Editing Orca (section)

===Whale watching===
[[Whale watching]] continues to increase in popularity, but may have some problematic impacts on orcas. Exposure to exhaust gases from large amounts of vessel traffic is causing concern for the overall health of the 75 remaining southern resident orcas (SRKWs) left as of early 2019.<ref>{{Cite web|url=https://www.bewhalewise.org/|title=Home|website=Be Whale Wise|access-date=October 31, 2019|archive-date=October 31, 2019|archive-url=https://web.archive.org/web/20191031050019/https://www.bewhalewise.org/|url-status=live}}</ref> This population is followed by approximately 20 vessels for 12 hours a day during the months May–September.<ref name="Lachmuth et al. 2011">{{cite journal |last1=Lachmuth |first1=Cara L. |last2=Barrett-Lennard |first2=Lance G. |last3=Steyn |first3=D. Q. |last4=Milsom |first4=William K. |title=Estimation of southern resident killer whale exposure to exhaust emissions from whale-watching vessels and potential adverse health effects and toxicity thresholds |journal=Marine Pollution Bulletin |date=April 2011 |volume=62 |issue=4 |pages=792–805 |doi=10.1016/j.marpolbul.2011.01.002 |pmid=21276987|bibcode=2011MarPB..62..792L }}</ref> Researchers discovered that these vessels are in the line of sight for these whales for 98–99.5% of daylight hours.<ref name="Lachmuth et al. 2011"/> With so many vessels, the air quality around these whales deteriorates and impacts their health. Air pollutants that bind with exhaust fumes are responsible for the activation of the cytochrome P450 1A gene family.<ref name="Lachmuth et al. 2011"/> Researchers have successfully identified this gene in skin biopsies of live whales and also the lungs of deceased whales. A direct correlation between activation of this gene and the air pollutants can not be made because there are other known factors that will induce the same gene. Vessels can have either wet or dry exhaust systems, with wet exhaust systems leaving more pollutants in the water due to various gas solubility. A modelling study determined that the lowest-observed-adverse-effect-level (LOAEL) of exhaust pollutants was about 12% of the human dose.<ref name="Lachmuth et al. 2011"/>

As a response to this, in 2017 boats off the British Columbia coast now have a minimum approach distance of 200 metres compared to the previous 100 metres. This new rule complements Washington State's minimum approach zone of 180 metres that has been in effect since 2011. If a whale approaches a vessel it must be placed in neutral until the whale passes. The World Health Organization has set air quality standards in an effort to control the emissions produced by these vessels.<ref>{{Cite web|url = https://baleinesendirect.org/en/boats-to-maintain-greater-distance-from-killer-whales/|title = Boats to Maintain Greater Distance from Killer Whales &#124; Whales online|date = November 8, 2017|access-date = March 14, 2019|archive-date = March 30, 2019|archive-url = https://web.archive.org/web/20190330230118/https://baleinesendirect.org/en/boats-to-maintain-greater-distance-from-killer-whales/|url-status = live}}</ref>