Southern Resident Killer Whale, Gavin Griffin

Southern Resident Killer Whales

(Orcinus orca)
By: Gavin Griffin

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Summary

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Orcas, commonly known as Killer Whales, are the worlds largest dolphin with males growing to maximum lengths of 32 ft and weighing in at a maximum 22,000 lbs. While their female counterparts attaining lengths and weights of 28 ft and 16,500 lbs, respectively (2). The sexes also have a distinct difference in the size and shape of their dorsal fin. Male dorsal fins are pointed and grow about 6 ft. On the other hand, female dorsal fins are rounded and only reach heights of 2.6 ft. The Killer Whale is largely dependent on underwater sound for orientation, hunting, and communication. They primarily use echolocation clicks for navigation. Pulsed calls and whistles are typically used for socializing. The most widely distributed marine mammal, the Killer Whale is found in most parts of the ocean. More abundantly in colder waters like Antarctica, the North Atlantic and Pacific Ocean. 

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Since Killer whales are top-level predators, their diet is broad ranging from fish to squid and other marine animals, but the Southern Resident killer whales have a diet that consists of salmonids.  Some populations utilize foraging strategies such as cooperative hunting and food sharing. They are the "only cetacean to routinely prey on marine mammals with attacks documented on more than 35 mammal species, including species as large as blue whales" (1). The iconic mammal has historically drawn public interest and curiosity. Many amusement parks put on performances with the amazing animal. However, the shows have created controversy related to the well-being of the Orcas in captivity. Killer whales also have strong ties to Indian Tribes in the Pacific Northwest. Where they are very important to the tribes both culturally and spiritually. 

Population

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The population of Orcas is difficult to track because of the overall scarcity and their unpredictable patterns of movement. In the recent decades photo-identification has been the method of surveying the species. However, for photo-identification to be accurate it must be conducted throughout multi-year periods and, because of the species mobility, over a large geographic area. Since killer whales are top-level predators they occur in low densities throughout most of their geographic range. With a much higher density in higher latitude. 

The population of the Southern Resident killer whales has been on a steady decline for years now. In the Northeastern Pacific the population is currently estimated at 2,500 killer whales (2), and an even lower number for the Southern Resident Community. As of September 2017 the Southern Resident killer whale community has dropped to 76 individuals (3). 

Listing Date

The species was listed as endangered under the Endangered Species Act (ESA) on November 18, 2005. 

Main Threats 

While there is no one reason the species was listed as endangered, there are many factors that contribute to the dwindling population. They main ones being: prey availability, pollution/contamination, vessel effects and acoustic effects.

Since the Southern Resident killer whales prey on Pacific salmon, the population can have difficulty finding meals if the number of salmon declines. Which is exactly what has happened in recent years. "Since the early 1990s, 27 evolutionarily significant units (ESUs) of salmon and steelhead in Washington, Oregon, Idaho, and California have been listed as threatened or endangered under the ESA" (1). The ever decreasing numbers of salmon forces the whales to spend more time hunting. Resulting in less time socializing and reproducing. Eventually leading to a higher mortality rate.

Despite the modern pollution controls that have been put in place, there is still a steady degradation of  habitat for the killer whales. Furthermore, "recent studies have documents high levels of PCBs (polychlorinated biphynels) in the Southern Resident [population]" (1).  These chemicals have been known to negatively impact the immune system, the reproduction ability, and illustrate other physiological effects on the species. Although, the use of the chemical is prohibited under current 

regulations they persist in the environment. Meaning the chemicals used in the past will continue to effect the orcas for decades. Especially since orcas are top-level predators. They receive high concentration of these harmful chemicals through trophic levels.

Because of their reliance on sound for navigating, increased vessel use has negatively impacted the Southern Resident orcas. Not only does it mask their echolocation signals, but it can temporarily or permanently damage hearing sensitivity. A majority of vessel traffic in the area can be contributed to commercial fishing boats. However, whale watching, ferry operations and recreational boating traffic still affects the mammals ability to locate prey and communicate via increased underwater sounds levels created by the engines. Leading scientist to believe "exposure to sound may therefore be detrimental to survival by impairing foraging and other behavior" (1). However, it is still unclear at what point underwater sounds generated by humans become harmful to the species.

It is apparent that the main threats to the killer whale's continued existence stem from human activity. What makes it more challenging for the species to recover is the compounding effect of all the threats together. Not only is their main source decreasing in numbers, but the increased underwater sound makes it harder to find the already scarce salmon. Additionally, the chemical runoff into the habitat can be contributed to the decline in salmon numbers. Those salmon that do live are likely to contain these harmful chemicals and pass them on to the killer whales through trophic levels. Effectively poisoning killer whales.


Recovery Plan
With uncertainty among experts as to which threat is the reason for population decline or which one is more important the recovery plan is a broad plan aimed to reduce and eliminate the suspected causes. The recovery plan has an adaptive management plan and strategy to address each factor with the best information available. The overall goal of the recovery plan is to restore the Southern Residents to the point where they no longer require protection by the ESA.

Prey Availability:
Aid in the salmon restoration efforts in the region including habitat, harvest and hatchery management.

Vessel Effects:
Continue with evaluation and improvement of guidelines for vessel activity near Southern Resident killer whales and evaluate the need for regulations or protected areas.

Oil Spills:
Prevent oil spills and improve response preparation to minimize effects on Southern Residents and their habitat in the event of a spill.

Acoustic Effects:
Continue agency coordination and use of existing ESA and MMPA mechanisms to minimize potential impacts from anthropogenic sound.

Education and Outreach:
Enhance public awareness, educate the public on actions they can participate in to conserve killer whales and improve reporting of Southern Resident killer whale sightings and strandings.


What can you do to help?
It may seem like there is not much one person can do to help the Southern Residents current situation. However, that is far from reality. Here are some simple steps one can take to contribute to the cause:

The first thing is knowing that everything is connected. So take the initiative to start recycling and reusing more often. Secondly, become an informed consumer. For example, chose to eat sustainably-harvested salmon that way we are not depleting the killer whale's main food source. Moreover, instead of trying to catch a glimpse of a orca on your own vessel, watch them from a responsibly managed whale watching vessel. Lastly, dispose of your chemicals properly. Do not just dump them in the toilet/sink or garbage. Find out if your community has a hazardous waste collection facility to dispose of your chemicals.

While these are not the only things you can do to give the Southern Resident Killer whales a chance to recover they are a few easy first steps you can take.

Other Resources

https://www.epa.gov/salish-sea/southern-resident-killer-whales

https://whalemuseum.org/pages/how-to-help-the-orcas

https://www.raincoast.org/killer-whales/



Sources

1. National Marine Fisheries Service. 2008. Recovery Plan for Southern Resident Killer Whales                    (Orcinus orca). National Marine Fisheries Service, Northwest Region, Seattle, Washington.

2. Fisheries, NOAA. “Killer Whale (Orcinus Orca).” NOAA Fisheries, NOAA Fisheries, 8 Jan. 2015,                       www.nmfs.noaa.gov/pr/species/mammals/whales/killer-whale.html.

3. Garrett, Howard. “Southern Resident Orca Community Demographics.” Orca Network, 23 Sept. 2017,             www.orcanetwork.org/Main/index.php?categories_file=Births%2Band%2BDeaths.