Carlos I. Pérez-Rostro

Reproductive exhaustion in shrimp (Penaeus vannamei) reflected in larval biochemical composition, survival and growth

Penaeus vannamei larval quality in terms of biochemical composition and survival was studied throughout a spawning period. Spawns from broodstock at three different times during a commercial production period were sampled (15, 45, and 75 days after ablation). Biochemical composition of eggs, nauplii, 15-day old postlarvae (PL15), and growth and survival during culture were determined. As the days after ablation increased, a reproductive exhaustion of spawners was reflected in the energy reserves of the eggs produced. Overall larval performance during culture and survival was considerably higher in recently ablated spawners (15 days) and decreased in spawners 45 and 75 days after ablation. At PL15, a test for larval resistance to a salinity stress was applied that showed a decreased PL condition related to reproductive exhaustion of spawners: survival to stress decreased from 89% in recently ablated to 68% in larvae produced 45 days after ablation, and to 39% in larvae produced to the end of the spawning period. Nauplii condition index (NCI), calculated from nauplii triacylglycerol (TG) levels, percentage of viable nauplii, and nauplii length declined in nauplii produced with spawners sampled 45 and 75 days after ablation. This study demonstrated that reproductive exhaustion of shrimp spawners occurs and it becomes largely evident as time after ablation increases: spawner exhaustion is reflected in the quality of the larvae produced.

Advances in Domestication and Culture Techniques for Crayfish Procambarus acanthophorus

The crayfish are a group of crustaceans that habit in different environments in the world, both in lotic systems as lentic, in addition to caverns, which makes them cosmopolitan organisms with a wide range of tolerance to environmental conditions. Over 600 crayfish species are known to exist in the worldwide, with at least 100 species in Australia and about 300 in the Americas (Holdich, 1993), mostly (85%) in North and Central America (Rojas, 1998). Species in Mexico include one in the Orconectes genus, 10 in the Cambarellus genus and 44 in the Procambarus genus, the latter also distributed in Belize, Honduras and the United States (Villalobos, 1948; Hobbs, 1984; Rojas, 1998; Lopez, 2006). The genus Procambarus habits in temporary water bodies, during the dry season can be seen in small holes in the soil, similar to the anteaters, which conduct to tunnels and chambers with sufficient moisture for the crayfish to survive to the drying (Lopez, 2008). The crayfish have been adapted in various ways, according to environmental conditions that occur in the places they want to colonize. The first adaptation is their ability to spend a lot of time, even months, faced with the lack of water and breathe atmospheric oxygen (Huner, 1995) in some cavemen environments it has been recorded that these organisms exhibit a diminution in their effective breathing rate as a response to the decrease in the concentration of oxygen, and undersupply of food (Mejia, 2010). Despite their abundance, less than a dozen crayfish species are cultivated worldwide and only two species constitute sizable commercial fisheries (Huner, 1994). Crayfish have a high potential for use in aquaculture systems because they are at the bottom of the trophic chain, feeding largely on carrion and detritus, for that they are therefore considered fundamental for maintaining ecological balance in

Reproduction efficiency of the crayfish Procambarus acanthophorus in relation to size and diet

ABSTRACT Reproductive efficiency of the largest individuals and a random group of broodstock of crayfish Procambarus acanthophorus was measured using two commercial shrimp feeds, Feed 1 (F1) broodstocks (40%/9% protein/lipids) and Feed 2 (F2) growth-out (35%/7% protein/lipids). An experimental design of four treatments with two replicates was used. Females were labeled with elastomers to determine the time between spawning and number of offspring per treatment. The number of ovigerous females in the largest individuals fed F2 (58) was significantly higher than ovigerous females in the control group fed F1 (30).The number of young crayfish per female produced in the largest individuals (173 ± 71.6) treatment was significantly higher than the crayfish produced in the control group (86.6 ± 42.6). The average interval between spawns, regardless of diet, in the largest females was 2.9 months and 2.6 months in control group females.