More on gillnets: an inadvertent experiment

29 05 2013

Coming close on the heels of last week’s post about estimated worldwide seabird bycatch in gillnets, an experiment that basically did itself. Paul Regular, William Montevecchi and several colleagues have a paper out in Biological Letters examining the effect of the closure of two major Canadian fisheries on murre populations. In 1992, cod and salmon gillnetting was effectively closed down in Atlantic Canada. This resulted in the removal of tens of thousands of gillnets from the foraging waters of seabirds like murres and razorbills, which are heavily impacted by bycatch in these nets. What followed was thus a kind of de facto experiment on the population impact of removing bycatch mortality for these birds. The study authors looked at impacts not only on birds likely to be entangled in gillnets, but also surface feeding seabirds like gulls which are comparatively unlikely to suffer that fate.

Populations of Herring Gulls and Common Murres before and after gillnet moratorium (Regular, et al.)

Populations of Herring Gulls and Common Murres before and after gillnet moratorium (Regular, et al.)

Using both bycatch data and breeding colony census information, the paper tracks the populations of the various species over the decades since the fisheries closures. Data was sufficiently robust to look closely at two species: Common Murres and Herring Gulls. The researchers found a dual and approximately opposite effect on the two species. Murre numbers climbed substantially once pressure from gillnets was removed, but Herring Gull numbers showed a decline. This is likely due to the withdrawal of offal and other fisheries waste when the gill nets were hauled up and stowed away in 1992. Opportunistic feeders, gulls feed heavily on discarded bait and other material tossed overboard by fishermen. As those anthropogenic food sources become less available, gull survival declines. The same phenomenon seems to have followed the closure of many open landfills after the 1970s. The declines in breeding gull populations over the past 30 years seem to reflect a “correction” of sorts–a return to baseline numbers in the absence of man-made buffets. Simultaneously, more specialized feeders like murres have benefited not only from closure of some fisheries, but also from stricter laws governing the discharge of petroleum products by ships off the coasts of the U.S. and Canada.

The closure of the cod and salmon gillnet fisheries in Canada afforded this opportunity to study the effects of bycatch pressure on seabirds, and it appears to be substantial. Fisheries don’t generally remain closed forever though, and if and when the salmon and cod fisheries off the Canadian Maritimes do reopen, the authors of the study point to potential changes in methods to continue to protect murres and other diving birds. One such possibility is cod pots, which operate similar to lobster traps, sitting on the ocean bottom with bait inside. Fish swim in and can’t swim out. This type of gear is highly unlikely to entrap seabirds, though I have known lobstermen who reported finding Common Eiders in their traps from time to time, so never say never.





Request for video clips of Seanetters in action!

24 05 2013
Even the most squeamish among the students sidled up eventually.

The world from a Seanetter’s perspective. Show us how you do it, folks!

My dear Seanetters, we have been invited to run a crowdfunding campaign through the science funding start up Endeavorist! We’re going to set a target of $8,000 to fund necropsies of seabirds involved in mass mortality events. I think we can do it, but to catch the eyes (and the wallets) of potential donors, we need to produce a engaging and compelling 2 minute video. I want to put together a little montage of beach walking footage. Here’s what I need from you:

You can record your video on an iPhone or similar device, so no need for fancy equipment. You can choose to appear on camera talking about SEANET, or you can submit footage (with voiceover or not) from your first person perspective looking out at the world. I would especially like to get footage of your feet as they walk along the beach (so you would literally point the camera at your feet as you walk. About 10 seconds of that is sufficient). Then I can string together a bunch of different people’s feet walking on different kinds of beaches.

If you find a dead bird, I would LOVE some footage of how you process it–tagging it, measuring, any of that stuff. Again, you can have someone else film you, or you can film from your own perspective. Shaky video is ok–I can work with it, and some of that ambiance is desirable.

Anything else you want to film is most welcome–the feel of your beach, why you SEANET, live birds hanging out, anything and everything, Seanetters!

Help a girl out here, and let’s see if we can’t raise 8K!

 

 





Seabird entanglement in gillnets: a global assessment

22 05 2013

Most of the time, when a dead bird is reported on a SEANET beach, we never find out what happened to it. Whether it’s a lack of resources to perform necropsies, or simply that no cause was evident at necropsy and no more extensive diagnostics could be performed, we often end up with unsatisfying partial answers. It’s the nature of the game, I’m afraid. But once in a while, a Seanetter comes upon a pile of waterlogged carcasses along a short stretch of beach. In many of those cases, necropsy is rewarding and the findings are consistent with drowning in fishing gear. We can never say with complete certainty what happened, except in cases where a bird is documented as its hauled up in the net, but we have seen certain signs in drowned birds that are consistent across events and across species.

Hauling in a gill net. Fish are usually caught by their gill covers but may be entangled in other arrangements too.

Hauling in a gill net. Fish are usually caught by their gill covers but may be entangled in other arrangements too.

Most of the time, the species involved in these sorts of events are Red-throated Loons. These birds forage near shore, swimming underwater in pursuit of fish. The most likely culprit in their drownings are near-shore gillnets–a veritable wall of mostly invisible monofilament that the birds don’t notice until its too late. While NOAA here in the U.S. stations marine observers on ocean-going fishing vessels to document bycatch of non-target fish and of marine mammals and seabirds, the near-shore fisheries are woefully under-monitored. We suspect that birds hauled up in such nets are tossed overboard and occasionally turn up in large batches on shore. It’s a difficult phenomenon to track and delineate, as evidenced by an ambitious review article in Biological Conservation. The study sought to identify particular species groups that are most susceptible to gillnet entanglement (think loons and alcids–razorbills, murres, etc) and also areas across the globe where those species are most likely to be severely impacted. Sub-polar and temperate regions (like most of SEANET territory) are high on the latter list. The study also documented some surprising findings, like that gulls, not generally thought particularly vulnerable to gillnets since they tend to feed on near the surface, are, in fact impacted as well.

A slew of Red-throated Loons found on Long Island. Gillnet entanglement was our suspicion here. (Photo by Peg Hart)

A slew of Red-throated Loons found on Long Island. Gillnet entanglement was our suspicion here. (Photo by Peg Hart)

The paper points out what we have been frustrated by for years–the lack of coordinated monitoring and documentation of bycatch in this fishery. By piecing together published and unpublished data from all over the world, these authors estimate a minimum of 400,000 seabirds are killed in gillnets each year, and they suspect the real number is considerably higher. As for what to do about it, the paper does not venture to make recommendations, but has pointed out some promising research into making the nets more visible to the birds, changing the depth at which they are deployed, or, in some cases, switching to another form of gear altogether, though in some cases this last method may only shift the problem to a new species group.

We’re glad this issue is gaining more attention throughout the world, and we will continue to try to do our part in documenting the extent of the problem here on the east coast.





Keeping out of trouble on Appledore

17 05 2013
Eviscerated Common Eider carcass; the work of a killer gull?

Eviscerated Common Eider carcass; the work of a killer gull?

I may be focused on the study of live gulls this week, but I never forget my roots, dear Seanetters. I have found more than 10 dead birds while here. Some were mere fragments of Northern Flickers or other smallish sorts of birds, but we also found a freshly dead female eider. Common Eiders nest on Appledore Island, very often in close proximity to gulls. The eiders don’t fare well, and most of the babies are picked off by Great Black-backed Gulls by season’s end. This adult showed the characteristic holes in the body wall that gulls often leave, and through which they pull the strands of viscera. Whether this bird was killed by a gull or merely scavenged by one is, as always, unclear.

I’ve found plenty of dead gulls, but my true prize was the gull skeleton still sporting his bands. I retrieved them, and collected the last data that he will ever contribute to this study.

Aside from dead birds, if you’d like to see what the team has been up to, please go visit Julie Ellis’ blog, The Gulls of Appledore, where I’ve tried to give an update on our activities here. Long days out here, but it’s been an utter joy as usual.

A hard day's work: at Smith's Cove.

A hard day’s work: at Smith’s Cove.





Appledore Island: Day One

14 05 2013

First, and in brief, there was broad, almost universal consensus on the Dead Bird Quiz: Bird A is an immature Bonaparte’s Gull and Bird B is a Snowy Egret (and Mary Wright even went a step further saying it’s an after-second-year (ASY) bird “based on the broad outer primaries.”) I buy this entirely since Mary knows her birds.

Carly (left) and Allie vie for resights.

Carly (left) and Allie vie for resights.

I won’t do my usual parsing of how we got to these identifications since I am now in an island mindset and all my usual responsibilities have gone out the window. Our gull sighting and banding team assembled on Appledore Island in Maine today and got right to work. Long-time guller Bill Clark, two undergraduates (Carly Emes and Allie Nadler) and yours truly are scouring the island looking for the banded gulls of Dr. Julie Ellis. Our focus this week is to find and document as many banded Herring Gulls and Great Black-backed Gulls as possible, note the locations of their nests, and, if their mates are not already banded, to band their mates too.

The weather is cool but lovely and most of the week should be much the same. We’re hoping for a spectacular run out here, and we’re off to a good start: 37 banded birds seen and sixteen nests tagged. Tomorrow, given a full day to work, who knows what kinds of numbers we’ll be posting. The fresh air, steady hiking and very hearty meals have a soporific effect; Carly is already asleep and the sun’s not yet quite set.  Gull banders don’t have to rise so inhumanly early as songbird banders, but still, we would do well to learn from our colleague’s example. So off to bed for me as well.

Until tomorrow, dear readers.

 

 





Dead Bird Quiz (new and revisited)

10 05 2013

We got a comment on a previous Dead Bird Quiz that gave me cause to revisit my i.d. I believe the comment is from birder Pam Hunt, as the commenter’s email traces back to this cool blog, Birding with Sacagawea. Pam (correct me if that’s not who you are, commenter!) wrote, “I’m pretty sure Bird B is NOT a woodcock. The pattern of bicolor on the bill is proportioned wrong, and the legs, toes, and tail are WAY too long for a woodcock. I’d concur with an earlier poster on Marbled Godwit, although the timing is VERY odd…” I took another look at the bird in light of that critique, and I see how the legs might appear quite long in this image, but I would maintain that this is one of the artifacts of death that tends to make dead birds appear very different from live ones. The legs are much more extended than they would ever have been in the bird’s life, making them look way too long for a woodcock. The feathers, however, extend almost all the way to the ankle joint. In a godwit, much more of the upper leg (tibiotarsus) would be bare. It’s hard to argue the point about bill color since the bill in our bird is turned so that we are seeing the lower bill from underneath. The point is well taken, though I find bill color in death seems to fade and alter rather quickly (dead gulls, for instance, tend to lose their characteristic bill coloration after a seemingly brief span in the elements.)

I post this since I very genuinely am no expert in shorebirds (including woodcock) so I would be most pleased if any of you wished to take a second look at that bird and see what you think.

As for this post, here’s another set of dead birds and bits for us to argue about!

Bird A, found by Wendy Stanton in North Carolina.

Bird A, found by Wendy Stanton in North Carolina.

Close up of the primary feathers (Wendy always provides excellent photo-documentation).

Close up of the primary feathers (Wendy always provides excellent photo-documentation).

Bird B, found by Kathleen Kelly in Maine. Underside of wing is also all white. Wing chord 27 cm.

Bird B, found by Kathleen Kelly in Maine. Underside of wing is also all white. Wing chord 27 cm.





SEANET Training coming up in South Carolina!

8 05 2013

Thanks to grant funding from the U.S. Fish and Wildlife Service, I will be traveling down to the Charleston, SC area for a volunteer training session on June 13th! Jennifer Koches, Craig Watson, and John Stanton have been hustling around to get us a venue, some prospective volunteers, and a sampler platter of museum specimens of seabirds. The session will take place at the Sewee Visitor and Environmental Education Center in Awendaw, SC.

Not a bad spot, the Sewee Center. (photo: Tricia Lynch/USFWS)

Not a bad spot, the Sewee Center. (photo: Tricia Lynch/USFWS)

Though I absolutely love visiting the Carolinas for any reason, it’s always an additional pleasure if we can fill a room with new recruits. So please help us spread the word! More details and contact information to RSVP can be found here.

In the meantime, I will be polishing up my powerpoint presentation and prepping answers to the ubiquitous southern question, “You’re not from around here, are you?” Nope. Most definitely not, but very happy to visit!