Summary of resul~s Anthony R. DeGange USFWS, OBS-CE Anchorage, Alaska During the summer of 1978, I participated on 2 one month cruises aboard the University of Hokkaido's Training Vessels OSHORO Y~U and HOKUSEI HARU. The OSHORO MARU cruise, from 5 June to J July concerned itself with fishery and oceanographic studies in the southern Bering Sea. The HOKUSEI :1\RU cruise, although of similar purpose, was confined to the Emperor Seamount area south of the Aleutian Islands The purpose of my work aboard the vessels was two-fold: 1) to study the problem of seabird entanglement in Japanese high seas gillnets, and 2) to study the distribution and abundance of seabirds in the North Pacific Ocean and Bering Sea. Densities of seabirds in the Bering Sea study area Nere variable, ranging from 0- 149 birds/Km2 (X= 11.3, Sx = 1.4)(see Fig.) The variability was due primarily to the presence or absence of Short-tailed Shearwaters, a southern hemisphere breeder wintering in northern waters. Four gillnec sets, each involving 130 tans (6.5km) of variable mesh monofilament net (see Table 1) were made in the Eering Sea. The following seabirds were captured: 31 Short-tailed ShearNaters (Puffinus tenuirostris), l.Fork- tailed Storm Petrel (Oceanodroma Eurcata), 6 Thick-billed Murres (Uria lomvia), 1 ~~cient Murrelet (Synthliboramphus antiquum) and 3 Tufted Puffins (Lunda cirrhata). In aGdition 4 Sooty Shear.oTaters (Puifinus griseus) were captured during an additional 13 gillnet sets made south of the Aleutian Islands • Densiciies of seabirds in the Emperor Seamount area were even more variable than in the southern Bering Sea, ranging from 0 - 2034 birds/Km2. (X= 36.9, Sx = 16.2). (see Fig.). Again, such variability was due to the patchy distribution of Sooty and Short-tailed Shearwaters. Shearwaters, Laysan Albatross and Northern Fulm<lrs rNere the most frequently observed species in this region. Nine gillnet sets, each involving 115 tans (5.8Km) o£ variable mesh monofilament net were made. The following see.birds were captured: 1 Northern Ful~ar (Fulmarus glacialis), 5 Sooty ShearHaters, and 1 Short-tailed Sh~arNater. Of these, 2 Sooty Shearwaters and the Northern Fulmcu- '..;ere captured alive and released. For the two cruises. the percent species composition for the 54 captured birds is indicated (see Table). For all the studies, Shear.Yaters made up a large percentage of the kill. Seabirds that dive below the surface ;.g Shear...;aters, murres, puffins and other alcids, are most frequently entangled. Other species, such as albatross and fulmars are usually 7aught only when attempting to feed on net-entangled organisms. G1.llnets are only 6m deep; however, seabirds are net caught at equal rates in all depths of the net. Of 3!+ birds for tvhich I have information, 32 (94%) were caught in the upper 1/3 of '::he net. In f,.lct, many of these birds were caught in the upper lm of the gillnet. On_ the ttvo :esearch vessels, seabirds wa:::e also entangled most frequentl:. l.n nets o: 82mm - iJOmm stretched measure. The accompanying figure suggests that seablrds are most frequently caught in those mesh sizes used by the commercial boats. It should be pointed out that this figure is based on a very limited amount of data (n = 31). Also, mesh size ranging from 115mm - 130mm were most frequently used on the research vessels; another factor which biases the results. King, Brown and Sanger (in press) have estimated the annual incidental kill of seabirds in the North Pacific and Bering Sea to be between 214,500 and 750,000 birds. They estimated the annual kill for the mothership fishery alone at between 75,000 and 250,000 birds. Their estimates were made in 1974 when the fishery was much larger (369 catcher boats) than at present . Also, their estimates were extrapolated from data collected aboard American boats. Estimates for the 1977 incidental seabird kill were provided by the Japanese Fishery Agency. Their estimate of seabird mortality for the 245 catcher boat mothership fleet was 183,181. Their estimate for the land-based fleet, reduced from 330 vessels in 1974 to 298 vessels in 1977 was 167,345 birds. The total of 350,526 is within the range provided by King et al. The 1978 ·mothership fishing effort was greatly reduced due to new agreements within the International North Pacific Fisheries ~anagement Council and between the Soviets and the Japanese (see figure). I used the estimated fishing effort of the mothership fleet (see Fig.) and seabird entanglement data from the 1977 Japanese research vessels to derive the estimate of 126,722 + 68,583 birds killed by the Japanese mothership fleet in 1978. To derive this figure, I only used 1977 research vessel data collected in the same 2° Lat x 5° Long blocksin which the mothership fleet was fishing.in 1978. Because of a lack of data, I did not weigh this information by the time of fishing season e.g May, June, July which may have an important bearing in this case. Gillnets capture and kill a wide variety of marine organisms including squid, fish, sea turtles, porpoise, and seals (see Table). The HOKUSEI MARU killed two Dall Porpoise (Phoeconoides dalli) in its nets during the summer cruise. One Dall Porpoise was caught on the OSHORO XARU but it was released alive .. Fur Seals (Callorhinus ursinus) frequently play about the nets or feed on entangled fish. One fur seal was captured on the HOKUSEI MARU but escaped prior to being taken aboard. Table 1. Number of tans of each mesh size and the linear order of tans for the gillnets of the OSHORO MARU and HOKUSEI MARU. OSHORO ~U HOKUS EI MARU MESH SIZE (mm) NO. TA.~S MESH SIZE NO. TA.~S 115 15 112 10 48 3 115 10 93 3 118 10 157 3 121 10 106 3 112 10 63 3 115 10 121 3 118 10 72 3 233 3 138 3 204 3 82 3 179 3 55 3 82 3 121 20 157 3 130 15 72 3 121 20 63 3 115 15 42 3 130 15 106 3 138 3 TOTAL TAl."'S = 130 55 3 93 3 48 3 33 3 121 3 TOTAL TAl."'S = 115 Table 2. Location, deployment time, retrit:!val time and duration of gillnet sets fo,: the OSHOlW MARU ant! HOKUSEI MARU, suuuner 1978. Deployment Elapsed Retrieval Elapsed Duration Set No. Position Time Time Time Time of Set 55°00' N 1 OM 17:57 - 18:58 1:01 03:00 - 05:43 2:4 3 11:116 177 ° 59 I W 52°55' N 2 OM 03:30 - 06:]0 2:00 11:00 176°59' w 19:30 - 20:30 1:00 --------- 54°59' N 3 OM 175"29' w 18:40 - 19:37 :57 03:00 - 05:15 2:15 10:55 54"00' N 4 OM 18:00 - 19:00 12:30 178"00' w 1:00 03:40 - 06:30 2:50 40"00' N l BM 175"30' E 18:00 - 18:43 :43 04:15- 07:50 3:35 13:50 --~----- ------ 41"28' N 2 llM 18:00 - 18:53 :53 03:58 - 07:15 3:17 13:15 175"37 I E -~--·-------·---- 43 "00' N 3HM 18:00 - 18:38 :38 04:00- 06:00 2:00 12:00 175"30' E ------ 44°38' N 4 HM 18:02 - 18:43 :41 04 : 00 - 0 fl : 4(1 1:114 11:42 17 5° 28 I E 45"59' N 5 liM 17:58- 18:40 :42 03:53 - 06:08 2:15 12:10 175"33 1 E ----·---·----· 47"30' N 6 liM 18:01 - 18:42 :41 03:55 - 05:58 2:03 ll :57 ll5"30' E ·--------· -- ·- 49"02' N 7 HM 169"17' E 19:06 - 19:45 :39 Ol1: 18 - 06: 21 2:03 11:15 8 liM 50"00' N 165°00' E 0'>:51- 06:18 :27 12:)] - 13:Jt) 1:08 7:48 49"29' N 9 HM ]8:30 - 19:10 :40 04:44 - 06:~)6 2:12 1.2:2o 161,"12' E Table 3. Seabirds caught at individual gillnet sites for the OSHORO XARU and HOKUSEI ~~RU, Summer 1978. Gillnet Set and Location Seabirds OSHORO MA..~U 53°00'N l77°59'W 2 Thick-billed Murres, 3 Tufted Puffins 52°55'N 176°59'W 16 Short-tailed Shearr.vaters, l Fork- tailed Storm Petrel, l Ancient Murrelet 54°59'N 175°29'W 2 Thick-billed Murres, 1 Horned Puffin 54°00'N 178°00'W 2 Thick-billed Murres, 15 Short-tailed Shearwaters 45°36'N l73°25'W None 44°03'N 174°58'W None 43°00'N 175°00'W :.:one 41° 59' N 175°00'W None 40°58'N l74°58'W None 39°59'N 174 ° 59 'W None 38°59'N 174°59'W None 38°58'N 177°43'W None 38°59'N 179°59'W None 40°25'N 179°55'E None 42°00'N l79°57'TJ None 43°30'N 180°00' 2 Sooty Shearwaters 44°58'N 179°58'E 2 Sooty Shearwaters HOKUSEI MARU 40°00'N l75°30'E None 4l 0 28'N 175°37'E 1 Sooty Shearwater 43°00'N 175°30'E None 44°38'N l75°28'E None 45°59'N 175°33'E 1 Sooty Shearwacer 47°30'N 175°30'E 3 Sooty Shearwaters 49°02'N 169°l7 1 E 1 Northern Fulmar 50°00'N l65°00'E None !.9°29'N 164°12'E l Short-tailed Shear.vater Table '•· Total Number of Seabi.rds caught on the OSHORO MARU and HOKUSEI MARU, Summer 1978 and a comparison of the species composition of seabirds caugl1t in the gillnets of various research vessels.