Tuesday, April 1, 2014

Monitoring seal migration for more than a decade

Robbie Hudson
Restoration Ecologist

FROM THE FIELD

Save The Bay has been monitoring seal migration in Narragansett Bay since 1993. There are four types of seals typically found in the Bay. Harbor seals (Phoca vitulina) are the most common, followed by gray seals (Halichoerus grypus), harp seals (Phoca groenlandica), and hooded seals (Cystophora cristata). The seals return to our waters around September in pursuit of herring, which is their primary food source, then return to northern waters in late April.

Save The Bay’s monitoring data have been used in the development of an oil spill response plan and in an impact assessment for a proposed port development project in the vicinity of the largest haul-out site in Narragansett Bay. Our volunteers have also reported the location of injured or stranded marine mammals to the marine stranding network in southern New England. Like all marine mammals, seals are negatively affected by habitat degradation and its effects which remains an important factor in monitoring their activities. If you know a site where seals haul-out and would like to monitor a site, please let us know. I am hoping to include more sites for the 2015 season (including coastal ponds and barrier beaches).  

Viewing harbor seals in Newport
Seals are a native and important species to our Bay. Prior to 1972 you may have only spotted a few seals, but today the population is in the range of 300-500 seals that visit our waters annually. The Marine Mammal Protection Act of 1972 allowed seal populations to rebound. The law makes it illegal to attempt to harass, hunt, capture, kill, or collect (live or dead); marine mammals. The also law mandates a safe distance of 150 feet for viewing the animals. Warning signs that you are too close to the seal (and are harassing the seal) are the seal is shaking its body or trembling, increased vocalizations, or the seal is eating rocks or sand, and if the resting seal continually lifts its head to warn off any approaching threat. 

Harbor seal on a rock off Fields Point in Providence
More information about safe and legal observation of migratory seals can be found by visiting the Birds and Mammals page on our website our website. If you haven't done so yet, join us for one of our Seal Watch Cruise in Newport or Westerly. We have just a few weekends left to view these majestic marine mammals.


If you witness an animal being harassed, discover a live marine mammal with obvious injuries or health problems, or find a dead marine mammal or sea turtle, please contact a marine mammal stranding coordinator. In Rhode Island and Connecticut call MysticAquarium & Institute for Exploration at 860-572-5955 ext. 107. In Southern Massachusetts call the International Fund for Animal Welfare/Cape Cod at 508-743-9548.

- Robbie 
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