DRIFTNET DATA COLLECTION PROGRAMS
The North Pacific Salmon Driftnet Fishery
In 1952, Japan initiated a salmon drift gillnet fishery using large scale
monofilament nylon driftnets. One year later, in 1953, the International
North Pacific Fisheries Commission (INPFC) was established under the International
Convention for the High Seas Fisheries of the North Pacific Ocean (North
Pacific Convention) to attempt to regulate this fishery and to ensure the
protection of North American salmon stocks.
Between 1962 and 1971, Japanese Fisheries Agency (JFA) research vessels
collected data on the North Pacific salmon mothership driftnet fishery.
Observers recorded both catch and by-catch data. They reported 0.37-0.65
cetaceans were caught per 1000 tans, with a maximum of 1.42 per 1000. Between
1977 and 1987, the JFA research vessels collected catch and by-catch data
on the Japanese salmon land-based fishery. They recorded 2,204 seabirds
belonging to 16 species killed in 413 net sets. Based on historic fishing
effort and estimated catch rates, Japanese and United States researchers
estimated that more than eight million seabirds were killed by only the
large-vessel component of the land-based fishery since 1952 (DeGange and
Day 1991). The United States also collected salmon driftnet fishery data
during the 1960s. Their data indicated an average of 6.66 cetaceans caught
per 1000 tans (approximately the amount of driftnet set by one squid vessel
each night). United States observers were first placed on board commercial
Japanese salmon motherships and catcherboats in 1980. In addition, each
year since 1978 Japan has reported to INPFC the total catch and by-catch
taken by both its mothership and land-based salmon driftnet fisheries.
Data on the North Pacific salmon fishery was also collected by Canada and
the United States. In 1987 and 1988, Canada conducted two salmon research
cruises on board the W.E. Ricker. The 1987 cruise took place in an area
where few, if any, salmon were expected to be found (38 - 45 deg N, 150
- 180 deg W) in 12 deg C water. All six species of salmon were caught (LeBrasseur
et al 1987). The cruise data also indicated that between 100 and 300 million
pomfret may have been discarded annually as unwanted by-catch. The 1988
cruise, again conducted in the squid fishing area (38 - 46 deg N, at 151
deg W and 155 deg W), caught both salmon and squid, indicating that the
segregation between the two species was not distinct (LeBrasseur et al 1988).
The cruise also observed 10 commercial vessels fishing north of where their
national regulations said they should be.
In 1980, a U.S research catcherboat monitored ten gillnet operations. An
average of 2.6 per set Dall's porpoise drowned in the nets. In 1980, 1981,
and 1982, U.S. observers were placed on board the Japanese mothership fleet
and monitored both motherships and catcherboats. The take of Dall's porpoise
ranged between 0.13 and 0.96 per set (Jones 1984; Odate 1984).
South Pacific Large-Mesh Driftnet Fisheries
Data Collection by Australia and New Zealand
Between 1981 and 1983, Australia monitored 157 sets by the large-mesh Taiwanese
fleet fishing in the Arafura and Timor seas (Harwood and Hembree 1987).
Based on the data collected, researchers estimated that on average each
driftnet vessel caught 1.8 sunfish, 2.2 sharks, 1.8 billfish, 11.1 Ray's
Bream, and 3.6 dolphins each night the vessel fished. The observed cetacean
catch totaled 4,463 and a significant decline in the cetacean catch rate
against the cumulative fishing effort was recorded during the study period.
The main species taken were the bottlenose dolphin, the spinner dolphin,
the spotted dolphin and the false killer whale. Australia brought the fishery
to an end in 1986. In 1989, Australia totally banned driftnet fishing from
its EEZ. New Zealand observers also monitored large-mesh driftnet vessels
in the Tasman Sea and the South Pacific convergence zone (SPCZ) in 1987
and 1989. Data collected by a New Zealander on board a Japanese fisheries
research agency (JAMARC) large-mesh driftnet vessel operating in the Tasman
Sea indicated a catch rate of 2.1 per 36 km set of the common dolphin and
0.5 per set of the relatively rare striped dolphin. Albacore dropout rates
averaged 8.9%. The data gathered from these monitoring programs convinced
New Zealand to ban driftnet fishing from its EEZ in 1989 and to sign the
Wellington Convention banning it from a large portion of the South Pacific.
In 1990, private environmental consultants from New Zealand conducted both
surface and underwater photographic observations to document the by-catch.
Quantitative data was collected for 126 km of driftnet set by the commercial
fleets fishing between 37 deg 40 min - 41 deg 42 min S and 156 deg 26 min
- 161 deg 03 min E (Coffey and Grace 1990).
Data Collected by Japan
Beginning in 1982, JAMARC began a series of 11 or more development surveys
to assess the commercial potential for driftnet fishing in the South Pacific.
The target species comprised less that 50% of the retained catch (SPF 1991).
Discards and dropout rates were not recorded. In 1989, the Japanese conducted
a research cruise in the Tasman Sea. A total of 712 km of net were monitored.
By-catch included skipjack tuna, yellowfin, bigeye tuna, slender tuna (132
per 1000 km), swordfish, striped marlin, blue marlin, shortbill spearfish,
flying squid (138 per 1000 km), blue shark, mako shark (93 per 1000 km),
hammerhead and pomfrets. Also caught were fifty common dolphins, ten striped
dolphins, one pilot whale and one or two southern bottlenose whales, three
leatherback turtles, and two unidentified birds. In 1989-1990, Japan conducted
a resource survey for new fishing grounds in the South Pacific Ocean. Common
dolphin and striped dolphins accounted for 78% and 14% of the total cetacean
by-catch. A southern bottlenose whale, still alive, was cut loose with net
still wrapped around it (Watanabe 1990).
Catch Data from a Virgin Waters Driftnet
In 1989, the Federated States of Micronesia (FSM) and Japan conducted a
trial joint venture in the EEZ of the FSM, in an area never before fished
by driftnets (Goldblatt 1989). An FSM observer was on board a 30 meter driftnet
fishing boat, the Monju Maru, during 30 days of driftnet fishing. Each evening
the boat set seven to eight nets, each approximately 3.2 km long, 7.6 m
deep, with a 76 mm mesh. The nets were retrieved in the early morning.
The observer reported that fish caught in the nets tended to died quickly,
but it was 7-14 hours before the dead fish were hauled on board, processed
and frozen. The captain called the fish "dogfood". The majority
of the yellowfin tuna caught were juveniles, weighing about 15 pounds. Yellowfin
tuna can grow to over 100 pounds in their first year of life. Sixteen percent
of the catch were discarded because they were not marketable, spoiled, or
had been bitten by sharks. The by-catch included 356 sharks, which were
discarded after their fins were cut off.
More than one third of the by-catch were classified as protected or endangered
species, including leatherback, green and hawksbill turtles, and eleven
whales, nine of which were caught in one set. The turtles were kept, except
for two leatherbacks that were discarded after being gaffed. Almost a hundred
dolphins were brought on board, one for every nine tuna caught, as well
as several dolphin tails. The rest of these dolphins had been eaten by sharks
as they hung in the net. Those dolphins still alive had their tails cut
off to facilitate removal from the net, after which they were thrown overboard.
At one time the boat's propeller became entangled in the net. A large section
of the net was cut away and discarded at sea leaving it to ghost fish on
The observer recommended no further driftnet fishing in the Federated States
of Micronesia. The reasons: low catch rate, poor quality of fish, large
amounts of discarded marine life, and the killing of protected and endangered
animals. The observer recommended alternative fishing methods, such as longlining,
as likely to be more profitable, yield a higher quality of fish and cause
much less destruction to the FSM's marine resources. As a result of this
study, the Federated States of Micronesia banned driftnet fishing from their
The North Pacific Large-Mesh Driftnet Fisheries
In 1982 and 1983, JAMARC carried out 51 driftnet operations for a Pacific
pomfret resource survey. Nine species of cetaceans were caught as by-catch.
Striped dolphin, northern right whale dolphin and common dolphin comprised
37%, 29% and 21% of the total catch, respectively (Watanabe 1990). In 1989,
the Fisheries Agency of Japan conducted a large-mesh survey cruise in the
North Pacific. A pair of mother and offspring pygmy sperm whales and a Pacific
white-sided dolphin were killed.
The North Pacific Squid Driftnet Fishery
Single Nation Research Cruises
Data is available from research cruises conducted by Japan in 1982, 1983,
1985, 1986, and 1987 (Murata et al 1988). By-catch of marine mammals and
birds were recorded. The catch commonly included Dall's porpoise, northern
right whale dolphin, pacific white-sided dolphin, and an assortment of other
dolphins, seals, whales and birds (Murata 1986; Takagi 1983). In 1986, the
Taiwanese conducted a research cruise using both monofilament and multifilament
nets. An average of 1.6 marine mammals were caught per set. In 1990, the
ROK conducted experimental squid fishing operations, testing 72 mm, 86 mm
and 96 mm meshes (Gong et al 1991). Between 1979 and 1987, Canada conducted
a number of cruises to assess the distribution, abundance, and fishery potential
of flying squid within 450 km of its coasts (Welch, Margolis, and Henderson
1991). By-catch included salmonids, marine mammals, and seabirds. Between
1986 and 1990, Canada began a series of annual cruises with the research
vessel W. E. Ricker to determine the high seas distribution of salmon and
squid. In 1988, the Canadians conducted a research cruise in the North Pacific
commercial squid fishing area using standard mesh and trammel mesh (Herczeg
1988). By-catch included five species of salmonids, blue shark, pomfret,
seabirds and marine mammals.
Joint Research Cruises
In 1983, 1985 and 1986, experimental squid driftnet fishing was conducted
by Japanese and Canadian vessels in the eastern Pacific Ocean. Pomfret and
blue shark were the major by-catch species. A total of 50 mammals were caught
by three vessels fishing in 1986 (Sloan 1984; Jamieson and Heritage 1987).
During 1986 United States scientists participated in two squid driftnet
research surveys with the ROK (Park et al 1987; Clausen 1986; Day 1986)
and Taiwan (Sigler 1986; Dahlberg 1986) and one squid/salmonid cruise with
Canada (Bernard 1986). In 1987, United States scientists participated in
four squid cruises, one each with the ROK (Gong et al 1989; Seger 1987)
and Taiwan (Kazama 1987; TFRI 1987), two with Japan (Johnson 1987; Risner
1988) and one squid/salmonid cruise with Canada (Muto 1987). In 1988, U.S.
scientists participated in two squid surveys with Taiwan (Fitzgerald 1988)
and the ROK (Rowlett 1989; Gong et al 1988). In 1989, a U.S scientist participated
in a squid survey with the ROK (Gong et al 1990).
Observers on Commercial Driftnet Vessels
Japan and the United States began placing observers on board Japanese commercial
squid drift net vessels in 1982 (Tsunoda 1989; Cary and Burgner 1983). The
data indicates that in the early 1980s the Japanese squid fishery averaged
1.7 cetaceans killed per 1000 tans fished, the average amount of driftnet
a single vessel sets each night of the fishing season. Japan reported 2,232
Dall's porpoises incidentally taken by the squid fishery in 1986 (INPFC
1988, Doc 3270). United States observers were permitted to observe commercial
squid driftnet operations on board a Korean vessel in 1988 (Gooder 1989).
A few additional observations have been made by observers from the vantage
point of Coast Guard cutters (Ignell, Bailey, and Joyce 1986) and private
vessels. In the early 1980s, Japan also regularly reported data from its
squid and large mesh driftnet fisheries to INPFC. The ROK began collecting
and analyzing data from its high seas squid driftnet fleet in 1981 (Kim
et al 1988; Gong et al 1985, Gong 1985).
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