The federal government faces a unique conservation challenge here on the islands because it is committed to restoring two threatened species to the region: northern abalone and the sea otters that eat them, Heidi Bevington wrties.
In a paper published this year called Northern Abalone: Using an Invertebrate to Focus Marine Conservation Ideas and Values, Dr. Norm Sloan of Gwaii Haanas looks at the issue.
Sea otters have been internationally protected since the Northern Fur Seal Treaty of 1911, writes Dr. Sloan. Northern Abalone have been protected since 1999 after heavy fishing almost wiped them out. Because both species are federally listed, the government has to protect them and promote their recovery by protecting habitat and possibly re-introducing species to areas where they used to live. But what would the re-introduction of sea otters to the islands mean for the struggling abalone population?
Shellfish are not normally thought of as ‘charismatic’, but endangered northern abalone are a flagship species that could build public understanding about the complexity of marine conservation, writes Dr. Sloan.
Abalone live in a web of life that also includes red sea urchin and kelp forests, and that once included sea otter. The abalone live by slowly moving across rocks grazing on algae, as do the sea urchins. Its not clear if the sea urchins compete with the abalone for space and food here on the islands, but there is evidence from other places like California that high numbers of sea urchins may push out the abalone. In addition, the sea urchins seem to have a negative affect on kelp forests under certain conditions, wrote Dr. Sloan.
The web of life quickly becomes tangled as scientists try to balance out the needs of abalone and kelp with sea otters and sea urchins, never mind the commercial, recreational and aboriginal fishers who want to harvest them.
If sea otter and abalone recover to the level scientists believe existed before European explorers came to the islands, it could mean that the abalone would be less abundant than they were in the mid-20th Century, suggested Dr. Sloan. The populations of both may have drastically expanded after the sea otters disappeared.
However, abalone and sea otters are not the only creatures in the waters around Gwaii Haanas. Sea urchins are thriving there, to the point that they could be a problem. Without sea otters eating them, sea urchin numbers have exploded. They graze on kelp, reducing the size of the kelp forests that are a necessary habitat for fish, wrote Dr. Sloan in a study of the mammals of Haida Gwaii called Living Marine Legacy of Gwaii Haanas IV. The introduction of sea otters would likely decrease the number of sea urchins and allow the kelp forests, and fish stocks, of the area to recover.
“Within Gwaii Haanas’s proposed marine waters, the prospect of conflicts between the recovery of sea otters and the recovery of northern abalone poses a thought-provoking challengeÂ….For example, having sea otter and self-sustaining but low levelsÂ…of northern abalone may be acceptable recovery under the SAR (species at risk) act, but not for those desiring some level of abalone (aboriginal, recreational) take,” wrote Dr. Sloan in Northern Abalone.
People will be faced with hard decisions about balancing the needs of the ecosystem as a whole with the individual species within it-including humans.
“I suggest that it is precisely the act of confronting such hard choices that will help develop the public’s understanding of the innate complexity of marine conservation. There are many more hard choices to come and an improved public dialogue on marine conservation needs to be developed now,” wrote Dr. Sloan.
For more information about Dr. Sloan’s publications, contact Gwaii Haanas at 559-8818.
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