#### Evaluate Tangle Nets for Selective Fishing

Geraldine Vander Haegen

Erik White

Larry LeClair

Washington Department of Fish and Wildlife

Fish Program, Science Division

600 Capitol Way North

Olympia, WA 98501-1091

Grant Number: NA06FD0278

November 13, 2023

### 

#  

[ABSTRACT 2](#abstract)

[EXECUTIVE SUMMARY 3](#executive-summary)

[PURPOSE 3](#purpose)

[APPROACH 4](#approach)

[General Methods 4](#general-methods)

[Budd Inlet -2000 7](#budd-inlet--2000)

[Budd Inlet - 2001 7](#budd-inlet---2001)

[Miller Bay - 2000 8](#miller-bay---2000)

[Puyallup River - 2000 9](#puyallup-river---2000)

[FINDINGS 9](#findings)

[Budd Inlet - 2000 9](#budd-inlet---2000)

[Budd Inlet 2001 11](#budd-inlet-2001)

[Miller Bay - 2000 13](#miller-bay---2000-1)

[Willapa River - 2000 14](#willapa-river---2000)

[Puyallup River - 2000 17](#puyallup-river---2000-1)

[EVALUATION 17](#evaluation)

[General Conclusions 17](#general-conclusions)

[Objective 1 18](#objective-1)

[Objective 2 18](#objective-2)

[Objective 3 19](#objective-3)

[Objective 4 19](#objective-4)

[REFERENCES 20](#references)

[ACKNOWLEDGEMENTS 21](#acknowledgements)

#   {#section-2 .unnumbered}

# ABSTRACT

Live capture, selective harvest may be one method to reduce the impacts
of commercial salmon fishing on weak stocks, while enabling fishers to
continue to harvest salmon from strong stocks. In fall 2000 and 2001, we
contracted local gill net fishers to fish nets that were half tangle net
and half conventional gill net to evaluate the merits of the tangle net
for harvesting coho salmon (*Oncorhynchus kisutch*) and fall chinook
salmon (O*. tschawytscha*). We compared the catch efficiency, immediate
mortality, post-release mortality, and capture of non-target species in
each net. Results were mixed between test sites. The tangle net showed
lower catch efficiency for fall chinook than the gill net, with little
improvement in immediate survival. However, the tangle net was as
efficient at capturing coho salmon as the gill net, and the immediate
mortality and capture of by-catch were similar. Tangle nets require
further testing as a live capture, selective harvest gear, but show
promise for capturing salmon.

###  

# EXECUTIVE SUMMARY

Protecting week salmon stocks in the Pacific Northwest has required
unprecedented restrictions of the commercial fishing industry. In a
mixed stock fishery, gear restrictions and time and area closures are
effective management techniques for avoiding non-target species, but
when many weak stocks are present, these strategies can restrict all
fishing. A possible alternative strategy is the use of live capture,
selective harvest techniques that would allow fishers to release
non-target species or stocks with a reasonable expectation for survival
after release. This technique, known as "selective fishing" would reduce
impacts to weak stocks that may be listed as threatened or endangered
under the Endangered Species Act, while allowing harvest on strong
stocks. We evaluated tangle nets as an alternative gear to the gill net
for selective harvest of coho salmon and fall chinook salmon in the
Pacific Northwest.

In fall 2000 and 2001, we contracted local gill net fishers to fish nets
that were half tangle net and half conventional gill net to evaluate the
merits of the tangle net as a commercially selective technique for
harvesting coho salmon (*Oncorhynchus kisutch*) and fall chinook salmon
(O*. tschawytscha*). We compared the catch efficiency, immediate
mortality, post-release mortality and capture of non-target species in
each net.

In our test fisheries, the tangle nets were an unsatisfactory substitute
for capturing fall chinook salmon. Their catch efficiency was low
compared to the gill net, and we encountered many more non-target
species in the tangle net than in the gill net. Due to poor tag
recoveries, our estimates of post-release survival from each net are
inconclusive, but suggest an advantage to fish released from the tangle
net. This aspect merits further studies, and positive results might be
obtained using different net configurations in different locations.

The tangle net did show promise for capturing coho salmon. On the
Willapa River, the tangle net was as effective at capturing coho salmon
as the gill net, with a slightly improved condition at capture. Further
research about the post-release survival of coho is necessary to
determine whether the released fish survive to complete their migration
and successfully spawn.

# PURPOSE

Effective management of mixed-stock salmon fisheries in the Pacific
Northwest relies on the ability to maximize the harvest of strong stocks
while preventing the overexploitation of weak stocks, some of which may
be listed as threatened or endangered under the Endangered Species Act.
Achieving escapement goals for weak stocks often requires the
implementation of more restrictive harvest regulations that result in a
surplus escapement of fish from strong stocks. The development of
methods that enable fishers to selectively harvest strong stocks without
jeopardizing weak stock recovery efforts is a key element in Pacific
salmon conservation strategy. If non-target stocks can be returned to
the water with reasonable certainty that their spawning migration will
not be affected through capture and release, then restrictions governing
the spatial and temporal limitations of the fishery may be relaxed,
enabling more opportunity for harvest from strong stocks. In this study,
we explored the feasibility of using a tangle net to decrease the
capture-related mortality of non-target stocks. In Washington, hatchery
coho and chinook salmon have been marked by removal of the adipose fin,
allowing fishers to visually distinguish them from the unmarked natural
populations.

Conventional gill nets are routinely constructed from single-strand
monofilament web and the mesh is sized to capture targeted fish by the
gill plates or body. Capturing fish by the gills or body often results
in extensive tissue damage and bleeding that may kill the fish, or
constriction of the gill plates that leads to death through suffocation.
Tangle nets are constructed from multi-strand webbing with reduced mesh
size. Rather than capturing fish by the gills or body they are designed
to ensnare fish by the maxillary and teeth, thus enabling the fish to
continue to respire while in the net, facilitating live release of the
unharvestable fish (Figure 1). Despite their differences in material and
construction, both nets are fished in the same manner.

![](media/image1.wmf)

Figure 1: Conventional monofilament gill net (left) and the multi-strand
tangle net (right).

In our evaluation, we simultaneously fished the tangle net with a
conventional gill net to compare characteristics of the two. We had four
objectives: 1) Estimate the catch per set for the tangle net and
conventional gill net; 2) Estimate the proportion of fish caught in the
tangle net and in the conventional gill net that is brought aboard dead;
3) Estimate the percentage of fish released from the tangle net and
conventional gill net that survived to complete their migration; and 4)
Coordinate our activities with fishery co-managers and fishers.

# 

# APPROACH

## General Methods

Fishing sites in Budd Inlet, Miller Bay, the Willapa River, and the
Puyallup River were selected for testing the nets (Figure 2). These
sites were chosen primarily based on historic run size and timing,
proximity to hatcheries, and cooperation from local fishers. At each
site, we compared immediate mortality, by-catch and catch efficiency of
the tangle net to a conventional gill net appropriate for that site. In
Budd Inlet, we cooperated with the Squaxin Island Tribe targeting fall
chinook salmon returning to Tumwater Falls Hatchery and released tagged
fish to estimate post-release survival. In Miller Bay, we cooperated
with the Suquamish Tribe, targeting fall chinook salmon returning to
Grovers Creek Hatchery, and released tagged fish to estimate
post-release survival. We cooperated with the Puyallup Tribe targeting
coho salmon returning to the Puyallup River. Finally, we worked with
non-treaty fishers on the Willapa River targeting coho salmon returning
to Forks Creek Hatchery.

![](media/image2.wmf)

Figure 2: Test fishing locations.

Local fishers familiar with each area and with gillnetting techniques
tested nets that consisted of one panel of tangle net, and one panel of
conventional gill net, with each panel the same length. The panels were
connected with shackles at the top and bottom, so that an opening formed
between the two net types in the center. The opening ensured that fish
attempting to avoid one panel could escape without being directed
toward, and possibly captured by, the other, biasing catch rate
estimates. In Budd Inlet, Miller Bay, and the Willapa River, we
contracted local fishers, and paid them on a per day basis so that we
could release all live fish. On the Puyallup River, members of the
Puyallup Tribe volunteered to fish dual panel nets and kept the fish as
compensation. In Budd Inlet and Miller Bay, dead fish were donated to
the cooperating tribe, and on the Willapa River, dead fish were sold to
a local buyer.

Fishers were responsible for selecting the time and location within
sites. Washington Department of Fish and Wildlife and tribal observers
were on board fishing vessels to tag fish, take biological data and
record other observations. Each vessel was equipped with a recovery box
made from ¾" plywood painted black (Figure 3). The recovery boxes were
built with two compartments for holding fish. Each compartment was about
42" long, 16" high and 7.5" wide. The compartments of the recovery box
were wide enough to allow a salmon to fit with its head facing the fresh
water flow but narrow enough to prevent the fish from turning around. A
12 V, 3800 gallon/h submersible bilge pump was connected to a 1.5"
discharge hose which supplied fresh water through pipes located at the
bottom of the box. Overflow outlets were located at the opposite end of
the recovery box. When the fish was judged ready for release, it was
gently lifted out of the box and placed overboard.

![](media/image3.jpeg){width="4.766666666666667in"
height="3.5694444444444446in"}

Figure 3: Recovery box used for reviving fish after capture. The fish is
oriented with its mouth into the flow of fresh water.

For each set, observers recorded the skipper, time, set length (the time
between when the first float entered the water and the last float was
removed), location (using a handheld GPS unit), weather conditions,
water temperature, and noted the presence of seals. For each fish
captured, we recorded the species, fork length, sex, net type where it
was captured and the condition of fish at capture and release. We used
numbers to represent the condition at capture as follows: 1 (vigorous),
2 (vigorous and bleeding), 3 (lethargic), 4 (lethargic and bleeding), or
5 (no visible movement or apparent ventilation). In Budd Inlet and
Miller Bay, fish receiving scores of 1 or 2 were immediately tagged with
colored, numbered jaw tags and released. The net type was associated
with a specific tag color, and the number referred to a specific fish.
Fish receiving scores greater than 2 were transferred to a recovery box
in an attempt to revive them. If revival was successful, the condition
of the fish was re-scored, then the fish was tagged and released. The
total time in the recovery box was recorded. No fish were tagged during
the Willapa River and Puyallup River test fisheries and lengths were not
taken for fish captured from the Puyallup River, otherwise, data
collection and handling was the same among sites (after revival, all
live fish captured on the Willapa River were released, and all coho
salmon captured on the Puyallup River were harvested).

## Budd Inlet -2000

To target fall chinook salmon in Budd Inlet in 2000, we used a net
consisting of one 300 foot panel net of 3.5" tangle net shackled to one
300 foot panel of 6.5" gill net. Both panels fished to a depth of 32
feet. The overall length, depth and color were similar to that
ordinarily used by commercial fishers in this fishing area. A Squaxin
Island Tribe fisher was contracted to fish the nets south of a line
extending from Cooper Point, east to Dover Point. The fisher had
extensive local knowledge and experience commercial fishing in the test
fishing area. The net was deployed and retrieved by hand from an open,
gas-powered skiff. Deploying the net typically took fewer than 5
minutes. Because the net had to be pulled by hand, it was impractical to
keep the sets short. Rather, once the net was fully deployed, the float
line was monitored from one end for cork line movement that would
indicate the presence of a fish. The entire net was also periodically
patrolled from end to end to remove debris and check for captured fish
that might otherwise have gone unnoticed**.** We recorded the time at
which each fish was captured. Fishing occurred on 11 nights between
August 18 and September 8 from 1900 h to 0400 h, except one time when we
fished from 0200 h to 0700 h.

Most of the Budd Inlet chinook run is presumed to be bound for Tumwater
Falls Hatchery on the Deschutes River, approximately one river kilometer
upstream of the mouth at the extreme south end of the inlet. Tag
recovery efforts included daily checks of salmon returning to the
hatchery throughout the duration of the run and weekly surveys on the
Deschutes River between the hatchery and the river mouth. Additionally,
other hatcheries in the south Puget Sound region, commercial and
recreational fishers, and spawning ground surveyors were alerted to
potential encounters with jaw tagged fish and were asked to report tag
numbers along with the date and location of capture.

## Budd Inlet - 2001

In 2001, we repeated our work in Budd Inlet, but attempted to increase
the number of tags we would recover by increasing our fishing effort and
tag recovery searches. We contracted with two Squaxin Island Tribe
fishers to fish in Budd Inlet in the same area and in the same manner as
in 2000. One fisher had a net with a 300-foot tangle net panel (4.5"
mesh) shackled to a 300-foot panel of 6.5" mesh gill net while the other
used 7.5\" mesh gill net. We changed to the 4.5" tangle net to attempt
to improve catch efficiency and reduce bycatch. The tangle net was
lighter in color than the gill net.

As in 2000, the net had to be pulled by hand, so once the net was fully
deployed, the float line was monitored from one end for cork line
movement that would indicate the presence of a fish. The entire net was
also periodically patrolled from end to end to remove flotsam and check
for captured fish that might otherwise have gone unnoticed**.** When
multiple sets were made, alternate ends of the net were deployed first,
in order to ensure approximately equal fishing time for each net type.
All fishing occurred between dusk and dawn over 32 boat-nights between
August 6 and September 8, 2001 with two boats fishing concurrently on 10
nights. On all but one occasion, the nets were allowed to drift with the
current. During the exception, the tangle net panel was made fast to the
beach and the net was held perpendicular to the shore for the duration
of the set. Fish were handled and tagged in the same way as in 2000.

Tag recovery efforts included daily checks of salmon returning to
Tumwater Falls Hatchery throughout the duration of the run and weekly
surveys on the Deschutes River between the hatchery and the river mouth.
Additionally, other hatcheries in the south Puget Sound, commercial and
recreational fishers, and spawning ground surveyors were alerted to
potential encounters with jaw tagged fish and were asked to report tag
numbers along with the date and location of capture. We expanded
recovery survey effort to include surveys on Percival Creek, a tributary
to Budd Inlet. A barrier installed at the mouth of the creek was in
place until October 16, 2001 when it was removed and fish could access
the creek. Stream surveys were done on the Deschutes River one hour each
week for 6 weeks and for 2 hours on three occasions on Percival Creek.

## Miller Bay - 2000

To target chinook salmon returning to Grovers Creek Hatchery, we net
with a 150-foot panel of 7.5" mesh gill net shackled to a 150-foot panel
of 3.5" mesh tangle net. The net fished to a depth of about 60 feet. The
overall length, depth and color were similar to that ordinarily used by
local commercial fishers to harvest chinook.

A Suquamish Tribe commercial gill netter was contracted to fish the net
within 1 mile of the mouth of Miller Bay. The net was fished from a 30\'
commercial fishing vessel equipped with a single deck-mounted hydraulic
reel used to deploy and retrieve the gear. Set length ranged from 25-80
minutes. Deployment generally took fewer than five minutes and the net
was usually allowed to drift freely. However, during inclement weather
the net was anchored. Between sets, the ends of the net were reversed so
that each net type would be fished equally in each location. Fishing
occurred between 1800 h and 0100 h over 9 boat-nights between August 17
and October 5, 2000.

A salmon hatchery located on Grover\'s Creek near the head of Miller Bay
was monitored for tag recoveries. Additionally, the tidal flats at the
mouth of Grover\'s Creek were surveyed for tagged chinook salmon each
week during low tide.

**Willapa River - 2000**

On the Willapa River, we evaluated a net consisting of a 540-foot of
3.5\" mesh tangle net shackled to a 540-foot panel of 5.75\" mesh gill
net to target coho salmon returning to Forks Creek Hatchery. Experienced
local fishers using commercial vessels equipped with deck mounted
hydraulic reels fished the nets. The nets were laid out across the river
in a typical curved pattern, and were retrieved to collect fish. The
ends of the nets were switched between sets so that each net type was
fished equally in each location. The overall length, depth, and color of
the net were similar to that ordinarily used by local fishermen to
harvest coho from the Willapa River. Each day, we fished with one
skipper in the morning and the other in the afternoon between September
11 and 15, then with one boat October 17 and 18, and one boat November 8
and 9.

## Puyallup River - 2000

On the Puyallup River, we evaluated a net consisting of a 50-foot panel
of 5" mesh gill net shackled to a 50-foot panel of 3.5" mesh tangle net
to target coho salmon. The net fished to a depth of about 14 feet. The
overall length, depth, and color of the net were similar to that
ordinarily used by local fishers to harvest coho from the Puyallup
River. The net was fished from an open 23\' power skiff. Set length
ranged from 5-60 minutes. Deployment generally took less than 2 minutes
and the net was allowed to drift freely downstream with the current for
the duration of the set. All fishing occurred between 0900 h and 1600 h
from river mile 5.8 to 1.8. This site was fished on 4 days, September
28, October 3, October 18, and November 3.

# FINDINGS

## Budd Inlet - 2000

A total of 130 adult chinook salmon were captured, with 102 (73.4%) in
the gill net and 37 (26.6%) in the tangle net. An additional 9 jacks
(immature males) were captured in the tangle net, of which 3 died before
release. The immediate mortality (fish which could not be revived for
release) of adult chinook salmon was not significantly different between
the gill net (40.2%, N=41) and the tangle net (21.4%, N=6;
Chi-square=2.60, df=1, P=0.11). In each case, 22% of the dead adult fish
showed evidence of having been killed by seals (major tissue trauma,
particularly bites in stomach and gill areas). Seals were observed
hunting in the vicinity of the nets each time we fished, and were seen
actively removing fish from the nets, and chasing fish into the nets.

Adult chinook salmon captured in the tangle net tended to be in better
condition than those captured in the gill net (Table 1). Few fish
removed from the tangle net were bleeding at capture. Bleeding tends to
be caused by the mesh cutting the gills, a capture method avoided by the
tangle net. In contrast, more fish captured in the gill net were
bleeding at capture, and a large proportion were lethargic (conditions 3
and 4) at capture, likely resulting from having the net closed around
their gills. Virtually every adult chinook salmon captured in the gill
net had net marks around the body in front of the dorsal fin or around
the gills, and virtually every adult captured in the tangle net had net
marks around the snout. Net marks on the body tended to be severe --
scales were dislodged and missing, and the underlying skin was often
abraded and red. While not visible, a loss of the protective slime layer
would be associated with this injury. Net marks from the tangle net
tended to be less severe as the snout does not have easily dislodged
scales. The marks tended to be dark lines where the net pressed on the
skin, and tended to be on the lower snout and jaw. The slime layer on
some of these fish may have been disturbed if they rubbed against the
net, or if the fish rolled itself into the net.

Table 1: Condition at capture and revival of chinook salmon captured in
the Budd Inlet test fishery in 2000. "% Cap" is the percentage of fish
scored in each condition at capture, "% Rel" is the percentage in each
category that were released live, and N is the number captured in each
condition at capture.

  -------------------------- -------- ------ ---- -------- ----- ---- ------- ----- ---
  Condition at Capture       6.5"                 3.5"                3.5"          
                             mesh,                mesh,               mesh,         
                             Adults               Adults              Jacks         

                             \% Cap   \% Rel N    \% Cap   \%    N    \% Cap  \%    N
                                                           Rel                Rel   

  1 (Lively)                 16.7     100    17   60.7     100   17   22.2    100   2

  2 (Lively, bleeding)       5.9      100    6    7.1      100   2                  0

  3 (Lethargic)              27.5     89.3   28   10.7     100   3    44.5    100   4

  4 (Lethargic, bleeding)    17.7     72.2   18   0              0                  0

  5 (No visible movement or  32.4     0      33   21.4     0     6    33.3    0     3
  ventilation)                                                                      
  -------------------------- -------- ------ ---- -------- ----- ---- ------- ----- ---

Revival of fish in conditions 2 and 3 was generally successful after a
short holding period in the recovery box (Table 1). We were unable to
revive any fish captured in condition 5 from either of the net types.
These fish included those injured by seals, but also fish that appeared
to have been in the nets for an extended period, or fish that were
captured in a manner that clamped their gills or mouth shut. In some
cases, the fish were missed during net checks, or if fish were captured
while we were picking up the net, it was impossible to get to them in a
timely manner.

There was a difference in the percent of male and female chinook caught
in each net. In the gill net, the ratio was nearly equal with 48.5%
females and 51.5% males. In contrast, 75.7% of the fish caught in the
tangle net were males (24.3% females). This difference is attributable
to the more developed kype in males making them more susceptible to
capture in the tangle net than females. The fork lengths of fall chinook
salmon captured in the gill net (mean fork length 77.6 cm, N=98) were on
average significantly larger than those captured in the tangle net (mean
fork length 71.1, N=37; df= 43, t=2.14, P=0.02). This difference is
mainly attributable to the presence of jacks (early maturing males) in
the tangle net that would pass through the gill net unimpeded.

We released 59 fish with tags from the gill net and 27 from the tangle
net. We recovered only 2 tags, both at Tumwater Falls Hatchery, and both
from fish captured in the gill net. This tells us little about the
post-release survival of chinook salmon, and while it is certain that
some proportion of the captured fish died after release, it is
impossible to estimate this proportion, the potential causes of death,
or what the difference between the net types may be. One concern is the
number of predatory seals in the area. We suspect that even fish that
swim vigorously away from the boat after release may be highly
susceptible to predation because they have been severely stressed by
capture without sufficient time for complete physiological recovery
(Farrell et al. 2000). This could result in impaired swimming ability or
disorientation.

While fishing, we recaptured four fish that had been previously tagged
that same night. All died after the second capture, which was from 2-3
hours after the original capture. We suspect that the stress effects of
multiple recaptures would reduce the probability of recovery. Bringing
fish on board in the best possible condition is imperative.

During our test fishery, we found the 6.5" mesh to be relatively species
selective -- few species other than chinook were captured (Table 2). In
contrast, the smaller 3.5" mesh captured many smaller fish that would
have passed through the 6.5" mesh unimpeded, as well as jellyfish. Not
only is this higher level of by-catch detrimental to those species, but
the time required to remove them from the net also increased the time
until the target species could be removed and would reduce their
survival.

Table 2: Bycatch of non-salmonids in the nets during test fishing in
Budd Inlet. Because it was virtually impossible to record all of the
bycatch, these numbers are more indicative of presence or absence than
the actual numbers captured.

  ----------------- ------------------- ----------------------------------
  Species           6.5" mesh           3.5" mesh

  Dogfish           22                  76

  Flounder          1                   

  Ratfish           1                   16

  Crab                                  Numerous, uncounted

  Jellyfish                             Numerous, uncounted

  Shad                                  1

  Sole                                  3
  ----------------- ------------------- ----------------------------------

## Budd Inlet 2001

We captured 165 fall chinook salmon, 115 (70%) in the 6.5" and 7.5" gill
nets and 50 (30%) in the tangle net. Thirty-eight died before they could
be released. There was no significant difference between the immediate
mortality rates of the gill net (19.1%, N=22) and the tangle net (32.0%,
N=16; Chi-square =2.57, df=1, P=0.11). Long soak times (because the nets
were worked manually and could not be removed for frequent inspections)
and high surface water temperatures during test fishing (15-20 ^o^C)
likely contributed to the high immediate mortality. Seven chinook salmon
were captured twice during our test fishery. Five of these were in the
conventional gill net and two were in the tangle net. These fish were
included in our totals because they were at liberty for more than two
hours and were released in condition 1.

Fall chinook salmon captured in the gill net were captured in similar
conditions to the tangle net, and we were successful at reviving fish in
conditions 2 through 4 for all nets, as well as a large percentage of
fish captured in condition 5 in the 6.5" gill net (Table 3). We were
unsuccessful at reviving any fish captured in condition 5 from the
tangle net, or the 7.5" gill net. Most chinook that died after capture
in the gill nets had been captured by gilling, while most of those that
died after capture in the tangle net had been captured by tangling
(Table 4). Seal predation continued to be a problem during our test
fishery. Seals killed 14% of the fish brought on board, and may have
killed others without leaving remains.

Table 3: Condition at capture and revival of chinook salmon captured in
the Budd Inlet test fishery in 2001. "% Cap" is the percentage of fish
scored in each condition at capture, "% Rel" is the percentage in each
category that were released live, and N is the number captured in each
condition category. Condition 5 includes fish killed by seals.

  ------------------------- ------ ------ ---- ------ ------ ---- ------ ------ ----
  Condition at Capture      7.5                6.5                4.5           

                            \% Cap \% Rel N    \% Cap \% Rel N    \% Cap \% Rel N

  1 (Lively)                30.4   100    21   50.0   100    23   30.6   100    15

  2 (Lively, bleeding)      8.7    83.3   6    6.5    100    3    8.2    100    4

  3 (Lethargic)             30.4   95.2   21   17.4   100    8    34.7   88.2   17

  4 (Lethargic, bleeding)   15.9   100    11   6.5    66.7   3    2.0    0      1

  5 (No visible movement or 14.5   0      10   19.6   11.1   9    24.5   0      12
  ventilation)                                                                  
  ------------------------- ------ ------ ---- ------ ------ ---- ------ ------ ----

Table 4: Capture type and recovery of chinook salmon captured during
test fishing in Budd Inlet in 2001.

  ------------------ ---------- ------ ---------- ------ ---------- ------
  Capture Type       7.5               6.5               4.5        

                     Released   Died   Released   Died   Released   Died

  Gilled             37         6      15         6      1          2

  Mouth Clamped      1          0      0          0      0          1

  Rolled             1          0      2          0      4          0

  Tangled            7          1      0          0      20         7

  Wedged             6          0      10         0      0          0

  Total              52         7      27         6      25         10
  ------------------ ---------- ------ ---------- ------ ---------- ------

The mean fork lengths of chinook salmon captured in the tangle net (72.4
cm, N=39) were similar to those captured in the 6.5" gill net (72.8 cm,
N=39; df=76, t=0.24, P=0.40), but significantly smaller than those
captured in the 7.5" gill net (78.0 cm, N=53; df=90, t=3.6, P=0.0002).
As we saw in 2000, the number of non-target species captured was
considerably higher in the tangle net than in the gill nets (Table 5).
With its smaller mesh size, the tangle net was particularly effective at
capturing small dogfish that would have passed through the gill nets
unimpeded.

Table 5: Bycatch of non-target species captured during test fishing in
Budd Inlet in 2001.

  -------------------- ---------------- ---------------- ----------------
  Species              4.5\" net        6.5\" net        7.5\" net

  Dogfish              414              26               7

  Flounder             1                0                0

  Shad                 2                0                0
  -------------------- ---------------- ---------------- ----------------

We tagged and released 90 chinook salmon from the gill nets and 36 from
the tangle net. We recovered 10 tags from each group, significantly more
from the tangle net (27.8%) than the gill net (11.1%; Chi-square=4.17,
df=1, P=0.041). Nineteen were recovered at Tumwater Falls Hatchery on
the Deschutes River and one at Minter Creek Hatchery on Purdy Creek,
north of the fishing area. The tagged fish were recovered between 20 and
48 days after release and had been captured in condition 1 (73.3%),
condition 2 (6.7%) or condition 3 (20.0%). The fish captured in
conditions 2 and 3 had been revived in the recovery box for a short time
and released in condition 1.

## Miller Bay - 2000

Fifteen chinook salmon were captured from 38 separate sets made on 9
days between August 17 and October 5. Thirteen were captured in the gill
net and two in the tangle net. There were two immediate mortalities, one
from each net type (Table 6). In both instances the fish were judged not
suitable for revival efforts due to substantial damage to the gill
tissue and surrounding skeletal structures. Thirteen chinook were tagged
and released. Three were recovered at the hatchery; two had been
captured on 17 Aug and recovered after 29 days at liberty; the third had
been captured on 28 Aug, was recovered after 28 days. They were all
originally captured in the gill net; scored as 1, 2, and 3 respectively
at the time of capture; and all were released in condition 1. The
condition 3 fish was revived in the recovery box for 7 minutes before
release. Of the four remaining fish that were transferred to the
recovery box, three, including one fish that was scored as a 5 at time
of capture, experienced notable improvements in condition and were
released in condition 1. The fourth (scored as a 3) showed no
improvement after 1.5 hours in the recovery box.

Table 6: Condition at capture and revival of chinook salmon captured in
the Miller Bay test fishery in 2000. "# Captured" is the number of fish
scored in each condition at capture, "# Released" is the number in each
category that were released live.

  -------------------------------- ---------- ---------- ---------- ----------
  Condition at Capture             7.5"                  3.5"       

                                   \#         \#         \#         \#
                                   Captured   Released   Captured   Released

  1 (Lively)                       7          7          0          0

  2 (Lively, bleeding)             1          1          0          0

  3 (Lethargic)                    2          2          1          1

  4 (Lethargic, bleeding)          2          1          0          0

  5 (No visible movement or        1          1          1          0
  ventilation)                                                      
  -------------------------------- ---------- ---------- ---------- ----------

A total of 811 non-targeted animals were captured in the tangle net and
37 were captured in the gill net. Incidentally harvested species
included spiny dogfish (*Squalus* *acanthias*), ratfish (*Hydrolagus*
*colliei*), sand sole (*Psettichys* *melanostictus*), starry flounder
(*Platichthys* *stellatus*), American shad (*Alosa* *sapidissima*),
Pacific herring (*Clupea* *pallasii*), Pacific cod (*Gadus*
*macrocephalus*), red rock crab (*Cancer* *productus*), and Dungeness
crab (*Cancer* *magister*). Most of the difference in incidental capture
between the two mesh types can be attributed to an increased capture
rate of spiny dogfish in the tangle net which was nearly three orders of
magnitude greater than that of the gill net. In addition, more than ten
times as many ratfish and sole were captured in the tangle net. Six of
the nine non-targeted species were captured in the gill net.

The number of non-target fish that are of little or no value to the
fisher is an important consideration in the comparative analysis of the
two net types. Managing incidental harvest is labor intensive and
curtails the amount of time productively spent capturing and managing
species of greater value to the fisher. While incidentally harvested
species may be of little value to the fisher, their ecological
importance is often poorly understood. Increasing the mesh size of the
tangle net may help to reduce the number of non-target fish caught, as
well as possibly improve the catch efficiency.

So few chinook were caught in this fishery that we stopped fishing
before the intended end of the project. The results suggest the tangle
net may be less efficient, but because there was such a low abundance,
little can be concluded. The use of monofilament tangle nets should be
reviewed as a possible solution for managing non-target species. No
conclusions about the effect of capture and release on long-term
survival can be drawn given the small number of fish tagged. While it
appears that fish landed in poor condition may derive some short-term
benefit from placement in the recovery box, it is not clear to what
extent these fish derive long-term benefit.

## Willapa River - 2000

We fished 2 boats per day for 5 days in September before the regular
commercial fishery opening in this area, then two more days with one
boat after the opening in October and 2 days with the other boat in
November. The net was made from one shackle of 3.5\" tangle net, and one
shackle of 7.25\" monofilament similar to the nets ordinarily used in
this areas for coho. Fish caught in this fishery were not tagged, but
biological data was collected before release.

During the fishery, we caught 773 salmon, and the tangle net caught as
many as the conventional gill net (Table 7). The abundance of fish was
very high in the September fisheries, and even very short sets yielded
good numbers of fish in both nets. In this fishery, the tangle net
improved condition at capture, particularly for chinook (Table 8). Of
the chinook caught in the gill net, 57 were not ranked as condition 1,
and of those, we were able to revive 72% to release. Of the chinook
caught in the tangle net, 36 were not ranked as condition 1, and we were
able to revive 83% of those to release. Of the coho caught, 190 and 159
were not ranked as condition 1 from the gill net and tangle net,
respectively. In each case, we were able to revive about 63% to release.

Table 7: Catch summary for the Willapa River test fishery.

  ----------- ----- --------- -------- ------ -------- ----------- -------- ------ --------
  Date        Sex   Chinook            Coho            Steelhead            Chum   

                    Gill      Tangle   Gill   Tangle   Gill        Tangle   Gill   Tangle

  11-Sep-00   F     5         3        21     18       0           0        0      0

              M     14        8        39     54       0           0        0      0

  12-Sep-00   F     4         8        12     10       0           2        0      0

              M     5         6        39     53       0           0        0      0

  13-Sep-00   F     15        11       45     29       1           2        0      0

              M     15        15       41     43       2           1        0      0

  14-Sep-00   F     4         10       19     23       0           1        0      0

              M     5         2        27     31       1           0        0      0

  15-Sep-00   F     5         6        15     6        4           1        0      0

              M     6         4        16     17       0           0        0      0

  17-Oct-00   F     0         0        1      0        1           0        1      1

              M     0         0        1      0        0           0        1      0

  18-Oct-00   F     0         0        5      2        0           0        1      0

              M     1         2        3      6        0           0        1      1

  08-Nov-00   F     0         0        3      2        0           0        0      1

              M     0         0        2      2        0           0        0      1

  09-Nov-00   F     0         0        1      2        0           0        0      0

              M     0         0        5      2        0           0        0      0

  Total             79        75       295    300      9           7        4      4
  ----------- ----- --------- -------- ------ -------- ----------- -------- ------ --------

Table 8: Condition at capture and revival of chinook salmon captured in
the Willapa River test fishery in 2000. "% Cap" is the percentage of
fish scored in each condition at capture, "% Rel" is the percentage in
each category that were released live, and N is the number captured in
each condition category.

<table style="width:100%;">
<colgroup>
<col style="width: 21%" />
<col style="width: 7%" />
<col style="width: 7%" />
<col style="width: 4%" />
<col style="width: 7%" />
<col style="width: 7%" />
<col style="width: 4%" />
<col style="width: 7%" />
<col style="width: 7%" />
<col style="width: 4%" />
<col style="width: 7%" />
<col style="width: 7%" />
<col style="width: 4%" />
</colgroup>
<tbody>
<tr class="odd">
<td rowspan="3"><p>Condition at</p>
<p>Capture</p></td>
<td colspan="6">Chinook</td>
<td colspan="6">Coho</td>
</tr>
<tr class="even">
<td colspan="3">5.75” Gill</td>
<td colspan="3">3.5” Tangle</td>
<td colspan="3">5.75” Gill</td>
<td colspan="3">3.5” Tangle</td>
</tr>
<tr class="odd">
<td>% Cap</td>
<td>% Rel</td>
<td>N</td>
<td>% Cap</td>
<td>% Rel</td>
<td>N</td>
<td>% Cap</td>
<td>% Rel</td>
<td>N</td>
<td>% Cap</td>
<td>% Rel</td>
<td>N</td>
</tr>
<tr class="even">
<td>1 (Lively)</td>
<td>26.9</td>
<td>100</td>
<td>21</td>
<td>51.4</td>
<td>100</td>
<td>38</td>
<td>35.4</td>
<td>100</td>
<td>104</td>
<td>46.3</td>
<td>100</td>
<td>137</td>
</tr>
<tr class="odd">
<td>2 (Lively, bleeding)</td>
<td>2.6</td>
<td>100</td>
<td>2</td>
<td>5.4</td>
<td>100</td>
<td>4</td>
<td>6.1</td>
<td>100</td>
<td>18</td>
<td>1.7</td>
<td>100</td>
<td>5</td>
</tr>
<tr class="even">
<td>3 (Lethargic)</td>
<td>51.3</td>
<td>80.0</td>
<td>40</td>
<td>31.1</td>
<td>95.7</td>
<td>23</td>
<td>31</td>
<td>78.0</td>
<td>91</td>
<td>35.8</td>
<td>79.2</td>
<td>106</td>
</tr>
<tr class="odd">
<td>4 (Lethargic, bleeding)</td>
<td>5.1</td>
<td>100</td>
<td>4</td>
<td>6.8</td>
<td>60.0</td>
<td>5</td>
<td>8.8</td>
<td>88.5</td>
<td>26</td>
<td>2.4</td>
<td>71.4</td>
<td>7</td>
</tr>
<tr class="even">
<td>5 (No visible movement or ventilation)</td>
<td>14.1</td>
<td>27.3</td>
<td>11</td>
<td>5.4</td>
<td>25.0</td>
<td>4</td>
<td>18.7</td>
<td>10.9</td>
<td>55</td>
<td>13.9</td>
<td>14.6</td>
<td>41</td>
</tr>
</tbody>
</table>

For each species, we observed a higher mortality rate for fish caught in
the gill net than for fish caught in the tangle net. However, the
overall survival of coho caught in the tangle net was still lower than
we had expected from other experiments done in British Columbia. We
found that the coho were very sensitive to handling during the September
fishery and were unable to withstand stress. They were silver-bright,
still had sea lice on them, and descaled easily. These were clearly fish
arriving freshly from the ocean - a physiological stage that is known to
make fish susceptible to stress. Furthermore, because of the abundance
of fish, and our goal of releasing all fish live, we were frequently
inundated by fish and unable to keep pace with reviving fish, collecting
data, and releasing the fish, in spite of set times as short as 5
minutes. We also made sure to complete the processing of all fish from
one set before beginning another. In the other studies, coho that were
to be revived were not encountered at this rate, allowing more care per
fish during the critical first minutes, and those studies were not done
on fish during the critical time of adaptation between salt and fresh
water. We learned a considerable amount about fish handling this year,
and are confident that this experience will improve survival somewhat.
Further work in this area will help to define what types of selective
fisheries are acceptable for a given area. It was also observed, as we
had in the other fisheries, that fish were much easier to remove from
the tangle net than from the gill net. As in the other fisheries, we
also noted more non-target species were caught in the tangle net than in
the gill net.

The frequency distributions of fork lengths of chinook (Figure 4) and
coho (Figure 5) showed that the tangle net tended to capture more jacks
(small males) than the gill net, and that the variance in lengths was
greater for the tangle net. There was no significant difference in the
mean length of fall chinook catpured in gill net and the tangle net
(mean fork lengths were 79.3 cm (N= 78) and 79.1 cm (N=74) respectively;
df=117, t=0.12, P=0.45). Coho salmon captured in the tangle net were on
average significantly smaller (mean fork length = 64.2 cm, N=298) than
those captured in the gill net (mean fork length = 67.4 cm, N=290;
df=487, t=1.65, P\<0.001).

![](media/image4.wmf)

Figure 4: Length frequency distributions of fall chinook salmon caught
in the tangle net and the conventional gill net during the Willapa River
test fishery.

![](media/image5.wmf)

Figure 5: Length frequency distribution of coho salmon caught in the
tangle net compared to coho salmon caught in the conventional gill net
on the Willapa River.

## 

##  

## Puyallup River - 2000

Thirty-five coho were captured from 21 separate sets made over 4 days
between 28 Sep and 03 Nov. Twenty-five coho were captured in the gill
net (44% male) and ten were captured in the tangle net (50% male). Two
starry flounder (*Platichthys stellatus)* were incidentally captured in
the tangle net. Nearly all of the fish were in excellent condition at
the time of capture (Table 9). Fishers involved at this particular site
felt that the gear could be improved to fish the Puyallup River. Changes
such as increasing the mesh size to 4" and attaching a lighter lead line
at the bottom were suggested as improvements that may increase the catch
efficiency of the tangle net.

Table 9: Condition of coho salmon at capture during the Puyallup
experimental fishery.

  ----------------------------------- --------------- --------------------
  Condition at Capture                Gill Net        Tangle Net

  1                                   72.4%           83.3%

  2                                   24.1%           0

  3                                   3.4%            16.7%
  ----------------------------------- --------------- --------------------

# EVALUATION

## General Conclusions

To protect weak and endangered stocks, the commercial salmon gill net
fisheries in the Western United States and Canada are facing
unprecedented restrictions. To regain fishing opportunity, or to at
least maintain the opportunities presently available, this industry must
consider live capture, selective harvest gears and techniques. We tested
the tangle net as an alternative gear to the gill net for targeting fall
chinook and coho salmon while allowing for the release of nontarget
species and stocks with minimal mortality. This net has shown great
promise on the Columbia River for targeting spring chinook salmon
(Vander Haegen et al. 2002) and sockeye and chinook salmon on the Skeena
River (F. Hawkshaw, pers. comm.). We found the tangle nets we tested to
be as effective for capturing coho salmon on the Willapa River, with
slightly decreased immediate mortality, and would therefore have
potential as a commercial gear if the post-release mortality of the coho
were improved by the use of the tangle nets. Further research is
required to evaluate this aspect. They also have potential for capturing
coho salmon on the Puyallup River with further refinement.

Our tests of the tangle nets found them to be an unsatisfactory
substitute for capturing fall chinook salmon near Miller Bay and in Budd
Inlet. The catch efficiency of the tangle net was lower compared to the
gill net, the immediate mortality of captured fall chinook salmon was
not improved, and many more non-target species of fish were captured in
the tangle net. However, fish captured in the tangle net had fewer net
marks than those captured in the gill net, and could realize higher
market prices. Our results of post-release survival also merit further
consideration as they suggest that fish released from the tangle nets
may survive at higher rates than those released from the gill nets.
Further refinement of the gear, and selection of sites with a high
abundance of fall chinook could provide positive results. Other gears
for live capture selective harvest (e.g. beach seines, traps, reef nets,
etc.) should be considered in areas where abundant stocks could be
harvested if they could be separated from the weak stocks they are
commingled with.

The concept of live harvest, selective fishing is a compelling method
for continuing harvest while protecting weak stocks and species.
Although we did not find a suitable method for selective harvest of fall
chinook, research and development should continue given its success in
other areas. As well as determining which gears are suitable for
capturing the target species with minimal mortality of non-target
species and stocks, the conservation benefits of releasing fish must be
evaluated. Many questions remain. What proportion of the released salmon
survives to complete their migration? Is the spawning ability or
reproductive fitness of those fish impaired? If fish are released from
one vessel during a fishery, they are susceptible to recapture. How
often does this occur, and how do multiple recaptures affect survival?
What is the fate of species other than salmonids that are released?

## Objective 1

(*Estimate the catch per set to +/- 10% at 95% confidence for the tangle
net and conventional gill nets. Estimate the age and size for each
species caught to +/-10% at 95% confidence for the tangle net and
conventional gill nets.*)

One consideration in substituting gears is how well the new gear
captures the intended target species in comparison to the gear already
being used. We estimated the catch per set at each location by counting
fish as they were brought on board. Fish that fell out of the net before
it was brought on board ("drop off"), and fish removed by seals could
not be accurately counted, and were not included. We used these
estimates to compare the catch efficiency of the gill net and the tangle
net each time they were fished together. We considered the result
positive if the tangle net caught as many or more of the target species
as the gill net, although in some situations, lower catch efficiency
might be acceptable if the higher quality of the captured fish would
realize a higher market price. We found the 3.5" tangle net to be as
effective as the 5.75" gill net when targeting coho salmon on the
Willapa River, but not on the Puyallup River, and the tangle net
captured only about 1/3 of the fall chinook encountered in the gill net
in Budd Inlet.

By their very nature, gill nets are size selective, and have been
identified as the cause for population-level reductions in size because
they disproportionately remove the larger animals. As each fish was
brought on board, we measured its fork length to evaluate whether the
tangle net was more or less size selective than the gill net. We found
that the tangle net tended to capture a wider range of fish sizes than
the gill net, particularly towards the smaller sizes, as is expected
from the smaller mesh size. In a commercial fishery, this could help to
reduce the pressure on the larger fish in the population.

We did not attempt to estimate the ages of the captured fish because the
live fish were too active for scale collection without causing them
undue harm.

## Objective 2 

*(Estimate the proportion of fish caught in the tangle net and in the
conventional gill net that are brought aboard dead (cannot be revived)
by species, to +/-2% at 95% confidence for each set.)*

We estimated the immediate mortality of the target species that were
captured in each net type, with the expectation that fish captured in
the tangle net would survive better than those captured in the gill net.
However, we found the differences between the nets to be relatively
small, and the immediate mortality to be high compared to the rates
encountered in other trials of the tangle net. Our test fisheries
occurred in late summer and early fall, when the water temperatures are
high, and the resulting stress on the maturing fish is likely greatest,
while other trials showing low immediate mortality mainly occurred
during late winter or spring. Temperatures during those fisheries would
have been much lower, and the fish were likely able to tolerate
handling. We suspect that the similar rates of mortality between the net
types reflect the inability of the fish to tolerate additional stress
from capture, whatever the capture method.

## Objective 3

*(For each species, estimate the percentage of fish released from the
tangle net and conventional gill net that survived to complete their
migration, to +/-25% at 90% confidence.)*

In 2000 and 2001, fewer spring chinook returned to Budd Inlet and Miller
Bay than expected and in spite of considerable fishing effort by
experienced fishers, we were unable to capture and tag large numbers of
fish for estimating post-release survival. In addition, of those fish
released with tags, few were ever recovered, even though we expected to
be fishing on the portions of each run that were returning to nearby
hatcheries. Our inability to recover tags either represents an high
number of long-term mortalities or more likely, means that the fish we
captured were dispersing to other areas. Seals colonize Budd Inlet, and
any fish that was impaired (as might be expected after capture) would be
more susceptible to predation, and our tagged fish may have been
disproportionately depredated. The fact that we do not know which of
these to be the case precludes us from making any estimates in regard to
survival and migration completion. The few tags we did recover in 2001
suggest that the fish released from the tangle nets may have a survival
advantage, and this aspect should be studied further in smaller systems
with abundant runs.

## Objective 4

*(Coordinate activities with fishery co-managers and fishers. In
Washington, the fisheries are co-managed by the Washington Department of
Fish and Wildlife (WDFW) and the Treaty Tribes of Washington State.
Because the Treaty Tribes influence and participate in statewide
fisheries management and research, we will notify and address comments
from all of them, but will work closely with only those tribes whose
usual and accustomed areas include or are near our test fishing sites.
)*

We successfully met Objective 4 in each area fished. In all areas, we
contracted with tribal members or local fishers, and tribal biologists
made substantial contributions toward implementing the test fisheries.

# REFERENCES

# 

Farrell, A.P., P. Gallaugher, C. Clarke, N. DeLury, H. Kreiberg, W.
Parkhouse and R. Routledge. 2000. Physiological status of coho salmon
(*Oncorhynchus kisutch*) captured in commercial non-retention fisheries.
Canadian Journal of Fisheries and Aquatic Science 57:1668-1678.

# 

Vander Haegen, G.E., K.W.Yi, C.E.Ashbrook, E.W.White, and L. L. LeClair.
2002. Evaluate live capture selective harvest methods. WDFW Report
#FPT-02-01, 35 p.

# ACKNOWLEDGEMENTS

We thank the Squaxin Island Tribe and particularly Mike Henderson, Will
Henderson, Richard Peters, and Jeff Dickison for their help in planning
and implementing the Budd Inlet test fishery. We thank the Suquamish
Tribe and especially Jay Zhischke, Jon Oleyear, Armand Schavez (FV
Salmon Bay) and Willard Pratt (FV Salmon Bay) for their help in the
Miller Bay test fishery. We thank Eric Petit, Norris Petit, and Brian
O'Shaughnessy for their participation in the Willapa River test fishery.
We also thank the Puyallup Tribe and especially Francis John, Sr. and
Fred Dillon for their voluntary participation. Finally, Washington
Department of Fish and Wildlife employees Anita Swanson, Rebecca
Bernard, Kyong Yi, Charmane Ashbrook, Shona Bruce, James Dixon, Brant
Boelts, Keith Sweeney, Jared Laine, Lorna Wargo, and Patrick Verhey
provided technical assistance.