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Expanding Boating Safety In Mosquito Lagoon

Irl Map

By Tiare “TJ” Fridrich, Manatee Biologist

Manatees share Florida’s waterways with over one million registered boaters, meaning that they are constantly under threat from boat strikes and watercraft-related mortality. To protect manatees from harmful collisions, the Florida Fish and Wildlife Conservation Commission (FWC) was given authority under the Florida Manatee Sanctuary Act of 1978 to regulate and restrict the speed and operation of vessels in areas where manatees are frequently sighted. These regulated speed zones are referred to as manatee protection zones (MPZs) and can be established to protect manatees not only from boat strikes but from harassment, habitat destruction by boats, and to provide manatees with limited safe havens where they can rest, feed, reproduce, give birth, or nurse undisturbed by human activity. MPZs are established using the best, most established scientific information, and previously established zones can be amended based on new information. Now, Save the Manatee Club is urging FWC to amend the zones in the northern Indian River Lagoon to provide manatees with increased protection from boat strikes.

The Indian River Lagoon (IRL) provides critically important habitat for the survival of the Florida manatee. The IRL is a 156-mile-long shallow lagoon located along Florida’s east coast. It is separated into three sublagoons: the Mosquito Lagoon, the Banana River, and the Indian River. Manatees are found throughout the IRL all year, and (prior to a significant loss of seagrass caused by recurring algal blooms that occurred between 2010 and 2019), the Atlantic Coast manatee population was regularly increasing. In late 2020, manatees in the IRL started dying in large numbers, with the primary cause of death attributed to starvation due to a lack of forage. This was exacerbated by cold winter temperatures, which restrict manatees’ movements, preventing them from leaving the IRL to find food elsewhere. In the winters of 2020/2021 and 2021/2022, over one thousand manatees died on Florida’s east coast, an estimated 25% of the total Atlantic Coast manatee population.

During the summer of 2022, seagrasses returned to the Mosquito Lagoon, resulting in significantly lower numbers of manatees dying from starvation. Researchers from the St. Johns River Water Management District believe that the seagrass grew from previously undetected seeds that had settled beneath the sediment. Between the summer of 2021 and now, lush seagrass beds have returned to the Mosquito Lagoon. While the rest of the IRL has not had anywhere near this level of seagrass regrowth, seagrass coverage is still increasing throughout the IRL, with Mosquito Lagoon currently the largest source within the IRL.

Historically, when seagrass was more abundant throughout the IRL, manatees were seen most often feeding in the Banana River. The Banana River, like the rest of the IRL, lost a significant amount of seagrass between 2010 and 2019, and with it, researchers from the Kennedy Space Center saw a ten-fold decrease in manatee counts there. Manatees shifted their distribution north to the Mosquito Lagoon, where seagrass was more abundant. In the summer of 2022, over 900 manatees were seen in the Mosquito Lagoon during aerial surveys, an unprecedentedly large number of manatees for that area.

With this huge shift in manatee distribution in the northern IRL, the MPZs in this area are no longer sufficient to protect manatees from boat strikes. Most of the Mosquito Lagoon is designated as a 30-mph daytime zone and 25-mph at night. When the MPZs were originally adopted in Volusia County in 1995, the 30/25-mph zones were created as a blanket rule for the parts of the Mosquito Lagoon that did not commonly have manatees. But the number of manatees dying or injured from boat strikes has increased significantly over the last decade. The manatees currently gathering in the Mosquito Lagoon represent the remnants of an already devastated population. We are working with the local, state, and federal governments to address this issue and will not rest until manatees in the Mosquito Lagoon are properly protected from watercraft injuries and death.

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