Subject: Birds and Gillnets
Date: Sep 29 18:06:44 1995
From: Jon Anderson - anderjda at dfw.wa.gov


Tweeters,

I placed this summary of the 1994 seabird/marine mammal studies into a
mailing to all Puget Sound commercial salmon license holders. The Natl
Marine Fisheries Service worked with WDFW, The Bureau of Indian Affairs,
several Treaty fishing Tribes, the Puget Sound Gillnetters Assoc., and
the Purse Seine Vessel Owners Association, to document sea bird and
mammal interactions in the most heavily-fished Washington salmon fishery:
that directed at the abundant Fraser River sockeye. U.S. fisheries
catches were 1.8 million sockeye.

1994 MARBLED MURRELET AND SEABIRD SAMPLING PROGRAMS

In 1994 major studies were undertaken to determine the extent of
seabird interactions with commercial salmon gear. Although the
studies focused on the marbled murrelet, since it is identified as
a threatened species under the Endangered Species Act, other
seabirds were observed as well.

Gillnet Observations: The gill net study involved the
collaborative efforts of the Puget Sound Gillnetters Association,
the Northwest Indian Fisheries Commission, Lummi Tribe, WDFW and
the National Marine Fisheries Service. Onboard observations of 400
vessel trips were needed to obtain a representative sample size of
the fishery. The actual number of observations totaled 443, with
269 nontreaty observations and 174 treaty observations. One
marbled murrelet was encountered during the study; the bird was
entangled in a gill net but released alive. In addition, the non-
treaty component encountered 195 other seabirds, mostly common
murres and rhinoceros auklets. Of those, 188 birds were
mortalities. Based on these observations the following table
displays expanded estimates for the fisheries. Approximately 75% of
seabirds encountered were common murres; 21% were rhinoceros
auklets.

Marbled Murrelet (Treaty and Nontreaty)
Areas 7/7A (Point Roberts/San Juan Islands)

Observed Vessel Trips: 443
Observed Encounters: 1 (This bird was released alive)
Entanglemt per set: 0.00045
Estimated Total Entanglemt: 15

Seabirds (Nontreaty Only)

Area 7/7A Area 7 Area 7A
Observed Vessel Trips: 259 80 189
Observed Encounters: 195 172 23
Entanglemt per set: 0.18 0.49 0.03
Estimated Total Entanglemt: 3,569 3,224 345

Purse Seine Observations: The program was conducted by Natural
Resources Consultants, Inc., under contract to the Purse Seine
Vessel Owners Association. A total of 1,194 sets were monitored
during the 1994 nontreaty sockeye purse seine fishery. Observer
coverage averaged 11% of the total fleet in Area 7/7A. No marbled
murrelets were observed either encircled or entrapped. A total of
98 other seabirds (97 rhinoceros auklets) were observed entrapped
and brought onboard, with five mortalities (all rhinoceros
auklets). Extrapolation of the observed seabird mortality to the
overall fleet produced an estimate of 45 rhinoceros auklets taken
during the 1994 Puget Sound sockeye fishery.

Paul Wade writes:

> Estimated take of marbled murrelets was low that year (15 estimated
entangled based on 1 observation) but it reads as if higher takes have
been observed in past years.

This was the first scientific look at sea bird bycatch in Washington
salmon fisheries. The only "study" to which we can compare it is the
estimate of marbled murrelet mortality done in Barkley Sound, B.C. by
Harry Carter and Spencer Sealy (1984. Marbled Murrelet mortality due to
gill-net fishing in Barkley Sound, British Columbia. Pages 212-220 in
D.N. Nettleship, GA Sanger and PF Springer, eds. Marine Birds: their
feeding ecology and commercial fisheries relationships. Spec. Publ. CWS,
Ottawa). In that study based on extrapolations of bird catches by 5
fishermen to the entire fleet, they found that intensive fishing in bird
concentration areas resulted in high mortality to the murrelets.

With the listing of the murrelet as Threatened under the ESA in 1992,
NMFS, the industry and the Tribes scraped together about $600K to study
the impact of the fishing fleet on the birds. As murrelets encounters
were expected to be somewhat rare, our biometricians designed the study
to determine statistically what the mortality would be in the most
intensive fishery that was associated with the most concentrated bird
populations - the Fraser sockeye fishery in the San Juans and Point
Roberts areas. I would have to look up the confidence intervals about
the point estimates for both the murrelets and the other species involved.

WDFW and the tribes hired dozens of observers, NMFS trained them, and
WDFW biologists Pam Erstad, Steve Jefferies, and John Pierce analyzed the
data and wrote the report - I believe the full report is available from John
Pierce - WDFW Wildlife Management in Olympia. This study was the first
comprehensive look at the situation in the Pacific Northwest, and
provides a pretty good baseline.

> I am not sure if all fisheries have been observed, either.

The reported bycatch was from the Fraser-origin sockeye fisheries in US
waters only. That was where the concentrations of birds and the
concentrations of fishing effort gave concern to the regulatory agencies,
environmental organizations, and the fishing industry.

Observations were also made during the chum-directed non-treaty fisheries in
South Puget Sound (Seattle/Tacoma) and in Hood Canal. I have not seen
the final numbers from those observations, but imagine that the bird
numbers were miniscule, because of the more dispersed bird numbers as
well as less intensive and more scattered effort by the fishing fleet
elsewhere in Puget Sound.

> Estimated takes of some other species were rhinoceros auklets (789),
and common murres (2,532). The take of murres may be of serious concern
because the breeding pop is estimated at 3000-7000 in WA.

Last Tuesday (9/26) I attended a seminar on fisheries bycatch prior to
the Fish Expo down at the Seattle Convention Center. Dr. Julia Parish of
the UDub (Univ of Wash, for 'outsiders') gave a presentation on
coast-wide murre status and distribution. She has studied the murre
colony at Tatoosh Island for the past 8 years.

She noted that the Wash. breeding population was in the neighborhood of
12-15,000 murres, similar to the breeding population at Langara (sp?)
Isl. in B.C. The Oregon populations are in the 700,000 range, and Calif's
population is about 360,000.

The Fraser sockeye fisheries take place through August. The Washington
coastal colonies fledge their chicks the 3rd and 4th week of August and
are generally *not* in the vicinity of most of the San Juans/Pt Roberts
fisheries. The birds that are likely impacted in the fisheries are those
from the Oregon colonies - the Three Arch Rocks birds fledge July 1-15 as
a rule and "dad" swims north to the Straits with "junior". "Mom" beats
feet when the kid jumps from the colony rock (how's that for women's
lib?). Anyhow, the catch of 2,500 murres from a population of 700,000 is
less than 1/2 of 1 percent - perhaps this loss is insignificant to the
population (compensatory mortality, etc.)? If the catch were composed of
a significant portion of the Washington Coast nesting birds, I think we
should all be screaming at USF&WS, WDFW, the Tribes, and the Canadian
Dept of Fisheries and Oceans to do something about it. But...

In 1995 WDFW closed a number of areas in the San Juan Islands, Saratoga
Passage, and in Hood Canal where numbers of marbled murrelets have been
observed in concentrations in areas subject to commercial net fishing.

Washington Sea Grant is working with the Puget Sound Gillnetters Assn to
develop gear which can significantly avoid bird impacts while still
catching harvestable runs of salmon. Ed Melvin of Sea Grant is principal
investigator on this work.

Anyway, I don't know if I've muddied the water on this one, or not, but
thought it might be of interest to the Tweets.

Jon. Anderson
Olympia, WA
anderjda at dfw.wa.gov