Stocking density influences common carp larval development. Can restocking processes activate compensatory growth consequent to previous high stocking density?

Abstract

Aim of study: to analyse the effect of stocking density on common carp larvae production. Since stocking density is one of the most important variables in recirculating aquaculture system, it is fundamental to understand its implication on fish larval development. Area of study: BrazilMaterial and methods: In an initial trial over a 30-day period, 18,000 Cyprinus carpio larvae were subjected to eight different stocking densities (5, 10, 15, 20, 25, 30, 35 and 40 larvae/L). In a second trial over a 15-day period, the larvae subjected to the 40 larvae/L treatment were selected according to size and 360 of them were subjected to restocking processes at a density of 5 larvae/L, in order to evaluate possible compensatory growth, while those subjected to the 5 larvae/L treatment were likewise selected according to size and were distributed at the same stocking density (5 larvae/L), to be the control treatment during the restocking process.Main results: The larvae kept at the density of 5 larvae/L showed better growth and development. Increased heterogeneity of the concomitant batch was observed with higher stocking density. Restocking at low density (5 larvae/L), for larvae that had previously been kept at high density (40 larvae/L), caused partial compensatory growth, with an increase in the specific growth rate. Increasing the density caused increased productivity up to the density level of 25 larvae/L, but from then on there was no significant difference (p > 0.05).Research highlights: Carp larvae reared at high densities need to be restocked during rearing in order to avoid the “shooting” problem.

Effect of periods of delayed first exogenous feeding in goldfish Carassius auratus (Linnaeus, 1758) larvae

“…The significant effect of fasting on the survival of goldfish larvae decreased the stocking density, which may have influenced the zootechnical performance of the larvae. According to Jobling (1995) and Motta et al (2020), competition for food interferes with the performance of fish larvae and juveniles.…”

Effects of different stocking densities on the CO2 fluxes at water-air interface and the respiration metabolism in sea cucumber Apostichopus japonicus (Selenka)

“…The aquaculture industry has grown rapidly in recent years due to the increasing requirements for higher quantities of aquatic products. Stocking density, an essential abiotic element, is generally affecting growth (Pei et al, 2014;, development (Motta et al, 2020), welfare (Liu et al, 2019a) and some other physiological processes (Pei et al, 2012;Xia et al, 2017a) of aquaculture species. Respiratory metabolism affected by stocking density may be variable or even contradictory, depending on the species, rearing conditions and developmental stage of aquatic animals.…”