Growth in adult gilthead sea bream (Sparus aurata L) as a result of interference in sexual maturation by different photoperiod regimes

Abstract

Gilthead sea bream (Sparus aurata L) pass through the period of sexual maturation while being intensively reared for commercial purposes. This process affects growth and food conversion efficiency. In an attempt to reduce this problem several lighting regimes have been utilized which impede gonad development by increasing the length of the day. A four hour increase in natural day length three months before reaching sexual maturation in fish of 390 g, improves growth in comparison to the control by about 15% (means SD of 606.2 ± 10.6 and 526.5 ± 12.7 g, respectively) towards the end of the natural reproductive season. However, these differences are subsequently compensated since the sexual maturation process is only delayed (rather than being permanently halted). The manipulated groups reached maturity and then stopped growing between three and four months after the control groups. For this reason, it would appear advantageous to manipulate sexual maturation through photoperiod alteration in those groups which go to market either during or towards the end of the reproductive season since greater fish weights will be achieved in addition to an improved food efficiency.

Effect of photoperiod on locomotor activity, growth, feed efficiency and gonadal development of Nile tilapia

“…This result differs from others, in which the manipulation of photoperiod influenced the gonadsomatic index (GSI) of fishes (Boeuf & Bail, 1999;Ginés et al, 2003;Ginés et al, 2004;Rad et al, 2006). However, comparisons of the GSI between fishes of statistically different weight do not represent actual gonadal development.…”

Efeito do fotoperíodo sobre a composição do filé de juvenis de tilápia do Nilo

“…Acreditase que os peixes submetidos a esse fotoperíodo apresentaram uma maior mobilização de lipídios, necessária para compensar a elevada demanda de energia para o crescimento e para uma alta taxa metabólica. Além disso, peixes expostos a longos fotoperíodos podem apresentar baixa concentração de lipídio corporal, indicando que parte desse lipídio pode ser utilizada para mobilizar energia para suprir uma elevada demanda energética devido à maior atividade dos animais 6,14 . O teor de gordura possui importância na validade comercial dos produtos e é essencial para a aceitação geral pelos consumidores.…”

“…Além disso, o fotoperíodo influencia tanto na estratégia alimentar como no estímulo das atividades metabólicas de vários peixes 7,8 . Para algumas espécies, dias ou fotoperíodos longos podem modificar indiretamente o crescimento, seja pela indução ao aumento do consumo de ração, desenvolvimento da massa muscular devido à maior atividade locomotora dos animais [9][10][11][12] , melhor eficiência na utilização dos nutrientes 6,13 e / ou devido ao redirecionamento da energia proveniente da maturação gonadal para o crescimento somático 9,14,15 .…”

Effects of Photoperiod Manipulation on Growth Performance and Hematological Responses of Juvenile Caspian Roach Rutilus rutilus caspicus

“…feeding activity, growth and feed utilization (Boehlert, 1981;Woiwode and Adelman, 1991). Photoperiod manipulation can regulate physiological functions of fish such as growth, survival, gonadal maturation, reproduction (Björnsson et al, 2000;Ginés et al, 2003;Bonnet et al, 2007) and metabolism (Biswas and Takeuchi, 2003;Biswas et al, 2005Biswas et al, , 2006Taylor et al, 2006). In general, long photoperiod improves the performance of fish, probably because of increased feed availability (Boeuf and Le Bail, 1999).…”