing phase 2. However, phase 2 had the highest gains in wet weight and length, alongside with lower feed conversion ratio (FCR).
It is important to highlight that the exclusive utilization of Magro led to decreased FCR rates, suggesting its capability to improve subsequent on-growing phases for ABT, as a logical progression, the next step of this trial involves the continuation of the artificial feeding regimen beyond the 200 g weight threshold. Another aspect worth contemplating for future trials involves exploring the potential to decrease or eliminate the use of YSL in the early stages of ABT larvae.