- February 03, 2022
- News
Many people often ask, “When can I see dolphins in upper Galveston Bay?” A recent study conducted by the Galveston Bay Dolphin Research Program indicates that both water temperature and salinity are factors in determining the presence of dolphins in upper Galveston Bay.
We are thrilled to announce that our study“Salinity and water temperature as predictors of bottlenose dolphin (Tursiops truncatus) encounter rates in upper Galveston Bay, Texas” was published in November in the journal Frontiers in Marine Science. Our main objectives in this study were to 1) evaluate if dolphins are found year-round in our primary study area in UGB and 2) investigate the effects of water temperature and salinity on dolphin presence in UGB. Dolphin presence was measured using “encounter rates” that are equivalent to the number of dolphins sighted (dolphins) per linear kilometer surveyed (km). Using multiple regression analyses, a statistical tool that identifies relationships between variables, we evaluated if and how water temperature and salinity predicted dolphin encounter rates.
The results of the study showed that dolphins are present in UGB year-round but many leave during the cooler months. Every year, dolphin encounter rates will increase in UGB after the water has warmed to about 23°C (73°F – typically in May) and will remain high throughout the summer. However, if there is a drop in salinity, usually due to heavy precipitation and flooding, many dolphins will leave UGB regardless of the time of year and water temperature. In conclusion, water temperature and salinity are both very important factors in determining dolphin presence in UGB, and low salinity will supersede temperature.
With these findings, we have scientific support to answer a question that we are asked often:“When can I see dolphins in upper Galveston Bay?” Unless heavy precipitation occurs and lowers salinity, June through September are the months of the year when you are most likely to see dolphins in UGB. But, you may be lucky enough to see them any time!
Now that we have completed this study, we are eager to learn more about where dolphins go during the cooler months and during periods of low salinity. It is the primary reason that we want to survey more areas of the Bay, as we suspect that many dolphins hang out in lower Bay during the winter.Please consider making a donation to support our surveys.You will help us answer important remaining questions about where these dolphins live throughout the year.
