Shrimp Culture Guayas & Santa Helena
Manabi
El Oro
Esmeralda
60,000
Total area (ha)
50,000
40,000
30,000
20,000
10,000
>2 ,0 00
50 01, 00 0 1, 00 02, 00 0
25 050 0
10 025 0
50 -1 00
40 -5 0
30 -4 0
20 -3 0
10 -2 0
010
0
Size of farms (ha)
Figure 2. Distribution of shrimp farm per unit size in the Ecuadorian provinces.
Post larvae supply Before 1999, there was a debate on whether to use wild post larvae or those from the hatcheries. Almost all hatcheries stocked wild caught broodstock in their maturation tanks and even ready to spawn females which fishermen delivered daily to the hatcheries. Most farmers preferred wild post larvae, because it was much easier to negotiate prices with fishermen rather than with hatchery biologists. Farmers, when buying post larvae in a hatchery, were always very concerned with post larvae quality and they used to record carefully the post larvae quality and the results of the stress test. Attention has always been on post larvae acclimatisation to pond water quality and not only on salinity or temperature. For that, farms were equipped with fixed or mobile acclimatisation stations. Acclimatisation is to gradually change the water used for transport with the water of the destination pond. This can last for up to 48 hours depending on the water quality of the rearing tank. During this period, domestication and genetic selection technologies were not available. Some companies tried to import specific pathogen free (SPF) broodstock from Hawaii, but it had always ended in failure with heavy mortality of the imported shrimp. So, the concept of SPF was not considered in the country and they selected families of broodstock from their own ponds.
Post TSV After the TSV outbreak some of the big farms began to look at shrimp culture differently. At the end of 1999 to 2000, crop failures caused by WSSV reached critical levels and the question of survival of the industry was widely discussed. As most of the available land to develop new shrimp farms were already taken up, it was almost impossible to open new ponds which normally are less susceptible to disease. To limit the impact on the drop in profits following the decreased production, most of the major
Feeding methods, from feed trays (left), using blowers (middle) to AQ1 feeders (right).
10
May/June 2018 AQUA Culture Asia Pacific Magazine
Figure 3. Illustration of the farm density in the delta of Guayas, (Photo credit: David Kawahigashi). farms reduced their costs by sharing fixed costs facilities such as hatcheries and processing plants. They started to improve technology by working at several levels of the production chain. A major and significant measure was to prohibit the importation of livestock and frozen food that could potentially be disease vectors and the use of wild broodstock and/or wild post larvae. For more efficient biosecurity, the production is most often divided into four phases as below but some smaller farms still continue with a single phase culture: • Hatchery: 15-18 days, nauplii to PL9 (≈ 500 PL/g) • Nursery: 15 days, PL9 to PL24 (≈ 15 PL/g) Pre-growing during 15 to 25 days up to 0.6 to 1 g. These are mostly intensive in covered raceways and semi-intensive in small earthen ponds • Grow-out in large earthen ponds during 90 to 120 days to reach harvest size 18 to 22 g. The main measures taken by the major companies to revive the growth of the Ecuadorian shrimp industry are summarised below.
Broodstock and family base selection Considering that most of the pathogens are present in the farm environment, Ecuadorian shrimp breeders began to select strains of shrimp with high survival in their environmentally-friendly managed shrimp farms, while respecting the biodiversity. The first criterion of selection was survival. The second was selection of fast growing breeders for faster growth and reproduction indicators in hatchery. Based on this concept, the breeding companies selected shrimp from ponds according to their survival performances after selection for external physical conditions and a strict health analysis. Two schemes were used to create the families: double cousins and some groups also used molecular marker technology