The Pacific Coast Feeding Group (PCFG) is comprised of approximately 200 gray whales (Eschrichtius robustus) who spend the summer months foraging off the coasts of Oregon, Washington, Canada and southeast Alaska instead of migrating all the way north to the Bering Sea with the rest of the northeast Pacific population. Gray whales can lose between 11-29% of their body mass during their migration to and from Baja California, so finding food, and being able to forage in peace is imperative to their survival. The preferred foraging habitat and migration routes of the gray whale occur in the nearshore environment, making them vulnerable to the cumulative effects of coastal anthropogenic impacts. In particular, gray whales are popular attractions for whale watching operations on their breeding grounds in Baja California, their migration route up the California coast, and their feeding grounds in Oregon, Washington, British Columbia, and Alaska. Repeated disruptions can be detrimental to the long term health of individuals, and being conscious of our impacts and intentional in our interactions can help conserve these whales and their habitat.
A gray whale turns underwater while foraging
Whale watching ecotourism is a strong and growing industry that can be an important source of revenue for many coastal communities. To avoid marine mammal disturbance while also balancing sustainable vessel-based operations, many efforts around the world have found success with community and industry led vessel operation guidelines. In the United States, the Marine Mammal Protection Act (MMPA) prohibits harassment of marine mammal species, and provides broad guidelines concerning approach distance, vessel behavior, time limits for viewing, and more. However, by combining federal regulations with smaller scale efforts tailored to local tourism target species, conservation efforts can be more effective. To address this concept on the Oregon Coast, we created a research project.
Whale watching near Depoe Bay
This study had several goals;
- To document and describe gray whale foraging behavior on the Oregon Coast in order to fill knowledge gaps.
- To assess whether vessel interactions have a significant impact on gray whale behavior.
- To work with the local whale watch community and other stakeholders to create sustainable, scientifically informed vessel operation guidelines for the Oregon Coast.
Our field team in Port Orford. The theodolite is the tall instrument which marks whale and vessel positions. Computer takes records while photographer identifies individuals.
During the summer of 2015 (June – September) we used non-invasive observational methods to study whale and boat interactions. Two sites along the Oregon Coast were monitored for approximately four weeks each to compare an area with relatively high vessel traffic and an active whale watch industry (Boiler Bay) to an area with low vessel traffic and minimal whale watch presence (Port Orford). Surveys began daily at sunrise (barring fog) and continued until we could no longer tell the difference between a whale spout and a white cap. Observers worked in teams of two or more to simultaneously track whales and vessels using binoculars and a theodolite, a surveyor’s tool that provides precise geo-located positions of the targets.
Summary of survey effort
In addition to whale location data at each surfacing, the following data was collected: photo-identification images, size, group composition (e.g., with calf, solitary), behavior state (e.g., feed, rest, social), and number of whales in a 100 m vicinity. Data on vessel characteristics was also recorded including vessel size, engine type, vessel type (e.g., fishing, tourist, recreational, kayak), speed of travel, and orientation to whale(s).
Figure 1. All the whale locations marked in Port Orford study region during 2015. The green spots are kelp beds, and the background color indicates increasing distance from kelp.
The location information gathered by theodolite can be visualized on maps such as figures 1 and 2. Figure 1 shows all the whale locations gathered in Port Orford, while figure 2 shows those same points after each point has been classified according to the whale’s behavior state.
Figure 2. Whale locations classified by behavior state. Black is travel, blue indicates search behavior, red indicates foraging behavior.
We sorted each location into three behavior classes (searching, foraging, or traveling) based on field observations and the “Residence in Space and Time” method created by Torres et al. (2016). We also divided the data into “control” and “contact”. Our “control” data includes any whales tracked when there were no vessels present within 100 meters of the whale. Our “contact” data includes all moments when a vessel was within 100 meters of a whale.
We used Markov chain models to assess whether these behavior states changed when vessels were present. Markov chains quantify the probability of transition between states, or how likely it is for a whale to switch from traveling to searching, or to continue foraging if it is already doing so. By comparing the transition probabilities between our control and contact data sets, we can better understand how vessel presence changes whale behavior.
Figure 3. This whale track (in blue) begins in the top right hand corner. Arrows indicate direction of travel. The pink boat, a small tourist zodiac, starts in the bottom left, goes up to the top right before our whale enters the scene, and shortly after we began tracking the whale, came back around and started to follow it. The green boat, a larger charter fishing/whale watching tour boat, arrived from the bottom left, spotted the whale around the 13:01 time stamp, and turned to follow. The question we explored is whether the whale’s large turn is a normal pattern, or a reaction to the vessels present. (Tracklines taken at Boiler Bay)
Our analysis found several statistically significant differences in whale behaviors when there were no vessels around compared to when there were vessels. For example, while gray whales spent the same amount of time traveling when vessels were present within 100 meters, they spent 8% less time searching for food compared to when there were no boats around. Whales were always more likely to continue in their current behavior state (search, travel, or forage) than to switch to another behavior. However, whales were more likely to continue traveling when vessels were present, and less likely to stop traveling and search for food. That being said, food trumps all, and gray whales in Oregon will forage if they find food, regardless of the number of vessels present. It should be noted that continued use of a space does not mean that whales are not impacted by nearby vessels or other human derived stressors while foraging. Future studies should investigate the physiological impacts of disturbance at various time scales to ensure that vessel guidelines resulting from this work are effective.
A gray whale and kayaker surprise each other, and both turn to avoid each other.
Throughout the two year research project community stakeholders were invited to a series of workshops through email, phone and personal invitations. Participants included whale watch operators, fishermen, local NGOs and conservation groups, Oregon Parks and Recreation, community members and other interested parties. Four workshops were held in the Depoe Bay and Port Orford communities to inform stakeholders of research efforts and preliminary results. Stakeholders discussed ongoing research, global examples of issues with whale watching, examples of other communities’ guidelines, and usefulness of guidelines. Common reactions from stakeholders included (1) desire for hard data before changing current practices, (2) concern that community led guidelines would become legislation in an already heavily regulated industry, (3) agreement that whales should be protected, and (4) irritation with shore-based incident reporters. We addressed these points by gathering and analyzing the data presented above and noting that there is no precedent that we know of where ecotourism industry guidelines became laws. We wrote our guidelines in conjunction with stakeholders, and built off the baseline provided by the MMPA. The Oregon “Watch out for Whales” vessel operation guidelines are as follows (Download the brochure here!):
- Stay at least 100 yards away from whales. If a calf is present, stay 150 yards away
- Do not fly drones within 300 yards (vertical or horizontal distance) of a whale
- Do not spend more than 30 minutes with an individual whale
- Let the animals decide where to go. Do not corral a whale between boats, or pin it against shore.
- Do not approach fast. Do not leave fast
- Keep noise to a minimum (do not bang on the side of your boat)
- Do not feed or attempt to swim with whales.
Finally, our mission is to distribute these guidelines widely up and down the Oregon coast. We aim to educate recreational boaters about what to do when they encounter a whale, so that all vessels are using the guidelines. By continuing outreach and education to the large community of boaters on the Oregon Coast, as well as local communities and visiting tourists, we will increase the awareness of Oregon as a sustainable, scientifically informed ecotourism destination.
This work was completed as part of Florence Sullivan’s master’s thesis at Oregon State University under the guidance of Dr. Leigh Torres with funding support from The Wild River Coast Alliance, The William and Francis McNeil Fellowship Award, and The American Cetacean Society – Oregon Chapter.
Interested in more projects? Visit the GEMM Lab blog for general marine mammal research updates: blogs.oregonstate.edu/gemmlab
References:
(2016) Animal movement analysis through residence in space and time. PeerJ Preprints 4:e2480v1https://doi.org/10.7287/peerj.preprints.2480v1
