Translation Series No.1211

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• - 199 - For the calculation of Z from (3) no absolute numbers are required. It is only necessary to have the rat::.o of the strength of the . stock at the time 0 to the strength at time t. It is true that it is necessary to insert the figures for one feecel-s-set in consecutive years. How- etc el-, ever, such data are available, since in 2.3.3.2. we consider the e-aptu4te per unit effort as an expression for the strength of the stock. If we re- calculate these figures (Table 15).for the corresponding age composition in per cent (Table 33), we obtain then the figures in Table 54. These Values show the losses of a .4ici-4-se "s t during the course of two years (providing there are no errors in the determination of the age and in the eta,t-f- determination of the captures per unit effort). If we examine, e.g., the -y-ea-r-l-s---set-ef-smca-t of 1955, which was present in 1956/57 as the sea year class A.1+. Of this yeart 18.5 salmon pèr 1000 hooks were caught. In the following season it yielded as A.2+ only 4.1 salmon per 1000 hooks and an.- other year:later as A.3+ -e.o..e.* only 0.6 salmon. The total losses during the second year in the sea amounted thus to almost 78 pèr cent, in the third year in the sea, they were 85 per cent. nad,c ,; If we insert the cieturco per unit effort cited into (3), we . obtain as coefficient of the total mortality ln (18.5/4.1)= 1.51. For the fishing periods under'discussion the mean value of the . losses in the . second year Z 2 ,--. 1.23 and in the third year Z 3 . 2.20. That corresponds to per centages of 70.8 per cent and 88.9 Per cent, respectively: During the first year of exPloitation tiremmLsean average of 70.8 per cent are being sh,ou . removed from the new y.s.9,-PLe-eat through fishing and other causes. The losses suffered by the remaining fish amount in the second year of exploitation to 88.9 per cent. Of the salmonthat had entered originally into 'the exploited phase only 3.2 per cent were left after two years. This
NUmber of salmon per Z Weigh- Season 1000 hooks ted Tot. A.1+ A.2+ A.3+ A.1+ A.2+ mean f +f f 13+1 2 - 200 -' result agrees.with.the findings that have been obtained on hand of the age analyses. Only the two sea year classes A.1+ and A.2+ play numerically any role in the stock of salmon in the Baltic Sea. LP. 54 8 1 Christensen (1964) could base his investigations on the Danish s and German:expenditures.He found total losses of Z 2 = 1.33 and Z 3 = 2*.23 that do not.deviate substantially from the above figures. The individual mortality values in Table 54 show considerable fluctuations. The value of Z = 0.05 as it has been obtained for the sea . year class A.1+ in the season 1957/58 cannot possibly be correct, consider- ing the recorded expenditure of f = 4.44 (Table 5). Let us therefore examine once more the figures used as a basis. For the calculation of Z were Table 54. Values of the total mortality in Baltic Sea salmon .(by using the eartierrey lineyper unit effort). 1956/57 24,0 18,5 . 5,1 0,4 1,51 2,14 1,61 4,91 4,68 1957/58 10,5 5,7 4,1 . 0,6 0,05 1,92 0,36 4,44 3,96 1958/59 22,5 16,2 • 0,6 1,42 3,30' 1,64 3,49 3,94 1959/60. 8,4 4,1 3,9 0,3 0,58 1,47 0,92 4,38 4,56 1960/61 10,8 8,3 2,3 0,9 1,78 2,44 1,89 4,74 5,16 1961/62 15,8 14,3 1,4 0,2 2,02 1,95 2,01 5,57 5,43 . 1962/63 8, 5,9 1,9 0,2 • 5,3 1 Mittel Me an 1,227 2,203 1,41 1 On account of the ice conditions the effective expenditure Was only 3.62 in 6 months. For 8.8 months we assume here f = 5.3, because the vessels of other countries could carry on fishing to the full eXtent. used the percentages of the age composition as well as the data of Sle eedei-ree- per unit effort. In regard to the age composition it has already been established that the results of the present analyse s . correspond rather well with the actual . conditions. Let us therefore examine what effect is due to the changes in the eeptures per unit effort. ldhe4 the value of the
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FISHERIES RESEARCH BOARD OF CANADA
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sos-2cto—lo-31 DEPARTMENTOFTHESEC
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• 6.1. Previous investigations 17
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-5-. and Kerr very much later menti
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treated as a quality, a special pop
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• -9-- per cent). Furthermore, th
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• - 11 - fishery, mentions the gr
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• - 13 - in LiepUva. These voyage
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• 1948/49 545 1949/50 730 1950/51
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• 2.2.1. River fishing - 16- The
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- 18- are 50 norsels, 60 to 80 cm l
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• nets give better results is onl
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• • G Fig. 4. End buoy for salm
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• with • Total length (cm) Mout
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• • - 25- of Bothnia. In the fa
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• • - 27- increase the catch. S
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• of • fishing representsavalue
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• to lower figures than in the fa
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• • Umfang = Cire umference - 3
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• - 35 - and nape corresponds to
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• • / 100 50 Selektion Selectio
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- 39 - In Table 9 have been calcula
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. Table 10. Number of salmon per 10
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• Table 11. Number of salmon per.
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• - 45 - cza-ci, es When consider
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- 47 - If We examine once more the
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- 49 - German fishermen work during
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• - 51 - is true, have to be corr
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Table 16. Seasonal yields of the fi
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Table 17. Monthly average weights o
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- 57 - In February and March hardly
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• Table 20. Additional catch of c
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• 100 50 60 100 cm Totallarle . 2
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• subject to an error of ± o.op9
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cycle) during the second . period o
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• their third year. , Recruitment
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50 r-■ 2 / bet; 56cm = 1 fis 1 li
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• - 71 - ovary that has already b
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5 - 73 - April 1960 the diameter of
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- 75 - oocytes can be demonstrated
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. ineftlerer Mean OocytendurcArness
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- 79 - furnish the energy fer the s
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' 1741 salmon, which were.caught be
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• - 83- the series of measurement
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- 85 - the relative amount of eggs
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- 87 - The calculation of a formula
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- 89 - area of distribution is form
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- 91 - as percentages of thé recov
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Table 22. The recapture of tagged s
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• II> Three conclusions can be dr
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• 6 65- 64 - 62-. 61 - 6 . 5 . 59
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• - 99 - fish. The tagging does n
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- 101 - tagging experiments'that sa
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- 103- Renne Bank in about 60 m dep
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• 9:1 0 a) el-4 o (XI -P CNI 4- o
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14,3 14,3 30,7 31,3 27,7 6,0 15,0 1
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Table 26. Catches of salmon in the
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- 111 - between Hela and Kahlberg r
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• - 113- 5 .. Age and growth of t
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cm 100 80 60 40 - 1 15- customarily
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found can be used for the recalcula
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v 0 00 0 I I - 119- of the scales.
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- 121 - The interpretation of the y
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• - 1 23 - the age groups 2.B to
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• L s - L c r s 0.85 Smolt Ls = l
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5.3. The'age composition of the Ger
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-129- with shares in the catch of o
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"ervoct. Yeer-Le- -e-t. '4.y-c.1*.e
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1955 1 2 3 4 23 3 61 506 7 3 135 21
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- 135 - yeAy-ctt4 thé explanation
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• • _ Table 33. The composition
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Table 34. Composition by age of cat
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- 141 - yeAy-cle..es Table 35. The
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- 143 - • U7,) tdL comparablenece
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• whereas the present data .(1957
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Sin% 0,1 2,8 37,0 96,8 100,0 - 147-
Page 153 and 154: • - 149 - these results 38 per ce
Page 155 and 156: • • Number of salmon J. en1967
Page 157 and 158: 4. number 50 e" • ); e e , lot nb
Page 159 and 160: they take account of the annual cha
Page 161 and 162: • -157- and in the stock are bein
Page 163 and 164: Table 43. Mean lengths of age group
Page 165 and 166: • - 161 - of these catches has be
Page 167 and 168: - 163 - of enolt in Fig. 36. From a
Page 169 and 170: --165 - increase'in weight is more
Page 171 and 172: • rl -P b..0 -e nzi -ri r-1 gl a)
Page 173 and 174: - 169 - CLA‘s set of smolt of 193
Page 175 and 176: Year's sets of smolt CILS present 7
Page 177 and 178: - 173 - necessary to follow the gro
Page 179 and 180: - 175 - • been ascertained from t
Page 181 and 182: (after K. A. Pyefinch 1955). — 17
Page 183 and 184: • gadids and sticklebacks (after
Page 185 and 186: - 181 - especially decisive in, the
Page 187 and 188: 6.3.1. Seasonal fluctuations 36,9 2
Page 189 and 190: • Number of Months Gear salmon in
Page 191 and 192: MagerdW hing 40 , 20 Filling of Sto
Page 193 and 194: Deep could be examined. - 188 - Chr
Page 195 and 196: - 190 - salmon . switch over to the
Page 197 and 198: • - 192 - recognizable after seve
Page 199 and 200: - 194 - amount of food. Under-consi
Page 201 and 202: - 196- expenditure, composition in
Page 203: • - 1 98- the stock losses are co
Page 207 and 208: • 'Table 55. Values of the total
Page 209 and 210: - 204 experiment were about 40 per
Page 211 and 212: - 206- strength of the stock N pert
Page 213 and 214: • N„ Z o = cf„ (M1- T) -- In
Page 215 and 216: — 210— the coefficient for the
Page 217 and 218: - 212- In a further paper Piggins (
Page 219 and 220: - 214- shifted and the fOod supply
Page 221 and 222: - 216 - concerns the yield of captu
Page 223 and 224: nachafter 00 04 0,3 0,4 2 1 0,5 6 9
Page 225 and 226: • 1. (5 100 000) (4 250 000) 4 25
Page 227 and 228: • •em.ilts - 222 - in an error
Page 229 and 230: • - 224- BRANDT, A. y. , 1959: Fa
Page 231 and 232: - 226 - Paw, T. H., 1938: Fluctuati
Page 233 and 234: - 228- PETERSEN, C. G. .11, and Orr
Page 235 and 236: Table I. Captures per unit effort w
Page 237 and 238: Table II. Captures per unit effort
Page 239 and 240: • Yea.r Sweden Continuation Table
Page 241 and 242: Table VI. Ratio between fork le . B
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Translation Series No.1211

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