Galveston Bay Dolphin Research Program Activities
January – March 2021
Galveston Bay Foundation and the Environmental Institute of Houston (University of Houston at Clear Lake) are pleased to share the latest Galveston Bay Dolphin Research Program (GDRP) quarterly newsletter. Thank you for your interest in our research!
A Splashy Overview
Please spread the word and help support our dolphin research when you adopt or name a Galveston Bay dolphin mom this Mother’s Day! Details below.
Winter in Galveston Bay usually brings a lot of wind, and when we get a rare calm day, along comes dense fog! The quarter followed this trend, and researchers were largely forced to stay on land. Safety and visibility are always a priority! Fortunately, the crew was able to take advantage of a few days with good weather and made it on the research boat two days in January, and one day each in February and March. Although this is not the level of coverage that we aim to achieve, we were glad to be able to complete some surveying in our primary study area and service our hydrophones (dolphin listening stations). In total, we completed 10.25hrs of observation (covering 177km of effort) and sighted approximately 40 dolphins in seven groups.
GDRP researchers identify dolphins using nicks and notches that create a unique pattern in their dorsal fins. These markings are usually created naturally, though sometimes may be the result of interactions with boats, fishing gear or even sharks. When GDRP researchers conduct surveys in Galveston Bay, they take photographs of each dolphin’s dorsal fin. These photographs are carefully analyzed and sorted to generate the GDRP catalog which is the foundation of our research. This research method, referred to as “photo-identification”, is utilized worldwide to study dolphin populations. The GDRP has identified over 700 unique individuals in the inshore waters of Galveston Bay, and we are excited to be able to share our catalog with other research groups along the coast of the Gulf of Mexico.
In March, researchers snapped this photo of a dolphin with prominent rake marks on its peduncle, the area between the dorsal fin and the fluke (tail fin). These marks are identifiable as evenly spaced parallel lines, caused by other dolphins’ teeth during social interactions. Rake marks are often shallow and heal quickly, so they are not typically used as features for long-term photo identification of an individual.
The Gulf of Mexico Dolphin Identification System (GoMDIS) is a repository of dolphin fins submitted by dolphin research organizations throughout the Gulf of Mexico. It is managed by the Chicago Zoological Society’s Sarasota Dolphin Research Program, and allows researchers to see where dolphins in their catalog may go outside of the region where they study by matching fins in catalogs submitted by other research groups. This is accomplished by utilizing an online photo-identification application run by Duke University’s Marine Geospatial Ecology Lab. The application is part of the Ocean Biodiversity Information System Spatial Ecological Analysis of Megavertebrate Populations (OBIS-SEAMAP), a spatially and temporally interactive online archive for marine mammal, sea turtle, seabird and ray & shark data. As of Spring 2021, GoMDIS holds 40 project catalogs with more than 24,000 individual dolphins, and it is still growing! This is a great resource for scientists and the perfect collaborative tool to help programs work together to understand dolphin movements in the Gulf of Mexico.
GDRP is proud to be a part of this effort, and has contributed 721 distinct individuals to GoMDIS, 344 of which have been matched to the “North Texas” (NORTX) catalog submitted by Errol Ronje with the National Marine Fisheries Service (NMFS) and the Texas Marine Mammal Stranding Network (TMMSN). This catalog covers surveys completed in Galveston Bay, Sabine Lake, West Bay and the passes and coastal regions between these areas, along with some historical sightings provided by Texas A&M at Galveston.
GDRP is excited to see where the dolphins in our catalog go when they move outside of our study area. This provides important information about their home range, seasonal movements, residency patterns, and habitat needs. Many of our cataloged dolphins have only been sighted in areas within Galveston Bay near where we often see them, but some have been sighted in Bolivar Roads, outside the Bay along the coast, and even in Sabine Lake!
Galveston Bay Foundation’s Education team offers a virtual STEM workshop about dolphins to grade levels K-12th. Students learn about the anatomy of a dolphin, where dolphins are located in the Bay, the threats that dolphins face, and even pretend to be a dolphin researcher through this highly interactive workshop. So far, 1,776 students have participated in our virtual dolphin workshop this year!
The content of this section is available to current members of our Dolphin Society. To become a member and receive updates on our individual dolphins, please adopt or name one of our dolphins. Adoption kits are a fun and unique gift! All funds go directly to the Galveston Bay Dolphin Research Program.
Two of our dolphin moms are available for adoption as Mother’s Day gifts: Dumbledolph (#28) and Jersey (#43). Dolphin #4, pictured above with her adorable calf, is available for naming. Gift adoption kits are delivered electronically and include photographs, a sighting map, and membership in our Dolphin Society.
Please spread the word and help support our important dolphin research with this unique Mother’s Day gift!
What YOU want to Know…
“Do dolphins prefer to stay in waters with certain salinity and temperature or do they live all around the world?”
Bottlenose dolphins (Tursiops truncatus) are found throughout the world in tropical and temperate waters. They are found nearshore in estuaries like Galveston Bay, as well as in the open ocean. Both salinity and temperature are important factors in determining their distribution and movement patterns.
We are currently studying the effects of both of these environmental variables on the dolphin population in Galveston Bay. We have found that there are fewer dolphins in our primary study area in upper Galveston Bay (UGB) during the cooler months (November-April). Many dolphins appear to move south of our study area when water temperature drops to below 20°C (68°F). Our data also suggest that salinity is an important factor in determining dolphin presence in the UGB and dolphins tend to leave our study area when salinity levels drop due to increases in freshwater influx. We are currently finalizing the analyses for this study and we look forward to sharing more details soon!
If you have a question regarding the GDRP, Galveston Bay dolphins, or dolphin biology, please submit your question using the button below. We select questions to answer from your submissions. We look forward to knowing what YOU want to know!
All activities are conducted under a NMFS Scientific Research Permit.
Galveston Bay Foundation
1725 Highway 146
Kemah, TX 77565
Environmental Institute of Houston
University of Houston at Clear Lake
2700 Bay Area Blvd.
Houston, TX, 77058