- Animals: fish
- Animal Production: general animal production
- Sustainable Communities: employment opportunities
Over the past decade there has been a steady decline in embryo survival in hatchery reared Atlantic salmon. Spawning the broodstock is labor intensive and costly, and reductions in embryo survival have led to a significant financial bottleneck. Preliminary evidence of broodstock pairings suggests this problem is of maternal origin; therefore this project seeks to determine causative factors in female broodstock leading to reduced embryo survival in Atlantic salmon hatcheries. Because hormones direct much of early development, we will investigate maternal plasma hormone concentrations, as well as concentrations in the eggs, and correlate hormone concentrations with embryo survival. Hormones to be investigated include estradiol (E2), testosterone (T) and 11-ketotestosterone (11-KT). In addition, we will correlate embryo survival with key ovarian genes involved in steroidogenesis, as well as hepatic genes involved in clearing hormones from circulation. Further, we will measure ethoxyresorufin-O-deethylase (EROD)activity, which is a wellestablished biomarker of contaminant exposure, especially those known to disrupt hormone function. To date, blood, liver, ovary and egg samples have been collected from over 400 female broodstock Atlantic salmon during two spawning seasons from three Maine hatcheries. Preliminary results show positive correlations between E2 and 11-KT with embryo survival, whereas plasma T does not show a significant correlation. By understanding maternal hormones and the processes that regulate them, we aim to identify the underlying causes of embryo mortality, and improve the economic viability of the hatchery process.
Project objectives from proposal:
Our objectives are as follows:
1. Determine if maternal hormone concentrations correlate with embryo survival in cultured Atlantic salmon.
2. Determine if maternal deposition of hormones into the egg correlates with embryo survival.
3. Determine if egg calcium concentrations correlate with embryo survival.
4. Determine if maternal deposition of calcium into the egg correlates with embryo survival.
5. Determine if the expression of key genes involved in the production of steroid hormones correlates with embryo
6. Analyze two biomarkers of contaminant exposure and determine if they correlate with embryo survival.
7. Convey our findings to salmon hatcheries throughout the Northeast