Aquaculture 2022

February 28 - March 4, 2022

San Diego, California

THERMAL AND NUTRITIONAL STRATEGIES AS ALTERNATIVES TO ANTIBIOTICS IN AQUACULTURE

Raquel Carrilho1,2, Ana Paula Farinha1,2, Cláudia Raposo de Magalhães1.2, Márcio Moreira1,2,3, Pedro Rodrigues1,2 and Marco Cerqueira1,2*

 

1Universidade do Algarve, Campus de Gambelas, Faro, Portugal

2CCMAR, Universidade do Algarve, Faro, Portugal

3IPMA—Portuguese Institute for the Sea and Atmosphere, EPPO—Aquaculture Research Station,

Av. Parque Natural da Ria Formosa s/n, 8700-194 Olhão, Portugal

*Email: macerqueira@ualg.pt

 



Introduction

 Aquaculture industry is growing at an  astounding rate, overtaking capture fishery production and foresighted to represent 60% of global finfish production by 2030. The increasing demand for healthy and less expensive protein has catalysed intensification and favoured an ideal environment for  several  production-related  problems to flourish, impact ing the environment, the animals and human health .  One  of the best-understood risks that aquaculture intensification poses is the  heavy use of antibiotics and the concerning consequence of increasing antimicrobial resistance (AMR). On farms, fishes’ welfare is compromised by  poor health, nutrition, and rearing practices with implications in susceptibility to stress and diseases.  As  a result, the w eakened immune systems increase the possibility of disease outbreaks  and  lead to prophylactic and therapeutic  antibiotic overuse .  Managing antibiotic use associated with the prevention and control of aquatic animal diseases is, therefore, necessary to secure the business venture and product brand .  Research on  alternatives and sustainable management strategies against infection become crucial and imperative  to  safeguard the different actors of the aquaculture chain. Bearing this in mind, this research introduc es  environmentally friendly  alternatives to boost the fish’s immune system .  A nutritional strategy including diets supplemented with  natural immunostimulants, and a thermal strategy relying on physiological requirements and environmental availability,  will be developed to  increase fish’s fitness towards challenging situations and  reduce the use of antibiotics and mitigate their consequences. Overall, such alternatives will boost the welfare  of the fish and leverage the industry with forthcoming management protocols to promote  a more resilient and sustainable aquaculture -secure future.

Material and Methods

 In a first approach, gilthead seabream will be infected with the bacteria Tenacibaculus Maritimum to characterize the bacterial infection through Label-free shotgun proteomic (LC-MS/MS) analysis and identify possible disease biomarkers. In this experiment, the fish behavior will be observed through cameras displayed in the tanks and the optimal temperature of non-infected seabream will be assessed in thermal gradient tanks. Furthermore, hematologic, histological, and microbiological analyses will be performed.  In the second experiment, seabream will be subjected to infection and allowed to swim along a thermal gradient or being exposed to a constant temperature (obtained previously). Post-infection fish behavior and thermal preference will be evaluated through video recording.  At last, seabream will be subjected to a nutritional therapy where will be fed with two experimental diets with natural immunostimulants against a commercial diet. After this, fish will be infected with the bacteria to assess the diet’s impact  on fish disease behavioral phenotype and proteome. Biochemical parameters of plasma (cortisol, lactate, and glucose) and liver glycogen will be assessed.

Expected outcomes

Dietary supplementation with balanced  natural immunostimulants and environmental thermal gradient availability  improves welfare and enhance fitness of fish under challenging farming systems. Such strategies may well be promising avenues to  tailor  aquaculture management protocols to  boost aquaculture sustainability and consumer’s safety.

Acknowledgements

This work received Portuguese national funds from FCT- Foundation for Science and Technology through project UID/04326/2020 and integrates the project BIOIMMUNE (Refª MAR-02.05.01-FEAMP-0052, “Natural Antimicrobials and Pyrexia as Alternative Strategies for Antibiotic Use to Prevent Pathogens and Improve Welfare in Aquaculture”) financed by Mar2020, in the framework of the program Portugal 2020 .  Raquel Carrilho acknowledges a FCT PhD scholarship, Refª 2021.06786.BD.