Welfare Indicators in Tilapia: An Epidemiological Approach

Area of Science:

• Aquaculture
• Animal Welfare Science
• Fish Biology

Background:

• Growing concern exists regarding aquaculture rearing methods and their impact on animal welfare.
• Population-based welfare analysis, similar to production evaluation, is crucial for farmed fish.
• Common fish welfare indicators include gill state, fin damage, and body condition.

Purpose of the Study:

• To evaluate the effect of different feeding rates on the welfare indicators of Nile tilapia (Oreochromis niloticus).
• To utilize an epidemiological approach to assess fish welfare in a production setting.
• To identify key welfare indicators sensitive to feeding regimes across various growth stages.

Main Methods:

• Studied five growth stages of Oreochromis niloticus (1.2 to 360 g).
• Applied four feeding rate treatments: underfeeding (80%), recommended (100%), and overfeeding (120%, 140%).
• Assessed welfare indicators including lesions, body condition index (K), and biomass production, determining incidence and relative risk.

Main Results:

• Statistically significant associations were found between feeding rates and mortality, weight, body condition (K), and caudal/anal fin damage across all growth stages.
• Feeding rates directly influence both welfare indicators and overall production outcomes.
• Mortality, reduced body condition (K), and fin damage incidence are relevant indicators throughout O. niloticus development.

Conclusions:

• The epidemiological approach is a valuable tool for assessing and managing fish welfare in aquaculture production.
• Feeding rate management is critical for maintaining Nile tilapia welfare and optimizing production.
• A proposed risk traffic light method using welfare indicators can aid progressive evaluation and decision-making in fish culture.