Boaters departing Moss Landing Harbor early on the opening day of salmon season navigate carefully past a large group of sea otters near the jetty.
By Colleen Young and Gena Bentall
As sport and commercial fishing seasons come and go, speeding boats could put threatened marine mammals in harm’s way
From January 2003 to December 2017, 49 sea otters were recovered with trauma consistent with impact from a boat hull or propeller. The majority of these sea otters were recovered in Monterey Bay and Estero Bay during spring to late summer (Figure 1). April and July had the greatest occurrence of boat strike cases, which corresponds with increased vessel traffic, likely associated with the opening of recreational salmon (April) and favorable summer boating conditions (July).
Anglers are often in a hurry to head out as recreational fishing seasons open. But with large numbers of sea otters living in or near harbor areas along the central California coast, wildlife experts are concerned about accidental deaths of otters caused by boats speeding out to sea. Considering the proximity of boaters and sea otters in harbors and bays, boat strikes are relatively uncommon. Most central coast boaters are conscientious and aware of local wildlife, following both boating and wildlife safety practices. Unfortunately for sea otters, it only takes one speeding or inattentive boater to cause devastating, often fatal injury.
Foraging sea otters are at greatest risk for boat strike. Sea otters dive for food in the harbor and slough channels and may surface unexpectedly near water craft—it is the boater’s responsibility to avoid contact. Here are tips to help boaters avoid collisions with sea otters and other wildlife:
- Boaters should keep an eye out for otters diving or surfacing from dives when passing between the jetties while entering or exiting the harbor. Have a designated wildlife spotter keeping watch!
- Travel at safe speeds that enable avoidance of collisions with any wildlife using the harbor and channel. Respect “no wake” zones.
Resting sea otters are also at risk! Boaters entering or exiting harbors will often encounter sea otters resting alone or in groups inside the harbor. When the harbor is busy, resting otters may be subjected to repeated disturbance, causing them to swim away or dive to avoid any water-craft approaching too closely. Chronic disturbance to resting sea otters can waste energy, which is especially detrimental to sea otters, which don’t store energy in the form of a blubber layer like other marine mammals. Conserving energy is important for all sea otters but is particularly critical for mothers raising pups.
Tips for avoiding disturbance to resting sea otters:
- Allow plenty of space between your boat and sea otters. We recommend a distance equivalent to at least 5 lengths of your boat.
- Passing by parallel is less threatening to sea otters than a direct approach, and will ensure most boaters prevent disturbance, and vessel strikes, to resting rafts of otters.
- When passing near otters in any kind of vessel, watch for an alert behavior—head raised and looking at you—the otter is warning you that you are too close and should adjust your course to avoid disturbance.
- Know guidelines for wildlife viewing before you go! Observe and follow posted guidelines at harbors and other marine recreation access points. Resources:
The central California coast offers habitat ideal for both sea otters and human recreation. Sea otter deaths from boat strikes – while unintentional – are easily preventable through increased boater attentiveness and by practicing safe boating. Sea Otter Savvy joins the Monterey Bay Aquarium, California Department of Fish and Wildlife, US Fish and Wildlife Service, City of Morro Bay Harbor Department, and the Moss Landing, and Monterey Harbor Districts in reminding recreational anglers and boaters to safeguard sea otters and other marine mammals and birds by slowing down in harbors. Observe “no-wake zones” so both wildlife and humans can safely enjoy our coastal waters. Slower boats also have a better chance of observing natural sea otter behaviors; a real treat for those with the patience and respect to observe these amazing critters at a reduced speed and an appropriate distance.
Anthropogenic (human-caused) sources of sea otter mortality include gun shots, entanglement, entrapment, and boat strikes. Although these causes of mortality are relatively uncommon (see the CDFW web page), this category is the most preventable source of sea otter deaths in California. For those already observing wildlife safe boating practices—well done! Don't be afraid to remind others to follow your example.
What else can you do to help? Spread the word on social media, or on your website!
Colleen Young is an sea otter biologist with the California Department of Fish and Wildlife