Nr. 1 / 2011
As well as optimal health and robustness attributes, growth is one of the most important criteria for selection of broodstock in Aqua Gen’s breeding program. Broodstock that have been selected to produce eggs for delivery in the forthcoming season 2011/2012 have demonstrated excellent growth performance. By the use of both traditional and QTL-based selection, we will achieve a more precise and predictable transfer of growth and health characteristics of these broodstock parents to their offspring (eggs).
Operational optimization of sea sites
Aqua Gen has recently invested heavily in the upgrading of our sea sites in regard to equipment and operational expertise. Just as importantly, we have focused on optimization of the conditions for good health status through close monitoring from the first day that stock are transferred to sea. This has provided better biological conditions for optimal operation and data collection as the basis for evaluation and selection of broodstock and breeding candidates.
At Aqua Gen we are now stocking our smolts into 90 meter cages. We then carry out the initial size and quality grading at an average weight of approximately 1. 5 kg. The largest individuals are selected as broodstock candidates, the remainder of the fish are grown on for harvesting. After grading each of the groups are transferred into 120 meter cages.
|Fish groups from the elite populations||Time of weight registration||Robust(round weight)||Effective(round weight)|
|Smolt||25th May 2009||62g||65g|
|Small grade||29th January 2010||1,80 kg||1,91 kg|
|Small grade(slaughtered)||29th July 2010||4,77 kg||5,46 kg|
|Broodstock, candidates. 2011/2012||29th July 2010||5,74 kg||5,87 kg|
Table 1. Weight records for the harvest fish (small grade) and broodstock from the elite populations at Aqua Gen Tingvoll. The broodstock are going to produce eggs for our customers in 2011/2012. The elite populations consist of two main groups of salmon that are divided by different weighting of specific traits:
(1) Robust (health-related characteristics such as resistance to diseases, reduced deformities, reduced early sexual maturation) and (2) Effective (production-related characteristics such as growth, fillet color, fat content, harvest yield, body shape).
The feeding regime that is used for the small grade which does not qualify as ”broodstock candidates” is the same as that used for industry standard production fish and thus it is relevant for our breeding programme to collect data from these fish.
Achievements at Aqua Gen Tingvoll
The seawater phase for the upcoming season broodstock at our Tingvoll site commenced on the 25th May 2009 (Table 1). To comply with the requirements of ISA-free zone status, we transported the smolts in by road from Kyrksæterøra. The fish were sorted first time in the sea on 29th January 2010. Overall mortality recorded until harvest was 6.72 %. The main causes were related to transport and handling damage when sorting. Average density during the production phase was 14.5 kg / cubic meter. This site is located deep in the Sundalsfjorden and is exposed to fresh water. As a result it has a history of very low lice levels in the fjord system, in total in the sea phase, only one de-lousing was required (May 2010).
Very good growth performance
To attain a slaughter weight of 5.1 kg (round weight) in July from 1SW spring smolt is perhaps not surprising. But if you consider that the smolt were small when transferred from the hatchery and sorted again into a second small grade prior to slaughter after around 8 months more, the result is very satisfactory.
The average weight for the broodstock candidates had a ”slaughter weight” of 5.5 kg (round weight) after approximately 13 months production in the sea. Feed conversion ratio was 1.04 (biological) and 1.07 (economical). The weight of the brood stock candidates and their QTL status were assessed and recorded at the last broodstock selection when they were about 12 kg. From the growth curve we see the usefulness of sorting fish at an average weight of 1.5-2 kg (Figure 1). Growth of sorted Robust broodstock candidates following sorting after the removal of the small grade in August 2010 increased, and followed very closely that of the Effective group, which was only split in the sea. We usually expect to see a larger weight difference between Effective and Robust, in favor of Effective after the last broodstock sorting.