Tuesday, August 20, 2013

Sea otters: a conservation success story, or rats of the ocean?
By Raoul Wieland, Sarah Ravensbergen, Edward Gregr, and Kai Chan

After being re-introduced to the north end of Vancouver Island in the 1970s, sea otters can once again be found in many areas from which they were extirpated in the fur trade of the 18th and 19th centuries. From a conservation perspective, this is an important success story, yet events are rarely as black and white as they might appear. How could an animal returning to its natural habitat—the epitome of ‘charismatic megafauna’—be grounds for concern?

                                                                                                         A sea otter floats with her pup off the West Coast of Vancouver Island

In short, species conservation is complicated. Although the return of the sea otter is good news for many, it’s especially complicated because otters have a disproportionately large effect on ecosystems relative to their abundance (so much so that biologists call them ‘keystone’ species). Throwing otters back into the mix has had a wide variety of impacts, both positive and negative, on both marine ecosystems and local communities.

By eating urchins and other kelp-eating invertebrates, sea otters enable the vast expansion of kelp forests, thereby triggering a trophic cascade leading to a system with increased productivity and diversity. See, kelp forests are the tropical forests of the undersea world, housing and feeding all manner of critters in a lush, multi-storey cathedral of life. Researchers at UBC and elsewhere have shown how kelp forests are important nursery habitats for fish and invertebrate species. So on the one hand, sea otters are a species at risk, an attractive and potentially lucrative one (for tourism), and they are instrumental in bringing back the vast kelp forests of centuries gone by.

 Kelp forests like this one provide habitat for a great number of species, including birds, fish, invertebrates like snails and starfish, and even large mammals such as sea lions and grey whales

On the other hand, sea otters have decimated shellfish populations in many areas on the West Coast of Vancouver Island (WCVI), particularly in Kyuquot Sound. This causes real negative impacts on communities who rely on shellfish like crabs, urchins, geoduck, and clams, for their livelihoods. It is from the combination of these contrasting perspectives that the fierce tension in many coastal communities, particularly about otter management plans, ensues.

Enter the BC Coastal Ecosystem Services Project (BCCES, pronounced “BC Seas”), with a hub at the CHANS Lab at IRES at UBC. This 5-year project brought together a team of researchers who care deeply and equally for the natural environment and the human communities of Vancouver Island. Long-time marine enthusiasts like Russ Markel (who first approached Kai Chan about a possible collaboration; now at OuterShores have gained great insight into how the distribution and abundance of rocky reef fish and shellfish are affected by sea otters.


Researchers from UBC sample the kelp density, algae cover, and diversity of species in kelp beds  near Bamfield, BC, as part of the BC Coastal Ecosystem Services project

But what do these biological changes mean for human communities on the west coast? To answer this, we first need to understand how various human uses (like fishing and tourism) are affected by the abundance of different plants and animals in different places. So, the four of us (in particular Raoul Wieland and Sarah Ravensbergen) are contacting experts to check our assumptions about shellfish harvesting, recreational fishing, and tourism. Once we can represent how various kinds of fishing and tourism are affected by these changing abundances in different places (near, far, accessible, and less so), we can determine the suite of impacts sea otters have on people. In some places, like Kyuoquot Sound and the rest of northern WCVI, this is a matter of what sea otters have already changed; in other places, like Barkley Sound and southern WCVI, it’s what otters could change when they arrive en masse. We’re interested in both material goods (e.g. consuming or selling fish) and non-material experiences (e.g. leisure, education, culture).

The dialogue around the return of otters has centered around negative fisheries experiences vs. positive impacts on tourism. Our hope is that this research will broaden the dialogue to include other benefits and costs (like indirect boosts to some fisheries, for organisms who rely on kelp forests), and improve our understanding of how and where different groups of people (such as local fishers, harvesters, and tourists) are using, and getting the most out of, the ecosystem around them.  Incorporating such findings into management strategies is one step towards finding fair solutions, and possibly even elusive ‘win-wins’.

So, conservation poster-child or rat of the ocean? Otters are both, with delicious nuance.

No comments:

Post a Comment