Thiamine Allocation and Deficiency Status Throughout the Life Cycle of Cod.

Area of Science:

• Marine Biology
• Fish Physiology
• Nutritional Biochemistry

Background:

• Thiamine deficiency is a known issue in wild bird and fish populations, potentially causing mass mortality events.
• Atlantic cod (Gadus morhua) are ecologically and economically significant and suspected to be sensitive to thiamine deficiency.

Purpose of the Study:

• To investigate the dynamics and tissue-specific allocation of thiamine in Atlantic cod.
• To compare thiamine concentrations in cod from areas with and without recorded thiamine deficiency.

Main Methods:

• Sampling of Atlantic cod across various sizes and maturity stages from the Baltic Sea (known deficiency) and North Atlantic.
• Analysis of thiamine concentrations and vitamer composition in different tissues (muscle, liver, gonads).
• Assessment of transketolase activity and latency as indicators of thiamine status.

Main Results:

• Thiamine concentrations varied by tissue, decreasing in muscle and liver with growth/maturation but increasing in gonads.
• Approximately 70% of a female cod's total thiamine pool was allocated to gonads during early reproduction.
• No evidence of thiamine deficiency was found in the studied cod populations, with comparable thiamine statuses between regions when accounting for size and reproductive state.

Conclusions:

• Life cycle stage and tissue-specific thiamine dynamics are crucial for accurate thiamine status assessment in fish.
• Reproductive investment, particularly gonad allocation, significantly impacts thiamine dynamics.
• Specific life history traits related to spawning may increase a species' vulnerability to thiamine deficiency.