ATLANTIC SALl\lON IN RUSSIAN RIVERS. FISHERIES AND STATUS OF STOCKS IN 1996.

Transcription

1 International Council tor the Exploration of the Sea CM 1997/BB:04 Theme Session on Biology and Behaviour (I) ATLANTIC SALl\lON IN RUSSIAN RIVERS. FISHERIES AND STATUS OF STOCKS IN by A.V.Zubchenko Polar Research Institute of Marine Fiaheries and Oceanography (PINRO), ~Iurmansk, Russia A.A.Loenko, N.G.Popov Murmansk Regional Directorate on Fish Conservation and Enhancement, Murmansk, Russia V.P.Antonova Northern Affiliate of the Polar Research Institute of Marine Fisheries and Oceanography (SevPINRO), Archangel, Russia Karelian Reginal V.A.Valetov Directorate on Fish Conservation and Enhancement, Perozavodsk, Russia When evaluating the fisheries for Atlantic salmon in the European North of Russia in 1996 it should be noted that the situation that had developed in the last 5-6 years in general did not show any substantial changes. The majarity of stocks in rivers of the Archange1 Region and Karelia are still depressed or dose to extinction. Projects that could be aimed at rehabilitating the stocks are not realistic for economic reasons. In the Kola Peninsula the situation is much better, however, the rivers situated in the vicinity of big communities suffer an increasing pressure from illegal fishing. Poaching has become one of the main if not the only reason far depression of stocks in the other two regions in the narth of Russia, therefore increasing poaching pressure causes great concerns about the status of salmon stocks in rivers of the Kola Peninsula. In general in northern regions of Russia there remains a trend towards a shift of priorities in favour of sports fishing which is economically more beneficial. However, a cessation of fisheries at counting fences (in-river traps) would disrupt a quite long data series on abundance and biological parameters of salmon from largest populations since there are no other alternative ways of monitoring stock abundances at present. CONDITIONS AND RESULTS OF FISHERIES In 1996 high water levels resulted in fishing season in the Kola Peninsula begining only in the second 10 days of June (instead of the last 10 days of May normally) and finished in the seeond 10 days of Getober. Beeause of low water temperatures the summer run fish began to enter rivers in mid-july (normally last 10 days of June) and continued until late August

2 2 (normally first 10 days of August). A peak in the summer run was observed in late July - early August. The autumn run began in the first days of September. Commercial fishery was conducted at counting fences in 7 rivers (in 10 rivers in 1995) and at 23 coastal fishing stations (trap nets) 10cated between the Kachkovka and Knyazhaya rivers (29 stations in 1995). In the Archangel region the fishing season commenced at the usual time (in coastal areas in the second 10 days of June, on the Severnaya Dvina river in the second 10 days of July) and finished in the last 10 days of October. Minimum flow levels occurred at the beginning of August (normally it happens in mid-july), however, this did not have any impact on the spawning run dynamics. A peak of run was observed in the first and second 10 days of September. \Veakening and a complete stop of run was observed during the second 10 days of October (when the water temperature dec1ined to 6.0 C), which was somewhat later compared to normal times. The fishery was conducted on the Severnaya Dvina river (at 51 stretches) and in coastal areas between the Mezen and Severnaya Dvina rivers. A total of 415 fishing gears were set (trap nets, gill nets, drift nets, bag nets, seins), of them 85 in coastal zone and 330 in rivers. Since there is a ban on the fishery in the Pechora river only scientific fishing was carried out with one drift net. It was undertaken from 30 July to 17 September. The first fish entered the river at a time c10se to normal (late July). Peaks of run were observed in the first lo-day period of August and in the end of August. In the second lo-day period and first half of the third lo-day period of August there was a prolonged dec1ine in the intensity of spawning run which was not typical of the Pechora river salmon population. In general the run of salmon into the river was of a prolonged nature. In Karelia commcrcial fishcry was conductcd at 4 coastal fishing stations (killnots). On the Keret, Kem and Vyg rivers only work to control the abundance and enhance the stocks was undertaken. Surveying took place from 22 June to 18 October. Sports fishing Keret, Suma). took place on 73 rivers of the Kola Peninsula and 3 Karelian rivers (Vonga, In accordance with regulations established for the 1996 season not less than 67% of spawning runners passed unharmed through barrier fences in rivers of the Barents Sea basin before 25 June and not less than 50% after this date. On the Varzuga river during the whole fishing season not less than 63 % of runners were allowed to escape far spawning, and a catch limit was established for the Umba river salinon (1000 fish). On the Kola river where until recently 100% of spawning fish at the counting fence were taken as catch or removed as broodstock, 500 salinon were let escape for spawning grounds in the headwaters of the river. On the Pechora and Severnaya Dvina rivers catch limits were set (1000 fish and 11 t, respectively). Sea catch limit was established at 95 t, inc111ding a quota of 60t for the fishery along White Sea coast of the Kola Peninsula.. Licensed fishing by fareign anglers was based on catch-and-release, local residents were allowed to retain the catch. Fly rods and spin rods were used as fishing gears. Total commercial catch in 1996 was t, incillding 64. I tat coastal fishing stations and 3.9 t (check fishing) in the Pechora river. Table 1 shows the dynamics of catches in Sports fishery on the Barents Sea rivers yielded a catch of 2980 salmon, inc1uding 2196 salmon by catch-and-rclcasc. On the White Sea rivers the catch was 9716 salmon inciuding 8549 salillon by catch-and-re1ease. The total catch was fish incillding fish by catch-and-

3 3 release. In 1991 the catch was 4869 salt110n including 3221 by catch-and-release. In 1992 the catch was sa1l11on and salmon, respectively, in and salmon, in and Table 1. Catch of Atlantic sallnon in various regions of Russia in (t). Kola Peninsula Archangel Pechora Karelia Total Year Barents White Total Region catch Sea Sea ,3 362,9 446,2 90,8 4,9 771, ,4 304,4 65, ,3 497, ,9 187,5 232, ,1 475, ,9 272,9 86,4 92,3 3, , , ,6 6,3 663, ,5 229,5 52,3 178,6 2,7 463, ,2 172,7 209,9 57,3 93, , ,3 237, ,9 110,7 10,2 506, ,4 256,9 354,3 74,8 156,5 7,6 593, ,1 314,8 374,9 66, , ,8 256,5 301,3 75,2 225, , ,5 339,5 55,3 164, , ,1 201,4 233,5 65, ,8 419, ,1 199,4 267,5 52,9 28,8 14,5 363, ,5 171,9 253,4 52, ,3 112,9 160,2 48 4,7 2,3 215,2 6,9 312, ,4 78,1 137,5 23,2 3,8 2,2 166, ,1 70,8 104,9 28,2 5,3 0,7 139, ,6 76,4 102,3 33,5 2,2 0,5 138, ,4 50,8 87,2 30,4 11,6 0,4 129, ,5 82,4 101,9 24,0 3,9 0,7 130,5 \ 12056, in and salmon. Fig.1 demonstrates the ratio between catches by Russian and forcign anglers. Table 2 presents estimates of the total commercial exploitation rate on salmon stocks in rivers and coastal areas in the north-west of Russia in In addition the table also gives data relating to exploitation of most important salmon stocks subject to the fishery. With respect to the Barents Sea and White Sea basins separately, the exploitation rate on salmon in the Barents Sea rivers in 1996 was 36% and 53 % in the White Sea rivers. In 1991 it was 18% and 37 %, respectively, in % and 27%, in % and 28%, in % and 34%, in % and 32%. It should be noted that the reason behind.1 low exploitation

4 , rate for the Barents Sea rivers stocks is a cessation of fishery on the Pechora, Jokanga and Pechenga rivers. On the White Sea basin the exploitation rate is largely related to the abundance of the Varzuga river stock and 14-, , 12 -! :== r-r----, j ; ~ E:J C o -1'---' Year 10 Foreign anglers Russian anglers I Fig.l. Salmon catch by anglers in the success in taking out the quota established for the coastal fishery. In the ealculations exploitation rates on certain stocks in feeding areas has not been taken into account, however, this rate given the absence of the Faroese fishery and notable reduction of the Norwegian fishery is not presumably more than several percent. Table 2. Exploitation rates on salinon stocks in Russian rivers in 1996 (%) Number Number ER % ER % ER % ER % ER in Stock in Fishery ISW 2SW 3SW 4SW % PS Total Varsuga'R Umba'R Kola'R Tuloma'R In 1996 a daily eatch per fishing gear on the Severnaya Dvina river was 0.41 salmon (in 1994 it was 0.48 salmon, in salmon). By weight the catch on the Severnaya Dvina was 20 kg per fishing gear during a fishing season. This index in the coastal fishery \\las 190 kg. The analysis has shown that this index is inversely relate<! to the number of fishing gear. On the Pechora river average catch of salinon per unit effort was 3.9 salinon in 1996 (in 1995 it was 5.3 salmon).

5 5 DESCRIPTION OF CATCH AND STATUS OF STOCKS In rivers on thc Kola Peninsula grilse prevailed (88%). This was 18% higher than the long-term mean. With respect to individual rivers the lowest number of grilse was observed in the Ponoi river (56%), while the highest one in the Varzuga (92%) and Ura (95%) rivers. For the Varzuga river this was a normal situation, while unusually high numbers of grilse in such.. Barents Sea rivers as B.Z.Litsa (87%), Tuloma (87%), Kola (74%) could most probably be a result of a delayed commencement of the fishery. Consequently, a greater fraction of spawning runners at age 2SW, 3SW and older was not counted whereas their proportion in the Barents Sea rivers is usually,not less than 30%. This mayaiso explain why the average length and weight of spawning runners were less than in previous years (mean length varied from 53 to 67 cm, and weight from 1.7 to 3.7 kg). In the Severanay Dvina river (Archangel region) grilse accounted for.5.8%, 2SW salmon 81.7%, 3SW % of catches. The mean length of spawners was 81.1 cm, whieh was in conformity with the long-term mean, while the mean weight was 6.2 kg which was higher than the long-term mean and resulted from the increase of proportion of 3S\V salmon. In the Peehora river as in the previous two years the proportion of grilse inereased and accounted for 15.2% (in 1994 it was 7.5%, in %, in the average was 2.6%). 2SW salmoll aecounted for 72 %, 3SW - 12 % and 4SW - less than 1% of catches. Mean length and weight were 75.6 cm and 5.5 kg which are less than in previous years (long-term mean length is 83.5 cm and weight 6.7 kg). A considerable increase of grilse in spawning stocks of the Pechora sallnon in may be associated with favourable conditions in feeding areas for these fish during the first year of residence at s'ea. In that period positive water temperature anomalies in the summer-autumn season were registered not only in the west but'also over a vast area in the south-east of the Barents Sea. It can be presumed that in a eonsiderable proportion of smolts from the Peehora river did not perform extensive migrations to traditional feeding areas, instead they were foraging in the Barents Sea for one feeding season, attained the required physiologieai eondition and joined a spawning run. In Karelian rivers (data for the Keret river) grilse aeeounted for 35 %. Mean weight of spawners was 3.4 kg (in kg, in kg, in kg). The proportion of spawners of hatehery origin was 56%. In general for ail regions in Russia the age eomposition of the eateh in 1996 was notably different from that in previous years (Fig.2) t- ---j_ q Cl> 50-0> lls- r::... B Cl> c SW 2SW 3SW 4SW age, Fig.2. Age composition of salmon in Russian catches for PS

6 6 In 1996 the numbers of Atlantic salmon in commerciaily-important Russian rivers were found to be c10se to forecasted numbers with the exception of the Pechora river, where as shown by data from control fishing the abundance was almost three times higher than it was expected. This fact can be easily explained because after the cessation of fishing at the counting fence a reliable assessment of parent year-c1asses in the Pechora river became somewhat problematic in connection with establishing a catch limit of 1000 salinon in a scientific control fishing. In 1996 the bulk of spawning fish which entered Russian rivers were progeny from a fairly strong 1989 year-c1ass and average 1990 and 1991 year-c1asses. In total the abundance of commercial stock of all ages in 1996 was estimated at about fish (in revised figure salmon, average for salmon) and numbers of spawning runners in major commerciaily-important rivers are given in Table 3. Table 3. Numbers of Atlantic salinon in major commerciaily-important Russian rivers in Stock Pechora'R Varsuga'R Tuloma'R Umba'R Ponoy'R Kola'R Yokanga 'R. Z.Liza'R In 1997 the majority of spawning runners will result from average year-c1asses. An assessment based on positive correlation between the numbers of Atlantic salmon and mean yearly water temperature in the m depth interval along the Kola!\leridian transect, counts of fish at barrier fences, data relating to biological, age, sex, length and weight structures of individual populations as well as data on fecundity and survival rates at different life stages has providcd an estimate of Atlantic salinon in commercially-important Russian rivers for The assessment did not inc1ude the Pechora river salinon because for the first time for more than 30-year period the abundance of sallnon in this river had not been estimated due to the absence of data for 1990.